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Sample records for atmospheric chemistry experiment

  1. The Atmospheric Chemistry Experiment (ACE)

    Science.gov (United States)

    Bernath, P. F.

    2017-01-01

    The Atmospheric Chemistry Experiment (ACE), also called SCISAT, is a Canadian-led small satellite mission for remote sensing of the Earth's atmosphere. ACE was launched into a low Earth circular orbit by NASA on August 12, 2003 and it continues to function nominally. The ACE instruments are a high spectral resolution (0.02 cm-1) Fourier Transform Spectrometer (FTS) operating from 2.2 to 13.3 μm (750-4400 cm-1), a spectrophotometer known as Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) with wavelength coverage of 285-1020 nm and two filtered detector arrays to image the Sun at 0.525 and 1.02 μm. ACE operates in solar occultation mode to provide altitude profiles of temperature, pressure, atmospheric extinction and the volume mixing ratios (VMRs) for several dozen molecules and related isotopologues. This paper presents a mission overview and a summary of selected scientific results.

  2. The Atmospheric Chemistry Experiment (ACE): Mission Overview

    Science.gov (United States)

    Bernath, P.

    2003-04-01

    The ACE mission goals are: (1) to measure and to understand the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere, with a particular emphasis on the Arctic region; (2) to explore the relationship between atmospheric chemistry and climate change; (3) to study the effects of biomass burning in the free troposphere; (4) to measure aerosol number density, size distribution and composition in order to reduce the uncertainties in their effects on the global energy balance. ACE will make a comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols, and temperature by solar occultation from a satellite in low earth orbit. A high inclination (74 degrees) low earth orbit (650 km) will give ACE coverage of tropical, mid-latitudes and polar regions. The solar occultation advantages are high sensitivity and self-calibration. A high-resolution (0.02 cm-1) infrared Fourier Transform Spectrometer (FTS) operating from 2 to 13 microns (750-4100 cm-1) will measure the vertical distribution of trace gases, and the meteorological variables of temperature and pressure. The ACE concept is derived from the now-retired ATMOS FTS instrument, which flew on the Space Shuttle in 1985, 1992, 1993, 1994. Climate-chemistry coupling may lead to the formation of an Arctic ozone hole. ACE will provide high quality data to confront these model predictions and will monitor polar chemistry as chlorine levels decline. The ACE-FTS can measure water vapor and HDO in the tropical tropopause region to study dehydration and strat-trop exchange. The molecular signatures of massive forest fires will evident in the ACE infrared spectra. The CO_2 in our spectra can be used to either retrieve atmospheric pressure or (if the instrument pointing knowledge proves to be satisfactory) for an independent retrieval of a CO_2 profile for carbon cycle science. Aerosols and clouds will be monitored using the extinction of solar

  3. The THS experiment: probing Titan's atmospheric chemistry at low temperature

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Upton, Kathleen; Beauchamp, Jack L; Salama, Farid

    2014-06-01

    In Titan’s atmosphere, a complex chemistry between N2 and CH4 occurs at temperatures lower than 200K and leads to the production of heavy molecules and subsequently solid aerosols that form the haze surrounding Titan. The Titan Haze Simulation (THS) experiment has been developed at the NASA Ames COSmIC facility to study Titan’s atmospheric chemistry at low temperature in order to help interpret Cassini’s observational data. In the THS, the chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas is jet-cooled to Titan-like temperature 150K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge 200K). Different N2-CH4-based gas mixtures can be injected in the plasma, with or without the addition of heavier precursors present as trace elements on Titan. Both the gas phase and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed using a combination of complementary in situ and ex situ diagnostics.Here we present the complementary results of two studies of the gas and solid phase. A Mass spectrometry analysis of the gas phase has demonstrated that the THS experiment is a unique tool to probe the first and intermediate steps as well as specific chemical pathways of Titan’s atmospheric chemistry at Titan-like temperature. The more complex chemistry, observed in the gas phase when adding trace elements to the initial N2-CH4 mixture, has also been confirmed by an extensive study of the solid phase products: Scanning Electron Microscopy images have shown that aggregates produced in N2-CH4-C2H2-C6H6 mixtures (up to 5 μm in diameter) are much larger than those produced in N2-CH4 mixtures (0.1-0.5 μm), and Nuclear Magnetic Resonance results support a growth evolution of the chemistry when adding acetylene to the N2-CH4 mixture, resulting in the production of more complex hydrogen bonds than with a simple N2-CH4 mixture

  4. First Global Observations of Atmospheric COCIF from the Atmospheric Chemistry Experiment Mission

    Science.gov (United States)

    Fu, Dejian; Boone, Chris D.; Bernath, Peter F.; Weisenstein, Debra K.; Rinsland, Curtis P.; Manney, Gloria L.; Walker, Kaley A.

    2010-01-01

    Carbonyl chlorofluoride (COCIF) is an important reservoir of chlorine and fluorine in the Earth's atmosphere. Satellite-based remote sensing measurements of COCIF, obtained by the Atmospheric Chemistry Experiment (ACE) for a time period spanning February 2004 through April 2007, have been used in a global distribution study. There is a strong source region for COCIF in the tropical stratosphere near 27 km. A layer of enhanced COCIF spans the low- to mid-stratosphere over all latitudes, with volume mixing ratios of 40-100 parts per trillion by volume, largest in the tropics and decreasing toward the poles. The COCIF volume mixing ratio profiles are nearly zonally symmetric, but they exhibit a small hemispheric asymmetry that likely arises from a hemispheric asymmetry in the parent molecule CCl3 F. Comparisons are made with a set of in situ stratospheric measurements from the mid-1980s and with predictions from a 2-D model.

  5. The THS experiment: Simulating Titan's atmospheric chemistry at low temperature (200 K)

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Upton, Kathleen T.; Beauchamp, Jack L.; Salama, Farid

    2016-10-01

    In the Titan Haze Simulation (THS) experiment, Titan's atmospheric chemistry is simulated by plasma discharge in the stream of a supersonic expansion, i.e. at low Titan-like temperature (150 K). Here, we present complementary gas and solid phase analyses of four N2-CH4-based gas mixtures that demonstrate the unique capability of the THS to monitor the chemical growth evolution in order to better understand Titan's chemistry and the origin of aerosol formation.

  6. The Titan Haze Simulation experiment on COSmIC: Probing Titan's atmospheric chemistry at low temperature

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Ricketts, Claire L.; Salama, Farid

    2014-11-01

    The aim of the Titan Haze Simulation (THS) experiment is to contribute to a better understanding of aerosol formation in Titan's atmosphere through the study of the chemical formation pathways that link the simpler gas phase molecules resulting from the first steps of the N2-CH4 chemistry, to the more complex gas phase precursors of aerosols; and more specifically, to investigate the role of polycyclic aromatic hydrocarbons (PAHs) and nitrogenated polycyclic aromatic hydrocarbons (PANHs), among other hydrocarbons, in this process. In the THS experiment developed at the NASA Ames Cosmic simulation facility (COSmIC), Titan's atmospheric chemistry is simulated by a pulsed plasma jet expansion at temperature conditions (∼150 K) close to those found in Titan's atmosphere in regions where aerosols are formed. In addition, because of the very short residence time of the gas in the plasma discharge, only the initial steps of the chemistry occur, making the COSmIC/THS a unique tool to study the first and intermediate (when adding heavier precursors to the initial N2-CH4 mixture) steps of Titan's atmospheric chemistry at low temperature as shown in the study presented here. We further illustrate the potential of COSmIC/THS for the simulation of Titan's atmospheric chemistry by presenting very promising results from a preliminary comparison of the laboratory data to data from the Cassini Plasma Spectrometer-Ion Beam Spectrometer (CAPS-IBS) instrument.

  7. Investigating Titan's Atmospheric Chemistry at Low Temperature with the Titan Haze Simulation Experiment

    Science.gov (United States)

    Sciamma-O'Brien, E. M.; Salama, F.

    2012-12-01

    Titan, Saturn's largest satellite, possesses a dense atmosphere (1.5 bar at the surface) composed mainly of N2 and CH4. The solar radiation and electron bombardment from Saturn's magnetosphere induces a complex organic chemistry between these two constituents leading to the production of more complex molecules and subsequently to solid aerosols. These aerosols in suspension in the atmosphere form the haze layers giving Titan its characteristic orange color. Since 2004, the instruments onboard the Cassini orbiter have produced large amounts of observational data, unraveling a chemistry much more complex than what was first expected, particularly in Titan's upper atmosphere. Neutral, positively and negatively charged heavy molecules have been detected in the ionosphere of Titan, including benzene (C6H6) and toluene (C6H5CH3). The presence of these critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds suggests that PAHs might play a role in the production of Titan's aerosols. The aim of the Titan Haze Simulation (THS) experiment, developed at the NASA Ames COSmIC facility, is to study the chemical pathways that link the simple molecules resulting from the first steps of the N2-CH4 chemistry to benzene, and to PAHs and nitrogen-containing PAHs (PANHs) as precursors to the production of solid aerosols. In the THS experiment, Titan's atmospheric chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma discharge. Due to the short residence time of the gas in the plasma discharge, the THS experiment can be used to probe the first and intermediate steps of Titan's chemistry by injecting different gas mixtures in the plasma. The products of the chemistry are detected and studied using two complementary techniques: Cavity Ring Down Spectroscopy and Time-Of-Flight Mass Spectrometry. Thin tholin deposits are also produced

  8. The THS Experiment: Simulating Titans Atmospheric Chemistry at Low Temperature (200K)

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Upton, Kathleen; Beauchamp, Jack L.; Salama, Farid; Contreras, Cesar Sanchez; Bejaoui, Salma; Foing, Bernard; Pascale, Ehrenfreund

    2015-01-01

    In Titan's atmosphere, composed mainly of N2 (95-98%) and CH4 (2-5%), a complex chemistry occurs at low temperature, and leads to the production of heavy organic molecules and subsequently solid aerosols. Here, we used the Titan Haze Simulation (THS) experiment, an experimental setup developed at the NASA Ames COSmIC simulation facility to study Titan's atmospheric chemistry at low temperature. In the THS, the chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas is cooled to Titan-like temperature ( approximately 150K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge (approximately 200K). Different N2-CH4-based gas mixtures can be injected in the plasma, with or without the addition of heavier precursors present as trace elements on Titan, in order to monitor the evolution of the chemical growth. Both the gas- and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed using a combination of complementary in situ and ex situ diagnostics. A recent mass spectrometry[1] study of the gas phase has demonstrated that the THS is a unique tool to probe the first and intermediate steps of Titan's atmospheric chemistry at Titan-like temperature. In particular, the mass spectra obtained in a N2-CH4-C2H2-C6H6 mixture are relevant for comparison to Cassini's CAPS-IBS instrument. The results of a complementary study of the solid phase are consistent with the chemical growth evolution observed in the gas phase. Grains and aggregates form in the gas phase and can be jet deposited on various substrates for ex situ analysis. Scanning Electron Microscopy images show that more complex mixtures produce larger aggregates. A mass spectrometry analysis of the solid phase has detected the presence of aminoacetonitrile, a precursor of glycine, in the THS aerosols. X-ray Absorption Near Edge Structure (XANES) measurements also show the presence of imine

  9. On the use of plant emitted volatile organic compounds for atmospheric chemistry simulation experiments

    Science.gov (United States)

    Kiendler-Scharr, A.; Hohaus, T.; Yu, Z.; Tillmann, R.; Kuhn, U.; Andres, S.; Kaminski, M.; Wegener, R.; Novelli, A.; Fuchs, H.; Wahner, A.

    2015-12-01

    Biogenic volatile organic compounds (BVOC) contribute to about 90% of the emitted VOC globally with isoprene being one of the most abundant BVOC (Guenther 2002). Intensive efforts in studying and understanding the impact of BVOC on atmospheric chemistry were undertaken in the recent years. However many uncertainties remain, e.g. field studies have shown that in wooded areas measured OH reactivity can often not be explained by measured BVOC and their oxidation products (e.g. Noelscher et al. 2012). This discrepancy may be explained by either a lack of understanding of BVOC sources or insufficient understanding of BVOC oxidation mechanisms. Plants emit a complex VOC mixture containing likely many compounds which have not yet been measured or identified (Goldstein and Galbally 2007). A lack of understanding BVOC sources limits bottom-up estimates of secondary products of BVOC oxidation such as SOA. Similarly, the widespread oversimplification of atmospheric chemistry in simulation experiments, using single compound or simple BVOC mixtures to study atmospheric chemistry processes limit our ability to assess air quality and climate impacts of BVOC. We will present applications of the new extension PLUS (PLant chamber Unit for Simulation) to our atmosphere simulation chamber SAPHIR. PLUS is used to produce representative BVOC mixtures from direct plant emissions. We will report on the performance and characterization of the newly developed chamber. As an exemplary application, trees typical of a Boreal forest environment were used to compare OH reactivity as directly measured by LIF to the OH reactivity calculated from BVOC measured by GC-MS and PTRMS. The comparison was performed for both, primary emissions of trees without any influence of oxidizing agents and using different oxidation schemes. For the monoterpene emitters investigated here, we show that discrepancies between measured and calculated total OH reactivity increase with increasing degree of oxidation

  10. The Titan Haze Simulation experiment: laboratory simulation of Titan's atmospheric chemistry at low temperature

    Science.gov (United States)

    Sciamma-O'Brien, E.; Contreras, C. S.; Ricketts, C. L.; Salama, F.

    2012-04-01

    In Titan’s atmosphere, a complex organic chemistry between its two main constituents, N2 and CH4, leads to the production of heavy molecules and subsequently to solid organic aerosols. Several instruments onboard Cassini have detected neutral, positively and negatively charged particles and heavy molecules in the ionosphere of Titan[1,2]. In particular, the presence of benzene (C6H6) and toluene (C6H5CH3)[3], which are critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds, suggests that PAHs might play a role in the production of Titan’s aerosols. The Titan Haze Simulation (THS) experiment has been developed at NASA Ames’ Cosmic Simulation facility (COSmIC) to study the chemical pathways that link the simple precursor molecules resulting from the first steps of the N2-CH4 chemistry (C2H2, C2H4, HCN…) to benzene, and to PAHs and nitrogen-containing PAHs (or PANHs) as precursors to the production of solid aerosols. In the THS experiment, Titan’s atmospheric chemistry is simulated by plasma in the stream of a supersonic jet expansion. With this unique design, the gas mixture is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma discharge. Different gas mixtures containing the first products of Titan’s N2-CH4 chemistry but also much heavier molecules like PAHs or PANHs can be injected to study specific chemical reactions. The products of the chemistry are detected and studied using two complementary techniques: Cavity Ring Down Spectroscopy[4] and Time-Of-Flight Mass Spectrometry[5]. Thin tholin deposits are also produced in the THS experiment and can be analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) and Scanning Electron Microscopy (SEM). We will present the results of ongoing mass spectrometry studies on the THS experiment using different gas mixtures: N2-CH4, N2-C2H2, N2-C2H4, N2-C2H6, N2-C6H6, and similar mixtures with an N2-CH4 (90:10) mixture instead of pure N2, to study specific pathways

  11. Technical Note: A trace gas climatology derived from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer dataset

    Directory of Open Access Journals (Sweden)

    A. Jones

    2011-11-01

    Full Text Available The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS aboard the Canadian satellite SCISAT (launched in August 2003 was designed to investigate the composition of the upper troposphere, stratosphere, and mesosphere. ACE-FTS utilizes solar occultation to measure temperature and pressure as well as vertical profiles of over thirty chemical species including O3, H2O, CH4, N2O, CO, NO, NO2, N2O5, HNO3, HCl, ClONO2, CCl3F, CCl2F2, and HF. Global coverage for each species is obtained approximately over a three month period and measurements are made with a vertical resolution of typically 3–4 km. A quality-controlled climatology has been created for each of these 14 baseline species, where individual profiles are averaged over the period of February 2004 to February 2009. Measurements used are from the ACE-FTS version 2.2 data set including updates for O3 and N2O5. The climatological fields are provided on a monthly and three-monthly basis (DJF, MAM, JJA, SON at 5 degree latitude and equivalent latitude spacing and on 28 pressure surfaces (26 of which are defined by the Stratospheric Processes And their Role in Climate (SPARC Chemistry Climate Model validation activity. The ACE-FTS climatological dataset is available through the ACE website.

  12. Chemical isolation in the Asian monsoon anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS data

    Directory of Open Access Journals (Sweden)

    M. Park

    2008-02-01

    Full Text Available Evidence of chemical isolation in the Asian monsoon anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June–August of 2004–2006. Carbon monoxide (CO shows a broad maximum over the monsoon anticyclone region in the upper troposphere and lower stratosphere (UTLS; these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13–15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl exhibit decreased values inside the anticyclone between ~12–20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the anticyclone. The relative enhancements of tropospheric species inside the anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air suggest relatively rapid transport of fresh emissions up to the tropopause level inside the anticyclone.

  13. Chemical Isolation in the Asian monsoon anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS data

    Directory of Open Access Journals (Sweden)

    M. Park

    2007-09-01

    Full Text Available Evidence of chemical isolation in the Asian monsoon anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June–August of 2004–2006. Carbon monoxide (CO shows a broad maximum over the monsoon anticyclone region in the upper troposphere and lower stratosphere (UTLS; these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13–15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl exhibit decreased values inside the anticyclone between ~12–20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the anticyclone. The relative enhancements of tropospheric species inside the anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air suggest relatively rapid transport of fresh emissions up to tropopause level inside the anticyclone.

  14. Carbon Dioxide (CO2) Retrievals from Atmospheric Chemistry Experiment (ACE) Solar Occultation Measurements

    Science.gov (United States)

    Rinsland, Curtis P.; Chiou, Linda; Boone, Chris; Bernath, Peter

    2010-01-01

    The Atmospheric Chemistry Experiment ACE satellite (SCISAT-1) was launched into an inclined orbit on 12 August 2003 and is now recording high signal-to-noise 0.02 per centimeter resolution solar absorption spectra covering 750-4400 per centimeter (2.3-13 micrometers). A procedure has been developed for retrieving average dry air CO2 mole fractions (X(sub CO2)) in the altitude range 7-10 kilometers from the SCISAT-1 spectra. Using the N2 continuum absorption in a window region near 2500 per centimeter, altitude shifts are applied to the tangent heights retrieved in version 2.2 SCISAT-1 processing, while cloudy or aerosol-impacted measurements are eliminated. Monthly-mean XCO2 covering 60 S to 60 N latitude for February 2004 to March 2008 has been analyzed with consistent trends inferred in both hemispheres. The ACE XCO2 time series have been compared with previously-reported surface network measurements, predictions based on upper tropospheric aircraft measurements, and space-based measurements. The retrieved X(sub CO2) from the ACE-FTS spectra are higher on average by a factor of 1.07 plus or minus 0.025 in the northern hemisphere and by a factor of 1.09 plus or minus 0.019 on average in the southern hemisphere compared to surface station measurements covering the same time span. The ACE derived trend is approximately 0.2% per year higher than measured at surface stations during the same observation period.

  15. Validation of NO2 and NO from the Atmospheric Chemistry Experiment (ACE

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2008-02-01

    Full Text Available Vertical profiles of NO2 and NO have been obtained from solar occultation measurements by the Atmospheric Chemistry Experiment (ACE, using an infrared Fourier Transform Spectrometer, ACE-FTS, and an ultraviolet-visible-near-infrared spectrometer, MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation. In this paper, the quality of the ACE-FTS version 2.2 NO2 and NO and the MAESTRO version 1.2 NO2 data are assessed using other solar occultation measurements (HALOE, SAGE II, SAGE III, POAM III, SCIAMACHY, stellar occultation measurements (GOMOS, limb measurements (MIPAS, OSIRIS, nadir measurements (SCIAMACHY, balloon measurements (SPIRALE, SAOZ and ground-based measurements (UV-VIS, FTIR. Time differences between the comparison measurements were reduced using either a tight coincidence criterion, or where possible, chemical box models. ACE-FTS NO2 and NO and the MAESTRO NO2 are generally consistent with the correlative data. The ACE-FTS NO2 VMRs agree with the satellite data sets to within about 20% between 25 and 40 km, and suggest a negative bias between 23 and 40 km of about extminus10%. In comparisons with HALOE, ACE-FTS NO VMRs typically agree to ±8% from 22 to 64 km and to +10% from 93 to 105 km. Partial column comparisons for NO2 show that there is fair agreement between the ACE instruments and the FTIRs, with a mean difference of +7.3% for ACE-FTS and +12.8% for MAESTRO.

  16. Validation of NO2 and NO from the Atmospheric Chemistry Experiment (ACE

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2008-10-01

    Full Text Available Vertical profiles of NO2 and NO have been obtained from solar occultation measurements by the Atmospheric Chemistry Experiment (ACE, using an infrared Fourier Transform Spectrometer (ACE-FTS and (for NO2 an ultraviolet-visible-near-infrared spectrometer, MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation. In this paper, the quality of the ACE-FTS version 2.2 NO2 and NO and the MAESTRO version 1.2 NO2 data are assessed using other solar occultation measurements (HALOE, SAGE II, SAGE III, POAM III, SCIAMACHY, stellar occultation measurements (GOMOS, limb measurements (MIPAS, OSIRIS, nadir measurements (SCIAMACHY, balloon-borne measurements (SPIRALE, SAOZ and ground-based measurements (UV-VIS, FTIR. Time differences between the comparison measurements were reduced using either a tight coincidence criterion, or where possible, chemical box models. ACE-FTS NO2 and NO and the MAESTRO NO2 are generally consistent with the correlative data. The ACE-FTS and MAESTRO NO2 volume mixing ratio (VMR profiles agree with the profiles from other satellite data sets to within about 20% between 25 and 40 km, with the exception of MIPAS ESA (for ACE-FTS and SAGE II (for ACE-FTS (sunrise and MAESTRO and suggest a negative bias between 23 and 40 km of about 10%. MAESTRO reports larger VMR values than the ACE-FTS. In comparisons with HALOE, ACE-FTS NO VMRs typically (on average agree to ±8% from 22 to 64 km and to +10% from 93 to 105 km, with maxima of 21% and 36%, respectively. Partial column comparisons for NO2 show that there is quite good agreement between the ACE instruments and the FTIRs, with a mean difference of +7.3% for ACE-FTS and +12.8% for MAESTRO.

  17. Atmospheric and aerosol chemistry

    Energy Technology Data Exchange (ETDEWEB)

    McNeill, V. Faye [Columbia Univ., New York, NY (United States). Dept. of Chemical Engineering; Ariya, Parisa A. (ed.) [McGill Univ. Montreal, QC (Canada). Dept. of Chemistry; McGill Univ. Montreal, QC (Canada). Dept. of Atmospheric and Oceanic Sciences

    2014-09-01

    This series presents critical reviews of the present position and future trends in modern chemical research. Short and concise reports on chemistry, each written by the world renowned experts. Still valid and useful after 5 or 10 years. More information as well as the electronic version of the whole content available at: springerlink.com. Christian George, Barbara D'Anna, Hartmut Herrmann, Christian Weller, Veronica Vaida, D. J. Donaldson, Thorsten Bartels-Rausch, Markus Ammann Emerging Areas in Atmospheric Photochemistry. Lisa Whalley, Daniel Stone, Dwayne Heard New Insights into the Tropospheric Oxidation of Isoprene: Combining Field Measurements, Laboratory Studies, Chemical Modelling and Quantum Theory. Neil M. Donahue, Allen L. Robinson, Erica R. Trump, Ilona Riipinen, Jesse H. Kroll Volatility and Aging of Atmospheric Organic Aerosol. P. A. Ariya, G. Kos, R. Mortazavi, E. D. Hudson, V. Kanthasamy, N. Eltouny, J. Sun, C. Wilde Bio-Organic Materials in the Atmosphere and Snow: Measurement and Characterization V. Faye McNeill, Neha Sareen, Allison N. Schwier Surface-Active Organics in Atmospheric Aerosols.

  18. Exploring Atmospheric Aqueous Chemistry (and Secondary Organic Aerosol Formation) through OH Radical Oxidation Experiments, Droplet Evaporation and Chemical Modeling

    Science.gov (United States)

    Turpin, B. J.; Kirkland, J. R.; Lim, Y. B.; Ortiz-Montalvo, D. L.; Sullivan, A.; Häkkinen, S.; Schwier, A. N.; Tan, Y.; McNeill, V. F.; Collett, J. L.; Skog, K.; Keutsch, F. N.; Sareen, N.; Carlton, A. G.; Decesari, S.; Facchini, C.

    2013-12-01

    Gas phase photochemistry fragments and oxidizes organic emissions, making water-soluble organics ubiquitous in the atmosphere. My group and others have found that several water-soluble compounds react further in the aqueous phase forming low volatility products under atmospherically-relevant conditions (i.e., in clouds, fogs and wet aerosols). Thus, secondary organic aerosol can form as a result of gas followed by aqueous chemistry (aqSOA). We have used aqueous OH radical oxidation experiments coupled with product analysis and chemical modeling to validate and refine the aqueous chemistry of glyoxal, methylglyoxal, glycolaldehyde, and acetic acid. The resulting chemical model has provided insights into the differences between oxidation chemistry in clouds and in wet aerosols. Further, we conducted droplet evaporation experiments to characterize the volatility of the products. Most recently, we have conducted aqueous OH radical oxidation experiments with ambient mixtures of water-soluble gases to identify additional atmospherically-important precursors and products. Specifically, we scrubbed water-soluble gases from the ambient air in the Po Valley, Italy using four mist chambers in parallel, operating at 25-30 L min-1. Aqueous OH radical oxidation experiments and control experiments were conducted with these mixtures (total organic carbon ≈ 100 μM-C). OH radicals (3.5E-2 μM [OH] s-1) were generated by photolyzing H2O2. Precursors and products were characterized using electrospray ionization mass spectrometry (ESI-MS), ion chromatography (IC), IC-ESI-MS, and ultra high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Chemical modeling suggests that organic acids (e.g., oxalate, pyruvate, glycolate) are major products of OH radical oxidation at cloud-relevant concentrations, whereas organic radical - radical reactions result in the formation of oligomers in wet aerosols. Products of cloud chemistry and droplet evaporation have

  19. Organic chemistry experiment

    Energy Technology Data Exchange (ETDEWEB)

    Mun, Seok Sik

    2005-02-15

    This book deals with organic chemistry experiments, it is divided five chapters, which have introduction, the way to write the experiment report and safety in the laboratory, basic experiment technic like recrystallization and extraction, a lot of organic chemistry experiments such as fischer esterification, ester hydrolysis, electrophilic aromatic substitution, aldol reaction, benzoin condensation, wittig reaction grignard reaction, epoxidation reaction and selective reduction. The last chapter introduces chemistry site on the internet and way to find out reference on chemistry.

  20. Organic chemistry in Titan's atmosphere

    Science.gov (United States)

    Scattergood, T.

    1982-01-01

    Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

  1. Chemistry Of Atmospheric Brown Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey

    2015-05-27

    Organic carbon (OC) accounts for a large fraction of atmospheric aerosol and has profound effects on air quality, atmospheric chemistry and climate forcing. Molecular composition of the OC and its evolution during common processes of atmospheric aging have been a subject of extensive research over the last decade (see reviews of Ervens et al.,1 Hallquist et al.,2 Herckes et al.,3 Carlton et al.,4 Kroll and Seinfeld,5 Rudich et al.,6 and Kanakidou et al.7). Even though many fundamental advances have been reported in these studies, our understanding of the climate-related properties of atmospheric OC is still incomplete and the specific ways in which OC impacts atmospheric environment and climate forcing are just beginning to be understood. This review covers one topic of particular interest in this area –environmental chemistry of light-absorbing aerosol OC and its impact on radiative forcing.

  2. Experiments in physical chemistry

    CERN Document Server

    Wilson, J M; Denaro, A R

    1968-01-01

    Experiments in Physical Chemistry, Second Edition provides a compilation of experiments concerning physical chemistry. This book illustrates the link between the theory and practice of physical chemistry. Organized into three parts, this edition begins with an overview of those experiments that generally have a simple theoretical background. Part II contains experiments that are associated with more advanced theory or more developed techniques, or which require a greater degree of experimental skill. Part III consists of experiments that are in the nature of investigations wherein these invest

  3. Atmospheric chemistry over southern Africa

    Science.gov (United States)

    Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

    2012-03-01

    Changing Chemistry in a Changing Climate: Human and Natural Impacts Over Southern Africa (C4-SAR); Midrand, South Africa, 31 May to 3 June 2011 During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semipermanent atmospheric gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite- derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission on Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from Eskom, the South African power utility; and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa.

  4. Atmospheric Chemistry and Greenhouse Gases

    Energy Technology Data Exchange (ETDEWEB)

    Ehhalt, D.; Prather, M.; Dentener, F.; Derwent, R.; Dlugokencky, Edward J.; Holland, E.; Isaksen, I.; Katima, J.; Kirchhoff, V.; Matson, P.; Midgley, P.; Wang, M.; Berntsen, T.; Bey, I.; Brasseur, G.; Buja, L.; Collins, W. J.; Daniel, J. S.; DeMore, W. B.; Derek, N.; Dickerson, R.; Etheridge, D.; Feichter, J.; Fraser, P.; Friedl, R.; Fuglestvedt, J.; Gauss, M.; Grenfell, L.; Grubler, Arnulf; Harris, N.; Hauglustaine, D.; Horowitz, L.; Jackman, C.; Jacob, D.; Jaegle, L.; Jain, Atul K.; Kanakidou, M.; Karlsdottir, S.; Ko, M.; Kurylo, M.; Lawrence, M.; Logan, J. A.; Manning, M.; Mauzerall, D.; McConnell, J.; Mickley, L. J.; Montzka, S.; Muller, J. F.; Olivier, J.; Pickering, K.; Pitari, G.; Roelofs, G.-J.; Rogers, H.; Rognerud, B.; Smith, Steven J.; Solomon, S.; Staehelin, J.; Steele, P.; Stevenson, D. S.; Sundet, J.; Thompson, A.; van Weele, M.; von Kuhlmann, R.; Wang, Y.; Weisenstein, D. K.; Wigley, T. M.; Wild, O.; Wuebbles, D.J.; Yantosca, R.; Joos, Fortunat; McFarland, M.

    2001-10-01

    Chapter 4 of the IPCC Third Assessment Report Climate Change 2001: The Scientific Basis. Sections include: Executive Summary 2414.1 Introduction 2434.2 Trace Gases: Current Observations, Trends and Budgets 2484.3 Projections of Future Emissions 2664.4 Projections of Atmospheric Composition for the 21st Century 2674.5 Open Questions 2774.6 Overall Impact of Global Atmospheric Chemistry Change 279

  5. Fine-Structure Measurements of Oxygen A Band Absorbance for Estimating the Thermodynamic Average Temperature of the Earth's Atmosphere: An Experiment in Physical and Environmental Chemistry

    Science.gov (United States)

    Myrick, M. L.; Greer, A. E.; Nieuwland, A.; Priore, R. J.; Scaffidi, J.; Andreatta, Daniele; Colavita, Paula

    2006-01-01

    The experiment describe the measures of the A band transitions of atmospheric oxygen, a rich series of rotation-electronic absorption lines falling in the deep red portion of the optical spectrum and clearly visible owing to attenuation of solar radiation. It combines pure physical chemistry with analytical and environmental science and provides a…

  6. Atmospheric Chemistry Over Southern Africa

    Science.gov (United States)

    Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

    2011-01-01

    During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semi-permanent atmosphere gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s, and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite-derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission for Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from the South African power utility, Eskom, and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa. The purpose of the workshop was to review some earlier findings as well as more recent findings on southern African climate vulnerability, chemical changes due to urbanization, land-use modification, and how these factors interact. Originally proposed by John Burrows, president of ICACGP, the workshop was the first ICACGP regional workshop to study the interaction of air pollution with global chemical and climate change. Organized locally by the University of the Witwatersrand, the workshop attracted more than 60 delegates from South Africa, Mozambique, Botswana, Zimbabwe, France, Germany, Canada, and the United States. More than 30 presentations were given, exploring both retrospective and prospective aspects of the science. In several talks, attention was focused on southern African chemistry, atmospheric pollution monitoring, and climate processes as they were studied in the field

  7. An Overview of the Lightning - Atmospheric Chemistry Aspects of the Deep Convective Clouds and Chemistry (DC3) Experiment

    Science.gov (United States)

    Pickering, K. E.; Barth, M. C.; Koshak, W.; Bucsela, E. J.; Allen, D. J.; Weinheimer, A.; Ryerson, T.; Huntrieser, H.; Bruning, E.; MacGorman, D.; Krehbiel, P.; Thomas, R.; Carey, L.

    2012-01-01

    Some of the major goals of the DC3 experiment are to determine the contribution of lightning to NO(x) in the anvils of observed thunderstorms, examine the relationship of lightning NO(x) production to flash rates and to lightning channel lengths, and estimate the relative production per flash for cloud-to-ground flashes and intracloud flashes. In addition, the effects of lightning NO(x) production on photochemistry downwind of thunderstorms is also being examined. The talk will survey the observation types that were conducted during DC3 relevant to these goals and provide an overview of the analysis and modeling techniques which are being used to achieve them. NO(x) was observed on three research aircraft during DC3 (the NCAR G-V, the NASA DC-8, and the DLR Falcon) in flights through storm anvils in three study regions (NE Colorado, Central Oklahoma to West Texas, and northern Alabama) where lightning mapping arrays (LMAs) and radar coverage were available. Initial comparisons of the aircraft NOx observations in storm anvils relative to flash rates have been conducted, which will be followed with calculations of the flux of NO(x) through the anvils, which when combined with observed flash rates can be used to estimate storm-average lightning NOx production per flash. The WRF-Chem model will be run for cloud-resolved simulations of selected observed storms during DC3. Detailed lightning information from the LMAs (flash rates and flash lengths as a function of time and vertical distributions of flash channel segments) will be input to the model along with assumptions concerning NO(x) production per CG flash and per IC flash. These assumptions will be tested through comparisons with the aircraft NOx data from anvil traverses. A specially designed retrieval method for lightning NO2 column amounts from the OMI instrument on NASA fs Aura satellite has been utilized to estimate NO2 over the region affected by selected DC3 storms. Combined with NO(x) to NO2 ratios from the

  8. Some advances in atmospheric chemistry

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the recent decade, researches have been carried out by our group on some aspects of atmospheric chemistry through field observation, mechanism analysis and model simulation. Here some main results on greenhouse gas (CH4, N2O) emission from Chinese agricultural fields, aerosol, global carbon cycle and ozone variation in surface laver over China are briefly reported.

  9. Atmospheric Chemistry and Air Pollution

    Directory of Open Access Journals (Sweden)

    Jeffrey S. Gaffney

    2003-01-01

    Full Text Available Atmospheric chemistry is an important discipline for understanding air pollution and its impacts. This mini-review gives a brief history of air pollution and presents an overview of some of the basic photochemistry involved in the production of ozone and other oxidants in the atmosphere. Urban air quality issues are reviewed with a specific focus on ozone and other oxidants, primary and secondary aerosols, alternative fuels, and the potential for chlorine releases to amplify oxidant chemistry in industrial areas. Regional air pollution issues such as acid rain, long-range transport of aerosols and visibility loss, and the connections of aerosols to ozone and peroxyacetyl nitrate chemistry are examined. Finally, the potential impacts of air pollutants on the global-scale radiative balances of gases and aerosols are discussed briefly.

  10. Technical Note: A trace gas climatology derived from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS data set

    Directory of Open Access Journals (Sweden)

    A. Jones

    2012-06-01

    Full Text Available The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS aboard the Canadian satellite SCISAT (launched in August 2003 was designed to investigate the composition of the upper troposphere, stratosphere, and mesosphere. ACE-FTS utilizes solar occultation to measure temperature and pressure as well as vertical profiles of over thirty chemical species including O3, H2O, CH4, N2O, CO, NO, NO2, N2O5, HNO3, HCl, ClONO2, CCl3F, CCl2F2, and HF. Global coverage for each species is obtained approximately over a three month period and measurements are made with a vertical resolution of typically 3–4 km. A quality-controlled climatology has been created for each of these 14 baseline species, where individual profiles are averaged over the period of February 2004 to February 2009. Measurements used are from the ACE-FTS version 2.2 data set including updates for O3 and N2O5. The climatological fields are provided on a monthly and three-monthly basis (DJF, MAM, JJA, SON at 5 degree latitude and equivalent latitude spacing and on 28 pressure surfaces (26 of which are defined by the Stratospheric Processes And their Role in Climate (SPARC Chemistry-Climate Model Validation Activity. The ACE-FTS climatological data set is available through the ACE website.

  11. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  12. Observations of peroxyacetyl nitrate (PAN in the upper troposphere by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    K. A. Tereszchuk

    2013-01-01

    Full Text Available Peroxyacetyl nitrate (CH3CO·O2NO2, abbreviated as PAN is a trace molecular species present in the troposphere and lower stratosphere due primarily to pollution from fuel combustion and the pyrogenic outflows from biomass burning. In the lower troposphere, PAN has a relatively short life-time and is principally destroyed within a few hours through thermolysis, but it can act as a reservoir and carrier of NOx in the colder temperatures of the upper troposphere where UV photolysis becomes the dominant loss mechanism. Pyroconvective updrafts from large biomass burning events can inject PAN into the upper troposphere and lower stratosphere (UTLS, providing a means for the long-range transport of NOx. Given the extended lifetimes at these higher altitudes, PAN is readily detectable via satellite remote sensing.

    A new PAN data product is now available for the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS Version 3.0 data set. We report measurements of PAN in Boreal biomass burning plumes recorded during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS campaign. The retrieval method employed and errors analysis are described in full detail.

    The retrieved volume mixing ratio (VMR profiles are compared to coincident measurements made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS instrument on the European Space Agency (ESA ENVIronmental SATellite (ENVISAT. Three ACE-FTS occultations containing measurements of Boreal biomass burning outflows, recorded during BORTAS, were identified as having coincident measurements with MIPAS. In each case, the MIPAS measurements demonstrated good agreement with the ACE-FTS VMR profiles for PAN.

    The ACE-FTS PAN data set is used to obtain zonal mean distributions of seasonal averages from ~5 to 20 km. A strong

  13. Oxygen Chemistry in Titan's Atmosphere

    Science.gov (United States)

    Wilson, E. H.; Atreya, S. K.

    2002-09-01

    Oxygen chemistry in the atmosphere of Titan is controlled by the presence of CO and a likely influx of extraplanetary oxygen. The presence of water vapor, corroborated by the Infrared Space Observatory (ISO) stratospheric detection [1], combined with CO induces the formation of CO2, which has also been observed [2]. However, the high CO/H2O ratio in Titan's atmosphere causes the propagation of oxygen chemistry to follow a different path than what is predicted for the Jovian planets. Specifically, the efficient CO recycling mechanisms serve to inhibit significant formation of larger oxygen compounds such as CH3OH (methanol) and CH2CO (ketene). The results of a 1-D photochemical model are presented in the context of identifying possible oxygen compounds that might be detected by the Cassini/Huygens mission which will arrive at Titan in 2004. This work was supported by the NASA Planetary Atmospheres Program and by the GCMS Project of the Cassini/Huygens mission. [1] A. Coustenis et al., Astron. Astrophys., 336, L85-L89, 1998. [2] A. Coustenis et al., Icarus, 80, 54-76, 1989.

  14. Atmospheric Chemistry of Micrometeoritic Organic Compounds

    Science.gov (United States)

    Kress, M. E.; Belle, C. L.; Pevyhouse, A. R.; Iraci, L. T.

    2011-01-01

    Micrometeorites approx.100 m in diameter deliver most of the Earth s annual accumulation of extraterrestrial material. These small particles are so strongly heated upon atmospheric entry that most of their volatile content is vaporized. Here we present preliminary results from two sets of experiments to investigate the fate of the organic fraction of micrometeorites. In the first set of experiments, 300 m particles of a CM carbonaceous chondrite were subject to flash pyrolysis, simulating atmospheric entry. In addition to CO and CO2, many organic compounds were released, including functionalized benzenes, hydrocarbons, and small polycyclic aromatic hydrocarbons. In the second set of experiments, we subjected two of these compounds to conditions that simulate the heterogeneous chemistry of Earth s upper atmosphere. We find evidence that meteor-derived compounds can follow reaction pathways leading to the formation of more complex organic compounds.

  15. Carbon Monoxide Affecting Planetary Atmospheric Chemistry

    Science.gov (United States)

    He, Chao; Horst, Sarah

    2016-10-01

    Atmospheric hazes are present in a range of solar system and extrasolar planetary atmospheres, and organic hazes, such as that in Titan's atmosphere, could be a source of prebiotic molecules.1 However, the chemistry occurring in planetary atmospheres and the resulting chemical structures are still not clear. Numerous experimental simulations2 have been carried out in the laboratory to understand the chemistry in N2/CH4 atmospheres, but very few simulations4 have included CO in their initial gas mixtures, which is an important component in many N2/CH4 atmospheres including Titan, Triton, and Pluto.3 Here we have conducted a series of atmosphere simulation experiments using AC glow discharge (cold plasma) as energy source to irradiate reactions in gas mixtures of CO, CH4, and N2 with a range of CO mixing ratios (from 0, 0.05%, 0.2%, 0.5%, 1%, 2.5%, to 5%) at low temperature (~100 K). Gas phase products are monitored during the reaction by quadrupole mass spectrometer (MS), and solid phase products are analyzed by solution-state nuclear magnetic resonance spectroscopy (NMR). MS results show that with the increase of CO in the initial gases, the production of nitrogenous organic molecules increases while the production of hydrogen molecules decreases in the gas phase. NMR measurements of the solid phase products show that with the increase of CO, hydrogen atoms bonded to nitrogen or oxygen in unsaturated structures increase while those bonded to saturated carbon decrease, which means more unsaturated species and less saturated species formed with the addition of CO. MS and NMR results demonstrate that the inclusion of CO affects the compositions of both gas and solid phase products, indicating that CO has an important impact on the chemistry occurring in our experiments and probably in planetary atmospheres.1. Hörst, S. M., et al. 2012, AsBio, 12, 8092. Cable, M. L., et al. 2012, Chem. Rev., 112, 18823. Lutz, B. L., et al. 1983, Sci, 220, 1374; Greaves, J. S., et al

  16. Atmospheric chemistry and physics in the atmosphere of a developed megacity (London: an overview of the REPARTEE experiment and its conclusions

    Directory of Open Access Journals (Sweden)

    R. M. Harrison

    2012-03-01

    Full Text Available The REgents PARk and Tower Environmental Experiment (REPARTEE comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160–190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h new information on the chemical composition and source apportionment of particulate

  17. Atmospheric chemistry and physics in the atmosphere of a developed megacity (London: an overview of the REPARTEE experiment and its conclusions

    Directory of Open Access Journals (Sweden)

    R. M. Harrison

    2011-11-01

    Full Text Available The Regents Park and Tower Environmental Experiment (REPARTEE comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160–190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h new information on the chemical composition and source apportionment of particulate

  18. Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): an overview of the REPARTEE experiment and its conclusions

    Science.gov (United States)

    Harrison, R. M.; Dall'Osto, M.; Beddows, D. C. S.; Thorpe, A. J.; Bloss, W. J.; Allan, J. D.; Coe, H.; Dorsey, J. R.; Gallagher, M.; Martin, C.; Whitehead, J.; Williams, P. I.; Jones, R. L.; Langridge, J. M.; Benton, A. K.; Ball, S. M.; Langford, B.; Hewitt, C. N.; Davison, B.; Martin, D.; Petersson, K. F.; Henshaw, S. J.; White, I. R.; Shallcross, D. E.; Barlow, J. F.; Dunbar, T.; Davies, F.; Nemitz, E.; Phillips, G. J.; Helfter, C.; Di Marco, C. F.; Smith, S.

    2012-03-01

    The REgents PARk and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160-190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size

  19. 1997 Atmospheric Chemistry Colloquium for Emerging Senior Scientists

    Energy Technology Data Exchange (ETDEWEB)

    Paul H. Wine

    1998-11-23

    DOE's Atmospheric Chemistry Program is providing partial funding for the Atmospheric Chemistry Colloquium for Emerging Senior Scientists (ACCESS) and FY 1997 Gordon Research Conference in Atmospheric Chemistry

  20. Research in physical chemistry and chemical education: Part A: Water Mediated Chemistry of Oxidized Atmospheric Compounds Part B: The Development of Surveying Tools to Determine How Effective Laboratory Experiments Contribute to Student Conceptual Understanding

    Science.gov (United States)

    Maron, Marta Katarzyna

    atmospherically measured oxidized organic molecules and predictions of atmospheric models at different relative humidities. The chemical education portion of this manuscript presented in Chapters VI and VII includes the development of a survey to determine how effective a laboratory experiment is in contributing to students' understanding of fundamental chemistry. The specific example used is an electrochemical cell. Our initial results showed that while most of our students could answer quantitative questions about the operation of the cell, their conceptual understanding of the microscopic processes that occur within the cell was inconsistent with the material presented in class. In particular, we noticed that while many students were able to correctly describe the events that take place at the surface of the anode and cathode, their understanding of the events that take place at the salt bridge was lacking. In this investigation, we were able to confirm the misconceptions reported in previous studies. Our results suggest that a relatively modest, incremental revision of the experiment reduces these misconceptions and helped the students to develop a molecular-scale picture of the processes that occur within an electrochemical cell.

  1. Modeling the atmospheric chemistry of TICs

    Science.gov (United States)

    Henley, Michael V.; Burns, Douglas S.; Chynwat, Veeradej; Moore, William; Plitz, Angela; Rottmann, Shawn; Hearn, John

    2009-05-01

    An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (keff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived keff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

  2. Energy, atmospheric chemistry, and global climate

    Science.gov (United States)

    Levine, Joel S.

    1991-01-01

    Global atmospheric changes due to ozone destruction and the greenhouse effect are discussed. The work of the Intergovernmental Panel on Climate Change is reviewed, including its judgements regarding global warming and its recommendations for improving predictive capability. The chemistry of ozone destruction and the global atmospheric budget of nitrous oxide are reviewed, and the global sources of nitrous oxide are described.

  3. Exoplanetary Atmospheres - Chemistry, Formation Conditions, and Habitability

    CERN Document Server

    Madhusudhan, Nikku; Moses, Julianne I; Hu, Yongyun

    2016-01-01

    Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties. We now enter a new era as we begin to investigate the chemical diversity of exoplanets, their atmospheric and interior processes, and their formation conditions. Recent developments in the field have led to unprecedented advancements in our understanding of atmospheric chemistry of exoplanets and the implications for their formation conditions. We review these developments in the present work. We review in detail the theory of atmospheric chemistry in all classes of exoplanets discovered to date, from highly irradiated gas giants, ice giants, and super-Earths, to directly imaged giant planets at large orbital separations. We then review the observational detections of chemical species in exoplanetary atmospheres of these various types using different methods, incl...

  4. Parallel computing in atmospheric chemistry models

    Energy Technology Data Exchange (ETDEWEB)

    Rotman, D. [Lawrence Livermore National Lab., CA (United States). Atmospheric Sciences Div.

    1996-02-01

    Studies of atmospheric chemistry are of high scientific interest, involve computations that are complex and intense, and require enormous amounts of I/O. Current supercomputer computational capabilities are limiting the studies of stratospheric and tropospheric chemistry and will certainly not be able to handle the upcoming coupled chemistry/climate models. To enable such calculations, the authors have developed a computing framework that allows computations on a wide range of computational platforms, including massively parallel machines. Because of the fast paced changes in this field, the modeling framework and scientific modules have been developed to be highly portable and efficient. Here, the authors present the important features of the framework and focus on the atmospheric chemistry module, named IMPACT, and its capabilities. Applications of IMPACT to aircraft studies will be presented.

  5. Research in Physical Chemistry and Chemical Education: Part A--Water Mediated Chemistry of Oxidized Atmospheric Compounds Part B--The Development of Surveying Tools to Determine How Effective Laboratory Experiments Contribute to Student Conceptual Understanding

    Science.gov (United States)

    Maron, Marta Katarzyna

    2011-01-01

    This dissertation is a combination of two research areas, experimental physical chemistry, Chapters I to V, and chemical education, Chapters VI to VII. Chapters I to V describe research on the water-mediated chemistry of oxidized atmospheric molecules and the impact that water has on the spectra of these environmental systems. The role of water…

  6. The Atmospheric Chemistry of Methyl Chavicol (Estragole)

    Science.gov (United States)

    Bloss, W. J.; Alam, M. S.; Rickard, A. R.; Hamilton, J. F.; Pereira, K. F.; Camredon, M.; Munoz, A.; Vazquez, M.; Alacreu, P.; Rodenas, M.; Vera, T.

    2012-12-01

    The oxidation of volatile organic compounds (VOCs) leads to formation of ozone and secondary organic aerosols (SOA), with consequences for health, air quality, crop yields, atmospheric chemistry and radiative transfer. It is estimated that ca. 90 % of VOC emissions to the atmosphere originate from biogenic sources (BVOC); such emissions may increase under future climates. Recent field observations have identified Methyl Chavicol ("MC" hereafter, also known as Estragole; 1-allyl-4-methoxybenzene, C10H12O) as a major BVOC above pine forests in the USA [Bouvier-Brown et al., 2009], and within an oil palm plantation in Malaysian Borneo, where it was found that MC could represent the highest single floral contribution of reactive carbon to the atmosphere [Misztal et al., 2010]. Palm oil cultivation, and hence emissions of MC, may be expected to increase with societal food and biofuel demand. We present the results of a series of simulation chamber experiments to assess the atmospheric fate of MC. Experiments were performed in the EUPHORE (European Photoreactor) facility in Valencia, Spain (200 m3 outdoor smog chamber), investigating the degradation of MC by reaction with OH, O3 and NO3. An extensive range of measurement instrumentation was used to monitor precursor and product formation, including stable species (FTIR, PTR-MS, GC-FID and GC-MS), radical intermediates (LIF), inorganic components (NOx, O3, HONO (LOPAP and aerosol production (SMPS) and composition (PILS and filters; analysed offline by LC-MS and FTICR-MS). Experiments were conducted at a range of NOx:VOC ratios, and in the presence and absence of radical (OH) scavenger compounds. This chamber dataset is used to determine the rate constants for reaction of MC with OH, O3 and NO3, the ozonolysis radical yields, and identify the primary degradation products for each initiation route, alongside the aerosol mass yields. Aerosol composition measurements are analysed to identify markers for MC contributions to

  7. Chemistry of Planetary Atmospheres: Insights and Prospects

    Science.gov (United States)

    Yung, Yuk

    2015-11-01

    Using observations from the Mariners, Pioneers, Vikings, Voyagers, Pioneer Venus, Galileo, Venus Express, Curiosity, Cassini, New Horizons, and numerous observatories both in orbit of Earth and on the ground, I will give a survey of the major chemical processes that control the composition of planetary atmospheres. For the first time since the beginning of the space age, we understand the chemistry of planetary atmospheres ranging from the primitive atmospheres of the giant planets to the highly evolved atmospheres of terrestrial planets and small bodies. Our understanding can be distilled into three important ideas: (1) The stability of planetary atmospheres against escape of their constituents to space, (2) the role of equilibrium chemistry in determining the partitioning of chemical species, and (3) the role of disequilibrium chemistry, which produces drastic departures from equilibrium chemistry. To these three ideas we must also add a fourth: the role of biochemistry at Earth's surface, which makes its atmospheric chemistry unique in the cosmochemical environment. Only in the Earth's atmosphere do strong reducing and oxidizing species coexist to such a degree. For example, nitrogen species in the Earth's atmosphere span eight oxidation states from ammonia to nitric acid. Much of the Earth's atmospheric chemistry consists of reactions initiated by the degradation of biologically produced molecules. Life uses solar energy to drive chemical reactions that would otherwise not occur; it represents a kind of photochemistry that is special to Earth, at least within the Solar System. It remains to be seen how many worlds like Earth there are beyond the Solar System, especially as we are now exploring the exoplanets using Kepler, TESS, HST, Spitzer, soon to be launched missions such as JWST and WFIRST, and ground-based telescopes. The atmospheres of the Solar System provide a benchmark for studying exoplanets, which in turn serve to test and extend our current

  8. Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

    Science.gov (United States)

    Sagan, C.

    1974-01-01

    The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

  9. Measuring Heterogeneous Reaction Rates with ATR-FTIR Spectroscopy to Evaluate Chemical Fates in an Atmospheric Environment: A Physical Chemistry and Environmental Chemistry Laboratory Experiment

    Science.gov (United States)

    Roberts, Jason E.; Zeng, Guang; Maron, Marta K.; Mach, Mindy; Dwebi, Iman; Liu, Yong

    2016-01-01

    This paper reports an undergraduate laboratory experiment to measure heterogeneous liquid/gas reaction kinetics (ozone-oleic acid and ozone-phenothrin) using a flow reactor coupled to an attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometer. The experiment is specially designed for an upper-level undergraduate Physical…

  10. Atmospheric Chemistry of Venus-like Exoplanets

    CERN Document Server

    Schaefer, Laura

    2010-01-01

    We use thermodynamic calculations to model atmospheric chemistry on terrestrial exoplanets that are hot enough for chemical equilibira between the atmosphere and lithosphere, as on Venus. The results of our calculations place constraints on abundances of spectroscopically observable gases, the surface temperature and pressure, and the mineralogy of the surface. These results will be useful in planning future observations of the atmospheres of terrestrial-sized exoplanets by current and proposed space observatories such as the Hubble Space Telescope (HST), Spitzer, James Webb Space Telescope (JWST), Terrestrial Planet Finder, and Darwin.

  11. Computational solution of atmospheric chemistry problems

    Science.gov (United States)

    Jafri, J.; Ake, R. L.

    1986-01-01

    Extensive studies were performed on problems of interest in atmospheric chemistry. In addition to several minor projects, four major projects were performed and described (theoretical studies of ground and low-lying excited states of ClO2; ground and excited state potential energy surfaces of the methyl peroxy radical; electronic states ot the FO radical; and theoretical studies S02 (H2O) (sub n)).

  12. Laser experiments for chemistry and physics

    CERN Document Server

    Compton, Robert N

    2016-01-01

    Lasers are employed throughout science and technology, in fundamental research, the remote sensing of atmospheric gases or pollutants, communications, medical diagnostics and therapies, and the manufacturing of microelectronic devices. Understanding the principles of their operation, which underlie all of these areas, is essential for a modern scientific education. This text introduces the characteristics and operation of lasers through laboratory experiments designed for the undergraduate curricula in chemistry and physics. Introductory chapters describe the properties of light, the history of laser invention, the atomic, molecular, and optical principles behind how lasers work, and the kinds of lasers available today. Other chapters include the basic theory of spectroscopy and computational chemistry used to interpret laser experiments. Experiments range from simple in-class demonstrations to more elaborate configurations for advanced students. Each chapter has historical and theoretical background, as well...

  13. Atmospheric Prebiotic Chemistry and Organic Hazes

    Science.gov (United States)

    Trainer, Melissa G.

    2012-01-01

    Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of pre biotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

  14. Submillimeter Planetary Atmospheric Chemistry Exploration Sounder

    Science.gov (United States)

    Schlecht, Erich T.; Allen, Mark A.; Gill, John J.; Choonsup, Lee; Lin, Robert H.; Sin, Seth; Mehdi, Imran; Siegel, Peter H.; Maestrini, Alain

    2013-01-01

    Planetary Atmospheric Chemistry Exploration Sounder (SPACES), a high-sensitivity laboratory breadboard for a spectrometer targeted at orbital planetary atmospheric analysis. The frequency range is 520 to 590 GHz, with a target noise temperature sensitivity of 2,500 K for detecting water, sulfur compounds, carbon compounds, and other atmospheric constituents. SPACES is a prototype for a powerful tool for the exploration of the chemistry and dynamics of any planetary atmosphere. It is fundamentally a single-pixel receiver for spectral signals emitted by the relevant constituents, intended to be fed by a fixed or movable telescope/antenna. Its front-end sensor translates the received signal down to the 100-MHz range where it can be digitized and the data transferred to a spectrum analyzer for processing, spectrum generation, and accumulation. The individual microwave and submillimeter wave components (mixers, LO high-powered amplifiers, and multipliers) of SPACES were developed in cooperation with other programs, although with this type of instrument in mind. Compared to previous planetary and Earth science instruments, its broad bandwidth (approx. =.13%) and rapid tunability (approx. =.10 ms) are new developments only made possible recently by the advancement in submillimeter circuit design and processing at JPL.

  15. Atmospheric Composition Change: Climate-Chemistry Interactions

    Science.gov (United States)

    Isaksen, I.S.A.; Granier, C.; Myhre, G.; Bernsten, T. K.; Dalsoren, S. B.; Gauss, S.; Klimont, Z.; Benestad, R.; Bousquet, P.; Collins, W.; Cox, T.; Eyring, V.; Fowler, D.; Fuzzi, S.; Jockel, P.; Laj, P.; Lohmann, U.; Maione, M.; Monks, T.; Prevot, A. S. H.; Raes, F.; Richter, A.; Rognerud, B.; Schulz, M.; Shindell, D.; Stevenson, D. S.; Storelvmo, T.; Wang, W.-C.; vanWeele, M.; Wild, M.; Wuebbles, D.

    2011-01-01

    Chemically active climate compounds are either primary compounds such as methane (CH4), removed by oxidation in the atmosphere, or secondary compounds such as ozone (O3), sulfate and organic aerosols, formed and removed in the atmosphere. Man-induced climate-chemistry interaction is a two-way process: Emissions of pollutants change the atmospheric composition contributing to climate change through the aforementioned climate components, and climate change, through changes in temperature, dynamics, the hydrological cycle, atmospheric stability, and biosphere-atmosphere interactions, affects the atmospheric composition and oxidation processes in the troposphere. Here we present progress in our understanding of processes of importance for climate-chemistry interactions, and their contributions to changes in atmospheric composition and climate forcing. A key factor is the oxidation potential involving compounds such as O3 and the hydroxyl radical (OH). Reported studies represent both current and future changes. Reported results include new estimates of radiative forcing based on extensive model studies of chemically active climate compounds such as O3, and of particles inducing both direct and indirect effects. Through EU projects such as ACCENT, QUANTIFY, and the AEROCOM project, extensive studies on regional and sector-wise differences in the impact on atmospheric distribution are performed. Studies have shown that land-based emissions have a different effect on climate than ship and aircraft emissions, and different measures are needed to reduce the climate impact. Several areas where climate change can affect the tropospheric oxidation process and the chemical composition are identified. This can take place through enhanced stratospheric-tropospheric exchange of ozone, more frequent periods with stable conditions favouring pollution build up over industrial areas, enhanced temperature-induced biogenic emissions, methane releases from permafrost thawing, and enhanced

  16. Validation of HNO3, ClONO2, and N2O5 from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    M. Ridolfi

    2008-02-01

    Full Text Available The Atmospheric Chemistry Experiment (ACE satellite was launched on 12 August 2003. Its two instruments measure vertical profiles of over 30 atmospheric trace gases by analyzing solar occultation spectra in the ultraviolet/visible and infrared wavelength regions. The reservoir gases HNO3, ClONO2, and N2O5 are three of the key species provided by the primary instrument, the ACE Fourier Transform Spectrometer (ACE-FTS. This paper describes the ACE-FTS version 2.2 data products, including the N2O5 update, for the three species and presents validation comparisons with available observations. We have compared volume mixing ratio (VMR profiles of HNO3, ClONO2, and N2O5 with measurements by other satellite instruments (SMR, MLS, MIPAS, aircraft measurements (ASUR, and single balloon-flights (SPIRALE, FIRS-2. Partial columns of HNO3 and ClONO2 were also compared with measurements by ground-based Fourier Transform Infrared (FTIR spectrometers. Overall the quality of the ACE-FTS v2.2 HNO3 VMR profiles is good from 18 to 35 km. For the statistical satellite comparisons, the mean absolute differences are generally within ±1 ppbv (±20% from 18 to 35 km. For MIPAS and MLS comparisons only, mean relative differences lie within ±10% between 10 and 36 km. ACE-FTS HNO3 partial columns (~15–30 km show a slight negative bias of −1.3% relative to the ground-based FTIRs at latitudes ranging from 77.8° S–76.5° N. Good agreement between ACE-FTS ClONO2 and MIPAS, using the Institut für Meteorologie und Klimaforschung and Instituto de Astrofísica de Andalucía (IMK-IAA data processor is seen. Mean absolute differences are typically within ±0.01 ppbv between 16 and 27 km and less than +0.09 ppbv between 27 and 34 km. The ClONO2 partial column comparisons show varying degrees of agreement, depending on the location and the quality of the FTIR measurements. Good agreement was found for the comparisons with the midlatitude Jungfraujoch partial columns for which

  17. Validation of HNO3, ClONO2, and N2O5 from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    P. Raspollini

    2008-07-01

    Full Text Available The Atmospheric Chemistry Experiment (ACE satellite was launched on 12 August 2003. Its two instruments measure vertical profiles of over 30 atmospheric trace gases by analyzing solar occultation spectra in the ultraviolet/visible and infrared wavelength regions. The reservoir gases HNO3, ClONO2, and N2O5 are three of the key species provided by the primary instrument, the ACE Fourier Transform Spectrometer (ACE-FTS. This paper describes the ACE-FTS version 2.2 data products, including the N2O5 update, for the three species and presents validation comparisons with available observations. We have compared volume mixing ratio (VMR profiles of HNO3, ClONO2, and N2O5 with measurements by other satellite instruments (SMR, MLS, MIPAS, aircraft measurements (ASUR, and single balloon-flights (SPIRALE, FIRS-2. Partial columns of HNO3 and ClONO2 were also compared with measurements by ground-based Fourier Transform Infrared (FTIR spectrometers. Overall the quality of the ACE-FTS v2.2 HNO3 VMR profiles is good from 18 to 35 km. For the statistical satellite comparisons, the mean absolute differences are generally within ±1 ppbv ±20% from 18 to 35 km. For MIPAS and MLS comparisons only, mean relative differences lie within±10% between 10 and 36 km. ACE-FTS HNO3 partial columns (~15–30 km show a slight negative bias of −1.3% relative to the ground-based FTIRs at latitudes ranging from 77.8° S–76.5° N. Good agreement between ACE-FTS ClONO2 and MIPAS, using the Institut für Meteorologie und Klimaforschung and Instituto de Astrofísica de Andalucía (IMK-IAA data processor is seen. Mean absolute differences are typically within ±0.01 ppbv between 16 and 27 km and less than +0.09 ppbv between 27 and 34 km. The ClONO2 partial column comparisons show varying degrees of agreement, depending on the location and the quality of the FTIR measurements. Good agreement was found for the comparisons with the midlatitude Jungfraujoch partial columns for which

  18. Atmospheric Aerosol Chemistry Analyzer: Demonstration of feasibility

    Energy Technology Data Exchange (ETDEWEB)

    Mroz, E.J.; Olivares, J.; Kok, G.

    1996-04-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to demonstrate the technical feasibility of an Atmospheric Aerosol Chemistry Analyzer (AACA) that will provide a continuous, real-time analysis of the elemental (major, minor and trace) composition of atmospheric aerosols. The AACA concept is based on sampling the atmospheric aerosol through a wet cyclone scrubber that produces an aqueous suspension of the particles. This suspension can then be analyzed for elemental composition by ICP/MS or collected for subsequent analysis by other methods. The key technical challenge was to develop a wet cyclone aerosol sampler suitable for respirable particles found in ambient aerosols. We adapted an ultrasonic nebulizer to a conventional, commercially available, cyclone aerosol sampler and completed collection efficiency tests for the unit, which was shown to efficiently collect particles as small as 0.2 microns. We have completed the necessary basic research and have demonstrated the feasibility of the AACA concept.

  19. The Role of Chemistry in Atmosphere-Forest Exchange (Invited)

    Science.gov (United States)

    Thornton, J. A.; Wolfe, G. M.; Bouvier-Brown, N. C.; Goldstein, A. H.; Park, J.; McKay, M.; Matross, D. M.; Mao, J.; Brune, W. H.; Lafranchi, B. W.; Browne, E. C.; Min, K.; Wooldridge, P. J.; Cohen, R. C.; Crounse, J.; Faloona, I. C.; Gilman, J. B.; Kuster, W. C.; de Gouw, J. A.; Huisman, A. J.; Keutsch, F. N.

    2010-12-01

    Forest-atmosphere exchange of hydrocarbons, ozone, oxidized nitrogen and other reactive species impacts both atmospheric composition and ecosystem productivity, with broad implications for air quality and climate. Recent interpretations of measured ozone and acyl peroxy nitrate fluxes have inferred that intra-canopy chemistry plays an important role in governing both the sign and magnitude of the atmosphere-forest flux of these compounds. I review these observational insights and present results from a recently constructed 1-D vertically-resolved chemical transport model (CAFE) developed for analysis and interpretation of observations made during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX). The model incorporates a fully resolved forest canopy; emissions from which are parameterized, in many cases, to match leaf-level and top-of-canopy fluxes measured at the ponderosa pine plantation. Model chemistry is based on the Master Chemical Mechanism (MCM), with several additions to simulate the oxidation of monoterpenes and sesquiterpenes not in the current MCM. The base model underestimates measured noontime OH concentrations by a factor of six. As a result we invoke enhanced OH-recycling from first generation isoprene and 2-methyl-3-buten-2-ol peroxy radicals to reconcile model and observed HOx components. Noting a few other aspects of model performance, I will focus on the model predictions of chemistry-induced fluxes. The model qualitatively reproduces the inferred sensitivity to intra-canopy chemistry for both ozone and acyl peroxy nitrates. In both cases, however, the model underestimates the observed exchange velocity suggesting non-stomatal losses (depositional or chemical) remain underestimated in the canopy. As an example of the potential importance of intra-canopy chemistry, the meteorological and structural characteristics of the forest are varied within the model. An intriguing result is that acyl peroxy nitrate (e.g., PAN) fluxes

  20. Atmospheric chemistry and physics from air pollution to climate change

    CERN Document Server

    Seinfeld, John H

    2016-01-01

    Expanded and updated with new findings and new features Since the second edition of Seinfeld and Pandis’ classic textbook, significant progress has taken place in the field of atmospheric chemistry and physics, particularly in the areas of tropospheric chemistry, aerosols, and the science of climate change. A new edition of this comprehensive work has been developed by the renowned author team. Atmospheric Chemistry and Physics, 3rd Edition, as the previous two editions have done, provides a rigorous and comprehensive treatment of the chemistry and physics of the atmosphere – including the chemistry of the stratosphere and troposphere, aerosol physics and chemistry, atmospheric new particle formation, physical meteorology, cloud physics, global climate, statistical analysis of data, and mathematical chemical/transport models of the atmosphere. Each of these topics is covered in detail and in each area the central results are developed from first principles. In this way the reader gains a significant un...

  1. Customized Laboratory Experience in Physical Chemistry

    Science.gov (United States)

    Castle, Karen J.; Rink, Stephanie M.

    2010-01-01

    A new physical chemistry laboratory experience has been designed for upper-level undergraduate chemistry majors. Students customize the first 10 weeks of their laboratory experience by choosing their own set of experiments (from a manual of choices) and setting their own laboratory schedule. There are several topics presented in the accompanying…

  2. Chemical experiment - the basis in learning chemistry

    Directory of Open Access Journals (Sweden)

    N. Dalabayeva

    2012-12-01

    Full Text Available Particular classification and method carrying out chemical experiment and their place in learning chemistry was considered. And also was showed that an application of kinds of chemical experiments competence develops in learning at the decision of experimental problems in chemistry. Features of solubility of firm substances in water are discussed at the chemical experiment and the process of dissolution.

  3. Chemical experiment - the basis in learning chemistry

    OpenAIRE

    N. Dalabayeva

    2012-01-01

    Particular classification and method carrying out chemical experiment and their place in learning chemistry was considered. And also was showed that an application of kinds of chemical experiments competence develops in learning at the decision of experimental problems in chemistry. Features of solubility of firm substances in water are discussed at the chemical experiment and the process of dissolution.

  4. Micro-polymer Chemistry Experiment Teaching Research

    Institute of Scientific and Technical Information of China (English)

    李青山

    2009-01-01

    For nearly thirty years,there has been made great progress in micro-polymer chemistry experiment teaching which has these characteristics that using less reagents,less pollution and more portable in comparison with the conventional experiment.In China,Zhou Ninghuai and others began to go on micro-scale experiment research firstly and Professor Li Qingshan who brought this innovation to polymer organic synthesis experiment has done a lot of works in micro-polymer chemistry experiment teaching.To carry out the study ofmicro-polymer chemistry experiments not only accords with teaching methods and reform,but also conforms to the trend of the times of green chemistry.So the research and application of micro-polymer chemistry experiment have broad prospects.

  5. Impact of aircraft emissions on the atmospheric chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Dameris, M.; Sausen, R.; Grewe, V.; Koehler, I.; Ponater, M. [Deutsche Forschungs- und Versuchsanstalt fuer Luft- und Raumfahrt e.V., Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Steil, B. [Max-Planck-Inst. fuer Meteorologie, Hamburg (Germany); Bruehl, Ch. [Max-Planck-Inst. fuer Chemie (Otto-Hahn-Institut), Mainz (Germany)

    1997-12-31

    A hierarchy of models of different complexity has been applied to estimate the impact of aircraft NO{sub x} emissions on atmospheric chemistry. The global circulation model ECHAM3 has been coupled with two types of chemistry modules. The first of these describes only a simplified (linear) NO{sub x} and HNO{sub 3} chemistry while the second one is a comprehensive chemistry module (CHEM), describing tropospheric and stratospheric chemistry including photochemical reactions and heterogeneous reactions on sulphate aerosols and PSCs. The module CHEM has been coupled either off-line or with feedback via the ozone concentration. First results of multilayer integrations (over decades) are discussed. (author) 27 refs.

  6. Mars Aqueous Chemistry Experiment (MACE)

    Science.gov (United States)

    Benton, Clark C. (Editor)

    1995-01-01

    The concept of an aqueous-based chemical analyzer for Martian surface materials has been demonstrated to be feasible. During the processes of analysis, design, breadboarding, and most importantly, testing, it has become quite apparent that there are many challenges in implementing such a system. Nonetheless, excellent progress has been made and a number of problems which arose have been solved. The ability to conduct this work under a development environment which is separate and which precedes the project-level development has allowed us to find solutions to these implementation realities at low cost. If the instrument had been selected for a mission without this laboratory pre-project work, the costs of implementation would be much higher. In the four areas covered in Sections D, E, F, and G of this Final Report, outstanding progress has been made. There still remains the task of flight-qualifying certain of the components. This is traditionally done under the aegis of a Flight Project, but just as the concept development can be done at much lower cost when kept small and focused, so could the qualification program of critical parts benefit. We recommend, therefore, that NASA consider means of such qualifications and brass-boarding, in advance of final flight development. This is a generic recommendation, but hardware such as the Mars aqueous chemistry experiment (MACE) and other similarly-new concepts are particularly applicable. MACE now has wide versatility, in being able to reliably dispense both liquids and solids as chemical reagents to an entire suite of samples. The hardware and the experiment is much simpler than was developed for the Viking Biology instrument, yet can accomplish all the inorganic chemical measurements that the Viking desing was capable of. In addition, it is much more flexible and versatile to new experiment protocols (and reagents) than the Viking design ever could have been. MACE opens up the opportunity for many different scientific

  7. Remote sensing of atmospheric chemistry; Proceedings of the Meeting, Orlando, FL, Apr. 1-3, 1991

    Science.gov (United States)

    Mcelroy, James L. (Editor); Mcneal, Robert J. (Editor)

    1991-01-01

    The present volume on remote sensing of atmospheric chemistry discusses special remote sensing space observations and field experiments to study chemical change in the atmosphere, network monitoring for detection of stratospheric chemical change, stratospheric chemistry studies, and the combining of model, in situ, and remote sensing in atmospheric chemistry. Attention is given to the measurement of tropospheric carbon monoxide using gas filter radiometers, long-path differential absorption measurements of tropospheric molecules, air quality monitoring with the differential optical absorption spectrometer, and a characterization of tropospheric methane through space-based remote sensing. Topics addressed include microwave limb sounder experiments for UARS and EOS, an overview of the spectroscopy of the atmosphere using an FIR emission experiment, the detection of stratospheric ozone trends by ground-based microwave observations, and a FIR Fabry-Perot spectrometer for OH measurements.

  8. Collaborative Research. Atmospheric Pressure Microplasma Chemistry-Photon Synergies

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung-Jin [Univ. of Illinois, Urbana, IL (United States); Eden, James Gary [Univ. of Illinois, Urbana, IL (United States)

    2015-12-01

    Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources offers the promise of greatly expanding the range of applications for each of them. The plasma sources create active chemical species and these can be activated further by the addition of photons and the associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. This project combined the construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling. Through a continuous discussion and co-design process with the UC-Berkeley Team, we have successfully completed the fabrication and testing of all components for a microplasma array-assisted system designed for photon-activated plasma chemistry research. Microcavity plasma lamps capable of generating more than 20 mW/cm2 at 172 nm (Xe dimer) were fabricated with a custom form factor to mate to the plasma chemistry setup, and a lamp was current being installed by the Berkeley team so as to investigate plasma chemistry-photon synergies at a higher photon energy (~7.2 eV) as compared to the UVA treatment that is afforded by UV LEDs operating at 365 nm. In particular, motivated by the promising results from the Berkeley team with UVA treatment, we also produced the first generation of lamps that can generate photons in the 300-370 nm wavelength range. Another set of experiments, conducted under the auspices of this grant, involved the use of plasma microjet arrays. The combination of the photons and excited radicals produced by the plasma column resulted in broad area deactivation of bacteria.

  9. Atmospheric Boundary Layer, Integrating Air Chemistry and Land Interactions

    NARCIS (Netherlands)

    Vilà-Guerau De Arellano, J.; Heerwaarden, van C.C.; Stratum, van B.J.H.; Dries, van den C.L.A.M.

    2015-01-01

    This textbook provides an introduction to the interactions between the atmosphere and the land for advanced undergraduate and graduate students and a reference text for researchers in atmospheric physics and chemistry, hydrology, and plant physiology. The combination of the book, which provides the

  10. Concluding remarks: Faraday Discussion on chemistry in the urban atmosphere.

    Science.gov (United States)

    Jimenez, Jose L

    2016-07-18

    This article summarises the Concluding remarks from the Faraday Discussion on Chemistry in the Urban Atmosphere. The following themes are addressed: (a) new results that inform our understanding of the evolving sources and composition of the urban atmosphere ("News"); (b) results that identify gaps in our understanding that necessitate further work ("Gaps");

  11. Stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O from measurements made by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    P. F. Bernath

    2013-02-01

    Full Text Available Long lived halogen-containing compounds are important atmospheric constituents since they can act both as a source of chlorine radicals, which go on to catalyse ozone loss, and as powerful greenhouse gases. The long term impact of these species on the ozone layer is dependent on their stratospheric lifetimes. Using observations from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS we present calculations of the stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O. The lifetimes were calculated using the slope of the tracer-tracer correlation of these species with CFC-11 at the tropopause. The correlation slopes were corrected for the changing atmospheric concentrations of each species based on age of air and CFC-11 measurements from samples taken aboard the Geophysica aircraft – along with the effective linear trend of the VMR from tropical ground-based AGAGE sites. Stratospheric lifetimes were calculated using a CFC-11 lifetime of 45 yr. These calculations produced values of 113 + (− 26 (18 yr (CFC-12, 35 + (− 11 (7 yr (CCl4, 195 + (− 75 (42 yr (CH4, 69 + (− 65 (23 yr (CH3Cl and 123 + (− 53 (28 yr (N2O. The errors on these values are the weighted 1-σ non-systematic errors. The stratospheric lifetime of CH3Cl represents the first calculations of the stratospheric lifetime of CH3Cl using data from a space based instrument.

  12. Stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O from measurements made by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS

    Directory of Open Access Journals (Sweden)

    A. T. Brown

    2013-07-01

    Full Text Available Long lived halogen-containing compounds are important atmospheric constituents since they can act both as a source of chlorine radicals, which go on to catalyse ozone loss, and as powerful greenhouse gases. The long-term impact of these species on the ozone layer is dependent on their stratospheric lifetimes. Using observations from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS we present calculations of the stratospheric lifetimes of CFC-12, CCl4, CH4, CH3Cl and N2O. The lifetimes were calculated using the slope of the tracer–tracer correlation of these species with CFC-11 at the tropopause. The correlation slopes were corrected for the changing atmospheric concentrations of each species based on age of air and CFC-11 measurements from samples taken aboard the Geophysica aircraft – along with the effective linear trend of the volume mixing ratio (VMR from tropical ground based AGAGE (Advanced Global Atmospheric Gases Experiment sites. Stratospheric lifetimes were calculated using a CFC-11 lifetime of 45 yr. These calculations produced values of 113 + (− 26 (18 yr (CFC-12, 35 + (− 11 (7 yr (CCl4, 69 + (− 65 (23 yr (CH3Cl, 123 + (− 53 (28 yr (N2O and 195 + (− 75 (42 yr (CH4. The errors on these values are the weighted 1σ non-systematic errors. Systematic errors were estimated by recalculating lifetimes using VMRs which had been modified to reflect differences between ACE-FTS retrieved VMRs and those from other instruments. The results of these calculations, including systematic errors, were as follows: 113 + (− 32 (20 for CFC-12, 123 + (− 83 (35 for N2O, 195 + (− 139 (57 for CH4, 35 + (− 14 (8 for CCl4 and 69 + (− 2119 (34 yr for CH3Cl. For CH3Cl & CH4 this represents the first calculation of the stratospheric lifetime using data from a space based instrument.

  13. Investigating Titan's Atmospheric Chemistry at Low Temperature in Support of the NASA Cassini Mission

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Salama, Farid

    2013-01-01

    Titan's atmosphere, composed mainly of N2 and CH4, is the siege of a complex chemistry induced by solar UV radiation and electron bombardment from Saturn's magnetosphere. This organic chemistry occurs at temperatures lower than 200 K and leads to the production of heavy molecules and subsequently solid aerosols that form the orange haze surrounding Titan. The Titan Haze Simulation (THS) experiment has been developed on the COSMIC simulation chamber at NASA Ames in order to study the different steps of Titan's atmospheric chemistry at low temperature and to provide laboratory data in support for Cassini data analysis. The chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is adiabatically cooled to Titan-like temperature (approx. 150 K) before inducing the chemistry by plasma discharge. Different gas mixtures containing N2, CH4, and the first products of the N2,-CH4 chemistry (C2H2, C2H4, C6H6...) but also heavier molecules such as PAHs or nitrogen containing PAHs can be injected. Both the gas phase and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed. Here we present the results of recent gas phase and solid phase studies that highlight the chemical growth evolution when injecting heavier hydrocarbon trace elements in the initial N2-CH4 mixture. Due to the short residence time of the gas in the plasma discharge, only the first steps of the chemistry have time to occur in a N2-CH4 discharge. However by adding acetylene and benzene to the initial N2-CH4 mixture, we can study the intermediate steps of Titan's atmospheric chemistry as well as specific chemical pathways. These results show the uniqueness of the THS experiment to help understand the first and intermediate steps of Titan fs atmospheric chemistry as well as specific chemical pathways leading to Titan fs haze formation.

  14. Atmospheric Chemistry in a Changing World

    Science.gov (United States)

    Brune, William H.

    The world is changing,and the atmosphere's composition is changing with it. Human activity is responsible for much of this. Global population growth and migration to urban centers, extensive biomass burning, the spread of fertilizer-intensive agribusiness, globalization of business and industry, rising standards of living in the developing world, and increased energy use fuels atmospheric change. If current practices continue, atmospheric increases are likely for the greenhouse gases carbon dioxide, methane, nitrous oxide; and for the chemically active gases nitric oxide, sulfur dioxide,and ammonia. Increases in global tropospheric ozone and aerosols are a distinct possibility.

  15. Atmospheric chemistry: The return of ethane

    Science.gov (United States)

    Hakola, Hannele; Hellén, Heidi

    2016-07-01

    Ethane emissions can lead to ozone pollution. Measurements at 49 sites show that long-declining atmospheric ethane concentrations started rising in 2010 in the Northern Hemisphere, largely due to greater oil and gas production in the USA.

  16. TROPOLITE, on the path of atmospheric chemistry made simple

    Science.gov (United States)

    Maresi, Luca; Van Der Meulen, Wencke; Vink, Rob

    2014-10-01

    Accurate, reliable and stable long term measurements of Earth's Atmospheric Chemistry from Space are currently done by complex instruments, whose mass is in excess of 100 Kg. TROPOMI is the more recent instrument being developed jointly by ESA and NSO and due for launch in 2015. TROPOMI, consisting of four spectrometers ranging from UV to SWIR, is paving the way to the development of high performance spectrometers that will compose the backbone of the European Copernicus system. The objective of TROPOMI is to measure trace gases with an accuracy one order of magnitude better of what is currently done from Space. While teams of engineers are still busy finalizing TROPOMI, ESA, NSO, and TNO have launched an initiative along a different development axis: to explore the possibility of a lighter version of TROPOMI, to address a market valuing a cost effective instrument for Atmospheric Chemistry. TROPOLITE, as it is dubbed, leverages on all the technology developments and the lessons learnt from TROPOMI, but with the clear objective of a design to cost solution. Furthermore, mass and power of the instrument shall be within the envelope of a payload of a small satellite, namely 20kg and 30W and possibly within a volume of 20 x 20 x 40 cm3. The scope of TROPOLITE is to address a larger user base that is interested in an affordable instrument to perform from a small satellite some specific tasks relevant to Air Quality and/or Climate. The paper, after a short overview of the TROPOMI design and current status, presents the design philosophy of TROPOLITE, and shows what are the technologies and processes stemming from the experience gained with TROPOMI that make possible a simplified, but still very performing, version of TROPOMI. A comparison in terms of performance and functionalities of the two instruments is discussed. Finally, the development plan from the current development status of TROPOLITE up to Qualification Model is presented.

  17. Quantifying atmospheric transport, chemistry, and mixing using a new trajectory-box model and a global atmospheric-chemistry GCM

    Directory of Open Access Journals (Sweden)

    H. Riede

    2009-12-01

    Full Text Available We present a novel method for the quantification of transport, chemistry, and mixing along atmospheric trajectories based on a consistent model hierarchy. The hierarchy consists of the new atmospheric-chemistry trajectory-box model CAABA/MJT and the three-dimensional (3-D global ECHAM/MESSy atmospheric-chemistry (EMAC general circulation model. CAABA/MJT employs the atmospheric box model CAABA in a configuration using the atmospheric-chemistry submodel MECCA (M, the photochemistry submodel JVAL (J, and the new trajectory submodel TRAJECT (T, to simulate chemistry along atmospheric trajectories, which are provided offline. With the same chemistry submodels coupled to the 3-D EMAC model and consistent initial conditions and physical parameters, a unique consistency between the two models is achieved. Since only mixing processes within the 3-D model are excluded from the model consistency, comparisons of results from the two models allow to separate and quantify contributions of transport, chemistry, and mixing along the trajectory pathways. Consistency of transport between the trajectory-box model CAABA/MJT and the 3-D EMAC model is achieved via calculation of kinematic trajectories based on 3-D wind fields from EMAC using the trajectory model LAGRANTO. The combination of the trajectory-box model CAABA/MJT and the trajectory model LAGRANTO can be considered as a Lagrangian chemistry-transport model (CTM moving isolated air parcels. The procedure for obtaining the necessary statistical basis for the quantification method is described as well as the comprehensive diagnostics with respect to chemistry.

    The quantification method presented here allows to investigate the characteristics of transport, chemistry, and mixing in a grid-based 3-D model. The analysis of chemical processes within the trajectory-box model CAABA/MJT is easily extendable to include, for example, the impact of different transport pathways or of mixing processes onto

  18. Lookup tables to compute high energy cosmic ray induced atmospheric ionization and changes in atmospheric chemistry

    OpenAIRE

    Atri, Dimitra; Melott, Adrian L.; Thomas, Brian C

    2008-01-01

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does not have the capability of incorporating the effects of substantial cosmic ray flux above 10 GeV . An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), is used to study atmospheric chem...

  19. The Atmospheric Chemistry of GJ 1214b: Photochemistry and Clouds

    CERN Document Server

    Kempton, Eliza Miller-Ricci; Fortney, Jonathan J

    2011-01-01

    Recent observations of the transiting super-Earth GJ 1214b reveal that its atmosphere may be hydrogen-rich or water-rich in nature, with clouds or hazes potentially affecting its transmission spectrum in the optical and very-near-IR. Here we further examine the possibility that GJ 1214b does indeed possess a hydrogen-dominated atmosphere, which is the hypothesis that is favored by models of the bulk composition of the planet. We study the effects of non-equilibrium chemistry (photochemistry, thermal chemistry, and mixing) on the planet's transmission spectrum. We furthermore examine the possibility that clouds could play a significant role in attenuating GJ 1214b's transmission spectrum at short wave- lengths. We find that non-equilibrium chemistry can have a large effect on the overall chemical composition of GJ 1214b's atmosphere, however these changes mostly take place above the height in the atmosphere that is probed by transmission spectroscopy. The effects of non-equilibrium chemistry on GJ 1214b's tran...

  20. Chemistry in the near-surface atmosphere at Ganymede

    Science.gov (United States)

    Shematovich, V. I.

    2013-09-01

    Theoretical predictions of the composition and chemical evolution of near-surface atmospheres of the icy satellites in the Jovian and Kronian systems are of great importance for assessing the biological potential of these satellites. Depending on the satellite mass the formation of the rarefied exosphere with the relatively dense near-surface layer is possible as, for example, in the case of the relatively heavy Galilean satellites Europa and Ganymede in the Jovian system [1-3]. Ganymede is of special interest, because observations indicate that Ganymede has a significant O2 near - surface atmosphere, probably subsurface ocean, and is the only satellite with its own magnetosphere. Processes of formation of the rarefied gaseous envelope of Ganymede and chemical exchange between atmosphere and icy surface will be considered. The water vapour is usually the domin ant parent species in such gaseous envelope because of the ejection from the satellite icy surface due to the thermal outgassing, non-thermal photolysis and radiolysis and other active processes at work on the surface. The photochemis try of water vapour in the near - surface atmospheric layer [4] and the radiolysis of icy regolith [5] result in the supplement of the atmosphere by an admixture of H2, O2, OH and O. Returning molecules have species-dependent behaviour on contact with icy surface of the satellite and non-thermal energy distributions for the chemical radicals. The H2 and O2 molecules stick with very low efficiency and are immediately desorbed thermally, but returning H2O, OH, H and O stick to the grains in the icy regolith with unit efficiency. The suprathermal radicals OH, H, and O entering the regolith can drive the surface chemistry. The numerical kinetic model to investigate on the molecular level the chemistry of the atmosphere - surface interface of the rarefied Н2О-dominant gaseous envelope at Ganymede was developed. Such numerical model simulates the gas-phase and diffusive surface

  1. Atmospheric chemistry of isoflurane, desflurane, and sevoflurane

    DEFF Research Database (Denmark)

    Andersen, Mads P. Sulbæk; Nielsen, Ole John; Karpichev, Boris

    2012-01-01

    The smog chamber/Fourier-transform infrared spectroscopy (FTIR) technique was used to measure the rate coefficients k(Cl + CF(3)CHClOCHF(2), isoflurane) = (4.5 ± 0.8) × 10(-15), k(Cl + CF(3)CHFOCHF(2), desflurane) = (1.0 ± 0.3) × 10(-15), k(Cl + (CF(3))(2)CHOCH(2)F, sevoflurane) = (1.1 ± 0.1) × 10...... (sevoflurane) are estimated at 3.2, 14, and 1.1 years, respectively. The 100 year time horizon global warming potentials of isoflurane, desflurane, and sevoflurane are 510, 2540, and 130, respectively. The atmospheric degradation products of these anesthetics are not of environmental concern....

  2. Ozone Depletion, UVB and Atmospheric Chemistry

    Science.gov (United States)

    Stolarski, Richard S.

    1999-01-01

    The primary constituents of the Earth's atmosphere are molecular nitrogen and molecular oxygen. Ozone is created when ultraviolet light from the sun photodissociates molecular oxygen into two oxygen atoms. The oxygen atoms undergo many collisions but eventually combine with a molecular oxygen to form ozone (O3). The ozone molecules absorb ultraviolet solar radiation, primarily in the wavelength region between 200 and 300 nanometers, resulting in the dissociation of ozone back into atomic oxygen and molecular oxygen. The oxygen atom reattaches to an O2 molecule, reforming ozone which can then absorb another ultraviolet photon. This sequence goes back and forth between atomic oxygen and ozone, each time absorbing a uv photon, until the oxygen atom collides with and ozone molecule to reform two oxygen molecules.

  3. Atmospheric chemistry of hydrofluorocarbons and hydrochlorofluorocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Sehested, J.

    1995-03-01

    Pulse radiolysis coupled with a time resolved UV absorption detection system and a FTIR spectrometer coupled to a 140 l reaction chamber was used to study the degradation of HCFCs and HFCs in the atmosphere. Reaction rates for a series of reactions of HFCs and HCFCs were investigated: F + RH, R + O{sub 2} + RO{sub 2} + NO, and RO{sub 2} + NO{sub 2} + M, together with UV absorption spectra of the halogenated alkyl (R) and halogenated alkyl peroxy radicals (RO{sub 2}). The products following the self reactions for RO{sub 2} radicals for RO{sub 2} = CF{sub 3}CF{sub 2}O{sub 2}, CF{sub 2}HCF{sub 2}O{sub 2}, CF{sub 3}CH{sub 2}O{sub 2}, CFH{sub 2}CFHO{sub 2}, CF{sub 3}O{sub 2}, and CF{sub 3}C(O)O{sub 2} were investigated by the FTIR setup. The results show that the self reaction of halogenated peroxy radicals give the alkoxy radical, RO, as product. The atmospheric fate of these radicals were C-C bond cleavage for CF{sub 3}CF{sub 2}O, CHF{sub 2}CF{sub 2}O, CFH{sub 2}CHFO, and CF{sub 3}C(O)O; while CF{sub 3}CH{sub 2}O radicals rect with O{sub 2} to give CF{sub 3}CHO and HO{sub 2}. the reaction between CFH{sub 2}O{sub 2} and HO{sub 2} was shown to give 29{+-}7 % CH{sub 2}FCOOH and 72{+-}11 % HCOF as the carbon containing products. (Abstract Truncated)

  4. Atmospheric chemistry of i-butanol.

    Science.gov (United States)

    Andersen, V F; Wallington, T J; Nielsen, O J

    2010-12-02

    Smog chamber/FTIR techniques were used to determine rate constants of k(Cl + i-butanol) = (2.06 ± 0.40) × 10(-10), k(Cl + i-butyraldehyde) = (1.37 ± 0.08) × 10(-10), and k(OH + i-butanol) = (1.14 ± 0.17) × 10(-11) cm(3) molecule(-1) s(-1) in 700 Torr of N(2)/O(2) diluent at 296 ± 2K. The UV irradiation of i-butanol/Cl(2)/N(2) mixtures gave i-butyraldehyde in a molar yield of 53 ± 3%. The chlorine atom initiated oxidation of i-butanol in the absence of NO gave i-butyraldehyde in a molar yield of 48 ± 3%. The chlorine atom initiated oxidation of i-butanol in the presence of NO gave (molar yields): i-butyraldehyde (46 ± 3%), acetone (35 ± 3%), and formaldehyde (49 ± 3%). The OH radical initiated oxidation of i-butanol in the presence of NO gave acetone in a yield of 61 ± 4%. The reaction of chlorine atoms with i-butanol proceeds 51 ± 5% via attack on the α-position to give an α-hydroxy alkyl radical that reacts with O(2) to give i-butyraldehyde. The atmospheric fate of (CH(3))(2)C(O)CH(2)OH alkoxy radicals is decomposition to acetone and CH(2)OH radicals. The atmospheric fate of OCH(2)(CH(3))CHCH(2)OH alkoxy radicals is decomposition to formaldehyde and CH(3)CHCH(2)OH radicals. The results are consistent with, and serve to validate, the mechanism that has been assumed in the estimation of the photochemical ozone creation potential of i-butanol.

  5. An Experiment in Forensic Chemistry: The Breathalyzer.

    Science.gov (United States)

    Timmer, William C.

    1986-01-01

    Describes a simple experiment done in a quantitative analysis course that illustrates the chemistry of the breath alcohol test. Discusses the development and use of the Breathalyzer. Outlines the experimental procedure, along with the appropriate calculations and discussion of the results. (TW)

  6. Chemistry of Atmospheres: An Introduction to the Chemistry of the Atmospheres of Earth, the Planets and Their Satellites

    Science.gov (United States)

    Beebe, Reta; Barnet, Chris

    The author of this book states that he has attempted to produce a text that will be “intelligible to readers approaching atmospheric chemistry from any scientific discipline.” He proposes to provide the links between atmospheric chemistry and the traditional approaches to physics, chemistry, and biology. Within this context, he has presented a very readable general discussion at a level slightly higher than the popular level.Wayne has chosen not to interrupt the text with direct references but rather to group them at the back of each chapter. Although this sometimes raises a question concerning the basis of a specific statement, the references are in general adequate and extend through 1984. The manner in which the material is presented is not intimidating, and the book would be a good vehicle for introducing students to the subject and providing a starting point for individual research papers.

  7. Understanding atmospheric peroxyformic acid chemistry: observation, modeling and implication

    Directory of Open Access Journals (Sweden)

    H. Liang

    2015-01-01

    Full Text Available The existence and importance of peroxyformic acid (PFA in the atmosphere has been under controversy. We present here, for the first time, the observation data for PFA from four field measurements carried out in China. These data provided powerful evidence that PFA can stay in the atmosphere, typically in dozens of pptv level. The relationship between PFA and other detected peroxides was examined. The results showed that PFA had a strong positive correlation with its homolog, peroxyacetic acid, due to their similar sources and sinks. Through an evaluation of PFA production and removal rates, we proposed that the reactions between peroxyformyl radical (HC(OO2 and formaldehyde or the hydroperoxyl radical (HO2 were likely to be the major source and degradation into formic acid (FA was likely to be the major sink for PFA. Based on a box model evaluation, we proposed that the HC(OO2 and PFA chemistry was a major source for FA under low NOx conditions. Furthermore, it is found that the impact of the HC(OO2 and PFA chemistry on radical cycling was dependent on the yield of HC(OO2 radical from HC(O + O2 reaction. When this yield exceeded 50%, the HC(OO2 and PFA chemistry should not be neglected for calculating the radical budget. To make clear the exact importance of HC(OO2 and PFA chemistry in the atmosphere, further kinetic, field and modeling studies are required.

  8. Research for the advancement of green chemistry practice: Studies in atmospheric and educational chemistry

    Science.gov (United States)

    Cullipher, Steven Gene

    Green chemistry is a philosophy of chemistry that emphasizes a decreasing dependence on limited non-renewable resources and an increasing focus on preventing pollution byproducts of the chemical industry. In short, it is the discipline of chemistry practiced through the lens of environmental stewardship. In an effort to advance the practice of green chemistry, three studies will be described that have ramifications for the practice. The first study examines the atmospheric oxidation of a hydrofluorinated ether, a third-generation CFC replacement compound with primarily unknown atmospheric degradation products. Determination of these products has the potential to impact decisions on refrigerant usage in the future. The second study examines chemistry students' development of understanding benefits-costs-risks analysis when presented with two real-world scenarios: refrigerant choice and fuel choice. By studying how benefits-costs-risks thinking develops, curricular materials and instructional approaches can be designed to better foster the development of an ability that is both necessary for green chemists and important in daily decision-making for non-chemists. The final study uses eye tracking technology to examine students' abilities to interpret molecular properties from structural information in the context of global warming. Such abilities are fundamental if chemists are to appropriately assess risks and hazards of chemistry practice.

  9. What makes urban atmospheric chemistry different and special?

    Science.gov (United States)

    Harrison, Roy M.

    2016-04-01

    There has been a tendency in the atmospheric chemistry community to regard urban atmospheric chemistry as no different to global processes and to differentiate only in terms of the emissions density in models. Such an approach may be suitable for assessing the impact of urban emissions upon regional and global processes but is unsuited to generating a clear understanding of processes within the urban atmosphere itself. The urban atmosphere differentiates itself from the global atmosphere in terms of its density of emissions and relatively short timescales for chemical reaction processes, a consequence of which is that the key processes in the urban atmosphere are often different from those in the regional and remote atmosphere. This lecture will give relevant examples. One of the key aspects of both urban and rural/remote atmospheres is the oxidation of primary pollutants and the formation of secondary species. Such processes may differ markedly between urban and non-urban environments as there are major differences in the behaviour of key oxidants such as ozone, hydroxyl and NO3 radical. In the remote atmosphere the key production process for hydroxyl is through the photolysis of ozone to form excited state oxygen atoms which react with water vapour to form OH. In the urban atmosphere, concentrations of ozone are typically depressed relative to the rural atmosphere and hence this source of OH is less favourable. There are likely to be much higher concentrations of both nitrous acid and formaldehyde in the urban atmosphere whose photolysis is probably the major source of OH. Additionally, there is far more possibility for nocturnal formation of OH in the urban atmosphere from reactions of Criegee intermediates resulting from the oxidation of alkenes. As a consequence, it has been shown that winter to summer ratios of hydroxyl radical concentrations are much higher in the urban atmosphere than is typical of rural atmospheres in northern mid-latitudes. In rural

  10. Atmospheric Entry Experiments at IRS

    Science.gov (United States)

    Auweter-Kurtz, M.; Endlich, P.; Herdrich, G.; Kurtz, H.; Laux, T.; Löhle, S.; Nazina, N.; Pidan, S.

    2002-01-01

    Entering the atmosphere of celestial bodies, spacecrafts encounter gases at velocities of several km/s, thereby being subjected to great heat loads. The thermal protection systems and the environment (plasma) have to be investigated by means of computational and ground facility based simulations. For more than a decade, plasma wind tunnels at IRS have been used for the investigation of TPS materials. Nevertheless, ground tests and computer simulations cannot re- place space flights completely. Particularly, entry mission phases encounter challenging problems, such as hypersonic aerothermodynamics. Concerning the TPS, radiation-cooled materials used for reuseable spacecrafts and ablator tech- nologies are of importance. Besides the mentioned technologies, there is the goal to manage guidance navigation, con- trol, landing technology and inflatable technologies such as ballutes that aim to keep vehicles in the atmosphere without landing. The requirement to save mass and energy for planned interplanetary missions such as Mars Society Balloon Mission, Mars Sample Return Mission, Mars Express or Venus Sample Return mission led to the need for manoeuvres like aerocapture, aero-breaking and hyperbolic entries. All three are characterized by very high kinetic vehicle energies to be dissipated by the manoeuvre. In this field flight data are rare. The importance of these manoeuvres and the need to increase the knowledge of required TPS designs and behavior during such mission phases point out the need of flight experiments. As result of the experience within the plasma diagnostic tool development and the plasma wind tunnel data base, flight experiments like the PYrometric RE-entry EXperiment PYREX were developed, fully qualified and successfully flown. Flight experiments such as the entry spectrometer RESPECT and PYREX on HOPE-X are in the conceptual phase. To increase knowledge in the scope of atmospheric manoeuvres and entries, data bases have to be created combining both

  11. Evaluated kinetic and photochemical data for atmospheric chemistry

    Science.gov (United States)

    Baulch, D. L.; Cox, R. A.; Hampson, R. F., Jr.; Kerr, J. A.; Troe, J.; Watson, R. T.

    1980-01-01

    This paper contains a critical evaluation of the kinetics and photochemistry of gas phase chemical reactions of neutral species involved in middle atmosphere chemistry (10-55 km altitude). Data sheets have been prepared for 148 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each reaction a preferred value of the rate coefficient at 298 K is given together with a temperature dependency where possible. The selection of the preferred value is discussed, and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an appendix listing the available data on enthalpies of formation of the reactant and product species.

  12. Recent Discoveries and Future Challenges in Atmospheric Organic Chemistry.

    Science.gov (United States)

    Glasius, Marianne; Goldstein, Allen H

    2016-03-15

    Earth's atmosphere contains a multitude of organic compounds, which differ by orders of magnitude regarding fundamental properties such as volatility, reactivity, and propensity to form cloud droplets, affecting their impact on global climate and human health. Despite recent major research efforts and advances, there are still substantial gaps in understanding of atmospheric organic chemistry, hampering efforts to understand, model, and mitigate environmental problems such as aerosol formation in both polluted urban and more pristine regions. The analytical toolbox available for chemists to study atmospheric organic components has expanded considerably during the past decade, opening new windows into speciation, time resolution and detection of reactive and semivolatile compounds at low concentrations. This has provided unprecedented opportunities, but also unveiled new scientific challenges. Specific groundbreaking examples include the role of epoxides in aerosol formation especially from isoprene, the importance of highly oxidized, reactive organics in air-surface processes (whether atmosphere-biosphere exchange or aerosols), as well as the extent of interactions of anthropogenic and biogenic emissions and the resulting impact on atmospheric organic chemistry.

  13. Laboratory experiments in the study of the chemistry of the outer planets

    Science.gov (United States)

    Scattergood, T. W.

    It is shown that much information about planetary chemistry and physics can be gained through laboratory work. The types of experiments relevant to planetary research concern fundamental properties, spectral/optical properties, 'Miller-Urey' syntheses, and detailed syntheses. Specific examples of studies of the chemistry in the atmosphere of Titan are described with attention given to gas phase chemistry in the troposphere and the composition of model Titan aerosols. A list of work that still needs to be done is provided.

  14. Studies of Arctic Middle Atmosphere Chemistry using Infrared Absorption Spectroscopy

    Science.gov (United States)

    Lindenmaier, Rodica

    The objective of this Ph.D. project is to investigate Arctic middle atmosphere chemistry using solar infrared absorption spectroscopy. These measurements were made at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, which is operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC). This research is part of the CANDAC/PEARL Arctic Middle Atmosphere Chemistry theme and aims to improve our understanding of the processes controlling the stratospheric ozone budget using measurements of the concentrations of stratospheric constituents. The instrument, a Bruker IFS 125HR Fourier transform infrared (FTIR) spectrometer, has been specifically designed for high-resolution measurements over a broad spectral range and has been used to measure reactive species, source gases, reservoirs, and dynamical tracers at PEARL since August 2006. The first part of this research focuses on the optimization of ozone retrievals, for which 22 microwindows were studied and compared. The spectral region from 1000 to 1005 cm-1 was found to be the most sensitive in both the stratosphere and troposphere, giving the highest number of independent pieces of information and the smallest total error for retrievals at Eureka. Similar studies were performed in coordination with the Network for the Detection of Atmospheric Composition Change for nine other species, with the goal of improving and harmonizing the retrieval parameters among all Infrared Working Group sites. Previous satellite validation exercises have identified the highly variable polar conditions of the spring period to be a challenge. In this work, comparisons between the 125HR and ACE-FTS (Atmospheric Chemistry Experiment-Fourier transform spectrometer) from 2007 to 2010 have been used to develop strict criteria that allow the ground and satellite-based instruments to be confidently compared. After applying these criteria, the differences between the two instruments were generally

  15. Synthesis of Aspirin: A General Chemistry Experiment

    Science.gov (United States)

    Olmsted, John A., III

    1998-10-01

    An experiment is described that is suitable for the early portion of the laboratory in a general chemistry course and integrates organic examples. It is the two-step synthesis of aspirin starting from oil of wintergreen. The mechanism for this synthesis provides examples of three major classes of chemical reactions: hydrolysis, condensation, and proton transfer. To understand the chemistry, the student must be able to recognize the common molecular framework shared by oil of wintergreen, salicylic acid, and aspirin and to identify the -OH and -CO2 sites where chemical changes occur. The experiment differs in three ways from traditional aspirin synthesis experiments for general chemistry. It is designed to be performed early rather than late; it starts from a naturally occurring material and requires two steps rather than one; and it utilizes FTIR spectroscopy to distinguish among oil of wintergreen starting material, salicylic acid intermediate, and aspirin product. The use of FTIR spectroscopy introduces students to a modern analytical technique that is currently used in research involving aspirin.

  16. Particle precipitation: How the spectrum fit impacts atmospheric chemistry

    Science.gov (United States)

    Wissing, J. M.; Nieder, H.; Yakovchouk, O. S.; Sinnhuber, M.

    2016-11-01

    Particle precipitation causes atmospheric ionization. Modeled ionization rates are widely used in atmospheric chemistry/climate simulations of the upper atmosphere. As ionization rates are based on particle measurements some assumptions concerning the energy spectrum are required. While detectors measure particles binned into certain energy ranges only, the calculation of a ionization profile needs a fit for the whole energy spectrum. Therefore the following assumptions are needed: (a) fit function (e.g. power-law or Maxwellian), (b) energy range, (c) amount of segments in the spectral fit, (d) fixed or variable positions of intersections between these segments. The aim of this paper is to quantify the impact of different assumptions on ionization rates as well as their consequences for atmospheric chemistry modeling. As the assumptions about the particle spectrum are independent from the ionization model itself the results of this paper are not restricted to a single ionization model, even though the Atmospheric Ionization Module OSnabrück (AIMOS, Wissing and Kallenrode, 2009) is used here. We include protons only as this allows us to trace changes in the chemistry model directly back to the different assumptions without the need to interpret superposed ionization profiles. However, since every particle species requires a particle spectrum fit with the mentioned assumptions the results are generally applicable to all precipitating particles. The reader may argue that the selection of assumptions of the particle fit is of minor interest, but we would like to emphasize on this topic as it is a major, if not the main, source of discrepancies between different ionization models (and reality). Depending on the assumptions single ionization profiles may vary by a factor of 5, long-term calculations may show systematic over- or underestimation in specific altitudes and even for ideal setups the definition of the energy-range involves an intrinsic 25% uncertainty for the

  17. Trends in Mesospheric Dynamics and Chemistry: Simulations With a Model of the Entire Atmosphere

    Science.gov (United States)

    Brasseur, G. P.

    2005-05-01

    The cooling resulting from infrared CO2 radiative transfer is a major contribution to the energy budget of the middle atmosphere and thermosphere. The rapid increase of the atmospheric CO2 concentration resulting from anthropogenic emissions is therefore expected to lead, in general, to a substantial cooling in this height range. This can potentially be counteracted by heating due to absorption of near infrared radiation by CO2. Changes in ozone as a consequence of increasing methane and water vapor may also have an impact on the energy budget as dynamical changes caused by increased tropospheric temperatures. By means of numerical simulations with a general circulation and chemistry model of the entire atmosphere we will address the following questions: 1.) Can state-of-the-art atmospheric modeling explain the mesospheric temperature trends observed during the last decades? 2.)Which part of the temperature changes resulting from an increase of atmospheric CO2 is caused by local changes in the radiative budget and which part is influenced by remote dynamical effects? The model used is the newly developed Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA) that resolves the atmosphere from the Earth's surface up to about 250 km altitude, and is based on the 3-D dynamics from the ECHAM5 general circulation model and the chemistry scheme from MOZART-3. Results from different time slice experiment representative of years 1970 and 2000, and for a doubling of CO2 will be presented.

  18. Integrated Global Observation Strategy - Ozone and Atmospheric Chemistry Project

    Science.gov (United States)

    Hilsenrath, Ernest; Readings, C. J.; Kaye, J.; Mohnen, V.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The "Long Term Continuity of Stratospheric Ozone Measurements and Atmospheric Chemistry" project was one of six established by the Committee on Earth Observing Satellites (CEOS) in response to the Integrated Global Observing Strategy (IGOS) initiative. IGOS links satellite and ground based systems for global environmental observations. The strategy of this project is to develop a consensus of user requirements including the scientific (SPARC, IGAC, WCRP) and the applications community (WMO, UNEP) and to develop a long-term international plan for ozone and atmospheric chemistry measurements. The major components of the observing system include operational and research (meeting certain criteria) satellite platforms planned by the space faring nations which are integrated with a well supported and sustained ground, aircraft, and balloon measurements program for directed observations as well satellite validation. Highly integrated and continuous measurements of ozone, validation, and reanalysis efforts are essential to meet the international scientific and applications goals. In order to understand ozone trends, climate change, and air quality, it is essential to conduct long term measurements of certain other atmospheric species. These species include key source, radical, and reservoir constituents.

  19. Titan's organic chemistry: Results of simulation experiments

    Science.gov (United States)

    Sagan, Carl; Thompson, W. Reid; Khare, Bishun N.

    1992-01-01

    Recent low pressure continuous low plasma discharge simulations of the auroral electron driven organic chemistry in Titan's mesosphere are reviewed. These simulations yielded results in good accord with Voyager observations of gas phase organic species. Optical constants of the brownish solid tholins produced in similar experiments are in good accord with Voyager observations of the Titan haze. Titan tholins are rich in prebiotic organic constituents; the Huygens entry probe may shed light on some of the processes that led to the origin of life on Earth.

  20. Gridded global surface ozone metrics for atmospheric chemistry model evaluation

    Directory of Open Access Journals (Sweden)

    E. D. Sofen

    2015-07-01

    Full Text Available The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent dataset for the evaluation of chemical transport and chemistry-climate (Earth System models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total dataset of approximately 6600 sites and 500 million hourly observations from 1971–2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regional background locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This dataset is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily eight-hour average (MDA8, SOMO35, AOT40, and metrics related to air quality regulatory thresholds. Gridded datasets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi:10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452. We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

  1. Gridded global surface ozone metrics for atmospheric chemistry model evaluation

    Science.gov (United States)

    Sofen, E. D.; Bowdalo, D.; Evans, M. J.; Apadula, F.; Bonasoni, P.; Cupeiro, M.; Ellul, R.; Galbally, I. E.; Girgzdiene, R.; Luppo, S.; Mimouni, M.; Nahas, A. C.; Saliba, M.; Tørseth, K.

    2016-02-01

    The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent data set for the evaluation of chemical transport and chemistry-climate (Earth System) models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total data set of approximately 6600 sites and 500 million hourly observations from 1971-2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regionally representative locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This data set is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily 8-hour average (MDA8), sum of means over 35 ppb (daily maximum 8-h; SOMO35), accumulated ozone exposure above a threshold of 40 ppbv (AOT40), and metrics related to air quality regulatory thresholds. Gridded data sets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi: 10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452). We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

  2. Chemistry of Atmospheric Aerosols at Pacifichem 2015 Congress

    Energy Technology Data Exchange (ETDEWEB)

    Nizkorodov, Sergey [Univ. of California, Irvine, CA (United States)

    2016-12-28

    This grant was used to provide participant support for a symposium entitled “Chemistry of Atmospheric Aerosols” at the 2015 International Chemical Congress of Pacific Basin Societies (Pacifichem) that took place in Honolulu, Hawaii, USA, on December 15-20, 2015. The objective was to help attract both distinguished scientists as well as more junior researchers, including graduate students, to this international symposium by reducing the financial barrier for its attendance. It was the second time a symposium devoted to Atmospheric Aerosols was part of the Pacifichem program. This symposium provided a unique opportunity for the scientists from different countries to gather in one place and discuss the cutting edge advances in the cross-disciplinary areas of aerosol research. To achieve the highest possible impact, the PI and the symposium co-organizers actively advertised the symposium by e-mail and by announcements at other conferences. A number of people responded, and the end result was a very busy program with about 100 oral and poster presentation described in the attached PDF file. Presentations by invited speakers occupied approximately 30% of time in each of the sessions. In addition to the invited speakers, each session also had contributed presentations, including those by graduate students and postdoctoral researchers. This symposium gathered established aerosol chemists from a number of countries including United States, Canada, China, Japan, Korea, Australia, Brazil, Hongkong, Switzerland, France, and Germany. There were plenty of time for the attendees to discuss new ideas and potential collaborations both during the oral sessions and at the poster sessions of the symposium. The symposium was very beneficial to graduate student researchers, postdoctoral fellows, and junior researchers whose prior exposure to international aerosol chemistry science had been limited. The symposium provided junior researchers with a much broader perspective of aerosol

  3. The 1-way on-line coupled atmospheric chemistry model system MECO(n – Part 1: The limited-area atmospheric chemistry model COSMO/MESSy

    Directory of Open Access Journals (Sweden)

    A. Kerkweg

    2011-06-01

    Full Text Available The numerical weather prediction model of the Consortium for Small Scale Modelling (COSMO, maintained by the German weather service (DWD, is connected with the Modular Earth Submodel System (MESSy. This effort is undertaken in preparation of a~new, limited-area atmospheric chemistry model. This model is as consistent as possible, with respect to atmospheric chemistry and related processes, with a previously developed global atmospheric chemistry general circulation model: the ECHAM/MESSy Atmospheric Chemistry (EMAC model. The combined system constitutes a new research tool, bridging the global to the meso-γ scale for atmospheric chemistry research. MESSy provides the infrastructure and includes, among others, the process and diagnostic submodels for atmospheric chemistry simulations. Furthermore, MESSy is highly flexible allowing model setups with tailor made complexity, depending on the scientific question. Here, the connection of the MESSy infrastructure to the COSMO model is documented. Previously published prototype submodels for simplified tracer studies are generalised to be plugged-in and used in the global and the limited-area model. They are used to evaluate the tracer transport characteristics of the new COSMO/MESSy model system, an important prerequisite for future atmospheric chemistry applications. A supplementary document with further details on the technical implementation of the MESSy interface into COSMO with a complete list of modifications to the COSMO code is provided.

  4. Promoting Chemistry Learning through Undergraduate Work Experience in the Chemistry Lab: A Practical Approach

    Science.gov (United States)

    Yu, Hong-Bin

    2015-01-01

    Hiring undergraduate lab assistants in chemistry departments is common in college. However, few studies have focused on promoting undergraduate chemistry learning and thinking skills through this work experience in chemistry teaching laboratories. This article discusses the strategy we implemented in the lab assistant program. The…

  5. Cocrystal Controlled Solid-State Synthesis: A Green Chemistry Experiment for Undergraduate Organic Chemistry

    Science.gov (United States)

    Cheney, Miranda L.; Zaworotko, Michael J.; Beaton, Steve; Singer, Robert D.

    2008-01-01

    Green chemistry has become an important area of concern for all chemists from practitioners in the pharmaceutical industry to professors and the students they teach and is now being incorporated into lectures of general and organic chemistry courses. However, there are relatively few green chemistry experiments that are easily incorporated into…

  6. Laboratory studies of nitrate radical chemistry - application to atmospheric processes

    Energy Technology Data Exchange (ETDEWEB)

    Noremsaune, Ingse

    1997-12-31

    This thesis studies atmospheric chemistry and tries in particular to fill gaps in the data base of atmospheric reactions. It studies the nitrate radical reactions with chloroethenes and with but-2-yne (2-butyne). The mechanisms and rate coefficients for the NO{sub 3}-initiated degradation of the chloroethenes and 2-butyne were investigated by means of the static reaction chamber and the fast flow-discharge technique. The reactions between the nitrate radical and the chloroethenes were studied at atmospheric pressure in a reaction chamber with synthetic air as bath gas. FTIR (Fourier Transform InfraRed spectroscopy) spectroscopy was used to follow the reactions and to identify the products. Products were observed for the reactions with (E)-1,2-dichloroethene and tetrachloroethene, although the absorption bands are weak. The alkyl peroxynitrate and nitrate compounds form very strong and characteristic absorption bands. The rate coefficients for the reactions between NO{sub 3} and the chloroethenes were investigated at room temperature by three different methods. The results are given in tables. 132 refs., 44 figs., 21 tabs.

  7. Greener Approaches to Undergraduate Chemistry Experiments.

    Science.gov (United States)

    Kirchhoff, Mary, Ed.; Ryan, Mary Ann, Ed.

    This laboratory manual introduces the idea of Green Chemistry, which is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. Instructional samples are included to help teachers integrate green chemistry into the college chemistry curriculum. Each laboratory includes: (1) a…

  8. Response of the AMOC to reduced solar radiation - the modulating role of atmospheric chemistry

    Science.gov (United States)

    Muthers, Stefan; Raible, Christoph C.; Rozanov, Eugene; Stocker, Thomas F.

    2016-11-01

    The influence of reduced solar forcing (grand solar minimum or geoengineering scenarios like solar radiation management) on the Atlantic Meridional Overturning Circulation (AMOC) is assessed in an ensemble of atmosphere-ocean-chemistry-climate model simulations. Ensemble sensitivity simulations are performed with and without interactive chemistry. In both experiments the AMOC is intensified in the course of the solar radiation reduction, which is attributed to the thermal effect of the solar forcing: reduced sea surface temperatures and enhanced sea ice formation increase the density of the upper ocean in the North Atlantic and intensify the deepwater formation. Furthermore, a second, dynamical effect on the AMOC is identified driven by the stratospheric cooling in response to the reduced solar forcing. The cooling is strongest in the tropics and leads to a weakening of the northern polar vortex. By stratosphere-troposphere interactions, the stratospheric circulation anomalies induce a negative phase of the Arctic Oscillation in the troposphere which is found to weaken the AMOC through wind stress and heat flux anomalies in the North Atlantic. The dynamic mechanism is present in both ensemble experiments. In the experiment with interactive chemistry, however, it is strongly amplified by stratospheric ozone changes. In the coupled system, both effects counteract and weaken the response of the AMOC to the solar forcing reduction. Neglecting chemistry-climate interactions in model simulations may therefore lead to an overestimation of the AMOC response to solar forcing.

  9. The THS: Simulating Titan’s atmospheric chemistry at low temperature

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Upton, Kathleen T.; Beauchamp, Jack L.; Salama, Farid

    2015-08-01

    In Titan’s atmosphere, composed mainly of N2 (95-98%) and CH4 (2-5%), a complex chemistry occurs at low temperature, and leads to the production of heavy organic molecules and subsequently solid aerosols. Here, we used the Titan Haze Simulation (THS) experiment, an experimental setup developed at the NASA Ames COSmIC simulation facility to study Titan’s atmospheric chemistry at low temperature. In the THS, the chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge (~200K). Different N2-CH4-based gas mixtures can be injected in the plasma, with or without the addition of heavier precursors present as trace elements on Titan, in order to monitor the evolution of the chemical growth. Both the gas- and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed using a combination of complementary in situ and ex situ diagnostics.A recent mass spectrometry study of the gas phase has demonstrated that the THS is a unique tool to probe the first and intermediate steps of Titan’s atmospheric chemistry at Titan-like temperature. In particular, the mass spectra obtained in a N2-CH4-C2H2-C6H6 mixture are relevant for comparison to Cassini’s CAPS-IBS instrument. The results of a complementary study of the solid phase are consistent with the chemical growth evolution observed in the gas phase. Grains and aggregates form in the gas phase and can be jet deposited on various substrates for ex situ analysis. Scanning Electron Microscopy images show that more complex mixtures produce larger aggregates. A DART mass spectrometry analysis of the solid phase has detected the presence of aminoacetonitrile, a precursor of glycine, in the THS aerosols. X-ray Absorption Near Edge Structure (XANES) measurements also show the presence of imine and nitrile

  10. Non-equilibrium CO chemistry in the solar atmosphere

    CERN Document Server

    Ramos, A A; Carlsson, M; Cernicharo, J

    2003-01-01

    Investigating the reliability of the assumption of instantaneous chemical equilibrium (ICE) for calculating the CO number density in the solar atmosphere is of crucial importance for the resolution of the long-standing controversy over the existence of `cool clouds' in the chromosphere, and for determining whether the cool gas owes its existence to CO radiative cooling or to a hydrodynamical process. Here we report the first results of such an investigation in which we have carried out time-dependent gas-phase chemistry calculations in radiation hydrodynamical simulations of solar chromospheric dynamics. We show that while the ICE approximation turns out to be suitable for modeling the observed infrared CO lines at the solar disk center, it may substantially overestimate the `heights of formation' of strong CO lines synthesized close to the edge of the solar disk, especially concerning vigorous dynamic cases resulting from relatively strong photospheric disturbances. This happens because during the cool phase...

  11. The effects of atmospheric chemistry on radiation budget in the Community Earth Systems Model

    Science.gov (United States)

    Choi, Y.; Czader, B.; Diao, L.; Rodriguez, J.; Jeong, G.

    2013-12-01

    The Community Earth Systems Model (CESM)-Whole Atmosphere Community Climate Model (WACCM) simulations were performed to study the impact of atmospheric chemistry on the radiation budget over the surface within a weather prediction time scale. The secondary goal is to get a simplified and optimized chemistry module for the short time period. Three different chemistry modules were utilized to represent tropospheric and stratospheric chemistry, which differ in how their reactions and species are represented: (1) simplified tropospheric and stratospheric chemistry (approximately 30 species), (2) simplified tropospheric chemistry and comprehensive stratospheric chemistry from the Model of Ozone and Related Chemical Tracers, version 3 (MOZART-3, approximately 60 species), and (3) comprehensive tropospheric and stratospheric chemistry (MOZART-4, approximately 120 species). Our results indicate the different details in chemistry treatment from these model components affect the surface temperature and impact the radiation budget.

  12. Teaching Lab Report Writing through Inquiry: A Green Chemistry Stoichiometry Experiment for General Chemistry

    Science.gov (United States)

    Cacciatore, Kristen L.; Sevian, Hannah

    2006-01-01

    We present an alternative to a traditional first-year chemistry laboratory experiment. This experiment has four key features: students utilize stoichiometry, learn and apply principles of green chemistry, engage in authentic scientific inquiry, and discover why each part of a scientific lab report is necessary. The importance and essential…

  13. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    Directory of Open Access Journals (Sweden)

    Z. Peng

    2015-09-01

    studies, and by humidification. SOA photolysis is shown to be insignificant for most functional groups, except for nitrates and especially aromatics, which may be photolyzed at high UV flux settings. Our work further establishes the OFR's usefulness as a tool to study atmospheric chemistry and enables better experiment design and interpretation, as well as improved future reactor design.

  14. Role of climate feedback on methane and ozone studied with a coupled ocean-atmosphere-chemistry model.

    OpenAIRE

    Johnson, C E; D. S. Stevenson; Collins, W. J.; R. G. Derwent

    2001-01-01

    We present results from two experiments carried out with a coupled ocean-atmosphere-tropospheric chemistry model run continously over the period 1990 to 2100. In the control experiment, climate is unforced, but emissions of trace gases to the chemical model increase in line with an illustrative scenario for future trace gas emissions with medium high growth. In the climate change experiment trace gas emissions are identical to the control, but climate is also forced using greenhouse gas conce...

  15. Quantum Dots: An Experiment for Physical or Materials Chemistry

    Science.gov (United States)

    Winkler, L. D.; Arceo, J. F.; Hughes, W. C.; DeGraff, B. A.; Augustine, B. H.

    2005-01-01

    An experiment is conducted for obtaining quantum dots for physical or materials chemistry. This experiment serves to both reinforce the basic concept of quantum confinement and providing a useful bridge between the molecular and solid-state world.

  16. Chemistry of atmospheres formed during accretion of the Earth and other terrestrial planets

    CERN Document Server

    Schaefer, L

    2009-01-01

    We used chemical equilibrium and chemical kinetic calculations to model chemistry of the volatiles released by heating different types of carbonaceous, ordinary and enstatite chondritic material as a function of temperature and pressure. Our results predict the composition of atmospheres formed by outgassing during accretion of the Earth and other terrestrial planets. Outgassing of CI and CM carbonaceous chondritic material produces H2O-rich (steam) atmospheres in agreement with the results of impact experiments. However, outgassing of other types of chondritic material produces atmospheres dominated by other gases. Outgassing of ordinary (H, L, LL) and high iron enstatite (EH) chondritic material yields H2-rich atmospheres with CO and H2O being the second and third most abundant gases. Outgassing of low iron enstatite (EL) chondritic material gives a CO-rich atmosphere with H2, CO2, and H2O being the next most abundant gases. Outgassing of CV carbonaceous chondritic material gives a CO2-rich atmosphere with ...

  17. Dynamics and Chemistry of Marine Stratocumulus (DYCOMS) Experiment.

    Science.gov (United States)

    Lenschow, D. H.; Paluch, I. R.; Bandy, A. R.; Pearson, R., Jr.; Kawa, S. R.; Weaver, C. J.; Huebert, B. J.; Kay, J. G.; Thornton, D. C.; Driedger, A. R., III

    1988-09-01

    A combined atmospheric chemistry-meteorology experiment, the Dynamics and Chemistry of the Marine Stratocumulus (DYCOMS), was carried out during the summer of 1985 over the eastern Pacific Ocean using the NCAR Electra aircraft. The objectives were to 1) study the budgets of several trace reactive species in a relatively pristine, steady-state, horizontally homogeneous, well-mixed boundary layer capped by a strong inversion and 2) study the formation. maintenance and dissipation of marine stratocumulus that persists off the California coast (as well as similar regions elsewhere) in summer. We obtained both mean and turbulence measurements of meteorological variables within and above the cloud-capped boundary layer that is typical of this region. Ozone was used successfully as a tracer for estimating entrainment rate. We found, however, that horizontal variability was large enough for ozone that a correction needs to be included in the ozone budget for the horizontal displacement due to turns even though the airplane was allowed to drift with the wind. The time rate-of-change term was significant in both the ozone and radon budgets; as a result, a considerably longer time interval than the two hours used between sets of flight legs would be desirable to improve the measurement accuracy of this tern.

  18. The Deep Convective Clouds and Chemistry (DC3) Field Experiment

    Science.gov (United States)

    Barth, M. C.; Brune, W. H.; Cantrell, C. A.; Rutledge, S. A.; Crawford, J. H.; Huntrieser, H.; Homeyer, C. R.; Nault, B.; Cohen, R. C.; Pan, L.; Ziemba, L. D.

    2014-12-01

    The Deep Convective Clouds and Chemistry (DC3) field experiment took place in the central U.S. in May and June 2012 and had the objectives of characterizing the effect of thunderstorms on the chemical composition of the lower atmosphere and determining the chemical aging of upper troposphere (UT) convective outflow plumes. DC3 employed ground-based radars, lightning mapping arrays, and weather balloon soundings in conjunction with aircraft measurements sampling the composition of the inflow and outflow of a variety of thunderstorms in northeast Colorado, West Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the UT convective plume. The DC3 data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, and chemistry in the UT that is affected by the convection. In this presentation, we give an overview of the DC3 field campaign and highlight results from the campaign that are relevant to the upper troposphere and lower stratosphere region. These highlights include stratosphere-troposphere exchange in connection with thunderstorms, the 0-12 hour chemical aging and new particle formation in the UT outflow of a dissipating mesoscale convective system observed on June 21, 2012, and UT chemical aging in convective outflow as sampled the day after convection occurred and modeled in the Weather Research and Forecasting coupled with Chemistry model.

  19. Motivating to learn chemistry by experimenting at home

    OpenAIRE

    Krašovec, Urša

    2013-01-01

    The thesis entitled “Motivation for learning chemistry by experimenting at home” looks into the motivation of pupils for learning chemistry and their motivational orientation towards learning the subject. Based on the questionnaires “Learning motivation”, “How do I learn chemistry” and “Subject realisation” we determined the following: how the pupils prefer to learn chemistry; whether they like it; which learning methods they find most motivational; what is their opinion about experimental wo...

  20. Urban Climate Effects on Air Pollution and Atmospheric Chemistry

    Science.gov (United States)

    Rasoul, Tara; Bloss, William; Pope, Francis

    2016-04-01

    Tropospheric ozone, adversely affects the environment and human health. The presence of chlorine nitrate (ClNO2) in the troposphere can enhance ozone (O3) formation as it undergoes photolysis, releasing chlorine reactive atoms (Cl) and nitrogen dioxide (NO2), both of which enhance tropospheric ozone formation. The importance of new sources of tropospheric ClNO2 via heterogeneous processes has recently been highlighted. This study employed a box model, using the Master Chemical Mechanism (MCM version 3.2) to assess the effect of ClNO2 on air quality in urban areas within the UK. The model updated to include ClNO2 production, photolysis, a comprehensive parameterisation of dinitrogen pentoxide (N2O5) uptake, and ClNO2 production calculated from bulk aerosol composition. The model simulation revealed the presence of ClNO2 enhances the formation of NO2, organic peroxy radical (CH3O2), O3, and hydroxyl radicals (OH) when compared with simulations excluding ClNO2. In addition, the study examined the effect of temperature variation upon ClNO2 formation. The response of ClNO2 to temperature was analysed to identify the underlying drivers, of particular importance when assessing the response of atmospheric chemistry processes under potential future climates.

  1. Synthesis of Ethyl Nalidixate: A Medicinal Chemistry Experiment

    Science.gov (United States)

    Leslie, Ray; Leeb, Elaine; Smith, Robert B.

    2012-01-01

    A series of laboratory experiments that complement a medicinal chemistry lecture course in drug design and development have been developed. The synthesis of ethyl nalidixate covers three separate experimental procedures, all of which can be completed in three, standard three-hour lab classes and incorporate aspects of green chemistry such as…

  2. A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms

    Directory of Open Access Journals (Sweden)

    G. Sarwar

    2013-03-01

    Full Text Available We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2 into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 predictions generally agree better with the observed data than the CB05TU predictions. RACM2 enhances ozone for all ambient levels leading to higher bias at low (70 ppbv concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. While RACM2 enhances ozone and secondary aerosols by relatively large margins, control strategies developed for ozone or fine particles using the two mechanisms do not differ appreciably.

  3. A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms

    Directory of Open Access Journals (Sweden)

    G. Sarwar

    2013-10-01

    Full Text Available We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2 into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 enhances ozone compared to CB05TU at all ambient levels. Although it exhibited greater overestimates at lower observed concentrations, it displayed an improved performance at higher observed concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. Any air pollution control strategies developed using the two mechanisms do not differ appreciably.

  4. A fast stratospheric chemistry solver: the E4CHEM submodel for the atmospheric chemistry global circulation model EMAC

    Directory of Open Access Journals (Sweden)

    A. J. G. Baumgaertner

    2010-02-01

    Full Text Available The atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC and the atmospheric chemistry box model CAABA are extended by a computationally very efficient submodel for atmospheric chemistry, E4CHEM. It focuses on stratospheric chemistry but also includes background tropospheric chemistry. It is based on the chemistry of MAECHAM4-CHEM and is intended to serve as a simple and fast alternative to the flexible but also computationally more demanding submodel MECCA. In a model setup with E4CHEM, EMAC is now also suitable for simulations of longer time scales. The reaction mechanism contains basic O3, CH4, CO, HOx, NOx and ClOx gas phase chemistry. In addition, E4CHEM includes optional fast routines for heterogeneous reactions on sulphate aerosols and polar stratospheric clouds (substituting the existing submodels PSC and HETCHEM, and scavenging (substituting the existing submodel SCAV. We describe the implementation of E4CHEM into the MESSy structure of CAABA and EMAC. For some species the steady state in the box model differs by up to 100% when compared to results from CAABA/MECCA due to different reaction rates. After an update of the reaction rates in E4CHEM the mixing ratios in both boxmodel and 3-D model simulations are in satisfactory agreement with the results from a simulation where MECCA with a similar chemistry scheme was employed. Finally, a comparison against a simulation with a more complex and already evaluated chemical mechanism is presented in order to discuss shortcomings associated with the simplification of the chemical mechanism.

  5. Poster 6: Influence of traces elements in the organic chemistry of upper atmosphere of Titan

    Science.gov (United States)

    Mathe, Christophe; Carrasco, Nathalie; Trainer, Melissa G.; Gautier, Thomas; Gavilan, Lisseth; Dubois, David; Li, Xiang

    2016-06-01

    In the upper atmosphere of Titan, complex chemistry leads to the formation of organic aerosols. Since the work of Khare et al. in 1984, several experiments investigated the formation of Titan aerosols, so called tholins, in the laboratory. It has been suggested that nitrogen-containing compounds may contribute significantly to the aerosols formation process. In this study, we focused on the influence of pyridine, the simplest nitrogenous aromatic hydrocarbon, on the chemistry of Titan's atmosphere and on aerosol formation. To assess the effect of pyridine on aerosol formation chemistry, we used two different experimental setups : a capacitively coupled radio-frequency (electronic impact), and a VUV Deuterium lamp (photochemistry) in a collaboration between LATMOS (Guyancourt) and NASA-GSFC (Greenbelt), respectively. Aerosols produced with both setups were first analyzed using a FTIR-ATR (Fourier Transform Infrared spectroscopy - Attenuated Total Reflection) with a spectral range of 4000-800 cm-1 to characterize their optical properties. Next the samples were analysed using a Bruker Autoflex Speed MALDI mass spectrometer with a m/z range up to 2000 Da in order to infer their composition. Infrared spectroscopy analysis showed that tholins produced with a nitrogen-methane gas mixture (95:5) and nitrogenpyridine gas mixture (99:250ppm) present very similar spectra features. Tholins produced with a mixture of nitrogenmethane-pyridine (99:1:250ppm) do not present aliphatic CH2 or CH3 vibrational signatures. This could indicate a cyclic polymerization by a pyridine skeleton. Mass spectrometry is still in progress to confirm this.

  6. An Organic Chemistry Experiment for Forensic Science Majors.

    Science.gov (United States)

    Rothchild, Robert

    1979-01-01

    The laboratory experiment described here is intended to be of use to the forensic science major enrolled in a course in organic chemistry. The experiment is the use of thin-layer chromotography for qualitative analysis, specifically for the identification of drugs. (Author/SA)

  7. Spectroelectrochemical Sensing of Aqueous Iron: An Experiment for Analytical Chemistry

    Science.gov (United States)

    Shtoyko, Tanya; Stuart, Dean; Gray, H. Neil

    2007-01-01

    We have designed a laboratory experiment to illustrate the use of spectroelectrochemical techniques for determination of aqueous iron. The experiment described in this article is applicable to an undergraduate laboratory course in analytical chemistry. Students are asked to fabricate spectroelectrochemical sensors, make electrochemical and optical…

  8. Oxidation Kinetics of Copper: An Experiment in Solid State Chemistry.

    Science.gov (United States)

    Ebisuzaki, Y.; Sanborn, W. B.

    1985-01-01

    Oxidation kinetics in metals and the role defects play in diffusion-controlled reactions are discussed as background for a junior/senior-level experiment in the physical or inorganic chemistry laboratory. Procedures used and typical data obtained are provided for the experiment. (JN)

  9. Interdisciplinary Chemistry Experiment: An Environmentally Friendly Extraction of Lycopene

    Science.gov (United States)

    Zhu, Jie; Zhang, Mingjie; Liu, Qingwei

    2008-01-01

    A novel experiment for the extraction of lycopene from tomato paste without the use of an organic solvent is described. The experiment employs polymer, green, and analytical chemistry. This environmentally friendly extraction is more efficient and requires less time than the traditional approach using an organic solvent. The extraction is…

  10. Biodiesel Synthesis and Evaluation: An Organic Chemistry Experiment

    Science.gov (United States)

    Bucholtz, Ehren C.

    2007-01-01

    A new lab esterification reaction based on biodiesel preparation and viscosity, which provides a model experience of industrial process to understand oxidation of vicinal alcohols by periodic acid, is presented. This new desertification experiment and periodate analysis of glycerol for the introductory organic chemistry laboratory provides an…

  11. Simulating the impacts of large scale insect- and disease-driven tree mortality on atmospheric chemistry

    Science.gov (United States)

    Geddes, J.; Heald, C. L.; Silva, S. J.; Martin, R.

    2015-12-01

    Land-use and land-cover change (LUC) is an important driver of global change through the alteration of local energy, moisture, and carbon exchanges. LUC can also directly impact the emission and deposition of important reactive trace gases, altering the oxidative chemistry of the atmosphere and subsequently air quality and climate. Large-scale tree mortality as a result of insects and disease may therefore have unexplored feedbacks on atmospheric chemistry. Between 2013 and 2027, over 80 million acres of treed land in the United States is predicted to experience basal area mortality rates exceeding 25%. We harmonized the description of land cover across the relevant surface-atmosphere exchange processes in the GEOS-Chem chemical transport model to facilitate LUC simulations, and used this adapted model to test the impact of projected tree mortality according to the 2012 USDA National Insect and Disease Risk Assessment. Nation-wide biogenic VOC emissions were reduced by 5%, with local impacts approaching 50% in some regions. By themselves, these emission reductions resulted in lower surface-level O3 mixing ratios, but this was counteracted by decreases in the O3 deposition velocity (by up to 10%) due to the reduction in vegetation density. Organic aerosol mass concentrations were also significantly affected across the United States, decreasing by 5-10% across the eastern U.S. and the northwest, with local impacts exceeding 25% in some regions. We discuss the general impacts on air quality in clean and polluted regions of the US, and point to developments needed for a more robust understanding of land cover change feedbacks.

  12. Direct variational data assimilation algorithm for atmospheric chemistry data with transport and transformation model

    Science.gov (United States)

    Penenko, Alexey; Penenko, Vladimir; Nuterman, Roman; Baklanov, Alexander; Mahura, Alexander

    2015-11-01

    Atmospheric chemistry dynamics is studied with convection-diffusion-reaction model. The numerical Data Assimilation algorithm presented is based on the additive-averaged splitting schemes. It carries out ''fine-grained'' variational data assimilation on the separate splitting stages with respect to spatial dimensions and processes i.e. the same measurement data is assimilated to different parts of the split model. This design has efficient implementation due to the direct data assimilation algorithms of the transport process along coordinate lines. Results of numerical experiments with chemical data assimilation algorithm of in situ concentration measurements on real data scenario have been presented. In order to construct the scenario, meteorological data has been taken from EnviroHIRLAM model output, initial conditions from MOZART model output and measurements from Airbase database.

  13. The Atmospheric Lifetime Experiment. II - Calibration

    Science.gov (United States)

    Rasmussen, R. A.; Lovelock, J. E.

    1983-10-01

    The calibration standards used in the Atmospheric Lifetime Experiment (ALE) for CFCl3, CF2Cl2, CH3CCl3, and CCl4 are described. This includes the preparation of the primary standards by static dilution and their propagation and stability for the period 1977-1982. Two independent assessments of the absolute concentrations of the primary standards used to initiate the ALE measurements in 1977-1978 are reported. For consistency in the ALE program the values assigned to the primary standards and subsequent working standards used in the field were not altered during the experiment when results of better estimates of the original concentration values were obtained. Rather, the appropriate factors by which the ALE mixing ratios for a given species should be multiplied to obtain the best estimate of the current concentration of a given species, are provided.

  14. Atmospheric Chemistry Research in New EU Countries. A survey on atmospheric chemistry research and monitoring of air pollution in some new EU Member States and Candidate Countries

    Energy Technology Data Exchange (ETDEWEB)

    Batchvarova, E.; Spassova, T.; Valkov, N.; Iordanova, L. [Department of Composition of the Atmosphere and Hydrosphere, National IInstitute of Meteorology and Hydrology, Bulgarian Academy of Sciences, Sofia (Bulgaria); Hjorth, J. (ed.) [Institute for Environment and Sustainability, Joint Research Centre JRC, Ispra (Italy)

    2005-07-01

    Historically some of the new EU Member States and the Candidate countries experienced high levels of pollution in the past. Enhanced management measures were and are needed to improve the air quality. The present survey on the ongoing air chemistry research is in support to such measures and the incorporation of the EU environmental legislation in the air quality management of these countries. The aim of the survey is to list the current research activities on atmospheric chemistry in these countries, as well as groups and institutions involved in it. The air chemistry plays essential part of air quality and climate change modelling, energy industry planning and health risk assessments. In addition, the air quality monitoring networks and management are briefly discussed, as well as some information on the air pollution modelling research. The ongoing research (field, laboratory and modelling) in the field of chemical transformation of trace compounds in the atmosphere is discussed here and parallels are drown among 10 of the new EU Member States and Candidate Countries, namely Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, the Slovak Republic and Slovenia. Laboratory studies traditionally emphasize on rate and equilibrium processes. Field studies are based on aircraft and surface measurements of reaction chemistry, advective influences on the chemical composition of the atmosphere, and air-surface exchange processes. Both types experimental studies on atmospheric chemistry are demanding concerning equipment and resources. Therefore, most of the studies in the field are coming from international projects, EU, ESF or NATO funded. Modelling efforts address both chemistry and dynamics on regional and global scales. The analysis of research activities in those fields is made with regards of the current EU practice in the field and the historical frames in the ten countries of interest. The unique traditions and achievements in

  15. Experimental and Theoretical Studies of Atmosphereic Inorganic Chlorine Chemistry

    Science.gov (United States)

    Sander, Stanley P.; Friedl, Randall R.

    1993-01-01

    Over the last five years substantial progress has been made in defining the realm of new chlorine chemistry in the polar stratosphere. Application of existing experimental techniques to potentially important chlorine-containing compounds has yielded quantitative kinetic and spectroscopic data as well as qualitative mechanistic insights into the relevant reactions.

  16. Vesper - Venus Chemistry and Dynamics Orbiter - A NASA Discovery Mission Proposal: Submillimeter Investigation of Atmospheric Chemistry and Dynamics

    Science.gov (United States)

    Chin, Gordon

    2011-01-01

    Vesper conducts a focused investigation of the chemistry and dynamics of the middle atmosphere of our sister planet- from the base of the global cloud cover to the lower thermosphere. The middle atmosphere controls the stability of the Venus climate system. Vesper determines what processes maintain the atmospheric chemical stability, cause observed variability of chemical composition, control the escape of water, and drive the extreme super-rotation. The Vesper science investigation provides a unique perspective on the Earth environment due to the similarities in the middle atmosphere processes of both Venus and the Earth. Understanding key distinctions and similarities between Venus and Earth will increase our knowledge of how terrestrial planets evolve along different paths from nearly identical initial conditions.

  17. Estimating numerical errors due to operator splitting in global atmospheric chemistry models: Transport and chemistry

    Science.gov (United States)

    Santillana, Mauricio; Zhang, Lin; Yantosca, Robert

    2016-01-01

    We present upper bounds for the numerical errors introduced when using operator splitting methods to integrate transport and non-linear chemistry processes in global chemical transport models (CTM). We show that (a) operator splitting strategies that evaluate the stiff non-linear chemistry operator at the end of the time step are more accurate, and (b) the results of numerical simulations that use different operator splitting strategies differ by at most 10%, in a prototype one-dimensional non-linear chemistry-transport model. We find similar upper bounds in operator splitting numerical errors in global CTM simulations.

  18. Non-equilibrium chemistry in the atmospheres of brown dwarfs

    CERN Document Server

    Saumon, D S; Freedman, R S; Lodders, K

    2002-01-01

    Carbon monoxide and ammonia have been detected in the spectrum of Gl 229B at abundances that differ substantially from those obtained from chemical equilibrium. Vertical mixing in the atmosphere is a mechanism that can drive slowly reacting species out of chemical equilibrium. We explore the effects of vertical mixing as a function of mixing efficiency and effective temperature on the chemical abundances in the atmospheres of brown dwarfs and on their spectra. The models compare favorably with the observational evidence and indicate that vertical mixing plays an important role in brown dwarf atmospheres.

  19. A Code to Compute High Energy Cosmic Ray Effects on Terrestrial Atmospheric Chemistry

    CERN Document Server

    Krejci, Alex J; Thomas, Brian C

    2008-01-01

    A variety of events such as gamma-ray bursts may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), can be used to study atmospheric chemistry changes. The effect on atmospheric chemistry from astrophysically created high energy cosmic rays can now be studied using the NGSFC code. A table has been created that, with the use of the NGSFC code can be used to simulate the effects of high energy cosmic rays (10 GeV to 1 PeV) ionizing the atmosphere. We discuss the table, its use, weaknesses, and strengths.

  20. Solution Calorimetry Experiments for Physical Chemistry.

    Science.gov (United States)

    Raizen, Deborah A.; And Others

    1988-01-01

    Presents two experiments: the first one measures the heat of an exothermic reaction by the reduction of permanganate by the ferris ion; the second one measures the heat of an endothermic process, the mixing of ethanol and cyclohexane. Lists tables to aid in the use of the solution calorimeter. (MVL)

  1. Electrostatic activation of prebiotic chemistry in substellar atmospheres

    CERN Document Server

    Stark, Craig R; Diver, Declan A; Rimmer, Paul B

    2013-01-01

    Charged dust grains in the atmospheres of exoplanets may play a key role in the formation of prebiotic molecules, necessary to the origin of life. Dust grains submerged in an atmospheric plasma become negatively charged and attract a flux of ions that are accelerated from the plasma. The energy of the ions upon reaching the grain surface may be sufficient to overcome the activation energy of particular chemical reactions that would be unattainable via ion and neutral bombardment from classical, thermal excitation. As a result, prebiotic molecules or their precursors could be synthesised on the surface of dust grains that form clouds in exoplanetary atmospheres. This paper investigates the energization of the plasma ions, and the dependence on the plasma electron temperature, in the atmospheres of substellar objects such as gas giant planets. Calculations show that modest electron temperatures of $\\approx 1$ eV ($\\approx 10^{4}$ K) are enough to accelerate ions to sufficient energies that exceed the activation...

  2. Simulating Titan’s atmospheric chemistry at low temperature (200K)

    Science.gov (United States)

    Sciamma-O'Brien, Ella; Upton, Kathleen T.; Beauchamp, Jesse L.; Salama, Farid

    2016-06-01

    We present our latest results on the Titan Haze Simulation (THS) experiment developed on the COSmIC simulation chamber at NASA Ames Research Center. In Titan’s atmosphere, a complex organic chemistry induced by UV radiation and electron bombardment occurs between N2 and CH4 and leads to the production of larger molecules and solid aerosols. In the THS, the chemistry is simulated by pulsed plasma in the stream of a supersonic expansion, at Titan-like temperature (150 K). The residence time of the gas in the pulsed plasma discharge is on the order of 3 µs, hence the chemistry is truncated allowing us to probe the first and intermediate steps of the chemistry by adding heavier precursors into the initial N2-CH4 gas mixture.Two complementary studies of the gas phase and solid phase products have been performed in 4 different gas mixtures: N2-CH4, N2-CH4-C2H2, N2-CH4-C6H6 and N2-CH4-C2H2-C6H6 using a combination of in situ and ex situ diagnostics. The mass spectrometry analysis of the gas phase was the first to demonstrate that the THS is a unique tool to monitor the different steps of the N2-CH4 chemistry (Sciamma-O’Brien et al. 2014). The results of the solid phase study are consistent with the chemical growth evolution observed in the gas phase. Grains and aggregates that form in the gas phase were jet deposited on various substrates then collected for ex situ analysis. Scanning Electron Microscopy images have shown that more complex mixtures produce larger aggregates (100-500 nm in N2-CH4, up to 5 µm in N2-CH4-C2H2-C6H6). Moreover, the morphology of the grains seems to depend on the precursors, which could have a large impact for Titan’s models. We will present the latest results of the X-ray Absorption Near Edge Structure measurements, that show the different functional groups present in our samples and give the C/N ratio; as well as the Direct Analysis in Real Time Mass Spectrometry coupled with Collision Induced Dissociation analyses that have been

  3. NASA's Upper Atmosphere Research Program (UARP) and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1997-1999

    Science.gov (United States)

    Kurylo, M. J.; DeCola, P. L.; Kaye, J. A.

    2000-01-01

    Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology development, and monitoring of the Earth's upper atmosphere, with emphasis on the upper troposphere and stratosphere. This program aims at expanding our chemical and physical understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Research Division in the Office of Earth Science at NASA. Significant contributions to this effort have also been provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aero-Space Technology. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper troposphere and the stratosphere and their control on the distribution of atmospheric chemical species such as ozone; assess possible perturbations to the composition of the atmosphere caused by human activities and natural phenomena (with a specific emphasis on trace gas geographical distributions, sources, and sinks and the role of trace gases in defining the chemical composition of the upper atmosphere); understand the processes affecting the distributions of radiatively active species in the atmosphere, and the importance of chemical-radiative-dynamical feedbacks on the meteorology and climatology of the stratosphere and troposphere; and understand ozone production, loss, and recovery in an atmosphere with increasing abundances of greenhouse gases. The current report is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported

  4. Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

    Science.gov (United States)

    Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

    2011-02-01

    Clouds are multiphasic atmospheric systems in which the dissolved organic compounds, dominated by carboxylic acids, are subject to multiple chemical transformations in the aqueous phase. Among them, solar radiation, by generating hydroxyl radicals (•OH), is considered as the main catalyzer of the reactivity of organic species in clouds. We investigated to which extent the active biomass existing in cloud water represents an alternative route to the chemical reactivity of carboxylic acids. Pure cultures of seventeen bacterial strains (Arthrobacter, Bacillus, Clavibacter, Frigoribacterium, Pseudomonas, Sphingomonas and Rhodococcus), previously isolated from cloud water and representative of the viable community of clouds were first individually incubated in two artificial bulk cloud water solutions at 17 °C and 5 °C. These solutions mimicked the chemical composition of cloud water from "marine" and "continental" air masses, and contained the major carboxylic acids existing in the cloud water (i.e. acetate, formate, succinate and oxalate). The concentrations of these carboxylic compounds were monitored over time and biodegradation rates were determined. In average, they ranged from 2 ×10-19 for succinate to 1 × 10-18 mol cell-1 s-1 for formate at 17 °C and from 4 × 10-20 for succinate to 6 × 10-19 mol cell-1 s-1 for formate at 5 °C, with no significant difference between "marine" and "continental" media. In parallel, irradiation experiments were also conducted in these two artificial media to compare biodegradation and photodegradation of carboxylic compounds. To complete this comparison, the photodegradation rates of carboxylic acids by •OH radicals were calculated from literature data. Inferred estimations suggested a significant participation of microbes to the transformation of carboxylic acids in cloud water, particularly for acetate and succinate (up to 90%). Furthermore, a natural cloud water sample was incubated (including its indigenous microflora

  5. Synthesis of Bisphenol Z: An Organic Chemistry Experiment

    Science.gov (United States)

    Gregor, Richard W.

    2012-01-01

    A student achievable synthesis of bisphenol Z, 4,4'-(cyclohexane-1,1-diyl)diphenol, from the acid-catalyzed reaction of phenol with cyclohexanone is presented. The experiment exemplifies all the usual pedagogy for the standard topic of electrophilic aromatic substitution present in the undergraduate organic chemistry curriculum, while providing…

  6. Ionic Liquids and Green Chemistry: A Lab Experiment

    Science.gov (United States)

    Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

    2010-01-01

    Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of…

  7. Biodiesel from Seeds: An Experiment for Organic Chemistry

    Science.gov (United States)

    Goldstein, Steven W.

    2014-01-01

    Plants can store the chemical energy required by their developing offspring in the form of triglycerides. These lipids can be isolated from seeds and then converted into biodiesel through a transesterification reaction. This second-year undergraduate organic chemistry laboratory experiment exemplifies the conversion of an agricultural energy…

  8. UNESCO Chemistry Teaching Project in Asia: Experiments on Nuclear Science.

    Science.gov (United States)

    Dhabanandana, Salag

    This teacher's guide on nuclear science is divided into two parts. The first part is a discussion of some of the concepts in nuclear chemistry including radioactivity, types of disintegration, radioactive decay and growth, and tracer techniques. The relevant experiments involving the use of radioisotopes are presented in the second part. The…

  9. A Physical Chemistry Experiment in Polymer Crystallization Kinetics

    Science.gov (United States)

    Singfield, Kathy L.; Chisholm, Roderick A.; King, Thomas L.

    2012-01-01

    A laboratory experiment currently used in an undergraduate physical chemistry lab to investigate the rates of crystallization of a polymer is described. Specifically, the radial growth rates of typical disc-shaped crystals, called spherulites, growing between microscope glass slides are measured and the data are treated according to polymer…

  10. Impact of Improvements in Volcanic Implementation on Atmospheric Chemistry and Climate in the GISS-E2 Model

    Science.gov (United States)

    Tsigaridis, Kostas; LeGrande, Allegra; Bauer, Susanne

    2015-01-01

    The representation of volcanic eruptions in climate models introduces some of the largest errors when evaluating historical simulations, partly due to the crude model parameterizations. We will show preliminary results from the Goddard Institute for Space Studies (GISS)-E2 model comparing traditional highly parameterized volcanic implementation (specified Aerosol Optical Depth, Effective Radius) to deploying the full aerosol microphysics module MATRIX and directly emitting SO2 allowing us the prognosically determine the chemistry and climate impact. We show a reasonable match in aerosol optical depth, effective radius, and forcing between the full aerosol implementation and reconstructions/observations of the Mt. Pinatubo 1991 eruption, with a few areas as targets for future improvement. This allows us to investigate not only the climate impact of the injection of volcanic aerosols, but also influences on regional water vapor, O3, and OH distributions. With the skill of the MATRIX volcano implementation established, we explore (1) how the height of the injection column of SO2 influence atmospheric chemistry and climate response, (2) how the initial condition of the atmosphere influences the climate and chemistry impact of the eruption with a particular focus on how ENSO and QBO and (3) how the coupled chemistry could mitigate the climate signal for much larger eruptions (i.e. the 1258 eruption, reconstructed to be approximately 10x Pinatubo). During each sensitivity experiment we assess the impact on profiles of water vapor, O3, and OH, and assess how the eruption impacts the budget of each.

  11. Seasonal changes in Titan's middle-atmosphere chemistry and dynamics

    Science.gov (United States)

    Teanby, N. A.; Irwin, P. G. J.; Nixon, C. A.; de Kok, R.; Vinatier, S.; Coustenis, A.; Sefton-Nash, E.; Calcutt, S. B.; Flasar, F. M.

    2013-09-01

    Titan is the largest satellite of Saturn and is the only moon in our solar system with a significant atmo- sphere. Titan's middle-atmosphere (stratosphere and mesosphere) circulation usually comprises a single hemisphere to hemisphere meridional circulation cell, with upwelling air in the summer hemisphere and sub- siding air at the winter pole with an associated winter polar vortex. Titan has an axial tilt (obliquity) of 26.7°, so during its 29.5 Earth year annual cycle pronounced seasonal effects are encountered as the relative solar insolation in each hemisphere changes. The most dramatic of these changes is the reversal in global meridional circulation as the peak solar heating switches hemispheres after an equinox. Titan's northern spring equinox occurred in August 2009, and since then many middle-atmosphere changes have been observed by Cassini that were previously impossible to study (1,2,3,4). Here we present a detailed analysis of the post equinox changes in middle-atmosphere temperature and composition measured with Cassini's Composite InfraRed Spectrometer (CIRS), use these to infer changes in atmospheric circulation, and explore implications for atmospheric photochemical and dynamical processes. Our results show that the meridional circulation has now reversed (1).

  12. The role of computational chemistry in the science and measurements of the atmosphere

    Science.gov (United States)

    Phillips, D. H.

    1978-01-01

    The role of computational chemistry in determining the stability, photochemistry, spectroscopic parameters, and parameters for estimating reaction rates of atmospheric constituents is discussed. Examples dealing with the photolysis cross sections of HOCl and (1 Delta g) O2 and with the stability of gaseous NH4Cl and asymmetric ClO3 are presented. It is concluded that computational chemistry can play an important role in the study of atmospheric constituents, particularly reactive and short-lived species which are difficult to investigate experimentally.

  13. Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

    Science.gov (United States)

    Isaksen, Ivar S.A.; Gauss, Michael; Myhre, Gunnar; Walter Anthony, Katey M.; Ruppel, Carolyn

    2011-01-01

    The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.

  14. A Review of Atmospheric Chemistry Research in China: Photochemical Smog, Haze Pollution, and Gas-Aerosol Interactions

    Institute of Scientific and Technical Information of China (English)

    MA Jianzhong; XU Xiaobin; ZHAO Chunsheng; YAN Peng

    2012-01-01

    In this paper we present a review of atmospheric chemistry research in China over the period 2006-2010,focusing on tropospheric ozone,aerosol chemistry,and the interactions between trace gases and aerosols in the polluted areas of China.Over the past decade,China has suffered severe photochemical smog and haze pollution,especially in North China,the Yangtze River Delta,and the Pearl River Delta.Much scientific work on atmospheric chemistry and physics has been done to address this large-scale,complex environmental problem.Intensive field experiments,satellite data analyses,and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China.In addition to strong emissions of primary pollutants,photochemical and heterogeneous reactions play key roles in the formation of complex pollution.More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban,regional,and global scales.

  15. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Overview and Description of Models, Simulations and Climate Diagnostics

    Science.gov (United States)

    Lamarque, J.-F.; Shindell, D. T.; Naik, V.; Plummer, D.; Josse, B.; Righi, M.; Rumbold, S. T.; Schulz, M.; Skeie, R. B.; Strode, S.; Young, P. J.; Cionni, I.; Dalsoren, S.; Eyring, V.; Bergmann, D.; Cameron-Smith, P.; Collins, W. J.; Doherty, R.; Faluvegi, G.; Folberth, G.; Ghan, S. J.; Horowitz, L. W.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.

    2013-01-01

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) consists of a series of time slice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting composition changes and the associated radiative forcing. In this overview paper, we introduce the ACCMIP activity, the various simulations performed (with a requested set of 14) and the associated model output. The 16 ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions are responsible for a significant range across models, mostly in the case of ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind) reveals biases consistent with state-of-the-art climate models. The model-to- model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results. However, models that are clear outliers are different enough from the other models to significantly affect their simulation of atmospheric chemistry.

  16. Inorganic chemistry of O2 in a dense primitive atmosphere

    Science.gov (United States)

    Rosenqvist, J; Chassefière, E

    1995-01-01

    A simple steady-state photochemical model is developed in order to determine typical molecular oxygen concentrations for a comprehensive range of primitive abiotic atmospheres. Carbon dioxide is assumed to be the dominant constituent in these atmospheres since CO2 photodissociation may potentially result in the enhancement of the O2 partial pressure. The respective effects of the H2O content, temperature, eddy diffusion coefficient and UV flux on the results are investigated. It is shown that for any pressure at the surface, the partial pressure of molecular oxygen does not exceed 10 mbar. The peculiar case of a runaway greenhouse which has possibly taken place on Venus is qualitatively envisaged. Although O2 is basically absent in the present Venus atmosphere, a transient presence in a primitive stage cannot be ruled out. Possible mechanisms for O2 removal in such an atmosphere are reviewed. At the present stage, we think that the detection of large O2 amounts would be at least a good clue for the presence of life on an extrasolar planet.

  17. Isoprene nitrates: preparation, separation, identification, yields, and atmospheric chemistry

    Directory of Open Access Journals (Sweden)

    A. L. Lockwood

    2010-07-01

    Full Text Available Isoprene is an important atmospheric volatile organic compound involved in ozone production and NOx (NO+NO2 sequestration and transport. Isoprene reaction with OH in the presence of NO can form either isoprene hydroxy nitrates ("isoprene nitrates" or convert NO to NO2 which can photolyze to form ozone. While it has been shown that isoprene nitrate production can represent an important sink for NOx in forest impacted environments, there is little experimental knowledge of the relative importance of the individual isoprene nitrate isomers, each of which has a different fate and reactivity. In this work, we have identified the 8 individual isomers and determined their total and individual production yields. The overall yield of isoprene nitrates at atmospheric pressure and 295 K was found to be 0.070(+0.025/−0.015. Three isomers, representing nitrates resulting from OH addition to a terminal carbon, represent 90% of the total IN yield. We also determined the ozone rate constants for three of the isomers, and have calculated their atmospheric lifetimes, which range from ~1–2 h, making their oxidation products likely more important as atmospheric organic nitrates and sinks for nitrogen.

  18. Isoprene nitrates: preparation, separation, identification, yields, and atmospheric chemistry

    Directory of Open Access Journals (Sweden)

    A. L. Lockwood

    2010-04-01

    Full Text Available Isoprene is an important atmospheric volatile organic compound involved in ozone production and NOx (NO+NO2 sequestration and transport. Isoprene reaction with OH in the presence of NO can form either isoprene nitrates or convert NO to NO2 which can photolyze to form ozone. While it has been shown that isoprene nitrate production can represent an important sink for NOx in forest impacted environments, there is little experimental knowledge of the relative importance of the individual isoprene nitrate isomers, each of which has a different fate and reactivity. In this work, we have identified the 8 individual isomers and determined their total and individual production yields. The overall yield of isoprene nitrates at atmospheric pressure and 295 K was found to be 0.070(+0.025/–0.015. Three isomers, the (4,3-IN, (1,2-IN and Z-(4,1-IN represent 90% of the total IN yield. We also determined the ozone rate constants for three of the isomers, and have calculated their atmospheric lifetimes, which range from ~1–2 h, making their oxidation products likely more important as atmospheric organic nitrates and sinks for nitrogen.

  19. Advances in atmospheric chemistry modeling: the LLNL impact tropospheric/stratospheric chemistry model

    Energy Technology Data Exchange (ETDEWEB)

    Rotman, D A; Atherton, C

    1999-10-07

    We present a unique modeling capability to understand the global distribution of trace gases and aerosols throughout both the troposphere and stratosphere. It includes the ability to simulate tropospheric chemistry that occurs both in the gas phase as well as on the surfaces of solid particles. We have used this capability to analyze observations from particular flight campaigns as well as averaged observed data. Results show the model to accurately simulate the complex chemistry occurring near the tropopause and throughout the troposphere and stratosphere.

  20. Capacitively coupled plasma used to simulate Titan's atmospheric chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Alcouffe, G; Cernogora, G; Ouni, F [Universite de Versailles St Quentin, LATMOS BP3 - 91371 Verrieres-le-Buisson Cedex (France); Cavarroc, M [MID Dreux Innovation, 4 rue Albert Caquot, 28500 Vernouillet (France); Jolly, A [LISA, Universite Paris 12, 61 avenue du General de Gaulle, 94010 Creteil Cedex (France); Boufendi, L [GREMI Universite d' Orleans BP6744 - 45067 Orleans Cedex2 (France); Szopa, C [UPMC, Univ Paris 06, LATMOS BP3-91371 Verrieres-le-Buisson Cedex (France)], E-mail: gregoire.alcouffe@latmos.ipsl.fr

    2010-01-15

    A complex chemistry in Titan's atmosphere leads to the formation of organic solid aerosols. We use a radio-frequency (RF) capacitively coupled plasma discharge produced in different N{sub 2}-CH{sub 4} mixtures (from 0% to 10% of CH{sub 4}) to simulate this chemistry. The work presented here was devoted to the study of the plasma discharge. In our experiment, the electron density is measured by the resonant cavity method and is about 10{sup 15} m{sup -3} in pure N{sub 2} plasma at 30 W excitation RF power. It decreases by a factor of 2 as soon as CH{sub 4} is present in the discharge, even for a proportion as small as 2% of CH{sub 4}. An optical emission spectroscopy diagnostic is installed on the experiment to study the evolution of the N{sub 2} bands and to perform actinometry measurements using Ar lines. This diagnostic allowed us to measure variations in the electron temperature and to show that a decrease in the density of the electrons can be compensated by an increase in their energy. We have also used an experimental setup where the plasma is tuned in a pulsed mode, in order to study the formation of dust particles. We observed variations in the self-bias voltage, the RF injected power and the intensities of the nitrogen bands, which indicated that dust particles were formed. The characteristic dust formation time varied, depending on the experimental conditions, from 4 to 110 s. It was faster for higher pressures and for smaller proportions of CH{sub 4} in the gas mixture.

  1. A photochemical reactor for studies of atmospheric chemistry

    DEFF Research Database (Denmark)

    Nilsson, Elna Johanna Kristina; Eskebjerg, Carsten; Johnson, Matthew Stanley

    2009-01-01

    A photochemical reactor for studies of atmospheric kinetics and spectroscopy has been built at the Copenhagen Center for Atmospheric Research. The reactor consists of a vacuum FTIR spectrometer coupled to a 100 L quartz cylinder by multipass optics mounted on electropolished stainless steel end...... for OH, 3 106 cm3 for O(1D), 3.3 1010 cm3 for O(3P) and 1.6 1012 cm3 for Cl. The reactor can be operated at pressures from 103 to 103 mbar and temperatures from 240 to 330 K. As a test of the system we have studied the reaction CHCl3 þ Cl using the relative rate technique and find kCHCl3þCl/ kCH4þCl ¼ 1...

  2. Spanish-Speaking English Language Learners' Experiences in High School Chemistry Education

    Science.gov (United States)

    Flores, Annette; Smith, K. Christopher

    2013-01-01

    This article reports on the experiences of Spanish-speaking English language learners in high school chemistry courses, focusing largely on experiences in learning the English language, experiences learning chemistry, and experiences learning chemistry in the English language. The findings illustrate the cognitive processes the students undertake…

  3. Spanish-Speaking English Language Learners' Experiences in High School Chemistry Education

    Science.gov (United States)

    Flores, Annette; Smith, K. Christopher

    2013-01-01

    This article reports on the experiences of Spanish-speaking English language learners in high school chemistry courses, focusing largely on experiences in learning the English language, experiences learning chemistry, and experiences learning chemistry in the English language. The findings illustrate the cognitive processes the students undertake…

  4. On the atmospheric chemistry of NO2 - O3 systems; a laboratory study.

    NARCIS (Netherlands)

    Verhees, P.W.C.

    1986-01-01

    In this dissertation a laboratory study dealing with the atmospheric chemistry of NO 2 -O 3 systems is described. Knowledge of this system is relevant for a better understanding of a number of air pollution problems, particularly th

  5. Modelling iodide – iodate speciation in atmospheric aerosol: Contributions of inorganic and organic iodine chemistry

    Directory of Open Access Journals (Sweden)

    S. Pechtl

    2007-01-01

    Full Text Available The speciation of iodine in atmospheric aerosol is currently poorly understood. Models predict negligible iodide concentrations but accumulation of iodate in aerosol, both of which is not confirmed by recent measurements. We present an updated aqueous phase iodine chemistry scheme for use in atmospheric chemistry models and discuss sensitivity studies with the marine boundary layer model MISTRA. These studies show that iodate can be reduced in acidic aerosol by inorganic reactions, i.e., iodate does not necessarily accumulate in particles. Furthermore, the transformation of particulate iodide to volatile iodine species likely has been overestimated in previous model studies due to negligence of collision-induced upper limits for the reaction rates. However, inorganic reaction cycles still do not seem to be sufficient to reproduce the observed range of iodide – iodate speciation in atmospheric aerosol. Therefore, we also investigate the effects of the recently suggested reaction of HOI with dissolved organic matter to produce iodide. If this reaction is fast enough to compete with the inorganic mechanism, it would not only directly lead to enhanced iodide concentrations but, indirectly via speed-up of the inorganic iodate reduction cycles, also to a decrease in iodate concentrations. Hence, according to our model studies, organic iodine chemistry, combined with inorganic reaction cycles, is able to reproduce observations. The presented chemistry cycles are highly dependent on pH and thus offer an explanation for the large observed variability of the iodide – iodate speciation in atmospheric aerosol.

  6. On the numerical treatment of problems in atmospheric chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Aro, Colin J. [Univ. of California, Davis, CA (United States)

    1995-09-01

    Atmospheric chemical-radiative-transport (CRT) models are vital in performing research on atmospheric chemical change. Even with the enormous computing capability delivered by massively parallel systems, extended three dimensional CRT simulations are still not computationally feasible. The major obstacle in a CRT model is the nonlinear ODE system describing the chemical kinetics in the model. These ODE systems are usually very stiff and account for anywhere from 75% to 90% of the CPU time required to run a CRT model. In this study, a simple explicit class of time stepping method is developed and demonstrated to be useful in treating chemical ODE systems without the use of a Jacobian matrix. These methods, called preconditioned time differencing methods, are tested on small mathematically idealized problems, box model problems, and full 2-D and 3-D CRT models. The methods are found to be both fast and memory efficient. Studies are performed on both vector and parallel systems. The preconditioned time differencing methods are established as a viable alternative to the more common backward differentiation formulas in terms of CPU speed across architectural platforms.

  7. Aerosol formation and heterogeneous chemistry in the atmosphere

    Directory of Open Access Journals (Sweden)

    Liu Y.

    2012-01-01

    Full Text Available A general presentation of the Earth’s atmosphere is provided, with the associated photochemical processes and oxidizing capacity. The article focuses on the atmospheric reactivity of Volatile Organic Compounds (VOCs and the associated reaction products in the gas phase (ozone, oxygenated organic compounds, organic nitrates … and in the particle phase, namely, the Secondary Organic Aerosols (SOA. The understanding of the processes leading to SOA formation is currently a “hot topic” because of: i their high concentrations in the measured total organic matter, and ii their potential important impacts on health and climate change. The initial theory of SOA formation was based on thermodynamic phase transfers of oxidized reaction products of VOCs, but it failed to explain the presence of high molecular weight (high-MW compounds observed in SOA as well as a 1 to 2 orders of magnitude discrepancy between models and observations on the quantity of SOA. Therefore, different research investigations have been proposed such as heterogeneous and aqueous phase reactivity of organic compounds.

  8. Bunsen conference 1999. Atmospheric physical chemistry; Bunsentagung 1999. Physikalische Chemie der Atmosphaere

    Energy Technology Data Exchange (ETDEWEB)

    Crutzen, P.J.; Zellner, R. [comps.

    2000-07-01

    The main subject of the 1999 Bunsen conference was atmospheric physical chemistry. There were lectures and posters on measurement and distribution of atmospheric trace gases, photochemical reactions in the different parts of the atmosphere, natural and anthropogenic emissions resulting from biomass combustion, thermodynamics and microphysics of aerosol, and air pollution abatement. [German] Die Bunsentagung 1999 beschaeftigte sich mit dem Thema Physikalische Chemie der Atmosphaere. Themen der Vortraege und Poster waren u.a. die Messung und Verteilung von Spurengasen in der Atmosphaere, photochemische Reaktionen in den verschiedenen Schichten der Atmosphaere, natuerliche und anthropogene Emissionen durch Verbrennung von Biomasse, Thermodynamik und Microphysik von Aerosolen und Klimaschutz.

  9. Spiers Memorial Lecture. Introductory lecture: chemistry in the urban atmosphere.

    Science.gov (United States)

    Baltensperger, Urs

    2016-07-18

    The urban atmosphere is characterised by a multitude of complex processes. Gaseous and particulate components are continuously emitted into the atmosphere from many different sources. These components are then dispersed in the urban atmosphere via turbulent mixing. Numerous chemical reactions modify the gas phase chemistry on multiple time scales, producing secondary pollutants. Through partitioning, the chemical and physical properties of the aerosol particles are also constantly changing as a consequence of dispersion and gas phase chemistry. This review presents an overview of the involved processes, focusing on the contributions presented at this conference and putting them into a broader context. Advanced methods for aerosol source apportionment are presented as well, followed by some aspects of health effects related to air pollution.

  10. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP: overview and description of models, simulations and climate diagnostics

    Directory of Open Access Journals (Sweden)

    J.-F. Lamarque

    2012-08-01

    Full Text Available The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP consists of a series of timeslice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting radiative forcing and the associated composition changes. Here we introduce the various simulations performed under ACCMIP and the associated model output. The ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions lead to a significant range in emissions, mostly for ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind reveals biases consistent with state-of-the-art climate models. The model-to-model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results, but with outliers different enough to possibly affect their representation of climate impact on chemistry.

  11. Trends in the chemistry of atmospheric deposition and surface waters in the Lake Maggiore catchment

    Directory of Open Access Journals (Sweden)

    M. Rogora

    2001-01-01

    Full Text Available The Lake Maggiore catchment is the area of Italy most affected by acid deposition. Trend analysis was performed on long-term (15-30 years series of chemical analyses of atmospheric deposition, four small rivers draining forested catchments and four high mountain lakes. An improvement in the quality of atmospheric deposition was detected, due to decreasing sulphate concentration and increasing pH. Similar trends were also found in high mountain lakes and in small rivers. Atmospheric deposition, however, is still providing a large and steady flux of nitrogen compounds (nitrate and ammonium which is causing increasing nitrogen saturation in forest ecosystems and increasing nitrate levels in rivers. Besides atmospheric deposition, an important factor controlling water acidification and recovery is the weathering of rocks and soils which may be influenced by climate warming. A further factor is the episodic deposition of Saharan calcareous dust which contributes significantly to base cation deposition. Keywords: trend, atmospheric deposition, nitrogen, stream water chemistry.

  12. A dynamic model reduction algorithm for atmospheric chemistry models

    Science.gov (United States)

    Santillana, Mauricio; Le Sager, Philippe; Jacob, Daniel J.; Brenner, Michael

    2010-05-01

    Understanding the dynamics of the chemical composition of our atmosphere is essential to address a wide range of environmental issues from air quality to climate change. Current models solve a very large and stiff system of nonlinear advection-reaction coupled partial differential equations in order to calculate the time evolution of the concentration of over a hundred chemical species. The numerical solution of this system of equations is difficult and the development of efficient and accurate techniques to achieve this has inspired research for the past four decades. In this work, we propose an adaptive method that dynamically adjusts the chemical mechanism to be solved to the local environment and we show that the use of our approach leads to accurate results and considerable computational savings. Our strategy consists of partitioning the computational domain in active and inactive regions for each chemical species at every time step. In a given grid-box, the concentration of active species is calculated using an accurate numerical scheme, whereas the concentration of inactive species is calculated using a simple and computationally inexpensive formula. We demonstrate the performance of the method by application to the GEOS-Chem global chemical transport model.

  13. Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces

    OpenAIRE

    Chapleski, Robert C.; Zhang, Yafen; Troya, Diego; Morris, John R.

    2015-01-01

    Heterogeneous chemistry of the most important atmospheric oxidants, O3, NO3, and OH, plays a central role in regulating atmospheric gas concentrations, processing aerosols, and aging materials. Recent experimental and computational studies have begun to reveal the detailed reaction mechanisms and kinetics for gas-phase O3, NO3, and OH when they impinge on organic surfaces. Through new research approaches that merge the fields of traditional surface science with atmospheric chemistry, research...

  14. Research Experiences for Undergraduates in Estuarine and Atmospheric Processes

    Science.gov (United States)

    Aller, J. Y.

    2009-12-01

    Our program in the School of Marine and Atmospheric Sciences at Stony Brook University is unique in emphasizing the interdisciplinary study of coastal ocean and atmospheric processes. We attract a large number of both male and female undergraduate applicants representing diverse ethnic groups from across the country. Many are multi-discipline majors merging geology, biology, chemistry, or physics with engineering, and/or mathematics and welcome the opportunity to combine their academic training to examine environmental problems. Our goal is a program reflective of today’s world and environmental challenges, one that provides a ‘hands-on’ research experience which illustrates the usefulness of scientific research for understanding real-world problems or phenomena, and one in which students are challenged to apply their academic backgrounds to develop intuition about natural systems and processes. Projects this past summer focused on assessing climate change and its effects on coastal environments and processes. Projects addressed the implications of a changing global climate over the next 50 years on hydrologic cycles and coastal environments like barrier islands and beaches, on seasonal weather conditions and extreme events, on aerosols and the Earth’s radiative balance, and on aquatic habitats and biota. Collaborative field and laboratory or computer-based projects involving two or three REU students, graduate students, and several mentors, enable undergraduate students appreciate the importance of teamwork in addressing specific scientific questions or gaining maximum insight into a particular phenomenon or process. We believe that our approach allows students to understand what their role will be as scientists in the next phase of our earth’s evolution.

  15. Variational fine-grained data assimilation schemes for atmospheric chemistry transport and transformation models

    Science.gov (United States)

    Penenko, Alexey; Penenko, Vladimir; Tsvetova, Elena

    2015-04-01

    The paper concerns data assimilation problem for an atmospheric chemistry transport and transformation models. Data assimilation is carried out within variation approach on a single time step of the approximated model. A control function is introduced into the model source term (emission rate) to provide flexibility to adjust to data. This function is evaluated as the minimum of the target functional combining control function norm to a misfit between measured and model-simulated analog of data. This provides a flow-dependent and physically-plausible structure of the resulting analysis and reduces the need to calculate model error covariance matrices that are sought within conventional approach to data assimilation. Extension of the atmospheric transport model with a chemical transformations module influences data assimilation algorithms performance. This influence is investigated with numerical experiments for different meteorological conditions altering convection-diffusion processes characteristics, namely strong, medium and low wind conditions. To study the impact of transformation and data assimilation, we compare results for a convection-diffusion model (without data assimilation), convection-diffusion with assimilation, convection-diffusion-reaction (without data assimilation) and convection-diffusion-reaction-assimilation models. Both high dimensionalities of the atmospheric chemistry models and a real-time mode of operation demand for computational efficiency of the algorithms. Computational issues with complicated models can be solved by using a splitting technique. As the result a model is presented as a set of relatively independent simple models equipped with a kind of coupling procedure. With regard to data assimilation two approaches can be identified. In a fine-grained approach data assimilation is carried out on the separate splitting stages [1,2] independently on shared measurement data. The same situation arises when constructing a hybrid model

  16. Quantum chemistry simulation on quantum computers: theories and experiments.

    Science.gov (United States)

    Lu, Dawei; Xu, Boruo; Xu, Nanyang; Li, Zhaokai; Chen, Hongwei; Peng, Xinhua; Xu, Ruixue; Du, Jiangfeng

    2012-07-14

    It has been claimed that quantum computers can mimic quantum systems efficiently in the polynomial scale. Traditionally, those simulations are carried out numerically on classical computers, which are inevitably confronted with the exponential growth of required resources, with the increasing size of quantum systems. Quantum computers avoid this problem, and thus provide a possible solution for large quantum systems. In this paper, we first discuss the ideas of quantum simulation, the background of quantum simulators, their categories, and the development in both theories and experiments. We then present a brief introduction to quantum chemistry evaluated via classical computers followed by typical procedures of quantum simulation towards quantum chemistry. Reviewed are not only theoretical proposals but also proof-of-principle experimental implementations, via a small quantum computer, which include the evaluation of the static molecular eigenenergy and the simulation of chemical reaction dynamics. Although the experimental development is still behind the theory, we give prospects and suggestions for future experiments. We anticipate that in the near future quantum simulation will become a powerful tool for quantum chemistry over classical computations.

  17. Atmospheric chemistry of polycyclic aromatic compounds with special emphasis on nitro derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Feilberg, A.

    2000-04-01

    Field measurements of polycyclic aromatic compounds (PAC) have been carried out at a semi-rural site and at an urban site. Correlation analyses, PAC indicators, and PAC ratios have been used to evaluate the importance of various sources of nitro-PAHs. A major source of nitro-PAHs is atmospheric transformation of PAHs initiated by OH radicals. Especially during long-range transport (LRT) of air pollution from Central Europe, the nitro-PAH composition in Denmark is dominated by nitro-PAHs formed in the atmosphere. Locally emitted nitro-PAHs are primarily from diesel vehicles. Levels of unsubstituted PAHs can also be strongly elevated in connection with LRT episodes. The ratio of 2-nitrofluoranthene relative to 1-nitropyrene is proposed as a measure of the relative photochemical age of particulate matter. Using this ratio, the relative mutagenicity of particle extracts appears to increase with increasing photochemical age. In connection with the field measurements, a method for measuring nitro-PAHs in particle extracts based on MS-MS detection has been developed. The atmospheric chemistry of nitronaphthalenes has been investigated with a smog chamber system combined with simulation with photochemical kinetics software. A methodology to implement gas-particle partitioning in a model based on chemical kinetics is described. Equilibrium constants (KP) for gas-particle partitioning of 1- and 2-nitronaphthalene have been determined. Mass transfer between the two phases appears to occur on a very short timescale. The gas phase photolysis of the nitronaphthalenes depends upon the molecular conformation. Significantly faster photolysis of 1-nitronaphthalene than of 2-nitronaphthalene is observed. The photochemistry of nitro-PAHs, and to some extent other PAC, associated with organic aerosols, has been studied with model systems simulating organic aerosol material. A number of aerosol constituents, including substituted phenols, benzaldehydes, and oxy-PAHs, are demonstrated to

  18. The 1953 Stanley L. Miller Experiment: Fifty Years of Prebiotic Organic Chemistry

    Science.gov (United States)

    Lazcano, Antonio; Bada, Jeffrey L.

    2003-01-01

    The field of prebiotic chemistry effectively began with a publication in Science 50 years ago by Stanley L. Miller on the spark discharge synthesis of amino acids and other compounds using a mixture of reduced gases that were thought to represent the components of the atmosphere on the primitive Earth. On the anniversary of this landmark publication, we provide here an accounting of the events leading to the publication of the paper. We also discuss the historical aspects that lead up to the landmark Miller experiment.

  19. Evaluation of NO+ reagent ion chemistry for online measurements of atmospheric volatile organic compounds

    Science.gov (United States)

    Koss, Abigail R.; Warneke, Carsten; Yuan, Bin; Coggon, Matthew M.; Veres, Patrick R.; de Gouw, Joost A.

    2016-07-01

    NO+ chemical ionization mass spectrometry (NO+ CIMS) can achieve fast (1 Hz and faster) online measurement of trace atmospheric volatile organic compounds (VOCs) that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument). Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC) interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1) NO+ is useful for isomerically resolved measurements of carbonyl species; (2) NO+ can achieve sensitive detection of small (C4-C8) branched alkanes but is not unambiguous for most; and (3) compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12-C15) n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.

  20. Interconnection of reactive oxygen species chemistry across the interfaces of atmospheric, environmental, and biological processes.

    Science.gov (United States)

    Anglada, Josep M; Martins-Costa, Marilia; Francisco, Joseph S; Ruiz-López, Manuel F

    2015-03-17

    Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in

  1. Ionization chemistry in the H2O-dominant atmospheres of the icy moons

    Science.gov (United States)

    Shematovich, V. I.; Johnson, R. E.

    2007-08-01

    The main pathways of the ionization chemistry for pure H2O- and mixed H2O+O2+CO2+NH3+CH4 atmospheres which are representative for neutral and ionized atmospheres of the icy bodies in the Jovian and Saturnian systems are discussed. The gaseous envelopes of the icy moons of the giant planets are formed usually due to the surface radiolysis by the solar UV radiation and energetic magnetospheric plasma (Johnson, 1990). The standard astrochemical UMIST2005 (UDFA05) network is used to infer the main chemical pathways of ionization chemistry in the pure or with admixtures of other volatile molecules water vapor atmospheres. In case of the H2O- dominant atmosphere the parent H2O molecules are easily dissociated and ionized by the solar UVradiation and the energetic magnetospheric electrons. These impact processes result in the formation of the secondary neutral and ionized products - chemically active radicals O and OH, and H+, H2+, O+, OH+, and H2O+ ions. Secondary ions have admixture abundances in the H2O-dominant atmospheres, because they are efficiently transformed to H3O+ hydroxonium ions in the fast ion-molecular reactions. The major H3O+ hydroxonium ion does not chemically interact with other neutrals, and is destroyed in the dissociative recombination with thermal electrons mainly reproducing the chemically simple H, H2, O, and OH species. In case of the mixed H2O+O2-dominant atmosphere corresponding to the near-surface atmospheres of icy moons (Shematovich et al., 2005), the ionization chemistry results in the formation of the second major ion O2+ - because ion of molecular oxygen has the lower ionization potential comparing with other parent species -H2, H2O, CO2. The H+, O+, OH+, and H2O+ ions can be easily converted to O2+ ions through the ion-molecular reactions. In case of significant admixture of molecular hydrogen it is possible to transfer the O2+ ions to the O2H+ ions through the fast reaction with H2 and further to the H3O+ ions through the ion

  2. Role of excited CF3CFHO radicals in the atmospheric chemistry of HFC-134a

    DEFF Research Database (Denmark)

    Wallington, T.J.; Hurley, M.D.; Fracheboud, J.M.;

    1996-01-01

    CFHO* radicals limits the formation of CF3C(O)F and hence CF3COOH in the atmospheric degradation of HFC-134a. We estimate that the CF3COOH yield from atmospheric oxidation of HFC-134a is 7-20%. Vibrationally excited alkoxy radicals may play an important role in the atmospheric chemistry of other...

  3. The impact of atmospheric circulation on the chemistry of the hot Jupiter HD 209458b

    CERN Document Server

    Agundez, M; Iro, N; Selsis, F; Hersant, F; Hebrard, E; Dobrijevic, M

    2012-01-01

    We investigate the effects of atmospheric circulation on the chemistry of the hot Jupiter HD 209458b. We use a simplified dynamical model and a robust chemical network, as opposed to previous studies which have used a three dimensional circulation model coupled to a simple chemical kinetics scheme. The temperature structure and distribution of the main atmospheric constituents are calculated in the limit of an atmosphere that rotates as a solid body with an equatorial rotation rate of 1 km/s. Such motion mimics a uniform zonal wind which resembles the equatorial superrotation structure found by three dimensional circulation models. The uneven heating of this tidally locked planet causes, even in the presence of such a strong zonal wind, large temperature contrasts between the dayside and nightside, of up to 800 K. This would result in important longitudinal variations of some molecular abundances if the atmosphere were at chemical equilibrium. The zonal wind, however, acts as a powerful disequilibrium process...

  4. Clouds and Chemistry Brown Dwarf Atmospheric Properties from Optical and Infrared Colors

    CERN Document Server

    Marley, M S; Saumon, D S; Lodders, K; Ackerman, A S; Freedman, R

    2001-01-01

    The optical and infrared colors of L and T dwarfs are sensitive to cloud sedimentation and chemical processes in their atmospheres. In particular the J-K color of a cooling brown dwarf is sensitive to the vertical distribution of condensates in its atmosphere. Only atmosphere models which include sedimentation of condensates are able to reproduce the observed trends in J-K in which objects first become redder, then bluer with falling effective temperature. The Sloan Digital Sky Survey color i'-z' is sensitive to assumptions surrounding the alkali metal chemistry. Chemical equilibrium models which account for cloud sedimentation predict redder colors, by up to 2 magnitudes, than models which neglect sedimentation. The i'-z' vs. J-K color-color diagram is thus interesting for the window it opens into diverse atmospheric processes. In addition, we predict the locus in this color-color diagram of brown dwarfs cooler than yet found.

  5. An Extended View of Ozone and Chemistry in the Atmosphere of Mars

    Science.gov (United States)

    Smith, Ramsey L.; Fast, Kelly E.; Kostiuk, T.; Lefevre, Frank; Hewagama, Tilak; Livengood, Timothy A.

    2011-01-01

    We present an ongoing effort to characterize chemistry in Mars' atmosphere in multiple seasons on timescales longer than spaceflight missions through coordinated efforts by GSFC's HIPWAC spectrometer and Mars Express SPICAM, archival measurements, and tests/application of photochemical models. The trace species ozone (03) is an effective probe of Mars' atmospheric chemistry because it is destroyed by odd-hydrogen species (HOx, from water vapor photolysis). Observed ozone is a critical test for specific predictions by 3-D photochemical models (spatial, diurnal, seasonal). Coordinated measurements by HIPWAC and SPICAM quantitatively linked mission data to the 23-year GSFC ozone data record and also revealed unanticipated inter-decadal variability of same-season ozone abundances, a possible indicator of changing cloud activity (heterogeneous sink for HOx). A detailed study of long-term conditions is critical to characterizing the predictability of Mars' seasonal chemical behavior, particularly in light of the implications of and the lack of explanation for reported methane behavior.

  6. Atmospheric chemistry of n-CxF2x+1CHO (x = 1, 2, 3, 4)

    DEFF Research Database (Denmark)

    Hurley, M. D.; Ball, J. C.; Wallington, T. J.;

    2006-01-01

    Smog chamber/FTIR techniques were used to study the atmospheric fate of n-C(x)F(2)(x)(+1)C(O) (x = 1, 2, 3, 4) radicals in 700 Torr O(2)/N(2) diluent at 298 +/- 3 K. A competition is observed between reaction with O(2) to form n-C(x)()F(2)(x)()(+1)C(O)O(2) radicals and decomposition to form n-C(x...... to the atmospheric chemistry of n-C(x)F(2)(x)(+1)C(O) radicals and their possible role in contributing to the formation of perfluorocarboxylic acids in the environment....

  7. Collaborative Research: Atmospheric Pressure Microplasma Chemistry-Photon Synergies Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Graves, David [Univ. of California, Berkeley, CA (United States)

    2017-02-07

    Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources shows greatly expanded range of applications of each of them. The plasma sources create active chemical species and these can be activated further by addition of photons and associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. The project combines construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling.

  8. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume III ? gas phase reactions of inorganic halogens

    OpenAIRE

    Atkinson, R.; Baulch, D. L.; Cox, R A; J. N. Crowley; Hampson, R. F.; Hynes, R. G.; Jenkin, M. E.; M. J. Rossi; Troe, J.

    2007-01-01

    International audience; This article, the third in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of inorganic halogen species, which were last published in J. Phys. Chem. Ref. Data, in 2000 (Atkinson et al., 2000), were updated on the IUPAC website in 2003 and are updated again in the present evaluation. The article consists of a summary sheet...

  9. Kinetic and photochemical data for atmospheric chemistry reactions of the nitrogen oxides

    Science.gov (United States)

    Hampson, R. F., Jr.

    1980-01-01

    Data sheets for thermal and photochemical reactions of importance in the atmospheric chemistry of the nitrogen oxides are presented. For each reaction the available experimental data are summarized and critically evaluated, and a preferred value of the rate coefficient is given. The selection of the preferred value is discussed and an estimate of its accuracy is given. For the photochemical process, the data are summarized, and preferred for the photoabsorption cross section and primary quantum yields are given.

  10. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II ? reactions of organic species

    OpenAIRE

    2005-01-01

    International audience; This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and eight appendices con...

  11. The Department of Energy's Atmospheric Chemistry Program: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    In response to a request from the Department of Energy's (DOE) Office of Health and Environmental Research (OHER), the Committee on Atmospheric Chemistry has reviewed OHER's Atmospheric Chemistry Program (ACP). This report contains the committee's evaluation and critique arising from that review. The review process included a two-day symposium held at the National Academy of Sciences on September 25 and 26, 1990, that focused on presenting the ACP's current components, recent scientific accomplishments, and scientific plans. Following the symposium, committee members met in a one-day executive session to formulate and outline this report. In undertaking this review, OHER and ACP management requested that the committee attempt to answer several specific questions involving the program's technical capability and productivity, its leadership and organization, and its future direction. These questions are given in the Appendix. This report represents the committee's response to the questions posed in the Appendix. Chapter I explores the committee's view of the role that atmospheric chemistry could and should assume within the DOE and its prospective National Energy Strategy. Chapter 2 assesses the current ACP, Chapter 3 presents recommendations for revising and strengthening it, and Chapter 4 restates the committee's conclusions and recommendations.

  12. The Department of Energy`s Atmospheric Chemistry Program: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-31

    In response to a request from the Department of Energy`s (DOE) Office of Health and Environmental Research (OHER), the Committee on Atmospheric Chemistry has reviewed OHER`s Atmospheric Chemistry Program (ACP). This report contains the committee`s evaluation and critique arising from that review. The review process included a two-day symposium held at the National Academy of Sciences on September 25 and 26, 1990, that focused on presenting the ACP`s current components, recent scientific accomplishments, and scientific plans. Following the symposium, committee members met in a one-day executive session to formulate and outline this report. In undertaking this review, OHER and ACP management requested that the committee attempt to answer several specific questions involving the program`s technical capability and productivity, its leadership and organization, and its future direction. These questions are given in the Appendix. This report represents the committee`s response to the questions posed in the Appendix. Chapter I explores the committee`s view of the role that atmospheric chemistry could and should assume within the DOE and its prospective National Energy Strategy. Chapter 2 assesses the current ACP, Chapter 3 presents recommendations for revising and strengthening it, and Chapter 4 restates the committee`s conclusions and recommendations.

  13. Matrix fluid chemistry experiment. Final report June 1998 - March 2003

    Energy Technology Data Exchange (ETDEWEB)

    Smellie, John A.T. [Conterra AB, Luleaa (Sweden); Waber, H. Niklaus [Univ. of Bern (Switzerland). Inst. of Geology; Frape, Shaun K. [Univ. of Waterloo (Canada). Dept. of Earth Sciences

    2003-06-01

    The Matrix Fluid Chemistry Experiment set out to determine the composition and evolution of matrix pore fluids/waters in low permeable rock located at repository depths in the Aespoe Hard Rock Laboratory (HRL). Matrix pore fluids/waters can be highly saline in composition and, if accessible, may influence the near-field groundwater chemistry of a repository system. Characterising pore fluids/waters involved in-situ borehole sampling and analysis integrated with laboratory studies and experiments on rock matrix drill core material. Relating the rate of in-situ pore water accumulation during sampling to the measured rock porosity indicated a hydraulic conductivity of 10{sup -14}-10{sup -13} m/s for the rock matrix. This was in accordance with earlier estimated predictions. The sampled matrix pore water, brackish in type, mostly represents older palaeo- groundwater mixtures preserved in the rock matrix and dating back to at least the last glaciation. A component of matrix pore 'fluid' is also present. One borehole section suggests a younger groundwater component which has accessed the rock matrix during the experiment. There is little evidence that the salinity of the matrix pore waters has been influenced significantly by fluid inclusion populations hosted by quartz. Crush/leach, cation exchange, pore water diffusion and pore water displacement laboratory experiments were carried out to compare extracted/calculated matrix pore fluids/waters with in-situ sampling. Of these the pore water diffusion experiments appear to be the most promising approach and a recommended site characterisation protocol has been formulated. The main conclusions from the Matrix Fluid Chemistry Experiment are: Groundwater movement within the bedrock hosting the experimental site has been enhanced by increased hydraulic gradients generated by the presence of the tunnel, and to a much lesser extent by the borehole itself. Over experimental timescales {approx}4 years) solute transport

  14. A Spectacular Experiment Exhibiting Atmospheric Pressure

    Science.gov (United States)

    Le Noxaïc, Armand

    2014-01-01

    The experiment described here is fairly easy to reproduce and dramatically shows the magnitude of ambient air pressure. Two circular plates of aluminum are applied one against the other. How do you make their separation very difficult? With only the help of an elastic band! You don't have to use a vacuum pump for this experiment.

  15. The Chemistry of Atmosphere-Forest Exchange (CAFE Model – Part 2: Application to BEARPEX-2007 observations

    Directory of Open Access Journals (Sweden)

    G. M. Wolfe

    2011-02-01

    Full Text Available In a companion paper, we introduced the Chemistry of Atmosphere-Forest Exchange (CAFE model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. Here, we apply CAFE to noontime observations from the 2007 Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007. In this work we evaluate the CAFE modeling approach, demonstrate the significance of in-canopy chemistry for forest-atmosphere exchange and identify key shortcomings in the current understanding of intra-canopy processes.

    CAFE generally reproduces BEARPEX-2007 observations but requires an enhanced radical recycling mechanism to overcome a factor of 6 underestimate of hydroxyl (OH concentrations observed during a warm (~29 °C period. Modeled fluxes of acyl peroxy nitrates (APN are quite sensitive to gradients in chemical production and loss, demonstrating that chemistry may perturb forest-atmosphere exchange even when the chemical timescale is long relative to the canopy mixing timescale. The model underestimates peroxy acetyl nitrate (PAN fluxes by 50% and the exchange velocity by nearly a factor of three under warmer conditions, suggesting that near-surface APN sinks are underestimated relative to the sources. Nitric acid typically dominates gross dry N deposition at this site, though other reactive nitrogen (NOy species can comprise up to 28% of the N deposition budget under cooler conditions. Upward NO2 fluxes cause the net above-canopy NOy flux to be ~30% lower than the gross depositional flux. CAFE under-predicts ozone fluxes and exchange velocities by ~20%. Large uncertainty in the parameterization of cuticular and ground deposition precludes conclusive attribution of non-stomatal fluxes to chemistry or surface uptake. Model-measurement comparisons of vertical concentration gradients for several emitted species suggests that the lower canopy airspace may be

  16. Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces.

    Science.gov (United States)

    Chapleski, Robert C; Zhang, Yafen; Troya, Diego; Morris, John R

    2016-07-01

    Heterogeneous chemistry of the most important atmospheric oxidants, O3, NO3, and OH, plays a central role in regulating atmospheric gas concentrations, processing aerosols, and aging materials. Recent experimental and computational studies have begun to reveal the detailed reaction mechanisms and kinetics for gas-phase O3, NO3, and OH when they impinge on organic surfaces. Through new research approaches that merge the fields of traditional surface science with atmospheric chemistry, researchers are developing an understanding for how surface structure and functionality affect interfacial chemistry with this class of highly oxidizing pollutants. Together with future research initiatives, these studies will provide a more complete description of atmospheric chemistry and help others more accurately predict the properties of aerosols, the environmental impact of interfacial oxidation, and the concentrations of tropospheric gases.

  17. Aqueous organic chemistry in the atmosphere: sources and chemical processing of organic aerosols.

    Science.gov (United States)

    McNeill, V Faye

    2015-02-03

    Over the past decade, it has become clear that aqueous chemical processes occurring in cloud droplets and wet atmospheric particles are an important source of organic atmospheric particulate matter. Reactions of water-soluble volatile (or semivolatile) organic gases (VOCs or SVOCs) in these aqueous media lead to the formation of highly oxidized organic particulate matter (secondary organic aerosol; SOA) and key tracer species, such as organosulfates. These processes are often driven by a combination of anthropogenic and biogenic emissions, and therefore their accurate representation in models is important for effective air quality management. Despite considerable progress, mechanistic understanding of some key aqueous processes is still lacking, and these pathways are incompletely represented in 3D atmospheric chemistry and air quality models. In this article, the concepts, historical context, and current state of the science of aqueous pathways of SOA formation are discussed.

  18. The 1-way on-line coupled atmospheric chemistry model system MECO(n – Part 1: Description of the limited-area atmospheric chemistry model COSMO/MESSy

    Directory of Open Access Journals (Sweden)

    A. Kerkweg

    2012-01-01

    Full Text Available The numerical weather prediction model of the Consortium for Small Scale Modelling (COSMO, maintained by the German weather service (DWD, is connected with the Modular Earth Submodel System (MESSy. This effort is undertaken in preparation of a new, limited-area atmospheric chemistry model. Limited-area models require lateral boundary conditions for all prognostic variables. Therefore the quality of a regional chemistry model is expected to improve, if boundary conditions for the chemical constituents are provided by the driving model in consistence with the meteorological boundary conditions. The new developed model is as consistent as possible, with respect to atmospheric chemistry and related processes, with a previously developed global atmospheric chemistry general circulation model: the ECHAM/MESSy Atmospheric Chemistry (EMAC model. The combined system constitutes a new research tool, bridging the global to the meso-γ scale for atmospheric chemistry research. MESSy provides the infrastructure and includes, among others, the process and diagnostic submodels for atmospheric chemistry simulations. Furthermore, MESSy is highly flexible allowing model setups with tailor made complexity, depending on the scientific question. Here, the connection of the MESSy infrastructure to the COSMO model is documented and also the code changes required for the generalisation of regular MESSy submodels. Moreover, previously published prototype submodels for simplified tracer studies are generalised to be plugged-in and used in the global and the limited-area model. They are used to evaluate the TRACER interface implementation in the new COSMO/MESSy model system and the tracer transport characteristics, an important prerequisite for future atmospheric chemistry applications. A supplementary document with further details on the technical implementation of the MESSy interface into COSMO with a complete list of modifications to the COSMO code is provided.

  19. A synthesis of atmospheric mercury depletion event chemistry linking atmosphere, snow and water

    Directory of Open Access Journals (Sweden)

    A. Steffen

    2007-07-01

    Full Text Available It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg. This phenomenon is termed atmospheric mercury depletion events (AMDEs and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review the history of Hg in Polar Regions, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the roles that the snow pack, oceans, fresh water and the sea ice play in the cycling of Hg are presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not

  20. A new Geoengineering Model Intercomparison Project (GeoMIP experiment designed for climate and chemistry models

    Directory of Open Access Journals (Sweden)

    S. Tilmes

    2014-08-01

    Full Text Available A new Geoengineering Model Intercomparison Project (GeoMIP experiment "G4 specified stratospheric aerosols" (short name: G4SSA is proposed to investigate the impact of stratospheric aerosol geoengineering on atmospheric composition, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulphur dioxide (SO2 into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annual tropical emission of 8 Tg SO2 year−1. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of two years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the significance of the impact of geoengineering and the abrupt termination after 50 years on climate and composition of the atmosphere in a changing environment. The zonal and monthly mean stratospheric aerosol input dataset is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.

  1. Mercury in the global atmosphere: Chemistry, deposition, and land-atmosphere interactions

    Science.gov (United States)

    Selin, Noelle Eckley

    This thesis uses a global 3-D chemical transport model (GEOS-Chem), in conjunction with worldwide atmospheric observations, to better understand and quantify biogeochemical cycling and deposition of mercury. GEOS-Chem includes gaseous elemental (Hg(0)), divalent (Hg(II)), and particulate (Hg(P)) mercury in the atmosphere, and includes coupling with the ocean, developed at University of Washington, and with land, developed in this work. Observed concentrations and seasonal variation of total gaseous mercury (TGM) are consistent with photochemical oxidation for Hg(0) partly balanced by in-cloud photochemical reduction of Hg(II). High TGM concentrations from ship cruises in the Northern Hemisphere are not reproduced, implying a problem either in measurements or our understanding of sources. Model results, supported by observations, suggest Hg(II) to be dominant at higher altitudes. Diurnal variability observed at marine sites suggests uptake by sea salt aerosols is a major deposition mechanism. Global biogeochemical cycles of mercury are constructed for pre-industrial and present-day using the first fully-coupled, global 3-D land-atmosphere-ocean mercury model. Atmosphere-surface cycling increases the effective mercury lifetime more than threefold against transfer to long-lived soil and ocean reservoirs. It is estimated that 68% of deposition to the U.S. is anthropogenic, including 16% from the legacy of anthropogenic mercury accumulated in soils and the deep ocean. Observed seasonal variations in U.S. wet deposition are used to constrain redox and deposition processes influencing the fate of North American and international emissions. The model reproduces the seasonal variation and latitudinal gradient of wet deposition flux measured in the eastern U.S., with a maximum in the Southeast and higher fluxes in summer and at lower latitudes. Seasonal variation is attributed to variations in oxidation and wet deposition rates at northern latitudes, and to seasonal

  2. International geophysics series theory of planetary atmospheres an introduction to their physics and chemistry

    CERN Document Server

    Marshall, John

    1978-01-01

    For advanced undergraduate and beginning graduate students in atmospheric, oceanic, and climate science, Atmosphere, Ocean and Climate Dynamics is an introductory textbook on the circulations of the atmosphere and ocean and their interaction, with an emphasis on global scales. It will give students a good grasp of what the atmosphere and oceans look like on the large-scale and why they look that way. The role of the oceans in climate and paleoclimate is also discussed. The combination of observations, theory and accompanying illustrative laboratory experiments sets this text apart by m

  3. Development of a Grid-Independent Geos-Chem Chemical Transport Model (v9-02) as an Atmospheric Chemistry Module for Earth System Models

    Science.gov (United States)

    Long, M. S.; Yantosca, R.; Nielsen, J. E; Keller, C. A.; Da Silva, A.; Sulprizio, M. P.; Pawson, S.; Jacob, D. J.

    2015-01-01

    The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been re-engineered to also serve as an atmospheric chemistry module for Earth system models (ESMs). This was done using an Earth System Modeling Framework (ESMF) interface that operates independently of the GEOSChem scientific code, permitting the exact same GEOSChem code to be used as an ESM module or as a standalone CTM. In this manner, the continual stream of updates contributed by the CTM user community is automatically passed on to the ESM module, which remains state of science and referenced to the latest version of the standard GEOS-Chem CTM. A major step in this re-engineering was to make GEOS-Chem grid independent, i.e., capable of using any geophysical grid specified at run time. GEOS-Chem data sockets were also created for communication between modules and with external ESM code. The grid-independent, ESMF-compatible GEOS-Chem is now the standard version of the GEOS-Chem CTM. It has been implemented as an atmospheric chemistry module into the NASA GEOS- 5 ESM. The coupled GEOS-5-GEOS-Chem system was tested for scalability and performance with a tropospheric oxidant-aerosol simulation (120 coupled species, 66 transported tracers) using 48-240 cores and message-passing interface (MPI) distributed-memory parallelization. Numerical experiments demonstrate that the GEOS-Chem chemistry module scales efficiently for the number of cores tested, with no degradation as the number of cores increases. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemistry module means that the relative cost goes down with increasing number of cores in a massively parallel environment.

  4. Development of a grid-independent GEOS-Chem chemical transport model (v9-02) as an atmospheric chemistry module for Earth system models

    Science.gov (United States)

    Long, M. S.; Yantosca, R.; Nielsen, J. E.; Keller, C. A.; da Silva, A.; Sulprizio, M. P.; Pawson, S.; Jacob, D. J.

    2015-03-01

    The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been re-engineered to also serve as an atmospheric chemistry module for Earth system models (ESMs). This was done using an Earth System Modeling Framework (ESMF) interface that operates independently of the GEOS-Chem scientific code, permitting the exact same GEOS-Chem code to be used as an ESM module or as a stand-alone CTM. In this manner, the continual stream of updates contributed by the CTM user community is automatically passed on to the ESM module, which remains state of science and referenced to the latest version of the standard GEOS-Chem CTM. A major step in this re-engineering was to make GEOS-Chem grid independent, i.e., capable of using any geophysical grid specified at run time. GEOS-Chem data sockets were also created for communication between modules and with external ESM code. The grid-independent, ESMF-compatible GEOS-Chem is now the standard version of the GEOS-Chem CTM. It has been implemented as an atmospheric chemistry module into the NASA GEOS-5 ESM. The coupled GEOS-5-GEOS-Chem system was tested for scalability and performance with a tropospheric oxidant-aerosol simulation (120 coupled species, 66 transported tracers) using 48-240 cores and message-passing interface (MPI) distributed-memory parallelization. Numerical experiments demonstrate that the GEOS-Chem chemistry module scales efficiently for the number of cores tested, with no degradation as the number of cores increases. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemistry module means that the relative cost goes down with increasing number of cores in a massively parallel environment.

  5. Development of a grid-independent GEOS-chem chemical transport model as an atmospheric chemistry module for Earth System Models

    Science.gov (United States)

    Long, M. S.; Yantosca, R.; Nielsen, J. E.; Keller, C. A.; da Silva, A.; Sulprizio, M. P.; Pawson, S.; Jacob, D. J.

    2014-11-01

    The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been re-engineered to also serve as an atmospheric chemistry module for Earth System Models (ESMs). This was done using an Earth System Modelling Framework (ESMF) interface that operates independently of the GEOS-Chem scientific code, permitting the exact same GEOS-Chem code to be used as an ESM module or as a stand-alone CTM. In this manner, the continual stream of updates contributed by the CTM user community is automatically passed on to the ESM module, which remains state-of-science and referenced to the latest version of the standard GEOS-Chem CTM. A major step in this re-engineering was to make GEOS-Chem grid-independent, i.e., capable of using any geophysical grid specified at run time. GEOS-Chem data "sockets" were also created for communication between modules and with external ESM code via the ESMF. The grid-independent, ESMF-compatible GEOS-Chem is now the standard version of the GEOS-Chem CTM. It has been implemented as an atmospheric chemistry module into the NASA GEOS-5 ESM. The coupled GEOS-5/GEOS-Chem system was tested for scalability and performance with a tropospheric oxidant-aerosol simulation (120 coupled species, 66 transported tracers) using 48-240 cores and MPI parallelization. Numerical experiments demonstrate that the GEOS-Chem chemistry module scales efficiently for the number of processors tested. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemistry module means that the relative cost goes down with increasing number of MPI processes.

  6. Some current problems in atmospheric ozone chemistry; role of chemical kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Cox, R.A.

    1987-03-01

    A review is given on selected aspects of the reaction mechanisms of current interest in the chemistry of atmospheric ozone. Atmospheric ozone is produced and removed by a complex series of elementary gas-phase photochemical reactions involving O/sub x/, HO/sub x/, NO/sub x/, CIO/sub x/ and hydrocarbon species. At the present time there is a good knowledge of the basic processes involved in ozone chemistry in the stratosphere and the troposphere and the kinetics of most of the key reactions are well defined. There are a number of difficulties in the theoretical descriptions of observed ozone behaviour which may be due to uncertainties in the chemistry. Examples are the failure to predict present day ozone in the photochemically controlled region above 35 Km altitude and the large reductions in the ozone column in the Antartic Spring which has been observed in recent years. In the troposphere there is growing evidence that ozone and other trace gases have changed appreciably from pre-industrial concentrations, due to chemical reactions involving man-made pollutants. Quantitative investigation of the mechanisms by which these changes may occur requires a sound laboratory kinetics data base.

  7. Atmospheric deposition and lake chemistry trends at a high mountain site in the eastern Alps

    Directory of Open Access Journals (Sweden)

    Bertha THALER

    2000-02-01

    Full Text Available Records of atmospheric precipitation chemistry starting in 1983 and a series of limnological investigations at two high mountain reference lakes starting in 1988 enable us to describe the response of lake water chemistry to changes in precipitation chemistry and climate. The lakes are located at an altitude well above the timberline in a watershed composed of acidic rocks. Despite the observed reduction in the sulphur atmospheric deposition, the reference lakes showed no corresponding decline in sulphate concentrations, but a marked increase in the acid neutralising capacity was apparent. Changes of the seasonal distribution pattern of the precipitation amounts and a general increase of the air temperature have likely produced an increased weathering which increased the concentration of many inlake solutes and drove the lakes toward more buffered conditions. This phenomenon superimposed to changes like other physical factors (radiation, nutritional conditions and biological factors (enhanced production, competition, predation has produced in the last years greater modifications than merely those to be expected from the decreased acidic input.

  8. A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

    Directory of Open Access Journals (Sweden)

    A. J. Poulain

    2008-03-01

    Full Text Available It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg. This phenomenon is termed atmospheric mercury depletion events (AMDEs and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does

  9. Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus

    CERN Document Server

    Visscher, C

    2005-01-01

    We use thermochemical equilibrium and kinetic calculations to model sulfur and phosphorus chemistry in the atmospheres of giant planets, brown dwarfs, low-mass stars, and extrasolar giant planets (EGPs). The chemical behavior of individual S- and P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. Our results are independent of any particular model atmosphere and the behavior of different gases can be used to constrain atmospheric structure and metallicity. Hydrogen sulfide is the dominant sulfur gas in substellar atmospheres and approximately represents the atmospheric sulfur inventory. Depending on the prevailing S and C chemistry, the abundance of minor sulfur gases may constrain atmospheric temperatures or metallicity. Disequilibrium abundances of PH3 are expected in the observable atmospheres of substellar objects, and PH3 is representative of the total P abundance in giant planets and T dwarfs. A number of other phosphorus gases become relatively abunda...

  10. Study of the atmospheric chemistry of radon progeny in laboratory and real indoor atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Hopke, P.K.

    1992-07-01

    This report covers the second year of the 28 month grant current grant to Clarkson University to study the chemical and physical behavior of the polonium 218 atom immediately following its formation by the alpha decay of radon. Because small changes in size for activity result in large changes in the delivered dose per unit exposure, this behavior must be understood if the exposure to radon progeny and it dose to the cells in the respiratory tract are to be fully assessed. Two areas of radon progeny behavior are being pursued; laboratory studies under controlled conditions to better understand the fundamental physical and chemical process that affect the progeny's atmospheric behavior and studies in actual indoor environments to develop a better assessment of the exposure of the occupants of that space to the size and concentration of the indoor radioactive aerosol. This report describes the progress toward achieving these objectives.

  11. Striking a Balance: Experiment and Concept in Undergraduate Inorganic Chemistry.

    Science.gov (United States)

    Frey, John E.

    1990-01-01

    Described is an inorganic chemistry course based on the premise that a balanced understanding of inorganic chemistry requires knowledge of the experimental, theoretical, and technological aspects of the subject. A detailed description of lectures and laboratories is included. (KR)

  12. Analytical Models of Exoplanetary Atmospheres. III. Gaseous C-H-O-N Chemistry with Nine Molecules

    Science.gov (United States)

    Heng, Kevin; Tsai, Shang-Min

    2016-10-01

    We present novel, analytical, equilibrium-chemistry formulae for the abundances of molecules in hot exoplanetary atmospheres that include the carbon, oxygen, and nitrogen networks. Our hydrogen-dominated solutions involve acetylene (C2H2), ammonia (NH3), carbon dioxide (CO2), carbon monoxide (CO), ethylene (C2H4), hydrogen cyanide (HCN), methane (CH4), molecular nitrogen (N2), and water (H2O). By considering only the gas phase, we prove that the mixing ratio of carbon monoxide is governed by a decic equation (polynomial equation of 10 degrees). We validate our solutions against numerical calculations of equilibrium chemistry that perform Gibbs free energy minimization and demonstrate that they are accurate at the ˜ 1 % level for temperatures from 500 to 3000 K. In hydrogen-dominated atmospheres, the ratio of abundances of HCN to CH4 is nearly constant across a wide range of carbon-to-oxygen ratios, which makes it a robust diagnostic of the metallicity in the gas phase. Our validated formulae allow for the convenient benchmarking of chemical kinetics codes and provide an efficient way of enforcing chemical equilibrium in atmospheric retrieval calculations.

  13. Active Upper-atmosphere Chemistry and Dynamics from Polar Circulation Reversal on Titan

    Science.gov (United States)

    Teanby, Nicholas A.; Irwin, Patrick Gerard Joseph; Nixon, Conor A.; DeKok, Remco; Vinatier, Sandrine; Coustenis, Athena; Sefton-Nash, Elliot; Calcutt, Simon B.; Flasar, Michael F.

    2012-01-01

    Saturn's moon Titan has a nitrogen atmosphere comparable to Earth's, with a surface pressure of 1.4 bar. Numerical models reproduce the tropospheric conditions very well but have trouble explaining the observed middle-atmosphere temperatures, composition and winds. The top of the middle-atmosphere circulation has been thought to lie at an altitude of 450 to 500 kilometres, where there is a layer of haze that appears to be separated from the main haze deck. This 'detached' haze was previously explained as being due to the colocation of peak haze production and the limit of dynamical transport by the circulation's upper branch. Herewe report a build-up of trace gases over the south pole approximately two years after observing the 2009 post-equinox circulation reversal, from which we conclude that middle-atmosphere circulation must extend to an altitude of at least 600 kilometres. The primary drivers of this circulation are summer-hemisphere heating of haze by absorption of solar radiation and winter-hemisphere cooling due to infrared emission by haze and trace gases; our results therefore imply that these effects are important well into the thermosphere (altitudes higher than 500 kilometres). This requires both active upper-atmosphere chemistry, consistent with the detection of high-complexity molecules and ions at altitudes greater than 950 kilometres, and an alternative explanation for the detached haze, such as a transition in haze particle growth from monomers to fractal structures.

  14. Results of an interactively coupled atmospheric chemistry - general circulation model. Comparison with observations

    Energy Technology Data Exchange (ETDEWEB)

    Hein, R.; Dameris, M.; Schnadt, C. [and others

    2000-01-01

    An interactively coupled climate-chemistry model which enables a simultaneous treatment of meteorology and atmospheric chemistry and their feedbacks is presented. This is the first model, which interactively combines a general circulation model based on primitive equations with a rather complex model of stratospheric and tropospheric chemistry, and which is computational efficient enough to allow long-term integrations with currently available computer resources. The applied model version extends from the Earth's surface up to 10 hPa with a relatively high number (39) of vertical levels. We present the results of a present-day (1990) simulation and compare it to available observations. We focus on stratospheric dynamics and chemistry relevant to describe the stratospheric ozone layer. The current model version ECHAM4.L39(DLR)/CHEM can realistically reproduce stratospheric dynamics in the Arctic vortex region, including stratospheric warming events. This constitutes a major improvement compared to formerly applied model versions. However, apparent shortcomings in Antarctic circulation and temperatures persist. The seasonal and interannual variability of the ozone layer is simulated in accordance with observations. Activation and deactivation of chlorine in the polar stratospheric vortices and their interhemispheric differences are reproduced. The consideration of the chemistry feedback on dynamics results in an improved representation of the spatial distribution of stratospheric water vapor concentrations, i.e., the simulated meriodional water vapor gradient in the stratosphere is realistic. The present model version constitutes a powerful tool to investigate, for instance, the combined direct and indirect effects of anthropogenic trace gas emissions, and the future evolution of the ozone layer. (orig.)

  15. NATO Advanced Study Institute on Pollutants from Combustion Formation and Impact on Atmospheric Chemistry

    CERN Document Server

    2000-01-01

    This volume is based on the lectures presented at the NATO Advanced Study Institute: (ASI) «Pollutants Formation from Combustion. Formation Mechanisms and Impact on th th Atmospheric Chemistry» held in Maratea, Italy, from 13 to 26 september 1998. Preservation of the environment is of increasing concern in individual countries but also at continental or world scales. The structure of a NATO ASI which involve lecturers and participants of different nationalities was thought as especially well suited to address environmental issues. As combustion is known to substantially contribute to the damaging of the atmosphere, it was natural to concentrate the ASI program on reviewing the currently available knowledge of the formation mechanisms of the main pollutants liberated by combustion systems. In most situations, pollutants are present as trace components and their formation and removal is strongly conditioned by the chemical reactions initiated by fuel consumption. Therefore specific lectures were aimed at defi...

  16. Airborne experiment results for spaceborne atmospheric synchronous correction system

    Science.gov (United States)

    Cui, Wenyu; Yi, Weining; Du, Lili; Liu, Xiao

    2015-10-01

    The image quality of optical remote sensing satellite is affected by the atmosphere, thus the image needs to be corrected. Due to the spatial and temporal variability of atmospheric conditions, correction by using synchronous atmospheric parameters can effectively improve the remote sensing image quality. For this reason, a small light spaceborne instrument, the atmospheric synchronous correction device (airborne prototype), is developed by AIOFM of CAS(Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences). With this instrument, of which the detection mode is timing synchronization and spatial coverage, the atmospheric parameters consistent with the images to be corrected in time and space can be obtained, and then the correction is achieved by radiative transfer model. To verify the technical process and treatment effect of spaceborne atmospheric correction system, the first airborne experiment is designed and completed. The experiment is implemented by the "satellite-airborne-ground" synchronous measuring method. A high resolution(0.4 m) camera and the atmospheric correction device are equipped on the aircraft, which photograph the ground with the satellite observation over the top simultaneously. And aerosol optical depth (AOD) and columnar water vapor (CWV) in the imagery area are also acquired, which are used for the atmospheric correction for satellite and aerial images. Experimental results show that using the AOD and CWV of imagery area retrieved by the data obtained by the device to correct aviation and satellite images, can improve image definition and contrast by more than 30%, and increase MTF by more than 1 time, which means atmospheric correction for satellite images by using the data of spaceborne atmospheric synchronous correction device is accurate and effective.

  17. The Integration of Green Chemistry Experiments with Sustainable Development Concepts in Pre-Service Teachers' Curriculum: Experiences from Malaysia

    Science.gov (United States)

    Karpudewan, Mageswary; Ismail, Zurida Hg; Mohamed, Norita

    2009-01-01

    Purpose: The purpose of this paper is to introduce green chemistry experiments as laboratory-based pedagogy and to evaluate effectiveness of green chemistry experiments in delivering sustainable development concepts (SDCs) and traditional environmental concepts (TECs). Design/methodology/approach: Repeated measure design was employed to evaluate…

  18. Atmospheric Line of Site Experiment (ALOSE) Final Campaign Summary

    Energy Technology Data Exchange (ETDEWEB)

    Smith, W. [Atmospheric Radiation Measurement (ARM) Climate Research Facility, Washington, DC (United States); Green, S. [Atmospheric Radiation Measurement (ARM) Climate Research Facility, Washington, DC (United States); Howard, M. [Atmospheric Radiation Measurement (ARM) Climate Research Facility, Washington, DC (United States); Yesalusky, M. [Atmospheric Radiation Measurement (ARM) Climate Research Facility, Washington, DC (United States); Modlin, N. [Atmospheric Radiation Measurement (ARM) Climate Research Facility, Washington, DC (United States)

    2016-03-01

    The Atmospheric Line of Site Experiment (ALOSE) was a project to produce best-estimate atmospheric state measurements at the: 1. DOE Atmospheric Radiation Measurement (ARM) Clouds and Radiation Test-bed (CART) site located in Lamont, Oklahoma (11–14 December 2012) 2. Poker Flat Alaska Research Range (PFRR) located in Poker Flat, Alaska (19–26 February 2013) 3. DOE ARM CART site located in Lamont, Oklahoma (24–28 April 2013) 4. DOE ARM CART site located in Lamont, Oklahoma (9–15 July 2013) 5. DOE ARM Tropical Western Pacific (TWP) site located in Darwin, Australia (27 September–3 October 2013).

  19. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    Science.gov (United States)

    Peng, Zhe; Day, Douglas A.; Ortega, Amber M.; Palm, Brett B.; Hu, Weiwei; Stark, Harald; Li, Rui; Tsigaridis, Kostas; Brune, William H.; Jimenez, Jose L.

    2016-04-01

    Oxidation flow reactors (OFRs) using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D), O(3P), and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H2O) and external OH reactivity (OHRext), as both non-OH reactants and OH scale roughly proportionally to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D), O(3P), and O3 have relative contributions to volatile organic compound (VOC) consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. We define "riskier OFR conditions" as those with either low H2O ( 200 s-1 in OFR254). We strongly suggest avoiding such conditions as the importance of non-OH reactants can be substantial for the most sensitive species, although OH may still dominate under some riskier conditions, depending on the species present. Photolysis at non-tropospheric wavelengths (185 and 254 nm) may play a significant (> 20 %) role in the degradation of some aromatics, as well as some oxidation intermediates, under riskier reactor conditions, if the quantum yields are high. Under riskier conditions, some biogenics can have substantial destructions by O3, similarly to the troposphere. Working under low O2 (volume mixing

  20. Data of long term atmospheric diffusion experiments (Winter, 1992)

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Takashi; Chino, Masamichi; Yamazawa, Hiromi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-10-01

    The data were obtained in the long-term atmospheric diffusion experiments in the Tokai area, autumn, 1991 which were a part of the Evaluation Safety Demonstration Experiments of Environmental Radiation entrusted with the Science and Technology Agency. The experiments were conducted by JAERI in cooperation with the Japan Weather Association. The report includes tracer concentration data of surface sampling points and meteorological data. (author)

  1. Impact of acid atmospheric deposition on soils: Field monitoring and aluminium chemistry.

    OpenAIRE

    1988-01-01

    The effect of acid atmospheric deposition on concentrations and transfer of major solutes in acid, sandy soils was studied. Emphasis was given to mobilization and transport of potentially toxic aluminum. Data on solute concentrations and fluxes in meteoric water as well as soil solutions were obtained from intensive monitoring programmes conducted at a number of sites in northwestern Europe and North-America. Specific hypotheses were tested in laboratory experiments.Atmospheric acid inputs do...

  2. Investigating the Chemical Pathways to PAH- and PANH-Based Aerosols in Titan's Atmospheric chemistry

    Science.gov (United States)

    Sciamma-O'Brien, Ella Marion; Contreras, Cesar; Ricketts, Claire Louise; Salama, Farid

    2011-01-01

    A complex organic chemistry between Titan's two main constituents, N2 and CH4, leads to the production of more complex molecules and subsequently to solid organic aerosols. These aerosols are at the origin of the haze layers giving Titan its characteristic orange color. In situ measurements by the Ion Neutral Mass Spectrometer (INMS) and Cassini Plasma Spectrometer (CAPS) instruments onboard Cassini have revealed the presence of large amounts of neutral, positively and negatively charged heavy molecules in the ionosphere of Titan. In particular, benzene (C6H6) and toluene (C6H5CH3), which are critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds, have been detected, suggesting that PAHs might play a role in the production of Titan s aerosols. Moreover, results from numerical models as well as laboratory simulations of Titan s atmospheric chemistry are also suggesting chemical pathways that link the simple precursor molecules resulting from the first steps of the N2-CH4 chemistry (C2H2, C2H4, HCN ...) to benzene, and to PAHs and nitrogen-containing PAHs (or PANHs) as precursors to the production of solid aerosols.

  3. The Chemistry of Atmosphere-Forest Exchange (CAFE Model – Part 1: Model description and characterization

    Directory of Open Access Journals (Sweden)

    G. M. Wolfe

    2010-09-01

    Full Text Available We present the Chemistry of Atmosphere-Forest Exchange (CAFE model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. CAFE integrates all key processes, including turbulent diffusion, emission, deposition and chemistry, throughout the forest canopy and mixed layer. It is the first model of its kind to incorporate the Master Chemical Mechanism (MCM and a suite of reactions for the oxidation of monoterpenes and sesquiterpenes, providing a more comprehensive description of the oxidative chemistry occurring within and above the forest. We use CAFE to simulate a young Ponderosa pine forest in the Sierra Nevada, CA. Utilizing meteorological constraints from the BEARPEX-2007 field campaign, we assess the sensitivity of modeled fluxes to parameterizations of diffusion, laminar sublayer resistance and radiation extinction. To characterize the general chemical environment of this forest, we also present modeled mixing ratio profiles of biogenic hydrocarbons, hydrogen oxides and reactive nitrogen. The vertical profiles of these species demonstrate a range of structures and gradients that reflect the interplay of physical and chemical processes within the forest canopy, which can influence net exchange.

  4. The Chemistry of Atmosphere-Forest Exchange (CAFE Model – Part 1: Model description and characterization

    Directory of Open Access Journals (Sweden)

    G. M. Wolfe

    2011-01-01

    Full Text Available We present the Chemistry of Atmosphere-Forest Exchange (CAFE model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. CAFE integrates all key processes, including turbulent diffusion, emission, deposition and chemistry, throughout the forest canopy and mixed layer. CAFE utilizes the Master Chemical Mechanism (MCM and is the first model of its kind to incorporate a suite of reactions for the oxidation of monoterpenes and sesquiterpenes, providing a more comprehensive description of the oxidative chemistry occurring within and above the forest. We use CAFE to simulate a young Ponderosa pine forest in the Sierra Nevada, CA. Utilizing meteorological constraints from the BEARPEX-2007 field campaign, we assess the sensitivity of modeled fluxes to parameterizations of diffusion, laminar sublayer resistance and radiation extinction. To characterize the general chemical environment of this forest, we also present modeled mixing ratio profiles of biogenic hydrocarbons, hydrogen oxides and reactive nitrogen. The vertical profiles of these species demonstrate a range of structures and gradients that reflect the interplay of physical and chemical processes within the forest canopy, which can influence net exchange.

  5. Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars.

    Science.gov (United States)

    Franz, Heather B; Kim, Sang-Tae; Farquhar, James; Day, James M D; Economos, Rita C; McKeegan, Kevin D; Schmitt, Axel K; Irving, Anthony J; Hoek, Joost; Dottin, James

    2014-04-17

    The geochemistry of Martian meteorites provides a wealth of information about the solid planet and the surface and atmospheric processes that occurred on Mars. The degree to which Martian magmas may have assimilated crustal material, thus altering the geochemical signatures acquired from their mantle sources, is unclear. This issue features prominently in efforts to understand whether the source of light rare-earth elements in enriched shergottites lies in crustal material incorporated into melts or in mixing between enriched and depleted mantle reservoirs. Sulphur isotope systematics offer insight into some aspects of crustal assimilation. The presence of igneous sulphides in Martian meteorites with sulphur isotope signatures indicative of mass-independent fractionation suggests the assimilation of sulphur both during passage of magmas through the crust of Mars and at sites of emplacement. Here we report isotopic analyses of 40 Martian meteorites that represent more than half of the distinct known Martian meteorites, including 30 shergottites (28 plus 2 pairs, where pairs are separate fragments of a single meteorite), 8 nakhlites (5 plus 3 pairs), Allan Hills 84001 and Chassigny. Our data provide strong evidence that assimilation of sulphur into Martian magmas was a common occurrence throughout much of the planet's history. The signature of mass-independent fractionation observed also indicates that the atmospheric imprint of photochemical processing preserved in Martian meteoritic sulphide and sulphate is distinct from that observed in terrestrial analogues, suggesting fundamental differences between the dominant sulphur chemistry in the atmosphere of Mars and that in the atmosphere of Earth.

  6. Analytical Models of Exoplanetary Atmospheres. III. Gaseous C-H-O-N Chemistry with 9 Molecules

    CERN Document Server

    Heng, Kevin

    2016-01-01

    We present novel, analytical, equilibrium-chemistry formulae for the abundances of molecules in hot exoplanetary atmospheres that include the carbon, oxygen and nitrogen networks. Our hydrogen-dominated solutions involve acetylene (C$_2$H$_2$), ammonia (NH$_3$), carbon dioxide (CO$_2$), carbon monoxide (CO), ethylene (C$_2$H$_4$), hydrogen cyanide (HCN), methane (CH$_4$), molecular nitrogen (N$_2$) and water (H$_2$O). By considering only the gaseous phase, we prove that the mixing ratio of carbon monoxide is governed by a decic equation (polynomial equation of degree 10). We validate our solutions against numerical calculations of equilibrium chemistry that perform Gibbs free energy minimization and demonstrate that they are accurate for temperatures from 500--3000 K. In hydrogen-dominated atmospheres, the ratio of abundances of HCN to CH$_4$ is nearly constant across a wide range of carbon-to-oxygen ratios, which makes it a robust diagnostic of the metallicity in the gas phase. Our validated formulae allow f...

  7. Lower Atmospheric Boundary Layer Experiment (LABLE) Final Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Klein, P [University of Oklahoma - School of Meteorology; Bonin, TA; Newman, JF [National Renewable Energy Laboratory; Turner, DD [National Oceanic and Atmospheric Administration; Chilson, P [University of Oklahoma; Blumberg, WG [University of Oklahoma; Mishra, S; Wainwright, CE; Carney, M [University of Oklahoma - School of Meteorology; Jacobsen, EP [University of Oklahoma; Wharton, S [Lawrence Livermore National Laboratory

    2015-11-01

    The Lower Atmospheric Boundary Layer Experiment (LABLE) included two measurement campaigns conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains site in Oklahoma during 2012 and 2013. LABLE was designed as a multi-phase, low-cost collaboration among the University of Oklahoma, the National Severe Storms Laboratory, Lawrence Livermore National Laboratory, and the ARM program. A unique aspect was the role of graduate students in LABLE. They served as principal investigators and took the lead in designing and conducting experiments using different sampling strategies to best resolve boundary-layer phenomena.

  8. Assimilation Experiments using Geodetic Observations to Diagnose AAM in a Chemistry-Climate Model

    Science.gov (United States)

    Neef, Lisa; Matthes, Katja

    2010-05-01

    Variation of the global angular momentum of the atmosphere (AAM) results from fluctuations in the mass-distribution and large-scale wind patterns of the atmosphere. It has moreoever been known for some time that global-scale natural modes of variability (such as ENSO) have clear footprints in the AAM history. Due to exchange of angular momentum between the atmosphere and the solid earth, fluctuations in AAM are reflected in observations of the Earth Rotation Parameters(ERPs). ERPs therefore provide an observational constraint for global climate models, via the simulated AAM. We are planning to assimilate ERPs into the chemistry-climate model ECHAM5/MESSy, to not only improve the agreement with observations but also to better diagnose model deficiencies. As a step toward developing such an assimilation system, we present a comparison between modeled AAM, and the AAM implied by ERP observations. We also illustrate and discuss the problem of extracting information about individual components of a model state from observations of a global integral quantity. This is done via data assimilation experiments in a highly simplified (Lorenz) dynamical system.

  9. Do organic surface films on sea salt aerosols influence atmospheric chemistry? ─ a model study

    Directory of Open Access Journals (Sweden)

    R. von Glasow

    2007-11-01

    Full Text Available Organic material from the ocean's surface can be incorporated into sea salt aerosol particles often producing a surface film on the aerosol. Such an organic coating can reduce the mass transfer between the gas phase and the aerosol phase influencing sea salt chemistry in the marine atmosphere. To investigate these effects and their importance for the marine boundary layer (MBL we used the one-dimensional numerical model MISTRA. We considered the uncertainties regarding the magnitude of uptake reduction, the concentrations of organic compounds in sea salt aerosols and the oxidation rate of the organics to analyse the possible influence of organic surfactants on gas and liquid phase chemistry with a special focus on halogen chemistry. By assuming destruction rates for the organic coating based on laboratory measurements we get a rapid destruction of the organic monolayer within the first meters of the MBL. Larger organic initial concentrations lead to a longer lifetime of the coating but lead also to an unrealistically strong decrease of O3 concentrations as the organic film is destroyed by reaction with O3. The lifetime of the film is increased by assuming smaller reactive uptake coefficients for O3 or by assuming that a part of the organic surfactants react with OH. With regard to tropospheric chemistry we found that gas phase concentrations for chlorine and bromine species decreased due to the decreased mass transfer between gas phase and aerosol phase. Aqueous phase chlorine concentrations also decreased but aqueous phase bromine concentrations increased. Differences for gas phase concentrations are in general smaller than for liquid phase concentrations. The effect on gas phase NO2 or NO is very small (reduction less than 5% whereas liquid phase NO2 concentrations increased in some cases by nearly 100%. We list suggestions for further laboratory studies which are needed for improved model studies.

  10. The Impacts of Marine Organic Emissions on Atmospheric Chemistry and Climate (Invited)

    Science.gov (United States)

    Meskhidze, N.; Gantt, B.

    2013-12-01

    Using laboratory studies and global/regional climate model results, this talk will contribute to two main research questions: 1) what can be learned about the carbon emission inducing stress factors for marine algae, and 2) what is a potential impact of marine biogenic volatile organic compound (VOC) emissions on global atmospheric chemistry and climate. Marine photosynthetic organisms emit VOCs which can form secondary organic aerosols (SOA). Currently large uncertainty exists in the magnitude of the marine biogenic sources, their spatiotemporal distribution, controlling factors, and contributions to natural background of organic aerosols. Here laboratory results for the production of isoprene and four monoterpene (α-pinene, β-pinene, camphene and d-limonene) compounds as a function of variable light and temperature regimes for 6 different phytoplankton species will be discussed. The experiment was designed to simulate the regions where phytoplankton is subjected to changeable light/temperature conditions. The samples were grown and maintained at a climate controlled room. VOCs accumulated in the water and headspace above the water were measured by passing the sample through a gas chromatography/mass system equipped with a sample pre-concentrator allowing detection of low ppt levels of hydrocarbons. The VOC production rates were distinctly different for light/temperature stressed (the first 12 hour cycle at light/temperature levels higher than what the cultures were acclimated to in a climate controlled room) and photo/temperature-acclimated (the second 12 hour light/temperature cycle) states. In general, all phytoplankton species showed a rapid increase in isoprene and monoterpene production at higher light levels (between 150 to 420 μE m-2 s-1) until a constant production rate was reached. Isoprene and α-pinene, production rates also increased with temperature until a certain level, after which the rates declined as temperature increased further. Two

  11. Guided-Inquiry Experiments for Physical Chemistry: The POGIL-PCL Model

    Science.gov (United States)

    Hunnicutt, Sally S.; Grushow, Alexander; Whitnell, Robert

    2015-01-01

    The POGIL-PCL project implements the principles of process-oriented, guided-inquiry learning (POGIL) in order to improve student learning in the physical chemistry laboratory (PCL) course. The inquiry-based physical chemistry experiments being developed emphasize modeling of chemical phenomena. In each experiment, students work through at least…

  12. Chemical Remediation of Nickel(II) Waste: A Laboratory Experiment for General Chemistry Students

    Science.gov (United States)

    Corcoran, K. Blake; Rood, Brian E.; Trogden, Bridget G.

    2011-01-01

    This project involved developing a method to remediate large quantities of aqueous waste from a general chemistry laboratory experiment. Aqueous Ni(II) waste from a general chemistry laboratory experiment was converted into solid nickel hydroxide hydrate with a substantial decrease in waste volume. The remediation method was developed for a…

  13. An Undergraduate Laboratory Experiment in Bioinorganic Chemistry: Ligation States of Myoglobin

    Science.gov (United States)

    Bailey, James A.

    2011-01-01

    Although there are numerous inorganic model systems that are readily presented as undergraduate laboratory experiments in bioinorganic chemistry, there are few examples that explore the inorganic chemistry of actual biological molecules. We present a laboratory experiment using the oxygen-binding protein myoglobin that can be easily incorporated…

  14. Making Sense of Olive Oil: Simple Experiments to Connect Sensory Observations with the Underlying Chemistry

    Science.gov (United States)

    Blatchly, Richard A.; Delen, Zeynep; O'Hara, Patricia B.

    2014-01-01

    In the last decade, our understanding of the chemistry of olive oil has dramatically improved. Here, the essential chemistry of olive oil and its important minor constituents is described and related to the typical sensory categories used to rate and experience oils: color, aroma, bitterness, and pungency. We also describe experiments to explore…

  15. An Atmospheric Science Observing System Simulation Experiment (OSSE) Environment

    Science.gov (United States)

    Lee, Meemong; Weidner, Richard; Qu, Zheng; Bowman, Kevin; Eldering, Annmarie

    2010-01-01

    An atmospheric sounding mission starts with a wide range of concept designs involving measurement technologies, observing platforms, and observation scenarios. Observing system simulation experiment (OSSE) is a technical approach to evaluate the relative merits of mission and instrument concepts. At Jet Propulsion Laboratory (JPL), the OSSE team has developed an OSSE environment that allows atmospheric scientists to systematically explore a wide range of mission and instrument concepts and formulate a science traceability matrix with a quantitative science impact analysis. The OSSE environment virtually creates a multi-platform atmospheric sounding testbed (MAST) by integrating atmospheric phenomena models, forward modeling methods, and inverse modeling methods. The MAST performs OSSEs in four loosely coupled processes, observation scenario exploration, measurement quality exploration, measurement quality evaluation, and science impact analysis.

  16. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

    Science.gov (United States)

    Lefèvre, Franck; Forget, François

    2009-08-06

    The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

  17. The Kinetics and Thermodynamics of the Phenol from Cumene Process: A Physical Chemistry Experiment.

    Science.gov (United States)

    Chen, Edward C. M.; Sjoberg, Stephen L.

    1980-01-01

    Presents a physical chemistry experiment demonstrating the differences between thermodynamics and kinetics. The experiment used the formation of phenol and acetone from cumene hydroperoxide, also providing an example of an industrially significant process. (CS)

  18. Diamond detectors for high-temperature transactinide chemistry experiments

    Science.gov (United States)

    Steinegger, Patrick; Dressler, Rugard; Eichler, Robert; Piguet, Dave; Streuli, Silvan; Türler, Andreas

    2017-04-01

    Here, we present the fabrication details and functional tests of diamond-based α-spectroscopic sensors, dedicated for high-temperature experiments, targeting the chemistry of transactinide elements. Direct heating studies with this sensor material, revealed a current upper temperature threshold for a safe α-spectroscopic operation of Tdet = 453 K . Up to this temperature, the diamond sensor could be operated in a stable manner over long time periods of the order of days. A satisfying resolution of ≈ 50 keVFWHM was maintained throughout all conducted measurements. However, exceeding the mentioned temperature limit led to a pronounced spectroscopic degradation in the range of 453 - 473 K , thereby preventing any further α-spectroscopic application. These findings are in full agreement with available literature data. The presented detector development generally enables the chemical investigation of more short-lived and less volatile transactinide elements and their compounds, yet unreachable with the currently employed silicon-based solid state sensors. In a second part, the design, construction, and α-spectroscopic performance of a 4-segmented diamond detector, dedicated and used for transactinide element research, is given as an application example.

  19. Geothermal injection treatment: process chemistry, field experiences, and design options

    Energy Technology Data Exchange (ETDEWEB)

    Kindle, C.H.; Mercer, B.W.; Elmore, R.P.; Blair, S.C.; Myers, D.A.

    1984-09-01

    The successful development of geothermal reservoirs to generate electric power will require the injection disposal of approximately 700,000 gal/h (2.6 x 10/sup 6/ 1/h) of heat-depleted brine for every 50,000 kW of generating capacity. To maintain injectability, the spent brine must be compatible with the receiving formation. The factors that influence this brine/formation compatibility and tests to quantify them are discussed in this report. Some form of treatment will be necessary prior to injection for most situations; the process chemistry involved to avoid and/or accelerate the formation of precipitate particles is also discussed. The treatment processes, either avoidance or controlled precipitation approaches, are described in terms of their principles and demonstrated applications in the geothermal field and, when such experience is limited, in other industrial use. Monitoring techniques for tracking particulate growth, the effect of process parameters on corrosion and well injectability are presented. Examples of brine injection, preinjection treatment, and recovery from injectivity loss are examined and related to the aspects listed above.

  20. Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

    CERN Document Server

    Anghel, I; Bergevin, M; Davies, G; Di Lodovico, F; Elagin, A; Frisch, H; Hill, R; Jocher, G; Katori, T; Learned, J; Northrop, R; Pilcher, C; Ramberg, E; Sanchez, M C; Smy, M; Sobel, H; Svoboda, R; Usman, S; Vagins, M; Varner, G; Wagner, R; Wetstein, M; Winslow, L; Yeh, M

    2014-01-01

    Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Wate...

  1. Letter of Intent: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

    CERN Document Server

    Anghel, I; Bergevin, M; Blanco, C; Catano-Mur, E; Di Lodovico, F; Elagin, A; Frisch, H; Griskevich, J; Hill, R; Jocher, G; Katori, T; Krennrich, F; Learned, J; Malek, M; Northrop, R; Pilcher, C; Ramberg, E; Repond, J; Sacco, R; Sanchez, M C; Smy, M; Sobel, H; Svoboda, R; Usman, S M; Vagins, M; Varner, G; Wagner, R; Weinstein, A; Wetstein, M; Winslow, L; Xia, L; Yeh, M

    2015-01-01

    Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Wate...

  2. Characterization of Settled Atmospheric Dust by the DART Experiment

    Science.gov (United States)

    Landis, Geoffrey A.; Jenkins, Phillip P.; Baraona, Cosmo

    1999-01-01

    The DART ("Dust Accumulation and Removal Test") package is an experiment which will fly as part of the MIP experiment on the Mars-2001 Surveyor Lander. Dust deposition could be a significant problem for photovoltaic array operation for long duration emissions on the surface of Mars. Measurements made by Pathfinder showed 0.3% loss of solar array performance per day due to dust obscuration. The DART experiment is designed to quantify dust deposition from the Mars atmosphere, measure the properties of settled dust, measure the effect of dust deposition on the array performance, and test several methods of mitigating the effect of settled dust on a solar array. Although the purpose of DART (along with its sister experiment, MATE) is to gather information critical to the design of future power systems on the surface of Mars, the dust characterization instrumentation on DART will also provide significant scientific data on the properties of settled atmospheric dust.

  3. Atmospheric impact of the 1783–1784 Laki eruption: Part I Chemistry modelling

    Directory of Open Access Journals (Sweden)

    D. S. Stevenson

    2003-01-01

    Full Text Available Results from the first chemistry-transport model study of the impact of the 1783–1784 Laki fissure eruption (Iceland: 64°N, 17°W upon atmospheric composition are presented. The eruption released an estimated 61 Tg(S as SO2 into the troposphere and lower stratosphere. The model has a high resolution tropopause region, and detailed sulphur chemistry. The simulated SO2 plume spreads over much of the Northern Hemisphere, polewards of ~40°N. About 70% of the SO2 gas is directly deposited to the surface before it can be oxidised to sulphuric acid aerosol. The main SO2 oxidants, OH and H2O2, are depleted by up to 40% zonally, and the lifetime of SO2 consequently increases. Zonally averaged tropospheric SO2 concentrations over the first three months of the eruption exceed 20 ppbv, and sulphuric acid aerosol reaches ~2 ppbv. These compare to modelled pre-industrial/present-day values of 0.1/0.5 ppbv SO2 and 0.1/1.0 ppbv sulphate. A total sulphuric acid aerosol yield of 17–22 Tg(S is produced. The mean aerosol lifetime is 6–10 days, and the peak aerosol loading of the atmosphere is 1.4–1.7 Tg(S (equivalent to 5.9–7.1 Tg of hydrated sulphuric acid aerosol. These compare to modelled pre-industrial/present-day sulphate burdens of 0.28/0.81 Tg(S, and lifetimes of 6/5 days, respectively. Due to the relatively short atmospheric residence times of both SO2 and sulphate, the aerosol loading approximately mirrors the temporal evolution of emissions associated with the eruption. The model produces a reason-able simulation of the acid deposition found in Greenland ice cores. These results appear to be relatively insensitive to the vertical profile of emissions assumed, although if more of the emissions reached higher levels (>12 km, this would give longer lifetimes and larger aerosol yields. Introducing the emissions in episodes generates similar results to using monthly mean emissions, because the atmospheric lifetimes are similar to the repose periods

  4. Influence of a Carrington-like event on the atmospheric chemistry, temperature and dynamics

    Directory of Open Access Journals (Sweden)

    M. Calisto

    2012-06-01

    Full Text Available We have modeled the atmospheric impact of a major solar energetic particle event similar in intensity to what is thought of the Carrington Event of 1–2 September 1859. Ionization rates for the August 1972 solar proton event, which had an energy spectrum comparable to the Carrington Event, were scaled up in proportion to the fluence estimated for both events. We have assumed such an event to take place in the year 2020 in order to investigate the impact on the modern, near future atmosphere. Effects on atmospheric chemistry, temperature and dynamics were investigated using the 3-D Chemistry Climate Model SOCOL v2.0. We find significant responses of NOx, HOx, ozone, temperature and zonal wind. Ozone and NOx have in common an unusually strong and long-lived response to this solar proton event. The model suggests a 3-fold increase of NOx generated in the upper stratosphere lasting until the end of November, and an up to 10-fold increase in upper mesospheric HOx. Due to the NOx and HOx enhancements, ozone reduces by up to 60–80% in the mesosphere during the days after the event, and by up to 20–40% in the middle stratosphere lasting for several months after the event. Total ozone is reduced by up to 20 DU in the Northern Hemisphere and up to 10 DU in the Southern Hemisphere. Free tropospheric and surface air temperatures show a significant cooling of more than 3 K and zonal winds change significantly by 3–5 m s−1 in the UTLS region. In conclusion, a solar proton event, if it took place in the near future with an intensity similar to that ascribed to of the Carrington Event of 1859, must be expected to have a major impact on atmospheric composition throughout the middle atmosphere, resulting in significant and persistent decrease in total ozone.

  5. Influence of a Carrington-like event on the atmospheric chemistry, temperature and dynamics

    Directory of Open Access Journals (Sweden)

    M. Calisto

    2012-09-01

    Full Text Available We have modeled the atmospheric impact of a major solar energetic particle event similar in intensity to what is thought of the Carrington Event of 1–2 September 1859. Ionization rates for the August 1972 solar proton event, which had an energy spectrum comparable to the Carrington Event, were scaled up in proportion to the fluence estimated for both events. We have assumed such an event to take place in the year 2020 in order to investigate the impact on the modern, near future atmosphere. Effects on atmospheric chemistry, temperature and dynamics were investigated using the 3-D Chemistry Climate Model SOCOL v2.0. We find significant responses of NOx, HOx, ozone, temperature and zonal wind. Ozone and NOx have in common an unusually strong and long-lived response to this solar proton event. The model suggests a 3-fold increase of NOx generated in the upper stratosphere lasting until the end of November, and an up to 10-fold increase in upper mesospheric HOx. Due to the NOx and HOx enhancements, ozone reduces by up to 60–80% in the mesosphere during the days after the event, and by up to 20–40% in the middle stratosphere lasting for several months after the event. Total ozone is reduced by up to 20 DU in the Northern Hemisphere and up to 10 DU in the Southern Hemisphere. Free tropospheric and surface air temperatures show a significant cooling of more than 3 K and zonal winds change significantly by 3–5 m s−1 in the UTLS region. In conclusion, a solar proton event, if it took place in the near future with an intensity similar to that ascribed to of the Carrington Event of 1859, must be expected to have a major impact on atmospheric composition throughout the middle atmosphere, resulting in significant and persistent decrease in total ozone.

  6. Monitoramento atmosférico passivo de SO2, NO2 e O3 em áreas urbanas e de influência industrial como prática de química ambiental para alunos de graduação Atmospheric passive monitoring of SO2, NO2 and O3 in urban areas and in those under industrial influence as an environmental chemistry experiment for undergraduate students

    Directory of Open Access Journals (Sweden)

    Vânia P. Campos

    2006-07-01

    Full Text Available This study is a result of undergraduate student participation in the Environmental Chemistry discipline provided by the Chemistry Institute/UFBA. The students were involved in the development of passive samplers, a project of the LAQUAM (Environmental Analytical Chemistry Laboratory. The students' residences and other neighborhoods were used to create a passive sampling network, allowing the measurement of atmospheric levels of pollutants in urban areas and in those under industrial influence. The assembly of the passive samplers, including impregnation of filters and chemical analysis were part of the students' practice tasks. The results were analyzed taking into consideration the Brazilian legislation.

  7. Inferring the unobserved chemical state of the atmosphere: idealized data assimilation experiments

    Science.gov (United States)

    Knote, C. J.; Barré, J.; Eckl, M.; Hornbrook, R. S.; Wiedinmyer, C.; Emmons, L. K.; Orlando, J. J.; Tyndall, G. S.; Arellano, A. F.

    2015-12-01

    Chemical data assimilation in numerical models of the atmosphere is a venture into uncharted territory, into a world populated by a vast zoo of chemical compounds with strongly non-linear interactions. Commonly assimilated observations exist for only a selected few of those key gas phase compounds (CO, O3, NO2), and assimilating those in models assuming linearity begs the question of: To what extent we can infer the remainder to create a new state of the atmosphere that is chemically sound and optimal? In our work we present the first systematic investigation of sensitivities that exist between chemical compounds under varying ambient conditions in order to inform scientists on the potential pitfalls when assimilating single/few chemical compounds into complex 3D chemistry transport models. In order to do this, we developed a box-modeling tool (BOXMOX) based on the Kinetic PreProcessor (KPP, http://people.cs.vt.edu/~asandu/Software/Kpp/) in which we can conduct simulations with a suite of 'mechanisms', sets of differential equations describing atmospheric photochemistry. The box modeling approach allows us to sample a large variety of atmospheric conditions (urban, rural, biogenically dominated, biomass burning plumes) to capture the range of chemical conditions that typically exist in the atmosphere. Included in our suite are 'lumped' mechanisms typically used in regional and global chemistry transport models (MOZART, RACM, RADM2, SAPRC99, CB05, CBMZ) as well as the Master Chemical Mechanism (MCM, U. Leeds). We will use an Observing System Simulation Experiment approach with the MCM prediction as 'nature' or 'true' state, assimilating idealized synthetic observations (from MCM) into the different ‚lumped' mechanisms under various environments. Two approaches to estimate the sensitivity of the chemical system will be compared: 1) adjoint: using Jacobians computed by KPP and 2) ensemble: by perturbing emissions, temperature, photolysis rates, entrainment, etc., in

  8. Touring the Tomato: A Suite of Chemistry Laboratory Experiments

    Science.gov (United States)

    Sarkar, Sayantani; Chatterjee, Subhasish; Medina, Nancy; Stark, Ruth E.

    2013-01-01

    An eight-session interdisciplinary laboratory curriculum has been designed using a suite of analytical chemistry techniques to study biomaterials derived from an inexpensive source such as the tomato fruit. A logical

  9. Partial Overhaul and Initial Parallel Optimization of KINETICS, a Coupled Dynamics and Chemistry Atmosphere Model

    Science.gov (United States)

    Nguyen, Howard; Willacy, Karen; Allen, Mark

    2012-01-01

    KINETICS is a coupled dynamics and chemistry atmosphere model that is data intensive and computationally demanding. The potential performance gain from using a supercomputer motivates the adaptation from a serial version to a parallelized one. Although the initial parallelization had been done, bottlenecks caused by an abundance of communication calls between processors led to an unfavorable drop in performance. Before starting on the parallel optimization process, a partial overhaul was required because a large emphasis was placed on streamlining the code for user convenience and revising the program to accommodate the new supercomputers at Caltech and JPL. After the first round of optimizations, the partial runtime was reduced by a factor of 23; however, performance gains are dependent on the size of the data, the number of processors requested, and the computer used.

  10. Compilation and analyses of emissions inventories for the NOAA atmospheric chemistry project. Progress report, August 1997

    Energy Technology Data Exchange (ETDEWEB)

    Benkovitz, C.M.

    1997-09-01

    Global inventories of anthropogenic emissions of oxides of nitrogen for circa 1985 and 1990 and non-methane volatile organic compounds (NMVOCs) for circa 1990 have been compiled by this project. Work on the inventories has been carried out under the umbrella of the Global Emissions Inventory Activity of the International Global Atmospheric Chemistry program. Global emissions of NOx for 1985 are estimated to be 21 Tg N/yr, with approximately 84% originating in the Northern Hemisphere. The global emissions for 1990 are 31 Tg N/yr for NOx and 173 Gg NMVOC/yr. Ongoing research activities for this project continue to address emissions of both NOx and NMVOCs. Future tasks include: evaluation of more detailed regional emissions estimates and update of the default 1990 inventories with the appropriate estimates; derivation of quantitative uncertainty estimates for the emission values; and development of emissions estimates for 1995.

  11. An adaptive reduction algorithm for efficient chemical calculations in global atmospheric chemistry models

    Science.gov (United States)

    Santillana, Mauricio; Le Sager, Philippe; Jacob, Daniel J.; Brenner, Michael P.

    2010-11-01

    We present a computationally efficient adaptive method for calculating the time evolution of the concentrations of chemical species in global 3-D models of atmospheric chemistry. Our strategy consists of partitioning the computational domain into fast and slow regions for each chemical species at every time step. In each grid box, we group the fast species and solve for their concentration in a coupled fashion. Concentrations of the slow species are calculated using a simple semi-implicit formula. Separation of species between fast and slow is done on the fly based on their local production and loss rates. This allows for example to exclude short-lived volatile organic compounds (VOCs) and their oxidation products from chemical calculations in the remote troposphere where their concentrations are negligible, letting the simulation determine the exclusion domain and allowing species to drop out individually from the coupled chemical calculation as their production/loss rates decline. We applied our method to a 1-year simulation of global tropospheric ozone-NO x-VOC-aerosol chemistry using the GEOS-Chem model. Results show a 50% improvement in computational performance for the chemical solver, with no significant added error.

  12. Atmospheric deposition chemistry in a subalpine area of the Julian Alps, NW Slovenia

    Directory of Open Access Journals (Sweden)

    Gregor Muri

    2013-04-01

    Full Text Available Wet-only precipitation was collected in Rateče, a remote village in the outskirts of the Julian Alps (Nort-West Slovenia during 2003-2011, in order to characterise atmospheric deposition chemistry. The samples were collected on a daily basis and combined into weekly samples that were analysed for pH, conductivity and major anions and cations. Ammonium, nitrate and sulphate were the most abundant ions, exhibiting volume-weighted mean values (2003-2011 of 22, 17 and 17 µeq L–1, respectively. Furthermore, the trends of the major parameters in the precipitation were assessed using a simple linear regression. A significant downward trend of both nitrate and sulphate was observed, explained by evident reductions in NOx and SOx emissions in the region. The decline of nitrate and sulphate was also reflected in a significant and downward trend of conductivity. While the trend of ammonium could also be downward, the trends of other major ions were not significant. Atmospheric nitrogen deposition, representing inorganic forms of nitrogen (i.e., ammonium and nitrate, was calculated to examine potential threats that the deposition of nitrogen may cause on lake ecosystems. Nitrogen deposition in Rateče ranged from 5.5 to 9.5 kg N ha–1 yr–1. Although this was below the critical threshold that might cause an impact on surface waters, nitrogen deposition in the nearby Julian Alps, where sensitive mountain lakes are situated, might be higher and its impact on the ecosystem greater. In fact, several studies performed on water chemistry, sedimentary organic matter and stable isotopes in Slovenian mountain lakes have shown progressive changes in their water columns and sediments that can be attributed to nitrogen deposition.

  13. The importance of high spatial resolution for the performance of atmospheric chemistry-transport models

    Science.gov (United States)

    Mantzius Hansen, Kaj

    2010-05-01

    We have investigated the importance of spatial resolution for the performance of the Danish Eulerian Hemispheric Model (DEHM), a state-of-the-art atmospheric chemistry-transport model covering the majority of the Northern Hemisphere with a horizontal grid resolution of 150 km X 150 km. DEHM has 29 vertical layers in terrain-following sigma-coordinates extending up to a height of 100 hPa. Two-way nesting options with a nesting factor of three can be applied with higher resolution over a limited area of the model. At present the model can be run without nests or with one, two or three nests, each with resolutions of 50 km X 50 km, 16.7 km X 16.7 km, and 5.6 km X 5.6 km, respectively. The model includes a comprehensive chemistry scheme with more than 100 reactions and 67 atmospheric constituents, of which 4 relate to primary particulates (PM2.5, PM10, TSP and sea salt), other species are SOx, NOx, NHx, VOCs, and secondary inorganic particulates. DEHM is driven by meteorological data from the numerical weather prediction model MM5v3. Three simulations were performed with DEHM: one simulation with only the mother domain, one simulation with one nest over Europe, and one simulation with an additional nest covering Denmark and surrounding countries. All three simulations cover the period from 1989 to 2006. The predicted concentrations were evaluated against measurements from the EMEP monitoring network. Only sites within the innermost nest were included in the evaluation and the evaluations of the three simulations were compared to test the influence of spatial resolution on the performance of the model.

  14. Tropospheric Ozone Changes, Radiative Forcing and Attribution to Emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    Science.gov (United States)

    Stevenson, D.S.; Young, P.J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; vanNoije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.; Archibald, A.

    2013-01-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (+/-1 standard deviation) in RFs of +/-17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of +/-10 percent. Applying two different tropopause definitions gives differences in RFs of +/-3 percent. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of +/-30 percent for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44+/-12 percent), nitrogen oxides (31 +/- 9 percent), carbon monoxide (15 +/- 3 percent) and non-methane volatile organic compounds (9 +/- 2 percent); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m(-2) DU(-1), a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m(-2); relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some

  15. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP

    Directory of Open Access Journals (Sweden)

    D. S. Stevenson

    2013-03-01

    Full Text Available Ozone (O3 from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP has been used to calculate tropospheric ozone radiative forcings (RFs. All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750 to present-day (2010 tropospheric ozone RF of 410 mW m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%, nitrogen oxides (31 ± 9%, carbon monoxide (15 ± 3% and non-methane volatile organic compounds (9 ± 2%; earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m−2; relative to 1750 for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5 of 350, 420, 370 and 460 (in 2030, and 200, 300, 280 and 600 (in 2100. Models show some coherent responses of ozone to climate change

  16. Atmospheric Boundary Layer Characteristics during BOBMEX-Pilot Experiment

    Indian Academy of Sciences (India)

    G S Bhat; S Ameenulla; M Venkataramana; K Sengupta

    2000-06-01

    The atmospheric boundary layer characteristics observed during the BOBMEX-Pilot experiment are reported. Surface meteorological data were acquired continuously through an automatic weather monitoring system and manually every three hours. High resolution radiosondes were launched to obtain the vertical thermal structure of the atmosphere. The study area was convectively active, the SSTs were high, surface air was warm and moist, and the surface air moist static energy was among the highest observed over the tropical oceans. The mean sea air temperature difference was about 1.25°C and the sea skin temperature was cooler than bucket SST by 0.5°C. The atmospheric mixed layer was shallow, fluctuated in response to synoptic conditions from 100 m to 900 m with a mean around 500 m.

  17. Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE)

    Science.gov (United States)

    Imhof, W. L.; Voss, H. D.; Mobilia, J.; Datlowe, D. W.; Chinn, V. L.; Hilsenrath, M.; Vondrak, R. R.

    1996-01-01

    This report summarizes the activities sponsored by the Office of Naval Research for the Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE). The MAXIE instrument was developed as a joint activity of Lockheed, The Aerospace Corporation, and the University of Bergen, Norway. Lockheed was responsible for the overall management of the program, interfacing with the appropriate government agencies, the overall electrical and mechanical design, flight software, environmental testing, spacecraft integration activities, on orbit checkout, and data processing activities. The Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE), the ONR 401 experiment, is the first in a new class of satellite-borne remote sensing instruments. The primary innovation is the ability to obtain rapid, sequential, images with high sensitivity of the earth's X ray aurora from a low altitude polar orbiting satellite. These images can be used to identify dynamic temporal variations in the three-dimensional (energy and position) distribution of electron precipitation into the atmosphere. MAXIE was launched on the TIROS NOAA-13 satellite on 9 August 1993. The experiment performed well during its turn-on sequence; however, the spacecraft bus failed on 21 August 1993. New spacebased technologies successfully used in MAXIE were mixed-mode ASIC microcircuits, a zero torque scanning system with associated viscoelastic damping, a paraffin stow release mechanism, a parallel integrating PHA processor, a low noise Si(Li) sensor telescope, and an advanced thermal cooling system. MAXIE's on orbit operation, control of penetrating particle backgrounds, and scientific data indicated good overall performance.

  18. Time-slice last millennium experiments with interactive gas-phase chemistry and aerosols

    Science.gov (United States)

    Tsigaridis, K.; Legrande, A. N.; Koch, D. M.

    2010-12-01

    Preliminary results from coupled atmosphere-ocean simulations with interactive gas-phase chemistry and aerosols are presented. These experiments are decadal scale time-slices within millennial-length simulations performed with the GISS GCM (ModelE), using two different ocean models. The boundary conditions for the transient simulations follow the last millennium coordinated PMIP3 experiment protocol. This experiment directly links in with other pre-Industrial experiments being completed as part of IPCC AR5, using the same model and resolution as in GISS IPCC AR5. Preliminary time-slice results from the early medieval and Maunder Minimum periods will be presented. The impact of the presence of short-lived gases and aerosols on the simulated climate is studied. An initial attempt to identify previously omitted additional forcing mechanisms will be performed during these contrasting climate periods, in short duration experiments driven by ocean conditions from the transient experiments. The results presented are the initial runs from a larger set of experiments that will assess the climate impact of changes to dust, sea-salt, and ocean-derived sulfate, biomass burning ozone-precursors and aerosols, organic carbon, wetland methane emissions, and a final set with all components. These species are standard components in the GISS model’s 20th century simulations, so that we may compare millennial variability characteristics with those better constrained from more recent climate periods. Dust and sea-salt are wind-driven aerosols from deserts and oceans, sulfate comes from oxidation of volcanic and oceanic precursors, while organic carbon comes from biomass burning, secondary plant sources and primary oceanic emissions. Comparison of model and proxy records will test model-simulated mechanisms while the model provides insight into factors contributing to proxy variability. The addition of potentially important forcing mechanisms will enable a more comprehensive

  19. Investigating Affective Experiences in the Undergraduate Chemistry Laboratory: Students' Perceptions of Control and Responsibility

    Science.gov (United States)

    Galloway, Kelli R.; Malakpa, Zoebedeh; Bretz, Stacey Lowery

    2016-01-01

    Meaningful learning requires the integration of cognitive and affective learning with the psychomotor, i.e., hands-on learning. The undergraduate chemistry laboratory is an ideal place for meaningful learning to occur. However, accurately characterizing students' affective experiences in the chemistry laboratory can be a very difficult task. While…

  20. Students Doing Chemistry: A Hand-On Experience for K-12

    Science.gov (United States)

    Selco, Jodye I.; Bruno, Mary; Chan, Sue

    2012-01-01

    A hands-on, minds-on inquiry chemistry experiment was developed for use in K-12 schools that enables students to combine the chemicals of their choice and observe the results. The chemistry involved is water based and builds upon acid-base, double displacement, and iodometric detection of starch reactions. Chemicals readily available in the…

  1. Filtrates & Residues: Hemoglobinometry--A Biochemistry Experiment that Utilizes the Principles of Transition Metal Chemistry.

    Science.gov (United States)

    Giuliano, Vincenzo; Rieck, John Paul

    1987-01-01

    Describes a chemistry experiment dealing with hemoglobinometry that can apply to transition metal chemistry, colorimetry, and biochemistry. Provides a detailed description of the experimental procedure, including discussions of the preparation of the cyanide reagent, colorimetric measurements, and waste disposal and treatment. (TW)

  2. Japanese Language Education for Science Students : Introductory Training through Chemistry Experiments

    Science.gov (United States)

    Takai, Kazuhiko

    This paper describes a course in Japanese language instruction for first year students in the Department of Applied Chemistry, Okayama University. The course is part of a guidance program and consists of (1) technical writing in Japanese for science students, (2) experimental report writing, and (3) project-based learning through chemistry experiments.

  3. The influence of Middle Range Energy Electrons on atmospheric chemistry and regional climate

    Science.gov (United States)

    Arsenovic, P.; Rozanov, E.; Stenke, A.; Funke, B.; Wissing, J. M.; Mursula, K.; Tummon, F.; Peter, T.

    2016-11-01

    We investigate the influence of Middle Range Energy Electrons (MEE; typically 30-300 keV) precipitation on the atmosphere using the SOCOL3-MPIOM chemistry-climate model with coupled ocean. Model simulations cover the 2002-2010 period for which ionization rates from the AIMOS dataset and atmospheric composition observations from MIPAS are available. Results show that during geomagnetically active periods MEE significantly increase the amount of NOy and HOx in the polar winter mesosphere, in addition to other particles and sources, resulting in local ozone decreases of up to 35%. These changes are followed by an intensification of the polar night jet, as well as mesospheric warming and stratospheric cooling. The contribution of MEE also substantially enhances the difference in the ozone anomalies between geomagnetically active and quiet periods. Comparison with MIPAS NOy observations indicates that the additional source of NOy from MEE improves the model results, however substantial underestimation above 50 km remains and requires better treatment of the NOy source from the thermosphere. A surface air temperature response is detected in several regions, with the most pronounced warming occurring in the Antarctic during austral winter. Surface warming of up to 2 K is also seen over continental Asia during boreal winter.

  4. Cometary airbursts and atmospheric chemistry: Tunguska and a candidate Younger Dryas event

    CERN Document Server

    Melott, Adrian L; Dreschhoff, Gisela; Johnson, Carey K

    2009-01-01

    We estimate atmospheric chemistry changes from ionization at the 1908 Tunguska airburst event, finding agreement with nitrate enhancement in GIS2PH and GISP2 ice cores and noting an unexplained accompanying ammonium spike. We then consider the candidate Younger Dryas comet impact. The estimated NOx production and O3 depletion are large, beyond accurate extrapolation. A modest nitrate deposition signal exists in ice core data. The predicted very large impulsive deposition might be visible in higher resolution data. Ammonium has been attributed to biomass burning, and found coincident with nitrate spikes at YD onset in both the GRIP and GISP2 ice cores. A similar result is well-resolved in Tunguska ice core data, but the Tunguska forest fire was far too small to account for this. Direct input of ammonia from a comet into the atmosphere is consistent with the spike for the candidate YD object, but also inadequate for Tunguska. An analog of the Haber process with hydrogen contributed by the cometary or surface wa...

  5. The atmospheric chemistry general circultation model ECHAM5/MESSy1: Consistent simulation of ozone from the surface to the mesosphere

    NARCIS (Netherlands)

    Jöckel, P.; Tost, H.; Pozzer, A.; Brülh, Ch.; Buchholz, J.; Ganzeveld, L.N.; Hoor, P.; Kerkweg, A.; Lawrence, M.G.; Sander, R.; Steil, B.; Stiller, G.; Tanarhte, M.; Taraborrelli, D.; Aardenne, van J.A.; Lelieveld, J.

    2006-01-01

    The new Modular Earth Submodel System (MESSy) describes atmospheric chemistry and meteorological processes in a modular framework, following strict coding standards. It has been coupled to the ECHAM5 general circulation model, which has been slightly modified for this purpose. A 90-layer model setup

  6. STREAMWATER ACID-BASED CHEMISTRY AND CRITICAL LOADS OF ATMOSPHERIC SULFUR DEPOSITION IN SHENANDOAH NATIONAL PARK, VIRGINIA

    Science.gov (United States)

    A modeling study was conducted to evaluate the acid-base chemistry of streams within Shenandoah National Park, Virginia and to project future responses to sulfur (S) and nitrogen (N) atmospheric emissions controls. Many of the major stream systems in the Park have acid neutraliz...

  7. Design of and initial results from a highly instrumented reactor for atmospheric chemistry (HIRAC

    Directory of Open Access Journals (Sweden)

    D. R. Glowacki

    2007-07-01

    Full Text Available The design of a Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC is described and initial results obtained from HIRAC are presented. The ability of HIRAC to perform in-situ laser-induced fluorescence detection of OH and HO2 radicals with the Fluorescence Assay by Gas Expansion (FAGE technique establishes it as internationally unique for a chamber of its size and pressure/temperature variable capabilities. In addition to the FAGE technique, HIRAC features a suite of analytical instrumentation, including: a multipass FTIR system; a conventional gas chromatography (GC instrument and a GC instrument for formaldehyde detection; and NO/NO2, CO, O3, and H2O vapour analysers. Ray tracing simulations and measurements of the blacklamp flux have been utilized to develop a detailed model of the radiation field within HIRAC. Comparisons between the analysers and the FTIR coupled to HIRAC have been performed, and HIRAC has also been used to investigate pressure dependent kinetics of the chlorine atom reaction with ethene and the reaction of O3 and t-2-butene. The results obtained are in good agreement with literature recommendations and Master Chemical Mechanism predictions. HIRAC thereby offers a highly instrumented platform with the potential for: (1 high precision kinetics investigations over a range of atmospheric conditions; (2 detailed mechanism development, significantly enhanced according to its capability for measuring radicals; and (3 field instrument intercomparison, calibration, development, and investigations of instrument response under a range of atmospheric conditions.

  8. Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b

    Energy Technology Data Exchange (ETDEWEB)

    Barman, T S; Macintosh, B A; Konopacky, Q M; Marois, C

    2011-03-21

    Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrow-band photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a Hydrogen-rich atmosphere. Only weak CH{sub 4} absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH{sub 4} ratio at photospheric depths. The H-band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best fitting bulk parameters, T{sub eff} = 1100K {+-} 100 and log(g) = 3.5 {+-} 0.5 (for solar composition). Given the observed luminosity (log L{sub obs}/L{sub {circle_dot}} {approx} -5.1), these values correspond to a radius of 0.75 R{sub Jup{sub 0.12}{sup +0.17}} and mass {approx} 0.72 M{sub Jup{sub -0.6}{sup +2.6}} - strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to {approx} 10 x that of the Sun) along with thick clouds and non-equilibrium chemistry are likely required to reproduce the complete ensemble of spectroscopic and photometric data and the low effective temperatures (< 1000K) required by the evolution models.

  9. The Impact of Nursing Students' Prior Chemistry Experience on Academic Performance and Perception of Relevance in a Health Science Course

    Science.gov (United States)

    Boddey, Kerrie; de Berg, Kevin

    2015-01-01

    Nursing students have typically found the study of chemistry to be one of their major challenges in a nursing course. This mixed method study was designed to explore how prior experiences in chemistry might impact chemistry achievement during a health science unit. Nursing students (N = 101) studying chemistry as part of a health science unit were…

  10. he Impact of Primary Marine Aerosol on Atmospheric Chemistry, Radiation and Climate: A CCSM Model Development Study

    Energy Technology Data Exchange (ETDEWEB)

    Keene, William C. [University of Virginia; Long, Michael S. [University of Virginia

    2013-05-20

    This project examined the potential large-scale influence of marine aerosol cycling on atmospheric chemistry, physics and radiative transfer. Measurements indicate that the size-dependent generation of marine aerosols by wind waves at the ocean surface and the subsequent production and cycling of halogen-radicals are important but poorly constrained processes that influence climate regionally and globally. A reliable capacity to examine the role of marine aerosol in the global-scale atmospheric system requires that the important size-resolved chemical processes be treated explicitly. But the treatment of multiphase chemistry across the breadth of chemical scenarios encountered throughout the atmosphere is sensitive to the initial conditions and the precision of the solution method. This study examined this sensitivity, constrained it using high-resolution laboratory and field measurements, and deployed it in a coupled chemical-microphysical 3-D atmosphere model. First, laboratory measurements of fresh, unreacted marine aerosol were used to formulate a sea-state based marine aerosol source parameterization that captured the initial organic, inorganic, and physical conditions of the aerosol population. Second, a multiphase chemical mechanism, solved using the Max Planck Institute for Chemistry's MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere) system, was benchmarked across a broad set of observed chemical and physical conditions in the marine atmosphere. Using these results, the mechanism was systematically reduced to maximize computational speed. Finally, the mechanism was coupled to the 3-mode modal aerosol version of the NCAR Community Atmosphere Model (CAM v3.6.33). Decadal-scale simulations with CAM v.3.6.33, were run both with and without reactive-halogen chemistry and with and without explicit treatment of particulate organic carbon in the marine aerosol source function. Simulated results were interpreted (1) to evaluate influences

  11. Stereoisomerism in Coordination Chemistry: A Laboratory Experiment for Undergraduate Students.

    Science.gov (United States)

    Gargallo, Maria Fe; And Others

    1988-01-01

    Describes an experimental procedure to acquaint inorganic chemistry students with stereochemical concepts using tris-(2,3-butanediamine)cobalt(III). Notes two isomeric forms exist and both form metal chelates. Separation is accomplished by chromatography and analysis is by NMR and infrared spectroscopy. Provides spectra of isomers. (MVL)

  12. Preparation of Gold Nanoparticles Using Tea: A Green Chemistry Experiment

    Science.gov (United States)

    Sharma, R. K.; Gulati, Shikha; Mehta, Shilpa

    2012-01-01

    Assimilating green chemistry principles in nanotechnology is a developing area of nanoscience research nowadays. Thus, there is a growing demand to develop environmentally friendly and sustainable methods for the synthesis of nanoparticles that utilize nontoxic chemicals, environmentally benign solvents, and renewable materials to avoid their…

  13. A Solid State Chemistry Experiment: Dislocations in Etched Calcite by Polaroid Photomicrography

    Science.gov (United States)

    Agnew, N. H.

    1972-01-01

    Suggests that adequate attention should be given to lattice imperfections in teaching solid state chemistry. Some concepts to be included in such a program are explained. An experiment to be performed by undergraduates on photomicrography is described in detail. (PS)

  14. Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

    Science.gov (United States)

    Challener, Roberta; Robbins, Lisa L.; Mcclintock, James B.

    2016-01-01

    Open ocean observations have shown that increasing levels of anthropogenically derived atmospheric CO2 are causing acidification of the world's oceans. Yet little is known about coastal acidification and studies are just beginning to characterise the carbonate chemistry of shallow, nearshore zones where many ecologically and economically important organisms occur. We characterised the carbonate chemistry of seawater within an area dominated by seagrass beds (Saint Joseph Bay, Florida) to determine the extent of variation in pH and pCO2 over monthly and daily timescales. Distinct diel and seasonal fluctuations were observed at daily and monthly timescales respectively, indicating the influence of photosynthetic and respiratory processes on the local carbonate chemistry. Over the course of a year, the range in monthly values of pH (7.36-8.28), aragonite saturation state (0.65-5.63), and calculated pCO2 (195-2537 μatm) were significant. When sampled on a daily basis the range in pH (7.70-8.06), aragonite saturation state (1.86-3.85), and calculated pCO2 (379-1019 μatm) also exhibited significant range and indicated variation between timescales. The results of this study have significant implications for the design of ocean acidification experiments where nearshore species are utilised and indicate that coastal species are experiencing far greater fluctuations in carbonate chemistry than previously thought.

  15. A three-dimensional general circulation model with coupled chemistry for the middle atmosphere

    Science.gov (United States)

    Rasch, P. J.; Boville, B. A.; Brasseur, G. P.

    1995-05-01

    We document a new middle atmosphere general circulation model that includes ozone photochemistry. The dynamical model component is based on the NCAR middle atmosphere version of the Community Climate Model. The chemistry model component simulates the evolution of 24 chemically reactive gases. The horizontal resolution is approximately 3° in latitude and 6° in longitude. It includes 44 levels, with a maximum vertical grid spacing of about 2.5 km and a top level at around 75 km. The chemical model distinguishes between species where we judge transport to be critical and those for which it may be neglected. Nine longer-lived species (N2O, CH4, H2O, HNO3, N2O5, CO, ClONO2, HCl, and HOCl) and four chemical families (NOy, NOx, Ox and Clx) are advected. Concentrations of 15 species which are typically shorter-lived or are members of the chemical families are diagnosed using quasi-equilibrium assumptions ( O(1D), OH, Cl, O(3P), O3, HO2, NO2, ClO, NO, HNO4, NO3, N, OClO, Cl2O2, H2O2). Distributions for a number of other species are prescribed. Results are presented from a 2-year simulation, which include only gas phase photochemical reactions and in which the ozone distribution forecast from the chemistry module does not affect the radiative forcing of the dynamical fields. The calculated distributions of trace species and their seasonal evolution are often quite realistic, particularly in the northern hemisphere extratropics. Distributions of long-lived species such as N2O and CH4 correspond well to satellite observations. Some features, such as the double peak structure occurring during equinoxes, are not reproduced. The latitudinal variation and seasonal evolution of the ozone column abundance is quite realistic. The calculated vertical distribution of the ozone mixing ratio exhibits significant differences from measured values. The model underestimates significantly the ozone in the upper stratosphere (40 km) and in the extratropics, where the maximum values occur at

  16. NASA's Upper Atmosphere Research Program UARP and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1994 - 1996. Report to Congress and the Environmental Protection Agency

    Science.gov (United States)

    Kendall, Rose (Compiler); Wolfe, Kathy (Compiler)

    1997-01-01

    Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology, and monitoring of the Earth's upper atmosphere, with emphasis on the stratosphere. This program aims at expanding our understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Science Division in the Office of Mission to Planet Earth at NASA. Significant contributions to this effort are also provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aeronautics. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper atmosphere and their effect on the distribution of chemical species in the stratosphere, such as ozone; understand the relationship of the trace constituent composition of the lower stratosphere and the lower troposphere to the radiative balance and temperature distribution of the Earth's atmosphere; and accurately assess possible perturbations of the upper atmosphere caused by human activities as well as by natural phenomena. In compliance with the Clean Air Act Amendments of 1990, Public Law 101-549, NASA has prepared a report on the state of our knowledge of the Earth's upper atmosphere, particularly the stratosphere, and on the progress of UARP and ACMAP. The report for the year 1996 is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported under NASA UARP and ACMAP in a document entitled, Research Summary 1994-1996. Part 2 is entitled Present State of Knowledge of the Upper Atmosphere

  17. Atmospheric science experiments applicable to Space Shuttle Spacelab missions

    Science.gov (United States)

    Wilson, G. S.; Christian, H. J., Jr.; Fichtl, G. H.; Vaughan, W. W.; Goodman, S. J.; Robertson, F. R.

    1984-01-01

    The present lack of a lower atmosphere research satellite program for the 1980s has prompted consideration of the Space Shuttle/Spacelab system as a means of flying sensor complements geared toward specific research problems, as well as continued instrument development. Three specific examples of possible science questions related to precipitation are discussed: (1) spatial structure of mesoscale cloud and precipitation systems, (2) lightning and storm development, and (3) cyclone intensification over oceanic regions. Examples of space sensors availab le to provide measurements needed in addressing these questions are also presented. Distinctive aspects of low-earth orbit experiments would be high resolution, multispectral sensing of atmospheric phenomena by complements of instruments, and more efficient sensor development through reflights of specific hardware packages.

  18. Laboratory experiments for Titan's ionosphere : the chemistry of N2+, N+, and N2++ nitrogen ions

    Science.gov (United States)

    Thissen, R.; Alcaraz, C.; Dutuit, O.; Nicolas, C.; Soldi-Lose, H.; Zabka, J.; Franceschi, P.

    Laboratory experiments for Titan's ionosphere : the chemistry of N+ , N+ , and N2+ nitrogen ions 2 2 R. Thissen (1), C. Alcaraz (1), O. Dutuit (1), C. Nicolas (2), H. Soldi-Lose (3), J. Zabka (4), P. Franceschi (5) (1) LCP, Bât. 350, Centre Universitaire Paris-Sud, F-91405 Orsay Cedex, France, (2) Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette, France, (3) Institut für Chemie, Fachgruppe Organische Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, (4) J. Heyrovsky Institute of Physical Chemistry, Dolejskova 3, CZ 18223 Praha 8 - Kobylisy, Czech Republik, (5) Dept. of Physics, University of Trento, Via Sommarive 14, 38050 Povo (TN), Italy (christian.alcaraz@lcp.u-psud.fr) N2 is the major neutral componant of Titan's atmosphere, its ionisation by solar radiation and by magnetospheric electron impact is the most important production of ions in Titan's ionosphere. These primary processes not only lead to N+ molecular 2 monocations but also to N+ atomic ions and to N2+ molecular dications, which can 2 pertain some internal or translational excitation. This contribution will summarize our efforts to caracterize in gaz phase laboratory experiments the reactivity of the nitrogen ions with the most important neutral targets of the Titan's atmosphere [1-3]: • N+ + CH4 , C2 H2 , and C2 H6 2 • N+ (3 P, 1 D) + CH4 , and C2 H4 • N2+ + N2 , CH4 , and C2 H4 2 In this work, particular attention has been paid on the effect of internal and/or translational excitation of the primary nitrogen ions on the rate constant and branching ratio of these ion-molecule reactions. The results from these studies have been compared to the literature values when available and some significant differences have been found. These new values have been used as input data in 1D models of the Titan's ionosphere to show the effect on the final density profiles of the main ions [4] and to demonstrate the existence of a N2+2 dication

  19. Atmospheric lifetime experiment. 1. Introduction, instrumentation, and overview

    Energy Technology Data Exchange (ETDEWEB)

    Prinn, R.G.; Simmonds, R.G.; Rasmussen, R.A.; Crawford, A.J.; Rosen, R.D.; Alyea, F.N.; Cardelino, C.A.; Cunnold, D.M.; Fraser, P.J.; Lovelock, J.E.

    1983-10-20

    The atmospheric lifetime experiment is designed to determine accurately the atmospheric concentrations of the four halocarbons CFCl/sub 3/, CF/sub 2/Cl/sub 2/, CCl/sub 4/, and also N/sub 2/O with emphasis on measurement of their long-term trends in the atmosphere. Comparison of these concentrations and trends for the four halocarbons with estimates of their industrial emission rates then enables calculations of their global circulation rates and globally averaged atmosphere lifetimes. The experiment utilizes automated dual-column electron-capture gas chromatographs which sample the background air about 4 times daily at the following globally distributed sites: Adrigole, Ireland (52/sup 0/N, 10/sup 0/W); Cape Meares, Oregon (45/sup 0/N, 124/sup 0/W); Ragged Point, Barbados (13/sup 0/N, 59/sup 0/W); Point Matatula, American Samoa (14/sup 0/S, 171/sup 0/W); and Cape Grim. Tasmania (41/sup 0/S, 145/sup 0/E). We review the climatology of these ''clean air'' sites and their ability to describe the global air mass. The instrumentation and methods for data acquisition and processing are then described. An overview of the data obtained and the trends derived during the 3-year period from July 1978 through June 1981 for each of the five species being measured is presented. The comparative behavior of the species with latitude and time is emphasized. The global average surface concentrations of CFCl/sub 3/, CF/sub 2/Cl/sub 2/, CH/sub 3/CCl/sub 3/, CCl/sub 4/, and N/sub 2/O are increasing at annually averaged rates of 5.7, 6.0, 8.7, 1.8, and 0.2% per year, respectively, at the midpoint of the 3-year period of the measurements.

  20. The Oil Drop Experiment: Do Physical Chemistry Textbooks Refer to Its Controversial Nature?

    Science.gov (United States)

    Niaz, Mansoor; Rodriguez, Maria A.

    2005-01-01

    Most general chemistry textbooks consider the oil drop experiment as a classic experiment, characterized by its simplicity and precise results. A review of the history and philosophy of science literature shows that the experiment is difficult to perform (even today!) and generated a considerable amount of controversy. Acceptance of the…

  1. Looking beyond Lewis Structures: A General Chemistry Molecular Modeling Experiment Focusing on Physical Properties and Geometry

    Science.gov (United States)

    Linenberger, Kimberly J.; Cole, Renee S.; Sarkar, Somnath

    2011-01-01

    We present a guided-inquiry experiment using Spartan Student Version, ready to be adapted and implemented into a general chemistry laboratory course. The experiment provides students an experience with Spartan Molecular Modeling software while discovering the relationships between the structure and properties of molecules. Topics discussed within…

  2. ETA chemistry experience and assessment on CPP in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Park, K.K.; Lee, J.B.; Yoon, S.W. [Korea Electric Power Research Inst., Taejon (Korea, Republic of)

    2002-07-01

    To reduce FAC of carbon steel in secondary system, water treatment chemistry was converted to ETA at Kori unit 1. Full scale tests to choose the optimum concentration of ETA were conducted and the evaluation after one cycle operation with ETA was also performed. Optimum concentration of ETA in final feed water was determined as 1.8 ppm. At this condition, iron concentration was reduced by 69.8% in final feed water and 69.7% in heater drain compared to ammonia-AVT. The amount of sludge removed from each steam generator was 11.3 kg, which was 88.2% lower than that of ammonia-AVT. With successful results of Kori unit 1, Applications of ETA were extended to other PWRs. Iron transport was found to be reduced significantly. Also, the output of electric power increased by 9 MWe at Young-Kwang unit 1. However, fouling of ion exchange resin in CPP was appeared. ETA appears to have a solvent function in the initial stage of ETA chemistry. Resin was restored when the fouling was removed with hot water and sodium bicarbonates. In particular, the MR type anion resin may be effective in resistance to fouling when ETA-chemistry is used. (authors)

  3. Description and evaluation of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (NMMB-MONARCH) version 1.0: gas-phase chemistry at global scale

    Science.gov (United States)

    Badia, Alba; Jorba, Oriol; Voulgarakis, Apostolos; Dabdub, Donald; Pérez García-Pando, Carlos; Hilboll, Andreas; Gonçalves, María; Janjic, Zavisa

    2017-02-01

    This paper presents a comprehensive description and benchmark evaluation of the tropospheric gas-phase chemistry component of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (NMMB-MONARCH), formerly known as NMMB/BSC-CTM, that can be run on both regional and global domains. Here, we provide an extensive evaluation of a global annual cycle simulation using a variety of background surface stations (EMEP, WDCGG and CASTNET), ozonesondes (WOUDC, CMD and SHADOZ), aircraft data (MOZAIC and several campaigns), and satellite observations (SCIAMACHY and MOPITT). We also include an extensive discussion of our results in comparison to other state-of-the-art models. We note that in this study, we omitted aerosol processes and some natural emissions (lightning and volcano emissions). The model shows a realistic oxidative capacity across the globe. The seasonal cycle for CO is fairly well represented at different locations (correlations around 0.3-0.7 in surface concentrations), although concentrations are underestimated in spring and winter in the Northern Hemisphere, and are overestimated throughout the year at 800 and 500 hPa in the Southern Hemisphere. Nitrogen species are well represented in almost all locations, particularly NO2 in Europe (root mean square error - RMSE - below 5 ppb). The modeled vertical distributions of NOx and HNO3 are in excellent agreement with the observed values and the spatial and seasonal trends of tropospheric NO2 columns correspond well to observations from SCIAMACHY, capturing the highly polluted areas and the biomass burning cycle throughout the year. Over Asia, the model underestimates NOx from March to August, probably due to an underestimation of NOx emissions in the region. Overall, the comparison of the modeled CO and NO2 with MOPITT and SCIAMACHY observations emphasizes the need for more accurate emission rates from anthropogenic and biomass burning sources (i.e., specification of temporal variability). The resulting

  4. Effects of atmospheric deposition nitrogen flux and its composition on soil solution chemistry from a red soil farmland, southeast China.

    Science.gov (United States)

    Cui, Jian; Zhou, Jing; Peng, Ying; Chan, Andrew; Mao, Jingdong

    2015-12-01

    A detailed study on the solution chemistry of red soil in South China is presented. Data are collected from two simulated column-leaching experiments with an improved setup to evaluate the effects of atmospheric N deposition (ADN) composition and ADN flux on agricultural soil acidification using a (15)N tracer technique and an in situ soil solution sampler. The results show that solution pH values decline regardless of the increase of the NH4(+)/NO3(-) ratio in the ADN composition or ADN flux, while exchangeable Al(3+), Ca(2+), Mg(2+), and K(+) concentrations increase at different soil depths (20, 40, and 60 cm). Compared with the control, ADN (60 kg per ha per year N, NH4(+)/NO3(-) ratio of 2 : 1) decreases solution pH values, increases solution concentrations of NO3(-)-N, Al(3+), Ca(2+) and Mg(2+) at the middle and lower soil depths, and promotes their removal. NH4(+)-N was not detected in red soil solutions of all the three soil layers, which might be attributed to effects of nitrification, absorption and fixation in farmland red soil. Some of the NO3(-)-N concentrations at 40-60 cm soil depth exceed the safe drinking level of 10 mg L(-1), especially when the ADN flux is beyond 60 kg ha(-1) N. These features are critical for understanding the ADN agro-ecological effects, and for future assessment of ecological critical loads of ADN in red soil farmlands.

  5. A new Differential Optical Absorption Spectroscopy instrument to study atmospheric chemistry from a high-altitude unmanned aircraft

    Science.gov (United States)

    Stutz, Jochen; Werner, Bodo; Spolaor, Max; Scalone, Lisa; Festa, James; Tsai, Catalina; Cheung, Ross; Colosimo, Santo F.; Tricoli, Ugo; Raecke, Rasmus; Hossaini, Ryan; Chipperfield, Martyn P.; Feng, Wuhu; Gao, Ru-Shan; Hintsa, Eric J.; Elkins, James W.; Moore, Fred L.; Daube, Bruce; Pittman, Jasna; Wofsy, Steven; Pfeilsticker, Klaus

    2017-03-01

    Observations of atmospheric trace gases in the tropical upper troposphere (UT), tropical tropopause layer (TTL), and lower stratosphere (LS) require dedicated measurement platforms and instrumentation. Here we present a new limb-scanning Differential Optical Absorption Spectroscopy (DOAS) instrument developed for NASA's Global Hawk (GH) unmanned aerial system and deployed during the Airborne Tropical TRopopause EXperiment (ATTREX). The mini-DOAS system is designed for automatic operation under unpressurized and unheated conditions at 14-18 km altitude, collecting scattered sunlight in three wavelength windows: UV (301-387 nm), visible (410-525 nm), and near infrared (900-1700 nm). A telescope scanning unit allows selection of a viewing angle around the limb, as well as real-time correction of the aircraft pitch. Due to the high altitude, solar reference spectra are measured using diffusors and direct sunlight. The DOAS approach allows retrieval of slant column densities (SCDs) of O3, O4, NO2, and BrO with relative errors similar to other aircraft DOAS systems. Radiative transfer considerations show that the retrieval of trace gas mixing ratios from the observed SCD based on O4 observations, the most common approach for DOAS measurements, is inadequate for high-altitude observations. This is due to the frequent presence of low-altitude clouds, which shift the sensitivity of the O4 SCD into the lower atmosphere and make it highly dependent on cloud coverage. A newly developed technique that constrains the radiative transfer by comparing in situ and DOAS O3 observations overcomes this issue. Extensive sensitivity calculations show that the novel O3-scaling technique allows the retrieval of BrO and NO2 mixing ratios at high accuracies of 0.5 and 15 ppt, respectively. The BrO and NO2 mixing ratios and vertical profiles observed during ATTREX thus provide new insights into ozone and halogen chemistry in the UT, TTL, and LS.

  6. The Chemistry of Atmosphere-Forest Exchange (CAFE Model – Part 2: Application to BEARPEX-2007 observations

    Directory of Open Access Journals (Sweden)

    G. M. Wolfe

    2010-09-01

    Full Text Available In a companion paper, we have introduced the Chemistry of Atmosphere-Forest Exchange (CAFE model, a vertically-resolved 1-D chemical transport model designed to probe the details of near-surface reactive gas exchange. Here, we use CAFE to interpret noontime observations from the 2007 phase of the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX-2007, conducted at a young Ponderosa pine plantation in the western Sierra Nevada. The model reproduces many features of the BEARPEX-2007 data and offers new insights into the forest-atmosphere exchange of reactive molecules at this location. Nitrogen oxide (NOx = NO + NO2 fluxes are driven by soil emissions of NO, while the partitioning between NO and NO2 fluxes is sensitive to in-canopy photochemical gradients. Enhanced thermolysis at the ground increases downward acyl peroxy nitrate (APN fluxes by as much as 50%, in general agreement with previous findings. APN fluxes are also influenced by in-canopy chemical production, especially when their formation is tied closely to oxidation of BVOC emissions. Gross dry N deposition is typically dominated by nitric acid, though other reactive nitrogen (NOy species can comprise up to 28% of the N deposition budget under cooler conditions. Upward NO2 fluxes cause the net above-canopy NOy flux to be ~30% lower than the gross depositional flux. Model-measurement comparison of hydrogen peroxide mixing ratios suggests this molecule deposits at the aerodynamic limit. CAFE under-predicts ozone fluxes by ~20%, which may indicate additional in-canopy chemical losses that are missing from the current model.

  7. Parameterization of gaseous dry deposition in atmospheric chemistry models: Sensitivity to aerodynamic resistance formulations under statically stable conditions

    Science.gov (United States)

    Toyota, Kenjiro; Dastoor, Ashu P.; Ryzhkov, Andrei

    2016-12-01

    Turbulence controls the vertical transfer of momentum, heat and trace constituents in the atmospheric boundary layer. In the lowest 10% of this layer lies the surface boundary layer (SBL) where the vertical fluxes of transferred quantities have been successfully parameterized using the Monin-Obukhov similarity theory in weather forecast, climate and atmospheric chemistry models. However, there is a large degree of empiricism in the stability-correction parameterizations used to formulate eddy diffusivity and aerodynamic resistance particularly under strongly stable ambient conditions. Although the influence of uncertainties in stability-correction parameterizations on eddy diffusivity is actively studied in boundary-layer meteorological modeling, its impact on dry deposition in atmospheric chemistry modeling is not well characterized. In this study, we address this gap by providing the mathematical basis for the relationship between the formulations of vertical surface flux used in meteorological and atmospheric chemistry modeling communities, and by examining the sensitivity of the modeled dry deposition velocities in statically stable SBL to the choice of stability-correction parameterizations used in three operational and/or research environmental models (GEM/GEM-MACH, ECMWF IFS and CMAQ-MM5). Aerodynamic resistances (ra) calculated by the three sets of parameterizations are notably different from each other and are also different from those calculated by a "z-less" scaling formulation under strongly stable conditions (the bulk Richardson number > 0.2). Furthermore, we show that many atmospheric chemistry models calculate ra using formulations which are inconsistent with the derivation of micro-meteorological parameters. Finally, practical implications of the differences in stability-correction algorithms are discussed for the computations of dry deposition velocities of SO2, O3 and reactive bromine compounds for specific cases of stable SBL.

  8. Laser flash photolysis studies of atmospheric free radical chemistry using optical diagnostic techniques

    Science.gov (United States)

    Wine, Paul H.; Nicovich, J. M.; Hynes, Anthony J.; Stickel, Robert E.; Thorn, R. P.; Chin, Mian; Cronkhite, Jeffrey A.; Shackelford, Christie J.; Zhao, Zhizhong; Daykin, Edward P.

    1993-01-01

    Some recent studies carried out in our laboratory are described where laser flash photolytic production of reactant free radicals has been combined with reactant and/or product detection using time-resolved optical techniques to investigate the kinetics and mechanisms of important atmospheric chemical reactions. Discussed are (1) a study of the radical-radical reaction O + BrO yields Br + O2 where two photolysis lasers are employed to prepare the reaction mixture and where the reactants O and BrO are monitored simultaneously using atomic resonance fluorescence to detect O and multipass UV absorption to detect BrO; (2) a study of the reaction of atomic chlorine with dimethylsulfide (CH3SCH3) where atomic resonance fluorescence detection of Cl is employed to elucidate the kinetics and tunable diode laser absorption spectroscopy is employed to investigate the HCl product yield; and (3) a study of the aqueous phase chemistry of Cl2(-) radicals where longpath UV absorption spectroscopy is employed to investigate the kinetics of the Cl2(-) + H2O reaction.

  9. Experiments of reconstructing discrete atmospheric dynamic models from data (I)

    Science.gov (United States)

    Lin, Zhenshan; Zhu, Yanyu; Deng, Ziwang

    1995-03-01

    In this paper, we give some experimental results of our study in reconstructing discrete atmospheric dynamic models from data. After a great deal of numerical experiments, we found that the logistic map, x n + 1 = 1- μx {2/n}, could be used in monthly mean temperature prediction when it was approaching the chaotic region, and its predictive results were in reverse states to the practical data. This means that the nonlinear developing behavior of the monthly mean temperature system is bifurcating back into the critical chaotic states from the chaotic ones.

  10. Effects of subject-area degree and classroom experience on new chemistry teachers' subject matter knowledge

    Science.gov (United States)

    Nixon, Ryan S.; Campbell, Benjamin K.; Luft, Julie A.

    2016-07-01

    Science teachers need to understand the subject matter they teach. While subject matter knowledge (SMK) can improve with classroom teaching experience, it is problematic that many secondary science teachers leave the profession before garnering extensive classroom experience. Furthermore, many new science teachers are assigned to teach science subjects for which they do not hold a degree. This study investigates the SMK of new secondary science teachers assigned to teach chemistry in their first three years of teaching. These new teachers do not have the advantage of years of experience to develop their SMK and half hold a degree in biology rather than chemistry. This qualitative study explores the effects of holding a degree in the subject area one teaches as well as classroom teaching experience on teachers' SMK for two chemistry topics, conservation of mass and chemical equilibrium. Qualitative analysis of semi-structured interviews indicated that the SMK of teachers who had a chemistry degree and more extensive classroom experience was more coherent, chemistry-focused, and sophisticated than that of teachers who lacked this preparation and experience. This study provides evidence that new science teachers' SMK is influenced by both holding a degree in the subject area and having classroom experience.

  11. Numerical study of variational data assimilation algorithms based on decomposition methods in atmospheric chemistry models

    Science.gov (United States)

    Penenko, Alexey; Antokhin, Pavel

    2016-11-01

    The performance of a variational data assimilation algorithm for a transport and transformation model of atmospheric chemical composition is studied numerically in the case where the emission inventories are missing while there are additional in situ indirect concentration measurements. The algorithm is based on decomposition and splitting methods with a direct solution of the data assimilation problems at the splitting stages. This design allows avoiding iterative processes and working in real-time. In numerical experiments we study the sensitivity of data assimilation to measurement data quantity and quality.

  12. Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b

    CERN Document Server

    Moses, Julianne I; Fortney, Jonathan J; Showman, Adam P; Lewis, Nikole K; Griffith, Caitlin A; Shabram, Megan; Friedson, A James; Marley, Mark S; Freedman, Richard S

    2011-01-01

    We have developed 1-D photochemical and thermochemical kinetics and diffusion models for the transiting exoplanets HD 189733b and HD 209458b to study the effects of disequilibrium chemistry on the atmospheric composition of "hot Jupiters." Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species, and we compare the model results with existing transit and eclipse observations. We find that the vertical profiles of molecular constituents are significantly affected by transport-induced quenching and photochemistry, particularly on cooler HD 189733b; however, the warmer stratospheric temperatures on HD 209458b can help maintain thermochemical equilibrium and reduce the effects of disequilibrium chemistry. For both planets, the methane and ammonia mole fractions are found to be enhanced over their equilibrium values at pressures of a few bar to less than a mbar due to transport-induced quenching, but CH$_4$ and NH$_3$ are photochemically removed at higher altitudes. Atomi...

  13. Innovation in chemistry courses in France in the mid-eighteenth century: experiments and affinities.

    Science.gov (United States)

    Lehman, Christine

    2010-03-01

    In the middle of the eighteenth century, chemistry was the object of spectacular public infatuation. Each course was specialised, depending on its particular audience. In order to meet the range of expectations of its diverse public, chemistry taught in France during this period combined apprenticeship and growing theoretical sophistication, while at the same time remaining popular and spectacular. The analysis of manuscript notes taken by Rouelle's, Venel's and Macquer's students reveals an innovative chemistry, based on experiment, in which theory and practice went hand in hand. The experimental approach was based on the widespread use of Geoffroy's affinity table, which made it possible to both interpret and predict operations.

  14. Laboratory Studies of Phosphine Chemistry Relevant to the Jovian and Saturnian Atmospheres

    Science.gov (United States)

    Liu, Yingdi; Matsiev, Daniel; Robertson, Robert; White, Jason

    2016-10-01

    The photochemistry of phosphine (PH3) in the tropospheres of Saturn and Jupiter is initiated by ultraviolet (UV) radiation and then follows a cascade of chemical reactions that result in P-H hydrides as well as the condensed chromophore red phosphorus (P4). A key intermediate in this pathway is diphosphine (P2H4). The rate constants for the photodissociation of phosphine into initial phosphino radicals and consequently into formation of diphosphine are currently unavailable, limiting their applicability to observational measurements. The condensation of diphosphine to ice in the cold tropospheres is also poorly understood due to the difficulties in synthesizing, handling, and analyzing the compound.Our presentation will describe two experiments at SRI International to produce rate constants for the photochemistry initiated by UV light interacting with phosphine and diphosphine and properties related to the condensed phases of these species. One study seeks to produce property values for application in photochemical and cloud/haze models. Specifically, we extend the measured vapor pressure curve for diphosphine to temperatures relevant to temperatures of Saturn and Jupiter. A sophisticated vapor pressure cell has been constructed and tested and is coupled to a Fourier transform infrared (FTIR) and mass spectrometer for high-fidelity species diagnostics. A companion study investigates phosphine photochemistry to measure the rate constants of key intermediate species related to the loss of PH3 and the formation of P2H4. The experiments employ laser photolysis at 193 nm followed by time-resolved mid-IR laser-based species detection of reactants, and the products provide basic chemical kinetic data useful for interpreting phosphine photochemistry in planetary atmospheres.These two studies are intended to supply basic physical measurements to aid in the interpretation of outer planet atmospheric observations. For both studies, we will present our latest laboratory

  15. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV ? gas phase reactions of organic halogen species

    OpenAIRE

    2007-01-01

    International audience; This article, the fourth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of organic halogen species, which were last published in 1997, and were updated on the IUPAC website in 2006. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and four appen...

  16. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

    OpenAIRE

    2006-01-01

    This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002, and subsequently during the preparation of this article. The article consists of a summary table of the recommended rate coefficients, containing the...

  17. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume I - gas phase reactions of Ox, HOx, NOx and SOx species

    OpenAIRE

    2004-01-01

    This article, the first in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on GasKinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Ox, HOx, NOx and SOx species, which were last published in 1997, and were updated on the IUPAC website in late 2001. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and five appendi...

  18. Developments for transactinide chemistry experiments behind the gas-filled separator TASCA

    Energy Technology Data Exchange (ETDEWEB)

    Even, Julia

    2011-12-13

    Topic of this thesis is the development of experiments behind the gas-filled separator TASCA (TransActinide Separator and Chemistry Apparatus) to study the chemical properties of the transactinide elements. In the first part of the thesis, the electrodepositions of short-lived isotopes of ruthenium and osmium on gold electrodes were studied as model experiments for hassium. From literature it is known that the deposition potential of single atoms differs significantly from the potential predicted by the Nernst equation. This shift of the potential depends on the adsorption enthalpy of therndeposited element on the electrode material. If the adsorption on the electrode-material is favoured over the adsorption on a surface made of the same element as the deposited atom, the electrode potential is shifted to higher potentials. This phenomenon is called underpotential deposition. Possibilities to automatize an electro chemistry experiment behind the gas-filled separator were explored for later studies with transactinide elements. The second part of this thesis is about the in-situ synthesis of transition-metal-carbonyl complexes with nuclear reaction products. Fission products of uranium-235 and californium-249 were produced at the TRIGA Mainz reactor and thermalized in a carbon-monoxide containing atmosphere. The formed volatile metal-carbonyl complexes could be transported in a gas-stream. Furthermore, short-lived isotopes of tungsten, rhenium, osmium, and iridium were synthesised at the linear accelerator UNILAC at GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt. The recoiling fusion products were separated from the primary beam and the transfer products in the gas-filled separator TASCA. The fusion products were stopped in the focal plane of TASCA in a recoil transfer chamber. This chamber contained a carbon-monoxide - helium gas mixture. The formed metal-carbonyl complexes could be transported in a gas stream to various experimental setups. All

  19. GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

    Science.gov (United States)

    Henck, Colin; Nally, Luke

    2007-01-01

    An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

  20. Thermodynamic Exploration of Eosin-Lysozyme Binding: A Physical Chemistry and Biochemistry Laboratory Experiment

    Science.gov (United States)

    Huisman, Andrew J.; Hartsell, Lydia R.; Krueger, Brent P.; Pikaart, Michael J.

    2010-01-01

    We developed a modular pair of experiments for use in the undergraduate physical chemistry and biochemistry laboratories. Both experiments examine the thermodynamics of the binding of a small molecule, eosin Y, to the protein lysozyme. The assay for binding is the quenching of lysozyme fluorescence by eosin through resonant energy transfer. In…

  1. An Enzymatic Clinical Chemistry Laboratory Experiment Incorporating an Introduction to Mathematical Method Comparison Techniques

    Science.gov (United States)

    Duxbury, Mark

    2004-01-01

    An enzymatic laboratory experiment based on the analysis of serum is described that is suitable for students of clinical chemistry. The experiment incorporates an introduction to mathematical method-comparison techniques in which three different clinical glucose analysis methods are compared using linear regression and Bland-Altman difference…

  2. Lysozyme Thermal Denaturation and Self-Interaction: Four Integrated Thermodynamic Experiments for the Physical Chemistry Laboratory

    Science.gov (United States)

    Schwinefus, Jeffrey J.; Schaefle, Nathaniel J.; Muth, Gregory W.; Miessler, Gary L.; Clark, Christopher A.

    2008-01-01

    As part of an effort to infuse our physical chemistry laboratory with biologically relevant, investigative experiments, we detail four integrated thermodynamic experiments that characterize the denaturation (or unfolding) and self-interaction of hen egg white lysozyme as a function of pH and ionic strength. Students first use Protein Explorer to…

  3. Linear Dichroism of Cyanine Dyes in Stretched Polyvinyl Alcohol Films: A Physical Chemistry Laboratory Experiment.

    Science.gov (United States)

    Natarajan, L. V.; And Others

    1983-01-01

    Provides background information, procedures, and results of an undergraduate physical chemistry experiment on the polarization of absorption spectra of cyanine dyes in stretched polyvinyl alcohol films. The experiment gives a simple demonstration of the concept of linear dichromism and the validity of the TEM method used in the analyses. (JN)

  4. Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry Laboratory

    Science.gov (United States)

    Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah

    2008-01-01

    We present a novel first-year chemistry laboratory experiment that connects solubility, equilibrium, and chemical periodicity concepts. It employs a unique format that asks students to replicate experiments described in different sample lab reports, each lacking some essential information, rather than follow a scripted procedure. This structure is…

  5. Enquiry-Based Learning: Experiences of First Year Chemistry Students Learning Spectroscopy

    Science.gov (United States)

    Lucas, Timothy; Rowley, Natalie M.

    2011-01-01

    We explored the experiences of first year chemistry students of an Enquiry-Based Learning (EBL) approach to learning spectroscopy. An investigation of how students' perceived confidences changed as a result of their experience of using EBL in the spectroscopy course was carried out. Changes in the students' perceived confidence, both in their…

  6. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    Directory of Open Access Journals (Sweden)

    W. H. Swartz

    2012-07-01

    Full Text Available The 11-yr solar cycle in solar spectral irradiance (SSI inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOSCCM. The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3–6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7 in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 – 3 times larger than the simulation using the NRL SSI. The GEOSCCM and the Goddard Space Flight Center (GSFC 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. This is important in that it means that chemistry-transport models should simulate the solar cycle in ozone well, while general circulation models without coupled chemistry will underestimate the temperature response to the solar cycle significantly in the middle atmosphere. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm

  7. Impact of continental outflow on chemistry of atmospheric aerosols over tropical Bay of Bengal

    Directory of Open Access Journals (Sweden)

    B. Srinivas

    2011-07-01

    Full Text Available The continental outflow from Indo-Gangetic Plain and south-east Asia dominates the widespread dispersal of pollutants over tropical Bay of Bengal (BoB during the late NE-monsoon (January–March. It is thus pertinent to assess the impact on marine atmospheric boundary layer of BoB. The chemical data, based on analyses of size-segregated (PM2.5 and PM10 aerosols, suggest the dominance of nss-SO42− (range: 1.3 to 28 μg m−3 in PM2.5. Almost all SO42− is of anthropogenic origin and accounts for as much as 65 % of the water-soluble inorganic constituents. The impact of anthropogenic sources is further evident from the widespread depletion of chloride (range: 40 to 100 % compared to sea-salt composition. The carbonaceous species (EC and OC contribute nearly 25 % to PM2.5; and significant linear relationship with K+ suggests biomass burning as their dominant source (biofuels and agricultural waste. The enhancement in the fractional solubility of aerosol Fe, as assessed in PM2.5, re-emphasizes the impact of combustion sources (biomass and fossil-fuel and chemical processing (of dust during the long-range transport. The high enrichment factors of heavy metals (Pb and Cd further demonstrate the influence of pollution sources on the chemistry of MABL. The downwind transport of pollutants and exchange across air-sea interface can, thus, have profound impact on the ocean surface biogeochemistry.

  8. Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry.

    Science.gov (United States)

    Farmer, D K; Matsunaga, A; Docherty, K S; Surratt, J D; Seinfeld, J H; Ziemann, P J; Jimenez, J L

    2010-04-13

    Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as NO(x)+ ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We evaluate the potential for using NO(x)+ fragment ratios, organonitrogen ions, HNO(3)+ ions, the ammonium balance of the nominally inorganic ions, and comparison to ion-chromatography instruments to constrain the concentrations of ON for ambient datasets, and apply these techniques to a field study in Riverside, CA. OS manifests as separate organic and sulfate components in the AMS with minimal organosulfur fragments and little difference in fragmentation from inorganic sulfate. The low thermal stability of ON and OS likely causes similar detection difficulties for other aerosol mass spectrometers using vaporization and/or ionization techniques with similar or larger energy, which has likely led to an underappreciation of these species.

  9. Discovering Factors that Influence the Decision to Pursue a Chemistry-Related Career: A Comparative Analysis of the Experiences of Non Scientist Adults and Chemistry Teachers in Greece

    Science.gov (United States)

    Salta, Katerina; Gekos, Michael; Petsimeri, Irene; Koulougliotis, Dionysios

    2012-01-01

    This study aims at identifying factors that influence students' choice not to pursue a chemistry-related career by analyzing the experiences of secondary education chemistry teachers in Greece and of Greek adults who have not pursued studies related to science. Data collection was done with the method of individual structured interviews. The…

  10. The Development of Thai Pre-Service Chemistry Teachers' Pedagogical Content Knowledge: From a Methods Course to Field Experience

    Science.gov (United States)

    Faikhamta, Chatree; Coll, Richard K.; Roadrangka, Vantipa

    2009-01-01

    This study investigated the journey of four Thai pre-service chemistry teachers as they sought to develop their Pedagogical Content Knowledge (PCK) throughout a PCK-based chemistry methods course and field experience. In an interpretive case study approach we drew upon classroom observations, semi-structured interviews, chemistry content knowledge…

  11. Synthesis and Metalation of a Ligand: An Interdisciplinary Laboratory Experiment for Second-Year Organic and Introductory Inorganic Chemistry Students

    Science.gov (United States)

    Kasting, Benjamin J.; Bowser, Andrew K.; Anderson-Wile, Amelia M.; Wile, Bradley M.

    2015-01-01

    An interdisciplinary laboratory experiment involving second-year undergraduate organic chemistry and introductory inorganic chemistry undergraduate students is described. Organic chemistry students prepare a series of amine-bis(phenols) via a Mannich reaction, and characterize their products using melting point; FTIR; and [superscript 1]H,…

  12. The Response of Atmospheric Chemistry on Earthlike Planets around F, G and K Stars to Small Variations in Orbital Distance

    CERN Document Server

    Grenfell, J L; Von Paris, P; Patzer, B; Titz, R; Segura, A; Rauer, H; Grenfell, John Lee; Stracke, Barbara; Paris, Philip von; Patzer, Beate; Titz, Ruth; Segura, Antigona; Rauer, Heike

    2006-01-01

    One of the prime goals of future investigations of extrasolar planets is to search for life as we know it. The Earth's biosphere is adapted to current conditions. How would the atmospheric chemistry of the Earth respond if we moved it to different orbital distances or changed its host star? This question is central to astrobiology and aids our understanding of how the atmospheres of terrestrial planets develop. To help address this question, we have performed a sensitivity study using a coupled radiative-convective photochemical column model to calculate changes in atmospheric chemistry on a planet having Earth's atmospheric composition, which we subjected to small changes in orbital position, of the order of 5-10 per cent for a solar-type G2V, F2V, and K2V star. We then applied a chemical source-sink analysis to the biomarkers in order to understand how chemical processes affect biomarker concentrations. We start with the composition of the present Earth, since this is the only example we know for which a sp...

  13. Atmospheric Chemistry of (CF3)2CF-C≡N: A Replacement Compound for the Most Potent Industrial Greenhouse Gas, SF6.

    Science.gov (United States)

    Sulbaek Andersen, Mads P; Kyte, Mildrid; Andersen, Simone Thirstrup; Nielsen, Claus J; Nielsen, Ole John

    2017-02-07

    FTIR/smog chamber experiments and ab initio quantum calculations were performed to investigate the atmospheric chemistry of (CF3)2CFCN, a proposed replacement compound for the industrially important sulfur hexafluoride, SF6. The present study determined k(Cl + (CF3)2CFCN) = (2.33 ± 0.87) × 10(-17), k(OH + (CF3)2CFCN) = (1.45 ± 0.25) × 10(-15), and k(O3 + (CF3)2CFCN) ≤ 6 × 10(-24) cm(3) molecule(-1) s(-1), respectively, in 700 Torr of N2 or air diluent at 296 ± 2 K. The main atmospheric sink for (CF3)2CFCN was determined to be reaction with OH radicals. Quantum chemistry calculations, supported by experimental evidence, shows that the (CF3)2CFCN + OH reaction proceeds via OH addition to -C(≡N), followed by O2 addition to -C(OH)═N·, internal H-shift, and OH regeneration. The sole atmospheric degradation products of (CF3)2CFCN appear to be NO, COF2, and CF3C(O)F. The atmospheric lifetime of (CF3)2CFCN is approximately 22 years. The integrated cross section (650-1500 cm(-1)) for (CF3)2CFCN is (2.22 ± 0.11) × 10(-16) cm(2) molecule(-1) cm(-1) which results in a radiative efficiency of 0.217 W m(-2) ppb(-1). The 100-year Global Warming Potential (GWP) for (CF3)2CFCN was calculated as 1490, a factor of 15 less than that of SF6.

  14. The influence of small-scale variations in isoprene concentrations on atmospheric chemistry over a tropical rainforest

    Directory of Open Access Journals (Sweden)

    T. A. M. Pugh

    2010-07-01

    Full Text Available Biogenic volatile organic compounds (BVOCs such as isoprene constitute a large proportion of the global atmospheric oxidant sink. Their reactions in the atmosphere contribute to processes such as ozone production and secondary organic aerosol formation. However, over the tropical rainforest, where 50% of the global emissions of BVOCs are believed to occur, atmospheric chemistry models have been unable to simultaneously simulate the measured daytime concentration of isoprene and that of its principal oxidant, hydroxyl (OH. One reason for this model-measurement discrepancy may be incomplete mixing of isoprene within the convective boundary layer, leading to patchiness or segregation in isoprene and OH mixing ratios and average concentrations that appear to be incompatible with each other. One way of capturing this effect in models of atmospheric chemistry is to use a reduced effective rate constant for their reaction. Recent studies comparing atmospheric chemistry global/box models with field measurements have suggested that this effective rate reduction may be as large as 50%; which is at the upper limit of that calculated using large eddy simulation models. To date there has only been one field campaign worldwide that has reported co-located measurements of isoprene and OH at the necessary temporal resolution to calculate the segregation of these compounds. However many campaigns have recorded sufficiently high resolution isoprene measurements to capture the small-scale fluctuations in its concentration. We use a box model of atmospheric chemistry, constrained by the spectrum of isoprene concentrations measured, to estimate segregation intensity of isoprene and OH from high-frequency isoprene time series. The method successfully reproduces the only directly observed segregation. The effective rate constant reduction for the reaction of isoprene and OH over a South-East Asian rainforest is calculated to be typically <15%. This estimate is not

  15. The influence of small-scale variations in isoprene concentrations on atmospheric chemistry over a tropical rainforest

    Directory of Open Access Journals (Sweden)

    T. A. M. Pugh

    2011-05-01

    Full Text Available Biogenic volatile organic compounds (BVOCs such as isoprene constitute a large proportion of the global atmospheric oxidant sink. Their reactions in the atmosphere contribute to processes such as ozone production and secondary organic aerosol formation. However, over the tropical rainforest, where 50 % of the global emissions of BVOCs are believed to occur, atmospheric chemistry models have been unable to simulate concurrently the measured daytime concentration of isoprene and that of its principal oxidant, hydroxyl (OH. One reason for this model-measurement discrepancy may be incomplete mixing of isoprene within the convective boundary layer, leading to patchiness or segregation in isoprene and OH mixing ratios and average concentrations that appear to be incompatible with each other. One way of capturing this effect in models of atmospheric chemistry is to use a reduced effective rate constant for their reaction. Recent studies comparing atmospheric chemistry global/box models with field measurements have suggested that this effective rate reduction may be as large as 50 %; which is at the upper limit of that calculated using large eddy simulation models. To date there has only been one field campaign worldwide that has reported co-located measurements of isoprene and OH at the necessary temporal resolution to calculate the segregation of these compounds. However many campaigns have recorded sufficiently high resolution isoprene measurements to capture the small-scale fluctuations in its concentration. Assuming uniform distributions of other OH production and loss processes, we use a box model of atmospheric chemistry, constrained by the spectrum of isoprene concentrations measured, as a virtual instrument, to estimate the variability in OH at a point and hence, to estimate the segregation intensity of isoprene and OH from high-frequency isoprene time series. The method successfully reproduces the only directly observed segregation, using

  16. The impact of temperature dependent CO2 cross section measurements: A role for heterogeneous chemistry in the atmosphere of Mars?

    Science.gov (United States)

    Anbar, A. D.; Allen, M.; Nair, H.; Leu, M-T.; Yung, Y. L.

    1992-01-01

    Carbon dioxide comprises over 95 percent of the Mars atmosphere, despite continuous photolysis of CO2 by solar ultraviolet (UV) radiation. Since the direct recombination of CO and O is spinforbidden, the chemical stability of CO2 in the Martian atmosphere is thought to be the result of a HO(x)-catalyzed recombination scheme. Thus the rate of CO oxidation is sensitive to the abundance and altitude distribution of OH, H, and HO2. Most Martian atmospheric models assume that HO(x) abundances are governed purely by gas phase chemistry. However, it is well established that reactive HO(x) radical are adsorbed by a wide variety of surfaces. The authors have combined laboratory studies of H, OH, and HO2 adsorption on inorganic surfaces, observational data of aerosol distributions, and an updated photochemical model to demonstrate that adsorption on either dust or ice aerosols is capable of reducing HO(x) abundances significantly, thereby retarding the rate of CO oxidation.

  17. Comprehensive mechanisms for combustion chemistry: Experiment, modeling, and sensitivity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dryer, F.L.; Yetter, R.A. [Princeton Univ., NJ (United States)

    1993-12-01

    This research program is an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work are conducted in large diameter flow reactors, at pressures from one to twenty atmospheres, temperatures from 550 K to 1200 K, and with observed reaction times from 10{sup {minus}2} to 5 seconds. Gas sampling of stable reactant, intermediate, and product species concentrations provides not only substantial definition of the phenomenology of reaction mechanisms, but a significantly constrained set of kinetic information with negligible diffusive coupling. Analytical techniques used for detecting hydrocarbons and carbon oxides include gas chromatography (GC), and gas infrared (NDIR) and FTIR methods are utilized for continuous on-line sample detection of light absorption measurements of OH have also been performed in an atmospheric pressure flow reactor (APFR), and a variable pressure flow (VPFR) reactor is presently being instrumented to perform optical measurements of radicals and highly reactive molecular intermediates. The numerical aspects of the work utilize zero and one-dimensional pre-mixed, detailed kinetic studies, including path, elemental gradient sensitivity, and feature sensitivity analyses. The program emphasizes the use of hierarchical mechanistic construction to understand and develop detailed kinetic mechanisms. Numerical studies are utilized for guiding experimental parameter selections, for interpreting observations, for extending the predictive range of mechanism constructs, and to study the effects of diffusive transport coupling on reaction behavior in flames. Modeling using well defined and validated mechanisms for the CO/H{sub 2}/oxidant systems.

  18. Lightning-driven inner radiation belt energy deposition into the atmosphere: implications for ionisation-levels and neutral chemistry

    Directory of Open Access Journals (Sweden)

    C. J. Rodger

    2007-08-01

    Full Text Available Lightning-generated whistlers lead to coupling between the troposphere, the Van Allen radiation belts and the lower-ionosphere through Whistler-induced electron precipitation (WEP. Lightning produced whistlers interact with cyclotron resonant radiation belt electrons, leading to pitch-angle scattering into the bounce loss cone and precipitation into the atmosphere. Here we consider the relative significance of WEP to the lower ionosphere and atmosphere by contrasting WEP produced ionisation rate changes with those from Galactic Cosmic Radiation (GCR and solar photoionisation. During the day, WEP is never a significant source of ionisation in the lower ionosphere for any location or altitude. At nighttime, GCR is more significant than WEP at altitudes <68 km for all locations, above which WEP starts to dominate in North America and Central Europe. Between 75 and 80 km altitude WEP becomes more significant than GCR for the majority of spatial locations at which WEP deposits energy. The size of the regions in which WEP is the most important nighttime ionisation source peaks at ~80 km, depending on the relative contributions of WEP and nighttime solar Lyman-α. We also used the Sodankylä Ion Chemistry (SIC model to consider the atmospheric consequences of WEP, focusing on a case-study period. Previous studies have also shown that energetic particle precipitation can lead to large-scale changes in the chemical makeup of the neutral atmosphere by enhancing minor chemical species that play a key role in the ozone balance of the middle atmosphere. However, SIC modelling indicates that the neutral atmospheric changes driven by WEP are insignificant due to the short timescale of the WEP bursts. Overall we find that WEP is a significant energy input into some parts of the lower ionosphere, depending on the latitude/longitude and altitude, but does not play a significant role in the neutral chemistry of the mesosphere.

  19. Parameterization of dust emissions in the global atmospheric chemistry-climate model EMAC: impact of nudging and soil properties

    Directory of Open Access Journals (Sweden)

    M. Astitha

    2012-11-01

    Full Text Available Airborne desert dust influences radiative transfer, atmospheric chemistry and dynamics, as well as nutrient transport and deposition. It directly and indirectly affects climate on regional and global scales. Two versions of a parameterization scheme to compute desert dust emissions are incorporated into the atmospheric chemistry general circulation model EMAC (ECHAM5/MESSy2.41 Atmospheric Chemistry. One uses a globally uniform soil particle size distribution, whereas the other explicitly accounts for different soil textures worldwide. We have tested these two versions and investigated the sensitivity to input parameters, using remote sensing data from the Aerosol Robotic Network (AERONET and dust concentrations and deposition measurements from the AeroCom dust benchmark database (and others. The two versions are shown to produce similar atmospheric dust loads in the N-African region, while they deviate in the Asian, Middle Eastern and S-American regions. The dust outflow from Africa over the Atlantic Ocean is accurately simulated by both schemes, in magnitude, location and seasonality. Approximately 70% of the modelled annual deposition data and 70–75% of the modelled monthly aerosol optical depth (AOD in the Atlantic Ocean stations lay in the range 0.5 to 2 times the observations for all simulations. The two versions have similar performance, even though the total annual source differs by ~50%, which underscores the importance of transport and deposition processes (being the same for both versions. Even though the explicit soil particle size distribution is considered more realistic, the simpler scheme appears to perform better in several locations. This paper discusses the differences between the two versions of the dust emission scheme, focusing on their limitations and strengths in describing the global dust cycle and suggests possible future improvements.

  20. Eliciting Metacognitive Experiences and Reflection in a Year 11 Chemistry Classroom: An Activity Theory Perspective

    Science.gov (United States)

    Thomas, Gregory P.; McRobbie, Campbell J.

    2013-06-01

    Concerns regarding students' learning and reasoning in chemistry classrooms are well documented. Students' reasoning in chemistry should be characterized by conscious consideration of chemical phenomenon from laboratory work at macroscopic, molecular/sub-micro and symbolic levels. Further, students should develop metacognition in relation to such ways of reasoning about chemistry phenomena. Classroom change eliciting metacognitive experiences and metacognitive reflection is necessary to shift entrenched views of teaching and learning in students. In this study, Activity Theory is used as the framework for interpreting changes to the rules/customs and tools of the activity systems of two different classes of students taught by the same teacher, Frances, who was teaching chemical equilibrium to those classes in consecutive years. An interpretive methodology involving multiple data sources was employed. Frances explicitly changed her pedagogy in the second year to direct students attention to increasingly consider chemical phenomena at the molecular/sub-micro level. Additionally, she asked students not to use the textbook until toward the end of the equilibrium unit and sought to engage them in using their prior knowledge of chemistry to understand their observations from experiments. Frances' changed pedagogy elicited metacognitive experiences and reflection in students and challenged them to reconsider their metacognitive beliefs about learning chemistry and how it might be achieved. While teacher change is essential for science education reform, students are not passive players in change efforts and they need to be convinced of the viability of teacher pedagogical change in the context of their goals, intentions, and beliefs.

  1. A kinetic chemistry tagging technique and its application to modelling the stable isotopic composition of atmospheric trace gases

    Directory of Open Access Journals (Sweden)

    S. Gromov

    2010-02-01

    Full Text Available Isotope composition, in many cases, holds unique information on sources, chemical modification and sinks of atmospheric trace gases. Vital to the interpretation and use of an increasing number of isotope analyses is appropriate modelling. However, the exact implementation of isotopic information is a challenge, and often studies use simplifications which limit their applicability. Here we confer a thorough isotopic extension to MECCA, a comprehensive kinetic chemistry sub-model. To this end, we devise a generic tagging technique for the kinetic chemistry mechanisms implemented as the sub-submodel MECCA-TAG. The technique constitutes a diagnostic tool that can benefit the investigation of various aspects of kinetic chemistry schemes; at the same time, the designed numerical optimisation reduces the computational effort while keeping important details unaffected. We further focus specifically on the modelling of stable isotopic composition, including the required extensions of the approach. The results of MECCA-TAG are evaluated against the reference sub-submodel MECCA-DBL, which is implicitly full-detailed, but necessarily is sub-optimal in practical applications due to its high computational demands. Furthermore, we evaluate the elaborate carbon and oxygen isotopic mechanism by simulating the multi-isotope composition of CO and other trace gases in the CAABA/MECCA box-model. The mechanism realistically simulates the oxygen isotope composition of key species resulting from the interchange with ozone and main atmospheric reservoirs, as well as the carbon isotope signature transfer. The model adequately reproduces the isotope chemistry features for CO under the limitation of the modelling domain. In particular, the mass-independently fractionated (MIF composition of CO due to reactions of ozone with unsaturated hydrocarbons (a source effect versus its intrinsic MIF enrichment induced in the removal reaction via oxidation by OH is assessed. As for

  2. Probing - and - Molecular Interactions via Irmpd Experiments and Computational Chemistry

    Science.gov (United States)

    Hopkins, Scott; McMahon, Terry

    2015-06-01

    Experiments carried out at the CLIO Free Electron Facility have been used to probe a range of novel bonding motifs and dissociation dynamics in a variety of chemical systems. Among these are species which exhibit anion-pi interactions in complexes of halide ions with aromatic ring systems with electron withdrawing substituents; charge solvated and zwitterionic clusters of protonated methylamines with phenylalanines; hydrogen bonded dimers of nucleic acid analogues and Pd complexes potentially involving agnostic hydrogen bond interactions. Accompanying DFT computational work is used to assist in identifying the most probable structure(s) present in the IRMPD experiments.

  3. A kinetic chemistry tagging technique and its application to modelling the stable isotopic composition of atmospheric trace gases

    Directory of Open Access Journals (Sweden)

    S. Gromov

    2010-08-01

    Full Text Available Isotope composition, in many cases, holds unique information on the sources, chemical modification and sinks of atmospheric trace gases. Vital to the interpretation and use of an increasing number of isotope analyses is appropriate modelling. However, the exact implementation of isotopic information in chemistry-climate models is a challenge, and often studies use simplifications which limit their applicability. Here we implement a thorough isotopic extension in MECCA, a comprehensive kinetic chemistry sub-model. To this end, we devise a generic tagging technique for the kinetic chemistry mechanisms implemented as the sub-submodel MECCA-TAG. The technique is diagnostic and numerically efficient and supports the investigation of various aspects of kinetic chemistry schemes. We focus specifically on the application to the modelling of stable isotopic composition. The results of MECCA-TAG are evaluated against the reference sub-submodel MECCA-DBL, which is implicitly full-detailed, but computationally expensive and thus sub-optimal in practical applications. Furthermore, we evaluate the elaborate carbon and oxygen isotopic mechanism by simulating the multi-isotope composition of CO and other trace gases in the CAABA/MECCA box-model. The mechanism realistically simulates the oxygen isotope composition of key species, as well as the carbon isotope signature transfer. The model adequately reproduces the isotope chemistry features for CO, taking into account the limits of the modelling domain. In particular, the mass-independently fractionated (MIF composition of CO due to reactions of ozone with unsaturated hydrocarbons (a source effect versus its intrinsic MIF enrichment induced in the removal reaction via oxidation by OH is assessed. The simulated ozone source effect was up to +1‰ in Δ17O(CO. The versatile modelling framework we employ (the Modular Earth Submodel System, MESSy opens the way for implementation of the novel detailed

  4. Electrochemistry in a Nutshell: A General Chemistry Experiment.

    Science.gov (United States)

    Baca, Glenn; Lewis, Dennis A.

    1978-01-01

    This experiment uses a nine-chambered plexiglas unit to facilitate rapid construction of galvanic cells and measurement of cell voltage. Using this procedure, a pair of students can construct and obtain the cell voltages of two precipitation cells, three concentration cells, and six redox cells in 30-40 minutes. (BB)

  5. Foam Fractionation of Lycopene: An Undergraduate Chemistry Experiment

    Science.gov (United States)

    Wang, Yan; Zhang, Mingjie; Hu, Yongliang

    2010-01-01

    A novel experiment for the extraction of lycopene from tomato paste by foam fractionation is described. Foam fractionation is a process for separating and concentrating chemicals by utilizing differences in their surface activities. Extraction of lycopene by foam fractionation is a new method that has not been previously reported in the…

  6. Cation Hydration Constants by Proton NMR: A Physical Chemistry Experiment.

    Science.gov (United States)

    Smith, Robert L.; And Others

    1988-01-01

    Studies the polarization effect on water by cations and anions. Describes an experiment to illustrate the polarization effect of sodium, lithium, calcium, and strontium ions on the water molecule in the hydration spheres of the ions. Analysis is performed by proton NMR. (MVL)

  7. An Enzyme Kinetics Experiment for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Olsen, Robert J.; Olsen, Julie A.; Giles, Greta A.

    2010-01-01

    An experiment using [superscript 1]H NMR spectroscopy to observe the kinetics of the acylase 1-catalyzed hydrolysis of "N"-acetyl-DL-methionine has been developed for the organic laboratory. The L-enantiomer of the reactant is hydrolyzed completely in less than 2 h, and [superscript 1]H NMR spectroscopic data from a single sample can be worked up…

  8. On the plasma chemistry of a cold atmospheric argon plasma jet with shielding gas device

    Science.gov (United States)

    Schmidt-Bleker, Ansgar; Winter, Jörn; Bösel, André; Reuter, Stephan; Weltmann, Klaus-Dieter

    2016-02-01

    A novel approach combining experimental and numerical methods for the study of reaction mechanisms in a cold atmospheric \\text{Ar} plasma jet is introduced. The jet is operated with a shielding gas device that produces a gas curtain of defined composition around the plasma plume. The shielding gas composition is varied from pure {{\\text{N}}2} to pure {{\\text{O}}2} . The density of metastable argon \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) in the plasma plume was quantified using laser atom absorption spectroscopy. The density of long-living reactive oxygen and nitrogen species (RONS), namely {{\\text{O}}3} , \\text{N}{{\\text{O}}2} , \\text{NO} , {{\\text{N}}2}\\text{O} , {{\\text{N}}2}{{\\text{O}}5} and {{\\text{H}}2}{{\\text{O}}2} , was quantified in the downstream region of the jet in a multipass cell using Fourier-transform infrared spectroscopy (FTIR). The jet produces a turbulent flow field and features guided streamers propagating at several \\text{km}~{{\\text{s}}-1} that follow the chaotic argon flow pattern, yielding a plasma plume with steep spatial gradients and a time dependence on the \\text{ns} scale while the downstream chemistry unfolds within several seconds. The fast and highly localized electron impact reactions in the guided streamer head and the slower gas phase reactions of neutrals occurring in the plasma plume and experimental apparatus are therefore represented in two separate kinetic models. The first electron impact reaction kinetics model is correlated to the LAAS measurements and shows that in the guided streamer head primary reactive oxygen and nitrogen species are dominantly generated from \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) . The second neutral species plug-flow model hence uses an \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) source term as sole energy input and yields good agreement with the RONS measured by FTIR spectroscopy.

  9. COMPILATION AND ANALYSES OF EMISSIONS INVENTORIES FOR THE NOAA ATMOSPHERIC CHEMISTRY PROJECT. PROGRESS REPORT, AUGUST 1997.

    Energy Technology Data Exchange (ETDEWEB)

    BENKOVITZ,C.M.

    1997-09-01

    Global inventories of anthropogenic emissions of oxides of nitrogen (NO{sub x}) for circa 1985 and 1990 and Non-Methane Volatile Organic Compounds (NMVOCs) for circa 1990 have been compiled by this project. Work on the inventories has been carried out under the umbrella of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry (IGAC) Program. The 1985 NO{sub x} inventory was compiled using default data sets of global emissions that were refined via the use of more detailed regional data sets; this inventory is being distributed to the scientific community at large as the GEIA Version 1A inventory. Global emissions of NO{sub x} for 1985 are estimated to be 21 Tg N y{sup -1}, with approximately 84% originating in the Northern Hemisphere. The 1990 inventories of NO{sub x} and NMVOCs were compiled using unified methodologies and data sets in collaboration with the Netherlands National Institute of Public Health and Environmental Protection (Rijksinstituut Voor Volksgezondheid en Milieuhygiene, RIVM) and the Division of Technology for Society of the Netherlands Organization for Applied Scientific Research, (IMW-TNO); these emissions will be used as the default estimates to be updated with more accurate regional data. The NMVOC inventory was gridded and speciated into 23 chemical categories. The resulting global emissions for 1990 are 31 Tg N yr{sup -1} for NO{sub x} and 173 Gg NMVOC yr{sup -1}. Emissions of NO{sub x} are highest in the populated and industrialized areas of eastern North America and across Europe, and in biomass burning areas of South America, Africa, and Asia. Emissions of NMVOCs are highest in biomass burning areas of South America, Africa, and Asia. The 1990 NO{sub x} emissions were gridded to 1{sup o} resolution using surrogate data, and were given seasonal, two-vertical-level resolution and speciated into NO and NO{sub 2} based on proportions derived from the 1985 GEIA Version 1B inventory. Global NMVOC

  10. An overview of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx)

    Science.gov (United States)

    Dulac, François

    2014-05-01

    The Chemistry-Aerosol Mediterranean Experiment (ChArMEx, http://charmex.lsce.ipsl.fr) is a French initiative of the MISTRALS meta-programme (Mediterranean Integrated Studies at Regional And Locals Scales, http://www.mistrals-home.org). It federates a great number of national and international cooperative research actions aiming at a scientific assessment of the present and future state of the atmospheric environment in the Mediterranean Basin, and of its impacts on the regional climate, air quality, and marine biogeochemistry. The target is short-lived particulate and gaseous tropospheric trace species which are the cause of poor air quality events, have two-way interactions with climate, or impact the marine biogeochemistry, in a context of strong regional anthropogenic and climatic pressures. The six ChArMEx work packages include Emissions, Chemical processes and ageing, Transport processes and air quality, Aerosol-radiation-climate interactions, Deposition, and Present and future variability and trends. For several years, efforts have been deployed in several countries to develop (i) a network of relevant stations for atmospheric chemistry at background sites on islands and continental coasts around the basin and (ii) several intensive field campaigns including the operation of surface supersites and various instrumented mobile platforms (large and ultra-light aircraft, sounding and drifting balloons, ZeroCO2 sailboat). This presentation is an attempt to provide an overview of the various experimental, remote sensing and modelling efforts produced and to highlight major findings, by referencing more detailed ChArMEx presentations given in this conference and recently published or submitted papers. During the first phase of the project experimental efforts have been mainly concentrated on the western basin. Plans for the 2nd phase of ChArMEx, more dedicated towards the eastern basin, will also be given. In particular we plan to develop monitoring activities at

  11. Condensing complex atmospheric chemistry mechanisms. 1: The direct constrained approximate lumping (DCAL) method applied to alkane photochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.W.; Georgopoulos, P.G. [Environmental and Occupational Health Sciences Inst., Piscataway, NJ (United States); Li, G.; Rabitz, H. [Princeton Univ., NJ (United States). Dept. of Chemistry

    1998-07-01

    Atmospheric chemistry mechanisms are the most computationally intensive components of photochemical air quality simulation models (PAQSMs). The development of a photochemical mechanism, that accurately describes atmospheric chemistry while being computationally efficient for use in PAQSMs, is a difficult undertaking that has traditionally been pursued through semiempirical (diagnostic) lumping approaches. The limitations of these diagnostic approaches are often associated with inaccuracies due to the fact that the lumped mechanisms have typically been optimized to fit the concentration profile of a specific species. Formal mathematical methods for model reduction have the potential (demonstrated through past applications in other areas) to provide very effective solutions to the need for computational efficiency combined with accuracy. Such methods, that can be used to condense a chemical mechanism, include kinetic lumping and domain separation. An application of the kinetic lumping method, using the direct constrained approximately lumping (DCAL) approach, to the atmospheric photochemistry of alkanes is presented in this work. It is shown that the lumped mechanism generated through the application of the DCAL method has the potential to overcome the limitations of existing semiempirical approaches, especially in relation to the consistent and accurate calculation of the time-concentration profiles of multiple species.

  12. Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney; Zhang, Fangtong; Gu, Xibin; Krishtal, Sergey P.; Mebel, Alexander M.; Kostko, Oleg; Ahmed, Musahid

    2010-03-16

    The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further the similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.

  13. Coloring a Superabsorbent Polymer with Metal Ions: An Undergraduate Chemistry Experiment

    Science.gov (United States)

    Yaung, Jing-Fun; Chen, Yueh-Huey

    2009-01-01

    A novel undergraduate chemistry experiment involving superabsorbent polymers commonly used in diapers and other personal care products is described. Students observe the removal of divalent transition-metal ions from aqueous solutions by the polymers. With the procedures provided, students are able to color the superabsorbent polymers with metal…

  14. A Multi-Technique Forensic Experiment for a Nonscience-Major Chemistry Course

    Science.gov (United States)

    Szalay, Paul S.; Zook-Gerdau, Lois Anne; Schurter, Eric J.

    2011-01-01

    This multi-technique experiment with a forensic theme was developed for a nonscience-major chemistry course. The students are provided with solid samples and informed that the samples are either cocaine or a combination of drugs designed to mimic the stimulant and anesthetic qualities of cocaine such as caffeine and lidocaine. The students carry…

  15. The Evaluation of Students' Written Reflection on the Learning of General Chemistry Lab Experiment

    Science.gov (United States)

    Han, Ng Sook; Li, Ho Ket; Sin, Lee Choy; Sin, Keng Pei

    2014-01-01

    Reflective writing is often used to increase understanding and analytical ability. The lack of empirical evidence on the effect of reflective writing interventions on the learning of general chemistry lab experiment supports the examination of this concept. The central goal of this exploratory study was to evaluate the students' written…

  16. Transitioning from Expository Laboratory Experiments to Course-Based Undergraduate Research in General Chemistry

    Science.gov (United States)

    Clark, Ted M.; Ricciardo, Rebecca; Weaver, Tyler

    2016-01-01

    General chemistry courses predominantly use expository experiments that shape student expectations of what a laboratory activity entails. Shifting within a semester to course-based undergraduate research activities that include greater decision-making, collaborative work, and "messy" real-world data necessitates a change in student…

  17. Measurement of the Compressibility Factor of Gases: A Physical Chemistry Laboratory Experiment

    Science.gov (United States)

    Varberg, Thomas D.; Bendelsmith, Andrew J.; Kuwata, Keith T.

    2011-01-01

    In this article, we describe an experiment for the undergraduate physical chemistry laboratory in which students measure the compressibility factor of two gases, helium and carbon dioxide, as a function of pressure at constant temperature. The experimental apparatus is relatively inexpensive to construct and is described and diagrammed in detail.…

  18. A Stopped-Flow Kinetics Experiment for the Physical Chemistry Laboratory Using Noncorrosive Reagents

    Science.gov (United States)

    Prigodich, Richard V.

    2014-01-01

    Stopped-flow kinetics techniques are important to the study of rapid chemical and biochemical reactions. Incorporation of a stopped-flow kinetics experiment into the physical chemistry laboratory curriculum would therefore be an instructive addition. However, the usual reactions studied in such exercises employ a corrosive reagent that can over…

  19. A Cost-Effective Two-Part Experiment for Teaching Introductory Organic Chemistry Techniques

    Science.gov (United States)

    Sadek, Christopher M.; Brown, Brenna A.; Wan, Hayley

    2011-01-01

    This two-part laboratory experiment is designed to be a cost-effective method for teaching basic organic laboratory techniques (recrystallization, thin-layer chromatography, column chromatography, vacuum filtration, and melting point determination) to large classes of introductory organic chemistry students. Students are exposed to different…

  20. Liquid-Liquid Extraction of Insecticides from Juice: An Analytical Chemistry Laboratory Experiment

    Science.gov (United States)

    Radford, Samantha A.; Hunter, Ronald E., Jr.; Barr, Dana Boyd; Ryan, P. Barry

    2013-01-01

    A laboratory experiment was developed to target analytical chemistry students and to teach them about insecticides in food, sample extraction, and cleanup. Micro concentrations (sub-microgram/mL levels) of 12 insecticides spiked into apple juice samples are extracted using liquid-liquid extraction and cleaned up using either a primary-secondary…

  1. Determination of Mercury in Milk by Cold Vapor Atomic Fluorescence: A Green Analytical Chemistry Laboratory Experiment

    Science.gov (United States)

    Armenta, Sergio; de la Guardia, Miguel

    2011-01-01

    Green analytical chemistry principles were introduced to undergraduate students in a laboratory experiment focused on determining the mercury concentration in cow and goat milk. In addition to traditional goals, such as accuracy, precision, sensitivity, and limits of detection in method selection and development, attention was paid to the…

  2. An Attenuated Total Reflectance Sensor for Copper: An Experiment for Analytical or Physical Chemistry

    Science.gov (United States)

    Shtoyko, Tanya; Zudans, Imants; Seliskar, Carl J.; Heineman, William R.; Richardson, John N.

    2004-01-01

    A sensor experiment which can be applied to advanced undergraduate laboratory course in physical or analytical chemistry is described along with certain concepts like the demonstration of chemical sensing, preparation of thin films on a substrate, microtitration, optical determination of complex ion stoichiometry and isosbestic point. It is seen…

  3. Computational Modeling of the Optical Rotation of Amino Acids: An "in Silico" Experiment for Physical Chemistry

    Science.gov (United States)

    Simpson, Scott; Autschbach, Jochen; Zurek, Eva

    2013-01-01

    A computational experiment that investigates the optical activity of the amino acid valine has been developed for an upper-level undergraduate physical chemistry laboratory course. Hybrid density functional theory calculations were carried out for valine to confirm the rule that adding a strong acid to a solution of an amino acid in the l…

  4. Molecular Orbitals of NO, NO[superscript+], and NO[superscript-]: A Computational Quantum Chemistry Experiment

    Science.gov (United States)

    Orenha, Renato P.; Galembeck, Sérgio E.

    2014-01-01

    This computational experiment presents qualitative molecular orbital (QMO) and computational quantum chemistry exercises of NO, NO[superscript+], and NO[superscript-]. Initially students explore several properties of the target molecules by Lewis diagrams and the QMO theory. Then, they compare qualitative conclusions with EHT and DFT calculations…

  5. The Synthesis of a Cockroach Pheromone: An Experiment for the Second-Year Organic Chemistry Laboratory

    Science.gov (United States)

    Feist, Patty L.

    2008-01-01

    This experiment describes the synthesis of gentisyl quinone isovalerate, or blattellaquinone, a sex pheromone of the German cockroach that was isolated and identified in 2005. The synthesis is appropriate for the second semester of a second-year organic chemistry laboratory course. It can be completed in two, three-hour laboratory periods and uses…

  6. X-Ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment

    Science.gov (United States)

    Varberg, Thomas D.; Skakuj, Kacper

    2015-01-01

    Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

  7. Solventless and One-Pot Synthesis of Cu(II) Phthalocyanine Complex: A Green Chemistry Experiment

    Science.gov (United States)

    Sharma, R. K.; Sharma, Chetna; Sidhwani, Indu Tucker

    2011-01-01

    With the growing awareness of green chemistry, it is increasingly important for students to understand this concept in the context of laboratory experiments. Although microwave-assisted organic synthesis has become a common and invaluable technique in recent years, there have been few procedures published for microwave-assisted inorganic synthesis…

  8. Nitration of Phenols Using Cu(NO[subscript 3])[subscript 2]: Green Chemistry Laboratory Experiment

    Science.gov (United States)

    Yadav, Urvashi; Mande, Hemant; Ghalsasi, Prasanna

    2012-01-01

    An easy-to-complete, microwave-assisted, green chemistry, electrophilic nitration method for phenol using Cu(NO[subscript 3])[subscript 2] in acetic acid is discussed. With this experiment, students clearly understand the mechanism underlying the nitration reaction in one laboratory session. (Contains 4 schemes.)

  9. Searching for Synthetic Antimicrobial Peptides: An Experiment for Organic Chemistry Students

    Science.gov (United States)

    Vasquez, Thomas E., Jr.; Saldan~a, Cristina; Muzikar, Katy A.; Mashek, Debra; Liu, Jane M.

    2016-01-01

    This laboratory experiment provides undergraduate students enrolled in organic chemistry the opportunity to design and synthesize their own peptide, which is then tested for antimicrobial activity. After reading a primary scientific paper on antimicrobial peptides, students design and synthesize their own hexapeptide that they hypothesize will…

  10. An Environmental Chemistry Experiment: The Determination of Radon Levels in Water.

    Science.gov (United States)

    Welch, Lawrence E.; Mossman, Daniel M.

    1994-01-01

    Describes a radiation experiment developed to complement a new environmental chemistry laboratory curriculum. A scintillation counter is used to measure radon in water. The procedure relies on the fact that toluene will preferentially extract radon from water. Sample preparation is complete in less than 90 minutes. Because the level of…

  11. Application of Calibrated Peer Review (CPR) Writing Assignments to Enhance Experiments with an Environmental Chemistry Focus

    Science.gov (United States)

    Margerum, Lawrence D.; Gulsrud, Maren; Manlapez, Ronald; Rebong, Rachelle; Love, Austin

    2007-01-01

    The browser-based software program, Calibrated Peer Review (CPR) developed by the Molecular Science Project enables instructors to create structured writing assignments in which students learn by writing and reading for content. Though the CPR project covers only one experiment in general chemistry, it might provide lab instructors with a method…

  12. Assessment of Antioxidant Capacities in Foods: A Research Experience for General Chemistry Students

    Science.gov (United States)

    Hoch, Matthew A.; Russell, Cianan B.; Steffen, Debora M.; Weaver, Gabriela C.; Burgess, John R.

    2009-01-01

    With the booming interest in health food and nutrition, investigations of the antioxidant capacities of various foods have come to the forefront of food science. This general chemistry laboratory curriculum provides students with an opportunity to design and implement their own experiments relating to antioxidants in food. The curriculum is six…

  13. Analysis of a Natural Yellow Dye: An Experiment for Analytical Organic Chemistry

    NARCIS (Netherlands)

    Villela, A.; Derksen, G.C.H.; Beek, van T.A.

    2014-01-01

    This experiment exposes second-year undergraduate students taking a course in analytical organic chemistry to high-performance liquid chromatography (HPLC) and quantitative analysis using the internal standard method. This is accomplished using the real-world application of natural dyes for textiles

  14. Introducing Ethics to Chemistry Students in a "Research Experiences for Undergraduates" (REU) Program

    Science.gov (United States)

    Hanson, Mark J.

    2015-01-01

    A three-day ethics seminar introduced ethics to undergraduate environmental chemistry students in the Research Experiences for Undergraduates (REU) program. The seminar helped students become sensitive to and understand the ethical and values dimensions of their work as researchers. It utilized a variety of resources to supplement lectures and…

  15. Simulating organic species with the global atmospheric chemistry general circulation model ECHAM5/MESSy1: a comparison of model results with observation

    NARCIS (Netherlands)

    Pozzer, A.; Jöckel, P.; Tost, H.; Sander, R.; Ganzeveld, L.N.; Kerkweg, A.; Lelieveld, J.

    2007-01-01

    The atmospheric-chemistry general circulation model ECHAM5/MESSy1 is evaluated with observations of different organic ozone precursors. This study continues a prior analysis which focused primarily on the representation of atmospheric dynamics and ozone. We use the results of the same reference simu

  16. Interfacial Atmospheric Chemistry: Quantum Chemical Calculations on the Mechanism of Protonation and Oligomerization of Isoprene on Aqueous Surfaces

    Science.gov (United States)

    Mishra, H.; Colussi, A. J.; Enami, S.; Nielsen, R. J.; Hoffmann, M. R.; Goddard, W. A.

    2012-12-01

    It has become increasingly apparent that atmospheric chemistry involves more than gas-phase reactions. Key processes, such as the decay of NO2 in urban plumes and the associated daytime formation of HONO, and the rapid chemistries observed in and over forest canopies at nighttime defy explanation by conventional atmospheric chemistry mechanisms. We have recently reported experimental results on several gas-liquid reactions of atmospheric interest, such as the facile protonation of gaseous isoprene on mildly acidic (pH bioenergetics coupling, 'on-water' catalysis, self-assembly and molecular recognition, little is known about the molecular mechanisms of such reactions. Herein we apply quantum mechanics to investigate how biogenic or anthropogenic olefins may get protonated and undergo oligomerization at the air-water interface by performing model calculations on small water clusters carrying an excess proton as surrogates for the surface of mildly acidic water as sensed by gaseous isoprene (ISO). We find that ISO binds weakly to the surface of water and accepts a proton from H+(H2O)3, leading to ISOH+ via a proton transfer hindered by a ΔG1‡ = 5.6 kcal mol-1 kinetic barrier. Subsequently, another ISO attaches loosely to this ensemble, before being attacked by the ISOH+. This process, which represents the first step of the cationic polymerization of ISO, is hindered by a similar ΔG2‡ = 5.7 kcal mol-1 barrier. Our theoretical results are consistent with experimental (~ 10-4) uptake coefficients for ISO measured on acidic water.

  17. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV – gas phase reactions of organic halogen species

    Directory of Open Access Journals (Sweden)

    R. Atkinson

    2008-08-01

    Full Text Available This article, the fourth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of organic halogen species, which were last published in 1997, and were updated on the IUPAC website in 2006/07. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and four appendices containing the data sheets, which provide information upon which the recommendations are made.

  18. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

    Directory of Open Access Journals (Sweden)

    R. Atkinson

    2006-01-01

    Full Text Available This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002, and subsequently during the preparation of this article. The article consists of a summary table of the recommended rate coefficients, containing the recommended kinetic parameters for the evaluated reactions, and eight appendices containing the data sheets, which provide information upon which the recommendations are made.

  19. CO2 Dissociation using the Versatile Atmospheric Dielectric Barrier Discharge Experiment (VADER

    Directory of Open Access Journals (Sweden)

    Michael Allen Lindon

    2014-09-01

    Full Text Available Dissociation of CO2 is investigated in an atmospheric pressure dielectric barrier discharge (DBD with a simple, zero dimensional (0-D chemical model and through experiment. The model predicts that the primary CO2 dissociation pathway within a DBD is electron impact dissociation and electron-vibrational excitation. The relaxation kinetics following dissociation are dominated by atomic oxygen chemistry. The experiments included investigating the energy efficiencies and dissociation rates of CO2 within a planar DBD, while the gas flow rate, voltage, gas composition, driving frequency, catalyst, and pulse modes were varied. Some of the VADER results include a maximum CO2 dissociation energy efficiency of 2.5 +/- 0.5%, a maximum CO$_2$ dissociation rate of 4 +/- 0.4*10^-6 mol CO2/s (5 +/- 0.5% percent dissociation, discovering that a resonant driving frequency of ~30 kHz, dependent on both applied voltage and breakdown voltage, is best for efficient CO2 dissociation and that TiO2, a photocatalyst, improved dissociation efficiencies by an average of 18% at driving frequencies above 5 kHz.

  20. Fitting It All In: Adapting a Green Chemistry Extraction Experiment for Inclusion in an Undergraduate Analytical Laboratory

    Science.gov (United States)

    Buckley, Heather L.; Beck, Annelise R.; Mulvihill, Martin J.; Douskey, Michelle C.

    2013-01-01

    Several principles of green chemistry are introduced through this experiment designed for use in the undergraduate analytical chemistry laboratory. An established experiment of liquid CO2 extraction of D-limonene has been adapted to include a quantitative analysis by gas chromatography. This facilitates drop-in incorporation of an exciting…

  1. Synthesis and Decomposition Kinetic Studies of Bis(lutidine)silver(I) Nitrate Complexes as an Interdisciplinary Undergraduate Chemistry Experiment

    Science.gov (United States)

    Monga, Vishakha; Bussie`re, Guillaume; Crichton, Paul; Daswani, Sailesh

    2016-01-01

    Interdisciplinary experiments are being offered in upper-division chemistry laboratory courses in an attempt to encourage students to make a connection between techniques learned in one discipline to affirm chemical principles that form the basis of chemical reactions in another chemistry discipline. A new interdisciplinary experiment is described…

  2. Atmospheric chemistry of 2,3-pentanedione: photolysis and reaction with OH radicals.

    Science.gov (United States)

    Szabó, Emese; Djehiche, Mokhtar; Riva, Matthieu; Fittschen, Christa; Coddeville, Patrice; Sarzyński, Dariusz; Tomas, Alexandre; Dóbé, Sándor

    2011-08-25

    The kinetics of the overall reaction between OH radicals and 2,3-pentanedione (1) were studied using both direct and relative kinetic methods at laboratory temperature. The low pressure fast discharge flow experiments coupled with resonance fluorescence detection of OH provided the direct rate coefficient of (2.25 ± 0.44) × 10(-12) cm(3) molecule(-1) s(-1). The relative-rate experiments were carried out both in a collapsible Teflon chamber and a Pyrex reactor in two laboratories using different reference reactions to provide the rate coefficients of 1.95 ± 0.27, 1.95 ± 0.34, and 2.06 ± 0.34, all given in 10(-12) cm(3) molecule(-1) s(-1). The recommended value is the nonweighted average of the four determinations: k(1) (300 K) = (2.09 ± 0.38) × 10(-12) cm(3) molecule(-1) s(-1), given with 2σ accuracy. Absorption cross sections for 2,3-pentanedione were determined: the spectrum is characterized by two wide absorption bands between 220 and 450 nm. Pulsed laser photolysis at 351 nm was used and the depletion of 2,3-pentanedione (2) was measured by GC to determine the photolysis quantum yield of Φ(2) = 0.11 ± 0.02(2σ) at 300 K and 1000 mbar synthetic air. An upper limit was estimated for the effective quantum yield of 2,3-pentanedione applying fluorescent lamps with peak wavelength of 312 nm. Relationships between molecular structure and OH reactivity, as well as the atmospheric fate of 2,3-pentanedione, have been discussed.

  3. Chemistry Simulations using the MERRA-2 Reanalysis with the GMI CTM and Replay in Support of the Atmospheric Composition Community

    Science.gov (United States)

    Oman, Luke D.; Strahan, Susan E.

    2017-01-01

    Simulations using reanalysis meteorological fields have long been used to understand the causes of atmospheric composition change in the recent past. Using the new MERRA-2 reanalysis, we are conducting chemistry simulations to create products covering 1980-2016 for the atmospheric composition community. These simulations use the Global Modeling Initiative (GMI) chemical mechanism in two different models: the GMI Chemical Transport Model (CTM) and the GEOS-5 model in Replay mode. Replay mode means an integration of the GEOS-5 general circulation model that is incrementally adjusted each time step toward the MERRA-2 reanalysis. The GMI CTM is a 1 deg x 1.25 deg simulation and the MERRA-2 GMI Replay simulation uses the native MERRA-2 grid of approximately 1/2 deg horizontal resolution on the cubed sphere. A specialized set of transport diagnostics is included in both runs to better understand trace gas transport and its variability in the recent past.

  4. Photolysis of 4-Phenyl-1,3-dioxolan-2-one: An Undergraduate Experiment in Free Radical Chemistry.

    Science.gov (United States)

    White, Rick C.; Ma, Sha

    1988-01-01

    Describes a photochemistry experiment designed to introduce photochemical techniques and experience free radical chemistry. Selects Nuclear Magnetic Resonance spectroscopy for the analysis. This activity is suggested for use in an upper level undergraduate organic course. (MVL)

  5. Middle Atmosphere Response to Different Descriptions of the 11-Year Solar Cycle in Spectral Irradiance in a Chemistry-Climate Model

    Science.gov (United States)

    Swartz, W. H.; Stolarski, R. S.; Oman, L. D.; Fleming, E. L.; Jackman, C. H.

    2012-01-01

    The 11-year solar cycle in solar spectral irradiance (SSI) inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE) suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL) SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOS CCM). The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3-6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7) in the tropics. The peak zonal mean tropical temperature response 50 using the SORCE SSI is nearly 2 K per 100 units 3 times larger than the simulation using the NRL SSI. The GEOS CCM and the Goddard Space Flight Center (GSFC) 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE) and Spectral Irradiance Monitor (SIM) on SORCE, respectively. A higher wavelength-resolution analysis of the spectral response could allow for a better prediction of the

  6. Exploring lag times between monthly atmospheric deposition and stream chemistry in Appalachian forests using cross-correlation

    Science.gov (United States)

    DeWalle, David R.; Boyer, Elizabeth W.; Buda, Anthony R.

    2016-12-01

    Forecasts of ecosystem changes due to variations in atmospheric emissions policies require a fundamental understanding of lag times between changes in chemical inputs and watershed response. Impacts of changes in atmospheric deposition in the United States have been documented using national and regional long-term environmental monitoring programs beginning several decades ago. Consequently, time series of weekly NADP atmospheric wet deposition and monthly EPA-Long Term Monitoring stream chemistry now exist for much of the Northeast which may provide insights into lag times. In this study of Appalachian forest basins, we estimated lag times for S, N and Cl by cross-correlating monthly data from four pairs of stream and deposition monitoring sites during the period from 1978 to 2012. A systems or impulse response function approach to cross-correlation was used to estimate lag times where the input deposition time series was pre-whitened using regression modeling and the stream response time series was filtered using the deposition regression model prior to cross-correlation. Cross-correlations for S were greatest at annual intervals over a relatively well-defined range of lags with the maximum correlations occurring at mean lags of 48 months. Chloride results were similar but more erratic with a mean lag of 57 months. Few high-correlation lags for N were indicated. Given the growing availability of atmospheric deposition and surface water chemistry monitoring data and our results for four Appalachian basins, further testing of cross-correlation as a method of estimating lag times on other basins appears justified.

  7. A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres

    CERN Document Server

    Helling, Ch; Allard, F; Dehn, M; Hauschild, P; Homeier, D; Lodders, K; Marley, M; Rietmeijer, F; Tsuji, T; Woitke, P

    2008-01-01

    The atmospheres of substellar objects contain clouds of oxides, iron, silicates, and other refractory condensates. Water clouds are expected in the coolest objects. The opacity of these `dust' clouds strongly affects both the atmospheric temperature-pressure profile and the emergent flux. Thus any attempt to model the spectra of these atmospheres must incorporate a cloud model. However the diversity of cloud models in atmospheric simulations is large and it is not always clear how the underlying physics of the various models compare. Likewise the observational consequences of different modeling approaches can be masked by other model differences, making objective comparisons challenging. In order to clarify the current state of the modeling approaches, this paper compares five different cloud models in two sets of tests. Test case 1 tests the dust cloud models for a prescribed L, L--T, and T-dwarf atmospheric (temperature T, pressure p, convective velocity vconv)-structures. Test case 2 compares complete mode...

  8. Russian contribution to ExoMars Trace Gas Orbiter: Atmospheric Chemistry Suite (ACS)

    Science.gov (United States)

    Shakun, Alexey; Korablev, Oleg; Trokhimovskiy, Alexander; Grigoriev, Alexey; Anufreychik, Konstantin; Fedorova, Anna; Ignatiev, Nikolay; Ivanov, Yuriy; Moshkin, Boris; Kalinnikov, Yuriy; Montmessin, Franck

    2016-04-01

    Atmospheric Chemistry Suite (ACS) is a part of science payload of Trace Gas Orbiter (TGO), ExoMars mission. This project developed by European Space Agency (ESA) in collaboration with Russian Space Agency (Roscosmos). Russian contribution to ExoMars TGO is the Proton rocket and two science instruments ACS (three infrared spectrometers) and FREND (neutron detector). ACS consists of three infrared spectrometers (ACS/NIR, ACS/MIR and ACS/TIRVIM) capable to take spectral measurements from near to thermal infrared range simultaneously or separately. Spectrometric channels of ACS share common mechanical, electrical, and thermal interfaces. Electronic box (ACS/BE) provides to spectrometric channels power and data transfer interfaces. SpaceWire link is used for science data transfer and MIL-1553 link - for commanding and housekeeping data transfer. The NIR channel is an echelle spectrometer with acousto-optic tunable filter (AOTF) for the selection of diffraction orders. ACS NIR is capable to perform nadir and occultation observations. NIR covers the spectral range of 0.7-1.7 μm with resolving power of ~25000. NIR will perform unique for TGO instruments nightglow science (searching for O2, OH, NO nightglow emissions on Mars). From the 1.38 μm band NIR will do water vapour mapping in nadir and H2O vertical profiling in solar occultations. High resolution NIR measurements of 1.27 μm O2(a1Δg) dayglow will supply indirect ozone observations on the dayside on nadir. In solar occultation mode, the O2 vertical profiles will be measured from the surface (in case of low dust activity) to the 40 km altitude based on 0.76 μm absorption band. Together with MIR channel in solar occultation NIR will support the measurements of CO2 density profiles (based on 1.43 μm band) and aerosols characterization from 0.7 to 4 μm. The wide spectral range will allow not just determine aerosol particle sizes and density at different altitudes, but also distinguish between dust and ice particles

  9. A study of the dissociative recombination of CaO+ with electrons: Implications for Ca chemistry in the upper atmosphere

    Science.gov (United States)

    Bones, D. L.; Gerding, M.; Höffner, J.; Martín, Juan Carlos Gómez; Plane, J. M. C.

    2016-12-01

    The dissociative recombination of CaO+ ions with electrons has been studied in a flowing afterglow reactor. CaO+ was generated by the pulsed laser ablation of a Ca target, followed by entrainment in an Ar+ ion/electron plasma. A kinetic model describing the gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a rate coefficient of (3.0 ± 1.0) × 10-7 cm3 molecule-1 s-1 at 295 K. This result has two atmospheric implications. First, the surprising observation that the Ca+/Fe+ ratio is 8 times larger than Ca/Fe between 90 and 100 km in the atmosphere can now be explained quantitatively by the known ion-molecule chemistry of these two metals. Second, the rate of neutralization of Ca+ ions in a descending sporadic E layer is fast enough to explain the often explosive growth of sporadic neutral Ca layers.

  10. Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn

    Directory of Open Access Journals (Sweden)

    P. Martinerie

    2009-01-01

    Full Text Available The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114, CFC-115, CCl4 and SF6 are studied by comparing measurements in polar firn air from two Arctic and three Antarctic sites, and simulation results of two numerical models: a 2-D atmospheric chemistry model and a 1-D firn diffusion model. The first one is used to calculate atmospheric concentrations from emission trends based on industrial inventories; the calculated concentration trends are used by the second one to produce depth concentration profiles in the firn. The 2-D atmospheric model is validated in the boundary layer by comparison with atmospheric station measurements, and vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn air measurements provide constraints on historical atmospheric concentrations over the last century. Age distributions in the firn are discussed using a Green function approach. Finally, our results are used as input to a radiative model in order to evaluate the radiative forcing of our target gases. Multi-species and multi-site firn air studies allow to better constrain atmospheric trends. The low concentrations of all studied gases at the bottom of the firn, and their consistency with our model results confirm that their natural sources are insignificant. Our results indicate that the emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF6 are well constrained, whereas it is not the case for CFC-114 and CCl4. Significant emission-dependent changes in the lifetimes of halocarbons destroyed in the stratosphere were obtained. Those result from the time needed for their transport from the surface where they are emitted to the stratosphere where they are destroyed. Efforts should be made to update and reduce the large uncertainties on CFC lifetimes.

  11. Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn

    Directory of Open Access Journals (Sweden)

    P. Martinerie

    2009-06-01

    Full Text Available The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114, CFC-115, CCl4 and SF6 are studied by comparing measurements in polar firn air from two Arctic and three Antarctic sites, and simulation results of two numerical models: a 2-D atmospheric chemistry model and a 1-D firn diffusion model. The first one is used to calculate atmospheric concentrations from emission trends based on industrial inventories; the calculated concentration trends are used by the second one to produce depth concentration profiles in the firn. The 2-D atmospheric model is validated in the boundary layer by comparison with atmospheric station measurements, and vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn air measurements provide constraints on historical atmospheric concentrations over the last century. Age distributions in the firn are discussed using a Green function approach. Finally, our results are used as input to a radiative model in order to evaluate the radiative forcing of our target gases. Multi-species and multi-site firn air studies allow to better constrain atmospheric trends. The low concentrations of all studied gases at the bottom of the firn, and their consistency with our model results confirm that their natural sources are small. Our results indicate that the emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF6 are well constrained, whereas it is not the case for CFC-114 and CCl4. Significant emission-dependent changes in the lifetimes of halocarbons destroyed in the stratosphere were obtained. Those result from the time needed for their transport from the surface where they are emitted to the stratosphere where they are destroyed. Efforts should be made to update and reduce the large uncertainties on CFC lifetimes.

  12. The Influence of Galactic Cosmic Rays on Ion-Neutral Hydrocarbon Chemistry in the Upper Atmospheres of Free-Floating Exoplanets

    CERN Document Server

    Rimmer, P B; Bilger, C

    2013-01-01

    Cosmic rays may be linked to the formation of volatiles necessary for prebiotic chemistry. We explore the effect of cosmic rays in a hydrogen-dominated atmosphere, as a proof-of-concept that ion-neutral chemistry may be important for modelling hydrogen-dominated atmospheres. In order to accomplish this, we utilize Monte Carlo cosmic ray transport models with particle energies of $10^6$ eV $< E < 10^{12}$ eV in order to investigate the cosmic ray enhancement of free electrons in substellar atmospheres. Ion-neutral chemistry is then applied to a Drift-Phoenix model of a free-floating giant gas planet. Our results suggest that the activation of ion-neutral chemistry in the upper atmosphere significantly enhances formation rates for various species, and we find that C$_2$H$_2$, C$_2$H$_4$, NH$_3$, C$_6$H$_6$ and possibly C$_{10}$H are enhanced in the upper atmospheres because of cosmic rays. Our results suggest a potential connection between cosmic ray chemistry and the hazes observed in the upper atmospher...

  13. The chemistry CATT–BRAMS model (CCATT–BRAMS 4.5: a regional atmospheric model system for integrated air quality and weather forecasting and research

    Directory of Open Access Journals (Sweden)

    K. M. Longo

    2013-02-01

    Full Text Available The Coupled Chemistry Aerosol-Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CCATT–BRAMS, version 4.5 is an online regional chemical transport model designed for local and regional studies of atmospheric chemistry from surface to the lower stratosphere suitable both for operational and research purposes. It includes gaseous/aqueous chemistry, photochemistry, scavenging and dry deposition. The CCATT–BRAMS model takes advantages of the BRAMS specific development for the tropics/subtropics and of the recent availability of preprocessing tools for chemical mechanisms and of fast codes for photolysis rates. BRAMS includes state-of-the-art physical parameterizations and dynamic formulations to simulate atmospheric circulations of scales down to meters. The online coupling between meteorology and chemistry allows the system to be used for simultaneous atmospheric weather and chemical composition forecasts as well as potential feedbacks between them. The entire system comprises three preprocessing software tools for chemical mechanism (which are user defined, aerosol and trace gases emission fields and atmospheric and chemistry fields for initial and boundary conditions. In this paper, the model description is provided along evaluations performed using observational data obtained from ground-based stations, instruments aboard of aircrafts and retrieval from space remote sensing. The evaluation takes into account model application on different scales from megacities and Amazon Basin up to intercontinental region of the Southern Hemisphere.

  14. An advanced modeling study on the impacts and atmospheric implications of multiphase dimethyl sulfide chemistry.

    Science.gov (United States)

    Hoffmann, Erik Hans; Tilgner, Andreas; Schrödner, Roland; Bräuer, Peter; Wolke, Ralf; Herrmann, Hartmut

    2016-10-18

    Oceans dominate emissions of dimethyl sulfide (DMS), the major natural sulfur source. DMS is important for the formation of non-sea salt sulfate (nss-SO4(2-)) aerosols and secondary particulate matter over oceans and thus, significantly influence global climate. The mechanism of DMS oxidation has accordingly been investigated in several different model studies in the past. However, these studies had restricted oxidation mechanisms that mostly underrepresented important aqueous-phase chemical processes. These neglected but highly effective processes strongly impact direct product yields of DMS oxidation, thereby affecting the climatic influence of aerosols. To address these shortfalls, an extensive multiphase DMS chemistry mechanism, the Chemical Aqueous Phase Radical Mechanism DMS Module 1.0, was developed and used in detailed model investigations of multiphase DMS chemistry in the marine boundary layer. The performed model studies confirmed the importance of aqueous-phase chemistry for the fate of DMS and its oxidation products. Aqueous-phase processes significantly reduce the yield of sulfur dioxide and increase that of methyl sulfonic acid (MSA), which is needed to close the gap between modeled and measured MSA concentrations. Finally, the simulations imply that multiphase DMS oxidation produces equal amounts of MSA and sulfate, a result that has significant implications for nss-SO4(2-) aerosol formation, cloud condensation nuclei concentration, and cloud albedo over oceans. Our findings show the deficiencies of parameterizations currently used in higher-scale models, which only treat gas-phase chemistry. Overall, this study shows that treatment of DMS chemistry in both gas and aqueous phases is essential to improve the accuracy of model predictions.

  15. Response of lake chemistry to atmospheric deposition and climate in selected Class I wilderness areas in the western United States, 1993-2009

    Science.gov (United States)

    Mast, M. Alisa

    2011-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Forest Service, Air Resource Management, conducted a study to evaluate long-term trends in lake-water chemistry for 64 high-elevation lakes in selected Class I wilderness areas in Colorado, Idaho, Utah, and Wyoming during 1993 to 2009. Understanding how and why lake chemistry is changing in mountain areas is essential for effectively managing and protecting high-elevation aquatic ecosystems. Trends in emissions, atmospheric deposition, and climate variables (air temperature and precipitation amount) were evaluated over a similar period of record. A main objective of the study was to determine if changes in atmospheric deposition of contaminants in the Rocky Mountain region have resulted in measurable changes in the chemistry of high-elevation lakes. A second objective was to investigate linkages between lake chemistry and air temperature and precipitation to improve understanding of the sensitivity of mountain lakes to climate variability.

  16. The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere

    Directory of Open Access Journals (Sweden)

    P. Jöckel

    2006-01-01

    Full Text Available The new Modular Earth Submodel System (MESSy describes atmospheric chemistry and meteorological processes in a modular framework, following strict coding standards. It has been coupled to the ECHAM5 general circulation model, which has been slightly modified for this purpose. A 90-layer model setup up to 0.01 hPa was used at spectral T42 resolution to simulate the lower and middle atmosphere. With the high vertical resolution the model simulates the Quasi-Biennial Oscillation. The model meteorology has been tested to check the influence of the changes to ECHAM5 and the radiation interactions with the new representation of atmospheric composition. In the simulations presented here a Newtonian relaxation technique was applied in the tropospheric part of the domain to weakly nudge the model towards the analysed meteorology during the period 1998–2005. This allows an efficient and direct evaluation with satellite and in-situ data. It is shown that the tropospheric wave forcing of the stratosphere in the model suffices to reproduce major stratospheric warming events leading e.g. to the vortex split over Antarctica in 2002. Characteristic features such as dehydration and denitrification caused by the sedimentation of polar stratospheric cloud particles and ozone depletion during winter and spring are simulated well, although ozone loss in the lower polar stratosphere is slightly underestimated. The model realistically simulates stratosphere-troposphere exchange processes as indicated by comparisons with satellite and in situ measurements. The evaluation of tropospheric chemistry presented here focuses on the distributions of ozone, hydroxyl radicals, carbon monoxide and reactive nitrogen compounds. In spite of minor shortcomings, mostly related to the relatively coarse T42 resolution and the neglect of inter-annual changes in biomass burning emissions, the main characteristics of the trace gas distributions are generally reproduced well. The MESSy

  17. The impact of dynamic processes on chemistry in atmospheric boundary layers over tropical and boreal forest

    OpenAIRE

    Ouwersloot, H. G.

    2013-01-01

    Improving our knowledge of the atmospheric processes that drive climate and air quality is very relevant for society. The application of this knowledge enables us to predict and mitigate the effects of human induced perturbations to our environment. Key factors in the current and future climate evolution are related to the emissions and atmospheric presence of carbon dioxide (CO2) and hydrocarbons. The latter group of chemical species, on which special emphasis is placed in this dissertation,...

  18. Description and Evaluation of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry Model (NMMB-MONARCH) Version 1.0: Gas-Phase Chemistry at Global Scale

    Science.gov (United States)

    Badia, Alba; Jorba, Oriol; Voulgarakis, Apostolos; Dabdub, Donald; Garcia-Pando, Carlos Perez; Hilboll, Andreas; Goncalves, Maria; Janjic, Zavisa

    2017-01-01

    This paper presents a comprehensive description and benchmark evaluation of the tropospheric gas-phase chemistry component of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (NMMBMONARCH), formerly known as NMMB/BSC-CTM, that can be run on both regional and global domains. Here, we provide an extensive evaluation of a global annual cycle simulation using a variety of background surface stations (EMEP, WDCGG and CASTNET), ozonesondes (WOUDC, CMD and SHADOZ), aircraft data (MOZAIC and several campaigns), and satellite observations (SCIAMACHY and MOPITT).We also include an extensive discussion of our results in comparison to other state-of-the-art models. We note that in this study, we omitted aerosol processes and some natural emissions (lightning and volcano emissions). The model shows a realistic oxidative capacity across the globe. The seasonal cycle for CO is fairly well represented at different locations (correlations around 0.3-0.7 in surface concentrations), although concentrations are underestimated in spring and winter in the Northern Hemisphere, and are overestimated throughout the year at 800 and 500 hPa in the Southern Hemisphere. Nitrogen species are well represented in almost all locations, particularly NO2 in Europe (root mean square error - RMSE - below 5 ppb). The modeled vertical distributions of NOx and HNO3 are in excellent agreement with the observed values and the spatial and seasonal trends of tropospheric NO2 columns correspond well to observations from SCIAMACHY, capturing the highly polluted areas and the biomass burning cycle throughout the year. Over Asia, the model underestimates NOx from March to August, probably due to an underestimation of NOx emissions in the region. Overall, the comparison of the modeled CO and NO2 with MOPITT and SCIAMACHY observations emphasizes the need for more accurate emission rates from anthropogenic and biomass burning sources (i.e., specification of temporal variability).

  19. Fostering Pre-service Teachers' Self-Determined Environmental Motivation Through Green Chemistry Experiments

    Science.gov (United States)

    Karpudewan, Mageswary; Ismail, Zurida; Roth, Wolff-Michael

    2012-10-01

    The global environmental crisis intensifies particularly in developing nations. Environmental educators have begun to understand that changing the environmental impact requires not only changes in pro-environmental knowledge and attitudes but also in associated, self-determined motivation. This study was designed to test the hypothesis that a green chemistry curriculum changes Malaysian pre-service teachers' environmental motivation. Two comparable groups of pre-service teachers participated in this study. The students in the experimental group ( N = 140) did green chemistry experiments whereas the control group ( N = 123) did equivalent experiments in a traditional manner. Posttest results indicate that there is significant difference between both the groups for intrinsic motivation, integration, identification, and introjections scales and no differences for external regulation and amotivation scales. The qualitative analysis of interview data suggests that the changes are predominantly due to the personal satisfaction that participants derived from engaging in pro-environmental behavior.

  20. The Radiometer Atmospheric Cubesat Experiment Post-Launch Results

    Science.gov (United States)

    Lim, B.; Misra, S.

    2015-12-01

    The Jet Propulsion Laboratory (JPL) developed the Radiometer Atmospheric CubeSat Experiment (RACE) that was lost during the Orbital 3 (Orb-3) launch anomaly on October 28, 2014. The 3U CubeSat mission would have measured 2 channels of the 183 GHz water vapor line and raised the technology readiness level (TRL) of various subsystems to 6. Despite the launch failure, several hundreds of hours of instrument operation data was taken, including measurements in thermal vacuum of the complete spacecraft system. These data is used to evaluate the 35 nm Indium Phosphide (InP) receivers, and the low noise amplifier (LNA) based internal calibration system. The thermal vacuum measurements included frequent observations of a 'cold' and 'hot' target allowing for various receiver parameters to be calculated. The payload thermal vacuum data show that the receiver front ends performed as expected in terms of the gain (>35 dB) and drift (0.06 dB/K). The data also shows that integration could be performed with decreasing noise up to ~30 seconds, allowing for the system to be calibrated within that time period. The expected spacecraft calibration period would have been every 12 seconds. The injected noise from the load terminated LNA show magnitudes from 50 - 150 K that can be tuned which would meet most requirements. However the temperature coefficient is large at ~3 K/K which is over an order of magnitude larger than typical noise diodes. For nanosatellite class spacecraft, the power required to properly maintain the physical temperature range (±0.1K) would be challenging. On larger spacecraft, this methodology may still be viable, depending on the availability of suitable noise diodes at 183 GHz. While the CubeSat did not take measurements in space, the ground data in the relevant environment and extensive testing allows us to raise the following subsystems to TRL 6: 1) 183 GHz 35 nm InP receiver, 2) 183 GHz direct detect receiver and 3) 183 GHz LNA based calibration system.

  1. Development of Teaching Materials for a Physical Chemistry Experiment Using the QR Code

    OpenAIRE

    吉村, 忠与志

    2008-01-01

    The development of teaching materials with the QR code was attempted in an educational environment using a mobile telephone. The QR code is not sufficiently utilized in education, and the current study is one of the first in the field. The QR code is encrypted. However, the QR code can be deciphered by mobile telephones, thus enabling the expression of text in a small space.Contents of "Physical Chemistry Experiment" which are available on the Internet are briefly summarized and simplified. T...

  2. Role of Atmospheric Chemistry in the Climate Impacts of Stratospheric Volcanic Injections

    Science.gov (United States)

    Legrande, Allegra N.; Tsigaridis, Kostas; Bauer, Susanne E.

    2016-01-01

    The climate impact of a volcanic eruption is known to be dependent on the size, location and timing of the eruption. However, the chemistry and composition of the volcanic plume also control its impact on climate. It is not just sulfur dioxide gas, but also the coincident emissions of water, halogens and ash that influence the radiative and climate forcing of an eruption. Improvements in the capability of models to capture aerosol microphysics, and the inclusion of chemistry and aerosol microphysics modules in Earth system models, allow us to evaluate the interaction of composition and chemistry within volcanic plumes in a new way. These modeling efforts also illustrate the role of water vapor in controlling the chemical evolution, and hence climate impacts, of the plume. A growing realization of the importance of the chemical composition of volcanic plumes is leading to a more sophisticated and realistic representation of volcanic forcing in climate simulations, which in turn aids in reconciling simulations and proxy reconstructions of the climate impacts of past volcanic eruptions. More sophisticated simulations are expected to help, eventually, with predictions of the impact on the Earth system of any future large volcanic eruptions.

  3. The response of atmospheric chemistry on earthlike planets around F, G and K Stars to small variations in orbital distance

    Science.gov (United States)

    Grenfell, John Lee; Stracke, Barbara; von Paris, Philip; Patzer, Beate; Titz, Ruth; Segura, Antigona; Rauer, Heike

    2007-04-01

    One of the prime goals of future investigations of extrasolar planets is to search for life as we know it. The Earth's biosphere is adapted to current conditions. How would the atmospheric chemistry of the Earth respond if we moved it to different orbital distances or changed its host star? This question is central to astrobiology and aids our understanding of how the atmospheres of terrestrial planets develop. To help address this question, we have performed a sensitivity study using a coupled radiative-convective photochemical column model to calculate changes in atmospheric chemistry on a planet having Earth's atmospheric composition, which we subjected to small changes in orbital position, of the order of 5-10% for a solar-type G2V, F2V, and K2V star. We then applied a chemical source-sink analysis to the biomarkers in order to understand how chemical processes affect biomarker concentrations. We start with the composition of the present Earth, since this is the only example we know for which a spectrum of biomarker molecules has been measured. We then investigate the response of the biomarkers to changes in the input stellar flux. Computing the thermal profile for atmospheres rich in H 2O, CO 2 and CH 4 is a major challenge for current radiative schemes, due, among other things, to lacking spectroscopic data. Therefore, as a first step, we employ a more moderate approach, by investigating small shifts in planet-star distance and assuming an earthlike biosphere. To calculate this shift we assumed a criteria for complex life based on the Earth, i.e. the earthlike planetary surface temperature varied between 0 °Cfamily species (and their reservoirs), which can catalytically destroy ozone. Hydrochloric acid (HCl), for example, is a chlorine reservoir (storage) molecule, which increased by a factor 64 in the mid-stratosphere (32 km) on moving outwards for the solar case. For the F2V and K2V stars, similar sources and sinks dominated the chemical biomarker budget

  4. Study of the atmospheric chemistry of radon progeny in laboratory and real indoor atmospheres. Final project report

    Energy Technology Data Exchange (ETDEWEB)

    Hopke, P.K.

    1996-09-01

    This report completes Clarkson University`s study of the chemical and physical behavior of the {sup 218}Po atom immediately following its formation by the alpha decay of radon. Because small changes in size for activity in the sub-10 nm size range result in large changes in the delivered dose per unit exposure, this behavior must be understood if the exposure to radon progeny and it dose to the cells in the respiratory tract are to be fully assessed. In order to pursue this general goal, two areas of radon progeny behavior are being pursued; laboratory studies under controlled conditions to better understand the fundamental physical and chemical processes that affect the progeny`s atmospheric behavior and studies in actual indoor environments to develop a better assessment of the exposure of the occupants of that space to the size and concentration of the indoor radioactive aerosol. Thus, two sets of specific goals have been established for this project. The specific tasks of the controlled laboratory studies are (1) Determine the formation rates of {circ}OH radicals formed by the radiolysis of air following radon decay; (2) Examine the formation of particles by the radiolytic oxidation of substances like SO{sub 2}, ethylene, and H{sub 2}S to lower vapor pressure compounds and determine the role of gas phase additives such as H{sub 2}O and NH{sub 3} in determining the particle size; (3) Measure the rate of ion-induced nucleation using a thermal diffusion cloud chamber, and (4) Measure the neutralization rate of {sup 218}PoO{sub x}{sup +} in O{sub 2} at low radon concentrations.

  5. Promoting Green Chemistry Experiments in Universities%推进高校化学实验绿色化

    Institute of Scientific and Technical Information of China (English)

    曹小霞

    2011-01-01

    介绍绿色化学的的定义和内涵,以及高校实行绿色化学实验的必要性和重要性,提出实现化学实验绿色化的途径,如发现绿色化学素材、开展串联实验、废料不废,以保护环境.%The paper introduces the definition and connotation of green chemistry, emphasizes the necessity and significance of carrying out green chemistry experiments in universities, and proposes channels for realizing green chemistry experiments in order to protect environment, such as finding green chemistry elements, taking chemistry experiments in sequence , and utilizing experimental wastes.

  6. HOCl chemistry in the Antarctic Stratospheric Vortex 2002, as observed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS

    Directory of Open Access Journals (Sweden)

    T. von Clarmann

    2009-03-01

    Full Text Available In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km (1000 K potential temperature, where HOCl abundances are ruled by gas phase chemistry and at around 18–24 km (475–625 K, which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. This is the altitude region where in midlatitudinal and tropic atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values are observed. After deformation and displacement of the polar vortex in the course of a major warming, ClO-rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv, exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979 rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. The measurements were compared to a model run where no polar stratospheric clouds appeared during the observation period. The fact that HOCl still was produced in the model run suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO, lower ClONO2 and earlier loss of HOCl in the measurements are

  7. HOCl chemistry in the Antarctic stratospheric vortex 2002, as observed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS

    Directory of Open Access Journals (Sweden)

    T. von Clarmann

    2008-11-01

    Full Text Available In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km, where HOCl abundances are ruled by gas phase chemistry and at around 24 km, which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km, where in midlatitudinal and tropical atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values are observed, polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. After deformation and displacement of the polar vortex in the course of a major warming, ClO rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv, exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979 rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. Comparison with a model run where no polar stratospheric clouds appeared during the observation period suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO and HOCl in the measurements is attributed to ongoing heterogeneous chemistry which is not reproduced by the model. In the following days, a decay of HOCl abundances was observed and on 11 October, polar vortex mean daytime

  8. Evaluation of Present-day Aerosols over China Simulated from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    Science.gov (United States)

    Liao, H.; Chang, W.

    2014-12-01

    High concentrations of aerosols over China lead to strong radiative forcing that is important for both regional and global climate. To understand the representation of aerosols in China in current global climate models, we evaluate extensively the simulated present-day aerosol concentrations and aerosol optical depth (AOD) over China from the 12 models that participated in Atmospheric Chemistry & Climate Model Intercomparison Project (ACCMIP), by using ground-based measurements and satellite remote sensing. Ground-based measurements of aerosol concentrations used in this work include those from the China Meteorological Administration (CMA) Atmosphere Watch Network (CAWNET) and the observed fine-mode aerosol concentrations collected from the literature. The ground-based measurements of AOD in China are taken from the AErosol RObotic NETwork (AERONET), the sites with CIMEL sun photometer operated by Institute of Atmospheric Physics, Chinese Academy of Sciences, and from Chinese Sun Hazemeter Network (CSHNET). We find that the ACCMIP models generally underestimate concentrations of all major aerosol species in China. On an annual mean basis, the multi-model mean concentrations of sulfate, nitrate, ammonium, black carbon, and organic carbon are underestimated by 63%, 73%, 54%, 53%, and 59%, respectively. The multi-model mean AOD values show low biases of 20-40% at studied sites in China. The ACCMIP models can reproduce seasonal variation of nitrate but cannot capture well the seasonal variations of other aerosol species. Our analyses indicate that current global models generally underestimate the role of aerosols in China in climate simulations.

  9. Probing Titan's Complex Atmospheric Chemistry Using the Atacama Large Millimeter/Submillimeter Array

    Science.gov (United States)

    Cordiner, Martin A.; Nixon, Conor; Charnley, Steven B.; Teanby, Nick; Irwin, Pat; Serigano, Joseph; Palmer, Maureen; Kisiel, Zbigniew

    2015-01-01

    Titan is Saturn's largest moon, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Atmospheric photochemistry results in the production of a wide range of complex organic molecules, including hydrocarbons, nitriles, aromatics and other species of possible pre-biotic relevance. Titan's carbon-rich atmosphere may be analogous to that of primitive terrestrial planets throughout the universe, yet its origin, evolution and complete chemical inventory are not well understood. Here we present spatially-resolved maps of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH in Titan's atmosphere, observed using the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012-2013. These data show previously-undetected spatial structures for the observed species and provide the first spectroscopic detection of C2H5CN on Titan. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with photochemical production and transport in the upper atmosphere followed by subsidence over the poles. The HNC emission peaks are offset from the polar axis, indicating that Titan's mesosphere may be more longitudinally variable than previously thought.

  10. The Effect of Guided-Inquiry Laboratory Experiments on Science Education Students' Chemistry Laboratory Attitudes, Anxiety and Achievement

    Science.gov (United States)

    Ural, Evrim

    2016-01-01

    The study aims to search the effect of guided inquiry laboratory experiments on students' attitudes towards chemistry laboratory, chemistry laboratory anxiety and their academic achievement in the laboratory. The study has been carried out with 37 third-year, undergraduate science education students, as a part of their Science Education Laboratory…

  11. Azeotropic Preparation of a "C"-Phenyl "N"-Aryl Imine: An Introductory Undergraduate Organic Chemistry Laboratory Experiment

    Science.gov (United States)

    Silverberg, Lee J.; Coyle, David J.; Cannon, Kevin C.; Mathers, Robert T.; Richards, Jeffrey A.; Tierney, John

    2016-01-01

    Imines are important in biological chemistry and as intermediates in organic synthesis. An experiment for introductory undergraduate organic chemistry is presented in which benzaldehyde was condensed with "p"-methoxyaniline in toluene to give 4-methoxy-"N"-(phenylmethylene)benzenamine. Water was removed by azeotropic…

  12. Introduction to Homogenous Catalysis with Ruthenium-Catalyzed Oxidation of Alcohols: An Experiment for Undergraduate Advanced Inorganic Chemistry Students

    Science.gov (United States)

    Miecznikowski, John R.; Caradonna, John P.; Foley, Kathleen M.; Kwiecien, Daniel J.; Lisi, George P.; Martinez, Anthony M.

    2011-01-01

    A three-week laboratory experiment, which introduces students in an advanced inorganic chemistry course to air-sensitive chemistry and catalysis, is described. During the first week, the students synthesize RuCl[subscript 2](PPh[subscript 3])[subscript 3]. During the second and third weeks, the students characterize the formed coordination…

  13. Validation of Global Ozone Monitoring Experiment zone profiles and evaluation of stratospheric transport in a global chemistry transport model

    NARCIS (Netherlands)

    Laat, A.T.J.de; Landgraf, J.; Aben, I.; Hasekamp, O.; Bregman, B.

    2007-01-01

    This paper presents a validation of Global Ozone Monitoring Experiment (GOME) ozone (O3) profiles which are used to evaluate stratospheric transport in the chemistry transport model (CTM) Tracer Model version 5 (TM5) using a linearized stratospheric O3 chemistry scheme. A comparison of GOME O3 profi

  14. DAVINCI: Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging

    Science.gov (United States)

    Glaze, Lori S.; Garvin, James B.; Robertson, Brent; Johnson, Natasha M.; Amato, Michael J.; Thompson, Jessica; Goodloe, Colby; Everette, Dave

    2017-01-01

    DAVINCI is one of five Discovery-class missions selected by NASA in October 2015 for Phase A studies. Launching in November 2021 and arriving at Venus in June of 2023, DAVINCI would be the first U.S. entry probe to target Venus atmosphere in 45 years. DAVINCI is designed to study the chemical and isotopic composition of a complete cross-section of Venus atmosphere at a level of detail that has not been possible on earlier missions and to image the surface at optical wavelengths and process-relevant scales.

  15. Plasma chemistry in an atmospheric pressure Ar/NH3 dielectric barrier discharge

    DEFF Research Database (Denmark)

    Fateev, A.; Leipold, F.; Kusano, Y.

    2005-01-01

    An atmospheric pressure dielectric barrier discharge (DBD) in Ar/NH3 (0.1 - 10%) mixtures with a parallel plate electrode geometry was studied. The plasma was investigated by emission and absorption spectroscopy in the UV spectral range. Discharge current and voltage were measured as well. UV...... of an atmospheric pressure Ar/NH3 DBD are H-2, N-2 and N2H4. The hydrazine (N2H4) concentration in the plasma and in the exhaust gases at various ammonia concentrations and different discharge powers was measured. Thermal N2H4 decomposition into NH2 radicals may be used for NOx reduction processes....

  16. Study on the Green Chemistry Experiment of Basic Organic Chemistry in University%高校基础有机化学实验的绿色化

    Institute of Scientific and Technical Information of China (English)

    马祥梅; 王斌; 冯道全; 邢宏龙

    2016-01-01

    Green chemistry,is also known as environmentally-friendly chemistry.According to college organic chemistry labo-ratory that cause the environmental pollution and the current conditions of the teaching of college chemistry experiment , some meas-ures such as reforming the experiment content, reducing the consumption of chemical reagents, using green catalysts, the applica-tion of multimedia technology and the modern synthetic methods etc are introduced to the organic synthesis experiment teaching based on the concept of green chemistry in this paper,which will fundamentally minimize the pollution,improve teaching quality and foster the innovation consciousness of students.%针对有机化学实验对环境污染的影响,结合高校化学实验的教学现状,通过实验内容的设置、绿色催化剂的使用、试剂用量的减少、多媒体技术的运用以及现代合成手段的融入等,将绿色化学理念应用到基础有机化学实验中,不仅有效地降低了实验教学带来的环境污染,而且还改善了教学效果,更有利于培养学生的创新意识。

  17. Data Pooling in a Chemical Kinetics Experiment: The Aquation of a Series of Cobalt(III) Complexes--A Discovery Chemistry Experiment

    Science.gov (United States)

    Herrick, Richard S.; Mills, Kenneth V.; Nestor, Lisa P.

    2008-01-01

    An experiment in chemical kinetics as part of our Discovery Chemistry curriculum is described. Discovery Chemistry is a pedagogical philosophy that makes the laboratory the key center of learning for students in their first two years of undergraduate instruction. Questions are posed in the pre-laboratory discussion and assessed using pooled…

  18. Atmospheric chemistry of CH3CHF2 (HFC-152a)

    DEFF Research Database (Denmark)

    Taketani, Fumikazu; Nakayama, Tomoki; Takahashi, Kenshi

    2005-01-01

    Smog chamber/Fourier transform infrared (FTIR) and laser-induced fluorescence (LIF) spectroscopic techniques were used to study the atmospheric degradation of CH3CHF2. The kinetics and products of the Cl(2P(3/2)) (denoted Cl) atom- and the OH radical-initiated oxidation of CH3CHF2 in 700 Torr...

  19. Impact of acid atmospheric deposition on soils: Field monitoring and aluminium chemistry.

    NARCIS (Netherlands)

    Mulder, J.

    1988-01-01

    The effect of acid atmospheric deposition on concentrations and transfer of major solutes in acid, sandy soils was studied. Emphasis was given to mobilization and transport of potentially toxic aluminum. Data on solute concentrations and fluxes in meteoric water as well as soil solutions were obtain

  20. The impact of dynamic processes on chemistry in atmospheric boundary layers over tropical and boreal forest

    NARCIS (Netherlands)

    Ouwersloot, H.G.

    2013-01-01

    Improving our knowledge of the atmospheric processes that drive climate and air quality is very relevant for society. The application of this knowledge enables us to predict and mitigate the effects of human induced perturbations to our environment. Key factors in the current and future climate evol

  1. ATMOSPHERIC-PRESSURE-IONIZATION MASS-SPECTROMETRY .2. APPLICATIONS IN PHARMACY, BIOCHEMISTRY AND GENERAL-CHEMISTRY

    NARCIS (Netherlands)

    BRUINS, AP

    1994-01-01

    Mass spectrometer ion sources are normally located inside a high-vacuum envelope. An ion source operating at atmospheric pressure is better suited, it not essential, for a growing number of applications. MS analysis of samples pyrolyzed under controlled conditions makes use of chemical ionization at

  2. Bridging the gap between atmospheric physics and chemistry in studies of small-scale turbulence

    NARCIS (Netherlands)

    Vilà-Guerau de Arellano, J.

    2003-01-01

    The current understanding of the influence of atmospheric turbulence on chemical reactions is briefly reviewed. The fundamentals of this influence and the consequences for the transport and mixing of the reactants are discussed. A classification of the turbulent reacting flows is proposed in terms o

  3. Atmospheric chemistry of HFC-134a. Kinetic and mechanistic study of the CF3CFHO2 + NO2 reaction

    DEFF Research Database (Denmark)

    Møgelberg, T.E.; Nielsen, O.J.; Sehested, J.;

    1994-01-01

    A pulse radiolysis system was used to study the kinetics of the reaction of CF3CFHO2 with NO2. By monitoring the rate of the decay of NO2 using its absorption at 400 nm the reaction rate constant was determined to be k = (5.0 +/- 0.5) x 10(-12) cm3 molecule-1 s-1. A long path length Fourier......-transform infrared technique was used to investigate the thermal decomposition of the product CF3CFHO2NO2. At 296 K in the presence of 700 Torr of air, decomposition of CF3CFHO2NO2 was rapid (greater than 90% decomposition within 3 min). The results are discussed in the context of atmospheric chemistry of CF3CFH2...

  4. Atmospheric Chemistry for Astrophysicists: A Self-consistent Formalism and Analytical Solutions for Arbitrary C/O

    CERN Document Server

    Heng, Kevin; Tsai, Shang-Min

    2015-01-01

    We present a self-consistent formalism for computing and understanding the atmospheric chemistry of exoplanets. Starting from the first law of thermodynamics, we demonstrate that the van't Hoff equation (which describes the equilibrium constant), Arrhenius equation (which describes the rate coefficients) and procedures associated with the Gibbs free energy (minimisation, rescaling) have a common physical and mathematical origin. We correct an ambiguity associated with the equilibrium constant, which is used to relate the forward and reverse rate coefficients, and rigorously derive its two definitions. By necessity, one of the equilibrium constants must be dimensionless and equate to an exponential function involving the Gibbs free energy, while the other is a ratio of rate coefficients and must therefore possess physical units. To avoid confusion, we simply term them the dimensionless and dimensional equilibrium constants. We demonstrate that the Arrhenius equation takes on a functional form that is more gene...

  5. Modelling atmospheric chemistry and long-range transport of emerging Asian pollutants

    CERN Document Server

    Wang, Kuo-Ying

    2008-01-01

    Modeling is a very important tool for scientific processes, requiring long-term dedication, desire, and continuous reflection. In this work, we discuss several aspects of modeling, and the reasons for doing it. We discuss two major modeling systems that have been built by us over the last 10 years. It is a long and arduous process but the reward of understanding can be enormous, as demonstrated in the examples shown in this work. We found that long-range transport of emerging Asian pollutants can be interpreted using a Lagrangian framework for wind analysis. More detailed processes still need to be modeled but an accurate representation of the wind structure is the most important thing above all others. Our long-term chemistry integrations reveal the capability of the IMS model in simulating tropospheric chemistry on a climate scale. These long-term integrations also show ways for further model development. Modeling is a quantitative process, and the understanding can be sustained only when theories are vigor...

  6. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium

    Science.gov (United States)

    Wang, Zhe-Chen; Bierbaum, Veronica M.

    2016-06-01

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry.

  7. Impacts of aerosols on the chemistry of atmospheric trace gases: a case study of peroxides and HO2 radicals

    Directory of Open Access Journals (Sweden)

    H. Liang

    2013-06-01

    Full Text Available Field measurements of atmospheric peroxides were obtained during the summer on two consecutive years over urban Beijing, and focused on the impacts of aerosols on the chemistry of peroxide compounds and hydroperoxyl radicals (HO2. The major peroxides were determined to be hydrogen peroxide (H2O2, methyl hydroperoxide (MHP, and peroxyacetic acid (PAA. A negative correlation was found between H2O2 and PAA in rainwater, providing evidence for a conversion between H2O2 and PAA in the aqueous phase. A standard gas phase chemistry model based on the NCAR Master Mechanism provided a good reproduction of the observed H2O2 profile on non-haze days but greatly overpredicted the H2O2 level on haze days. We attribute this overprediction to the reactive uptake of HO2 by the aerosols, since there was greatly enhanced aerosol loading and aerosol liquid water content on haze days. The discrepancy between the observed and modeled H2O2 can be diminished by adding to the model a newly proposed transition metal ion catalytic mechanism of HO2 in aqueous aerosols. This confirms the importance of the aerosol uptake of HO2 and the subsequent aqueous phase reactions in the reduction of H2O2. The closure of HO2 and H2O2 between the gas and aerosol phases suggests that the aerosols do not have a net reactive uptake of H2O2, because the conversion of HO2 to H2O2 on aerosols compensates for the H2O2 loss. Laboratory studies for the aerosol uptake of H2O2 in the presence of HO2 are urgently required to better understand the aerosol uptake of H2O2 in the real atmosphere.

  8. Determining the EDTA Content in a Consumer Shower Cleaner. An Introductory Chemistry Laboratory Experiment

    Science.gov (United States)

    Weigand, Willis A.

    2000-10-01

    At Altoona College, Chemistry 11 is offered to students as a preparatory course for the University's Chemical Principles course, Chem 12. A relevant laboratory is a source of motivation for the students to learn the chemistry. One way of making the laboratory relevant is to analyze the chemical components of consumer products. Several new shower-cleaning products have been introduced, which advertise that cleaning the shower is no longer necessary. The cleaners work using a combination of surfactants, alcohols, and a chelating agent. The Web site of a popular shower cleaner lists EDTA (ethylenediamine tetraacetate ion) as the chelating agent. The classic EDTA/calcium complexometric titration can be used to determine the EDTA content of the cleaner. This article describes the experiment to determine the EDTA content in a shower-cleaning product.

  9. Optical Profiling of the Atmospheric Limb CubeSat Experiment

    Science.gov (United States)

    Jeppesen, M.; Taylor, M. J.; Swenson, C.; Marchant, A.

    2014-12-01

    The Earth's lower thermosphere is an important interface region between the neutral atmosphere and the "space weather" environment. While the high-latitude region of the thermosphere responds promptly to energy inputs, relatively little is known about the global/regional response to these energy inputs. Global temperatures are predicted to respond within 3-6 hours, but the details of the thermal response of the atmosphere as energy transports away from high-latitude source regions is not well understood. The Optical Profiling of the Atmospheric Limb (OPAL) mission aims to characterize this thermal response through observation of the temperature structure of the lower thermosphere at mid- and low-latitudes. The OPAL instrument is designed to map global thermospheric temperature variability over the critical "thermospheric gap" region (~100-140 km altitude) by spectroscopic analysis of molecular oxygen A-band emission (758 - 768 nm). The OPAL instrument is a grating-based imaging spectrometer with refractive optics and a high-efficiency volume holographic grating (VHG). The scene is sampled by 7 parallel slits that form non-overlapping spectral profiles at the focal plane with resolution of 0.5 nm (spectral), 1.5 km (limb profiling), and 60 km (horizontal sampling). A CCD camera at the instrument focal plane delivers low noise and high sensitivity. The instrument is designed to strongly reject stray light from daylight regions of the earth. The OPAL mission is funded by the National Science Foundation (NSF) CubeSat-based Science Missions for Geospace and Atmospheric Research program. The OPAL instrument and mission will be designed, built and executed by a team comprised of students and professors from Utah State University, Dixie State University and the University of Maryland Eastern Shore, with support from professional scientists and engineers from the Space Dynamics Laboratory and Hawk Institute for Space Science.

  10. Lead-Lead and Rubidium-Strontium In Situ Dating Using the Chemistry, Organics, and Dating EXperiment (CODEX)

    Science.gov (United States)

    Anderson, F. S.; Whitaker, T. J.; Levine, J.; Beck, S.

    2016-10-01

    We describe new results for Pb-Pb dating, and progress on laser development, for the Pb-Pb and Rb-Sr measuring, organics detecting, and elemental abundance mapping Chemistry, Organics, and Dating EXperiment (CODEX) instrument.

  11. Research and Teaching: Computational Methods in General Chemistry--Perceptions of Programming, Prior Experience, and Student Outcomes

    Science.gov (United States)

    Wheeler, Lindsay B.; Chiu, Jennie L.; Grisham, Charles M.

    2016-01-01

    This article explores how integrating computational tools into a general chemistry laboratory course can influence student perceptions of programming and investigates relationships among student perceptions, prior experience, and student outcomes.

  12. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP

    Directory of Open Access Journals (Sweden)

    D. S. Stevenson

    2012-10-01

    Full Text Available Ozone (O3 from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP has been used to calculate tropospheric ozone radiative forcings (RFs. We calculate a~value for the pre-industrial (1750 to present-day (2010 tropospheric ozone RF of 0.40 W m−2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation in RFs of ±17%. Three different radiation schemes were used – we find differences in RFs between schemes (for the same ozone fields of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (47%, nitrogen oxides (29%, carbon monoxide (15% and non-methane volatile organic compounds (9%; earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 0.042 W m−2 DU−1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (W m−2; relative to 1850 – add 0.04 W m−2 to make relative to 1750 for the Representative Concentration Pathways in 2030 (2100 of: RCP2.6: 0.31 (0.16; RCP4.5: 0.38 (0.26; RCP6.0: 0.33 (0.24; and RCP8.5: 0.42 (0.56. Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in

  13. The martian atmosphere: Mariner 9 television experiment progress report

    Science.gov (United States)

    Leovy, C.B.; Briggs, G.A.; Young, A.T.; Smith, B.A.; Pollack, James B.; Shipley, E.N.; Wildey, R.L.

    1972-01-01

    Atmospheric phenomena appearing in the Mariner 9 television pictures are discussed in detail. The surface of the planet was heavily obscured by a global dust storm during the first month in orbit. Brightness data during this period can be fitted by a semi-infinite scattering and absorbing atmosphere model with a single-scattering albedo in the range 0.70-0.85. This low value suggests that the mean radius of the particles responsible for the obscuration was at least 10 ??m. By the end of the second month, this dust storm had largely dissipated, leaving a residual optical depth ???0.1. Much of the region north of 45??N was covered by variable clouds comprising the north polar hood. The cloud structures revealed extensive systems of lee waves generated by west-to-east flow over irregular terrain. Extensive cloud systems in this region resembled baroclinic wave cyclones. Clouds were also observed over several of the large calderas; these clouds are believed to contain water ice. Several localized dust storms were seen after the global dust storm cleared. These dust clouds appeared to be intensely convective. The convective nature of these storms and the stirring of large dust particles to great heights can be explained by vertical velocities generated by the absorption of solar radiation by the dusty atmosphere. ?? 1972.

  14. Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Massachusetts Institute of Technology; Kroll, Jesse H.; Donahue, Neil M.; Jimenez, Jose L.; Kessler, Sean H.; Canagaratna, Manjula R.; Wilson, Kevin R.; Altieri, Katye E.; Mazzoleni, Lynn R.; Wozniak, Andrew S.; Bluhm, Hendrik; Mysak, Erin R.; Smith, Jared D.; Kolb, Charles E.; Worsnop, Douglas R.

    2010-11-05

    A detailed understanding of the sources, transformations, and fates of organic species in the environment is crucial because of the central roles that organics play in human health, biogeochemical cycles, and Earth's climate. However, such an understanding is hindered by the immense chemical complexity of environmental mixtures of organics; for example, atmospheric organic aerosol consists of at least thousands of individual compounds, all of which likely evolve chemically over their atmospheric lifetimes. Here we demonstrate the utility of describing organic aerosol (and other complex organic mixtures) in terms of average carbon oxidation state (OSC), a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of OSC , using several such techniques, constrain the chemical properties of the organics and demonstrate that the formation and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state and carbon number (nC).

  15. Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol.

    Science.gov (United States)

    Kroll, Jesse H; Donahue, Neil M; Jimenez, Jose L; Kessler, Sean H; Canagaratna, Manjula R; Wilson, Kevin R; Altieri, Katye E; Mazzoleni, Lynn R; Wozniak, Andrew S; Bluhm, Hendrik; Mysak, Erin R; Smith, Jared D; Kolb, Charles E; Worsnop, Douglas R

    2011-02-01

    A detailed understanding of the sources, transformations and fates of organic species in the environment is crucial because of the central roles that they play in human health, biogeochemical cycles and the Earth's climate. However, such an understanding is hindered by the immense chemical complexity of environmental mixtures of organics; for example, atmospheric organic aerosol consists of at least thousands of individual compounds, all of which likely evolve chemically over their atmospheric lifetimes. Here, we demonstrate the utility of describing organic aerosol (and other complex organic mixtures) in terms of average carbon oxidation state, a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of the average carbon oxidation state, using several such techniques, constrain the chemical properties of the organics and demonstrate that the formation and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state and carbon number.

  16. Chemistry Notes

    Science.gov (United States)

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  17. A Potential Mechanism for Perchlorate Formation on Mars: Surface-Radiolysis-Initiated Atmospheric Chemistry

    Science.gov (United States)

    Wilson, Eric; Atreya, Sushil K.; Kaiser, Ralf-Ingo; Mahaffy, Paul

    2016-10-01

    Perchlorate (ClO4-) is prevalent on Earth, and with observations of perchlorate on lunar samples and chondrite meteorites, along with recent observations indicating the presence of perchlorate (ClO4-) in the Martian surface by the Phoenix lander and the Sample Analysis at Mars (SAM) on the Mars Science Laboratory (MSL) rover, it appears that the existence of perchlorate is widespread throughout the solar system. However, the abundance and isotopic composition of Martian perchlorate suggest that the perchlorate formation mechanism on Mars may involve a different path than perchlorate found elsewhere in the solar system. Motivated by this, we employ a one-dimensional chemical model to investigate the viability of perchlorate formation in the atmosphere of Mars, instigated by the radiolysis of the Martian surface by galactic cosmic rays. The surface-atmosphere interaction to produce Martian perchlorate involves the sublimation of chlorine oxides into the atmosphere, through surface radiolysis, and their subsequent synthesis to form perchloric acid (HClO4), followed by surface deposition and mineralization to form surface perchlorates. Considering the chlorine oxide, OClO, we find an OClO surface flux as low as 3.2x107 molecules cm-2 s-1, sublimated into the atmosphere from the surface could produce sufficient HClO4 to explain the perchlorate concentration on Mars, assuming an accumulation depth of 30 cm and integrated over the Amazonian period. Radiolysis provides an efficient pathway for the oxidation of chlorine, bypassing the efficient Cl/HCl recycling mechanism that characterizes HClO4 formation mechanisms proposed for the Earth but not Mars.

  18. Demystifying the Chemistry Literature: Building Information Literacy in First-Year Chemistry Students through Student-Centered Learning and Experiment Design

    Science.gov (United States)

    Bruehl, Margaret; Pan, Denise; Ferrer-Vinent, Ignacio J.

    2015-01-01

    This paper describes curriculum modules developed for first-year general chemistry laboratory courses that use scientific literature and creative experiment design to build information literacy in a student-centered learning environment. Two curriculum units are discussed: Exploring Scientific Literature and Design Your Own General Chemistry…

  19. Weekly variation of atmospheric particle micromorphology and chemistry in Brussels urban environment.

    Science.gov (United States)

    Zaady, Eli; Carati, D; Brenig, L; Vanderstraeten, P; Lénelle, Y; Meurrens, A; Offer, Z Y

    2010-10-01

    The purpose of this study was to measure the impact of urban activities on airborne particle dynamics during weekend periods in Brussels urban area. Differences in the granulometry and micromorphology between particles sampled on working days and weekends were studied. We quantified the area, size, number, and the chemistry parameters of the airborne particles and compared between Saturday, Sunday, and Monday. We report and analyze data on airborne particles up to PM10, measured in the Brussels region from October 2002 to September 2003. Our investigation reveals detailed information regarding chemical composition of the airborne particles over the weekend period in the Brussels urban area. Furthermore, the majority of the airborne particles in the Brussels region may belong to sources geographically outside the (in situ) Brussels area.

  20. The Chemistry CATT-BRAMS model (CCATT-BRAMS 4.5: a regional atmospheric model system for integrated air quality and weather forecasting and research

    Directory of Open Access Journals (Sweden)

    K. M. Longo

    2013-09-01

    Full Text Available Coupled Chemistry Aerosol-Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CCATT-BRAMS, version 4.5 is an on-line regional chemical transport model designed for local and regional studies of atmospheric chemistry from the surface to the lower stratosphere suitable both for operational and research purposes. It includes gaseous/aqueous chemistry, photochemistry, scavenging and dry deposition. The CCATT-BRAMS model takes advantage of BRAMS-specific development for the tropics/subtropics as well as the recent availability of preprocessing tools for chemical mechanisms and fast codes for photolysis rates. BRAMS includes state-of-the-art physical parameterizations and dynamic formulations to simulate atmospheric circulations down to the meter. This on-line coupling of meteorology and chemistry allows the system to be used for simultaneous weather and chemical composition forecasts as well as potential feedback between the two. The entire system is made of three preprocessing software tools for user-defined chemical mechanisms, aerosol and trace gas emissions fields and the interpolation of initial and boundary conditions for meteorology and chemistry. In this paper, the model description is provided along with the evaluations performed by using observational data obtained from ground-based stations, instruments aboard aircrafts and retrieval from space remote sensing. The evaluation accounts for model applications at different scales from megacities and the Amazon Basin up to the intercontinental region of the Southern Hemisphere.

  1. Chemistry Simulations Using MERRA-2 Reanalysis with the GMI CTM and Replay in Support of the Atmospheric Composition Community

    Science.gov (United States)

    Oman, Luke D.; Strahan, Susan E.

    2016-01-01

    Simulations using reanalyzed meteorological conditions have been long used to understand causes of atmospheric composition change over the recent past. Using the new Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) meteorology, chemistry simulations are being conducted to create products covering 1980-2016 for the atmospheric composition community. These simulations use the Global Modeling Initiative (GMI) chemical mechanism in two different models: the GMI Chemical Transport Model (CTM) and the GEOS-5 model developed Replay mode. Replay mode means an integration of the GEOS-5 general circulation model that is incrementally adjusted each time step toward the MERRA-2 analysis. The GMI CTM is a 1 x 1.25 simulation and the MERRA-2 GMI Replay simulation uses the native MERRA-2 approximately horizontal resolution on the cubed sphere. The Replay simulations is driven by the online use of key MERRA-2 meteorological variables (i.e. U, V, T, and surface pressure) with all other variables calculated in response to those variables. A specialized set of transport diagnostics is included in both runs to better understand trace gas transport and changes over the recent past.

  2. Development of the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE)

    CERN Document Server

    Ong, R A

    1998-01-01

    STACEE is a proposed atmospheric Cherenkov telescope for ground-based gamma-ray astrophysics between 25 and 500 GeV. The telescope will make use of the large solar mirrors (heliostats) available at a solar research facility to achieve an energy threshold lower than any existing ground-based instrument. This paper describes the development of STACEE, including an overview of the complete instrument design and a discussion of results from recent prototype tests at the large solar heliostat field of Sandia National Laboratories.

  3. On the atmospheric response experiment to a Blue Arctic Ocean

    Science.gov (United States)

    Nakamura, Tetsu; Yamazaki, Koji; Honda, Meiji; Ukita, Jinro; Jaiser, Ralf; Handorf, Dörthe; Dethloff, Klaus

    2016-10-01

    We demonstrated atmospheric responses to a reduction in Arctic sea ice via simulations in which Arctic sea ice decreased stepwise from the present-day range to an ice-free range. In all cases, the tropospheric response exhibited a negative Arctic Oscillation (AO)-like pattern. An intensification of the climatological planetary-scale wave due to the present-day sea ice reduction on the Atlantic side of the Arctic Ocean induced stratospheric polar vortex weakening and the subsequent negative AO. Conversely, strong Arctic warming due to ice-free conditions across the entire Arctic Ocean induced a weakening of the tropospheric westerlies corresponding to a negative AO without troposphere-stratosphere coupling, for which the planetary-scale wave response to a surface heat source extending to the Pacific side of the Arctic Ocean was responsible. Because the resultant negative AO-like response was accompanied by secondary circulation in the meridional plane, atmospheric heat transport into the Arctic increased, accelerating the Arctic amplification.

  4. Status and trend of atmospheric deposition chemistry at the CONECOFOR plots, 1998-2005

    Directory of Open Access Journals (Sweden)

    Aldo Marchetto

    2013-11-01

    Full Text Available Ion deposition in the open field and under the canopy was monitored in 13 CONECOFOR plots during 1998-2005. In spite of the remote location of most plots, atmospheric deposition carries considerable amounts of anthropogenic ions (sulphate, nitrate and ammonium. Deposition acidity is buffered by the deposition of base cations, partially due to the long-range transport of Saharan dust. In the study period, sulphate deposition and deposition acidity significantly decreased, because of the decrease in sulphur dioxide emissions in Europe, while nitrate and ammonia deposition did not show a clear temporal pattern.

  5. Atmospheric transport and chemistry of trace gases in LMDz5B: evaluation and implications for inverse modelling

    Directory of Open Access Journals (Sweden)

    R. Locatelli

    2014-07-01

    Full Text Available Representation of atmospheric transport is a major source of error in the estimation of greenhouse gas sources and sinks by inverse modelling. Here we assess the impact on trace gas mole fractions of the new physical parameterisations recently implemented in the Atmospheric Global Climate Model LMDz to improve vertical diffusion, mesoscale mixing by thermal plumes in the planetary boundary layer (PBL, and deep convection in the troposphere. At the same time, the horizontal and vertical resolution of the model used in the inverse system has been increased. The aim of this paper is to evaluate the impact of these developments on the representation of trace gas transport and chemistry, and to anticipate the implications for inversions of greenhouse gas emissions using such an updated model. Comparison of a one-dimensional version of LMDz with large eddy simulations shows that the thermal scheme simulates shallow convective tracer transport in the PBL over land very efficiently, and much better than previous versions of the model. This result is confirmed in three dimensional simulations, by a much improved reproduction of the Radon-222 diurnal cycle. However, the enhanced dynamics of tracer concentrations induces a stronger sensitivity of the new LMDz configuration to external meteorological forcings. At larger scales, the inter-hemispheric exchange is slightly slower when using the new version of the model, bringing them closer to observations. The increase in the vertical resolution (from 19 to 39 layers significantly improves the representation of stratosphere/troposphere exchange. Furthermore, changes in atmospheric thermodynamic variables, such as temperature, due to changes in the PBL mixing, significantly modify chemical reaction rates and the equilibrium value of reactive trace gases. One implication of LMDz model developments for future inversions of greenhouse gas emissions is the ability of the updated system to assimilate a larger

  6. Measuring the Mass Hierarchy with Muon and Hadron Events in Atmospheric Neutrino Experiments

    CERN Document Server

    Ghosh, Anushree

    2013-01-01

    Neutrino mass hierarchy can be measured in atmospheric neutrino experiments through the observation of earth matter effects. Magnetized iron calorimeters have been shown to be good in this regard due to their charge identification capabilities. The charged current interaction of $\

  7. Aerosol and cloud chemistry of amines from CCS - reactivity experiments and numerical modeling

    Science.gov (United States)

    Weller, Christian; Tilgner, Andreas; Herrmann, Hartmut

    2013-04-01

    Capturing CO2 from the exhaust of power plants using amine scrubbing is a common technology. Therefore, amines can be released during the carbon capture process. To investigate the tropospheric chemical fate of amines from CO2 capturing processes and their oxidation products, the impact of aqueous aerosol particles and cloud droplets on the amine chemistry has been considered. Aqueous phase reactivity experiments of NO3 radicals and ozone with relevant amines and their corresponding nitrosamines were performed. Furthermore, nitrosamine formation and nitrosamine photolysis was investigated during laboratory experiments. These experiments implicated that aqueous phase photolysis can be an effective sink for nitrosamines and that ozone is unreactive towards amines and nitrosamines. Multiphase phase oxidation schemes of amines, nitrosamines and amides were developed, coupled to the existing multiphase chemistry mechanism CAPRAM and built into the Lagrangian parcel model SPACCIM using published and newly measured data. As a result, both deliquescent particles and cloud droplets are important compartments for the multiphase processing of amines and their products. Amines can be readily oxidised by OH radicals in the gas and cloud phase during daytime summer conditions. However, amine oxidation is restricted during winter conditions with low photochemical activity leading to long lifetimes of amines. The importance of the gas and aqueous phase depends strongly on the partitioning of the different amines. Furthermore, the simulations revealed that the aqueous formation of nitrosamines in aerosol particles and could droplets is not a relevant process under tropospheric conditions.

  8. The role and importance of ozone for atmospheric chemistry and methods for measuring its concentration

    Directory of Open Access Journals (Sweden)

    Marković Dragan M.

    2003-01-01

    Full Text Available Depending on where ozone resides, it can protect or harm life on Earth. The thin layer of ozone that surrounds Earth acts as a shield protecting the planet from irradiation by UV light. When it is close to the planet's surface, ozone is a powerful photochemical oxidant that damage, icons frescos, museum exhibits, rubber, plastic and all plant and animal life. Besides the basic properties of some methods for determining the ozone concentration in working and living conditions, this paper presents a detailed description of the electrochemical method. The basic properties of the electrochemical method are used in the construction of mobile equipment for determining the sum of oxidants in the atmosphere. The equipment was used for testing the determination of the ozone concentration in working rooms, where the concentration was at a high level and caused by UV radiation or electrostatic discharge. According to the obtained results, it can be concluded that this equipment for determining the ozone concentration in the atmosphere is very powerful and reproducible in measurements.

  9. Hydration of atmospherically relevant molecular clusters: computational chemistry and classical thermodynamics.

    Science.gov (United States)

    Henschel, Henning; Navarro, Juan C Acosta; Yli-Juuti, Taina; Kupiainen-Määttä, Oona; Olenius, Tinja; Ortega, Ismael K; Clegg, Simon L; Kurtén, Theo; Riipinen, Ilona; Vehkamäki, Hanna

    2014-04-10

    Formation of new particles through clustering of molecules from condensable vapors is a significant source for atmospheric aerosols. The smallest clusters formed in the very first steps of the condensation process are, however, not directly observable by experimental means. We present here a comprehensive series of electronic structure calculations on the hydrates of clusters formed by up to four molecules of sulfuric acid, and up to two molecules of ammonia or dimethylamine. Though clusters containing ammonia, and certainly dimethylamine, generally exhibit lower average hydration than the pure acid clusters, populations of individual hydrates vary widely. Furthermore, we explore the predictions obtained using a thermodynamic model for the description of these hydrates. The similar magnitude and trends of hydrate formation predicted by both methods illustrate the potential of combining them to obtain more comprehensive models. The stabilization of some clusters relative to others due to their hydration is highly likely to have significant effects on the overall processes that lead to formation of new particles in the atmosphere.

  10. Middle atmosphere response to different descriptions of the 11-yr solar cycle in spectral irradiance in a chemistry-climate model

    Directory of Open Access Journals (Sweden)

    W. H. Swartz

    2012-03-01

    Full Text Available The 11-yr solar cycle in solar spectral irradiance (SSI inferred from measurements by the SOlar Radiation & Climate Experiment (SORCE suggests a much larger variation in the ultraviolet than previously accepted. We present middle atmosphere ozone and temperature responses to the solar cycles in SORCE SSI and the ubiquitous Naval Research Laboratory (NRL SSI reconstruction using the Goddard Earth Observing System chemistry-climate model (GEOS CCM. The results are largely consistent with other recent modeling studies. The modeled ozone response is positive throughout the stratosphere and lower mesosphere using the NRL SSI, while the SORCE SSI produces a response that is larger in the lower stratosphere but out of phase with respect to total solar irradiance above 45 km. The modeled responses in total ozone are similar to those derived from satellite and ground-based measurements, 3–6 Dobson Units per 100 units of 10.7-cm radio flux (F10.7 in the tropics. The peak zonal mean tropical temperature response using the SORCE SSI is nearly 2 K per 100 units F10.7 – 3 times larger than the simulation using the NRL SSI. The GEOS CCM and the Goddard Space Flight Center (GSFC 2-D coupled model are used to examine how the SSI solar cycle affects the atmosphere through direct solar heating and photolysis processes individually. Middle atmosphere ozone is affected almost entirely through photolysis, whereas the solar cycle in temperature is caused both through direct heating and photolysis feedbacks, processes that are mostly linearly separable. Further, the net ozone response results from the balance of ozone production at wavelengths less than 242 nm and destruction at longer wavelengths, coincidentally corresponding to the wavelength regimes of the SOLar STellar Irradiance Comparison Experiment (SOLSTICE and Spectral Irradiance Monitor (SIM on SORCE, respectively. A higher wavelength-resolution analysis of the spectral

  11. Design of the National Trends Network for monitoring the chemistry of atmospheric precipitation

    Science.gov (United States)

    Robertson, J.K.; Wilson, J.W.

    1985-01-01

    Long-term monitoring (10 years minimum) of the chemistry of wet deposition will be conducted at National Trends Network (NTN) sites across the United States. Precipitation samples will be collected at sites that represent broad regional characteristics. Design of the NTN considered four basic elements during construction of a model to distribute 50, 75, 100, 125 or 150 sites. The modeling oriented design was supplemented with guidance developed during the course of the site selection process. Ultimately, a network of 151 sites was proposed. The basic elements of the design are: (1) Assurance that all areas of the country are represented in the network on the basis of regional ecological properties (96 sites); (2) Placement of additional sites east of the Rocky Mountains to better define high deposition gradients (27 sites); (3) Placement of sites to assure that potentially sensitive regions are represented (15 sites); (4) Placement of sites to allow for other considerations, such as urban area effects (5 sites), intercomparison with Canada (3 sites), and apparent disparities in regional coverage (5 sites). Site selection stressed areas away from urban centers, large point sources, or ocean influences. Local factors, such as stable land ownership, nearby small emission sources (about 10 km), and close-by roads and fireplaces (about 0.5 km) were also considered. All proposed sites will be visited as part of the second phase of the study.

  12. The Discovery-Oriented Approach to Organic Chemistry. 7. Rearrangement of "trans"-Stilbene Oxide with Bismuth Trifluoromethanesulfonate and Other Metal Triflates: A Microscale Green Organic Chemistry Laboratory Experiment

    Science.gov (United States)

    Christensen, James E.; Huddle, Matthew G.; Rogers, Jamie L.; Yung, Herbie; Mohan, Ram S.

    2008-01-01

    Although green chemistry principles are increasingly stressed in the undergraduate curriculum, there are only a few lab experiments wherein the toxicity of reagents is taken into consideration in the design of the experiment. We report a microscale green organic chemistry laboratory experiment that illustrates the utility of metal triflates,…

  13. Comparison of the HadGEM2 climate-chemistry model against in situ and SCIAMACHY atmospheric methane data

    Directory of Open Access Journals (Sweden)

    G. D. Hayman

    2014-12-01

    Full Text Available Wetlands are a major emission source of methane (CH4 globally. In this study, we evaluate wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates are investigated: (a from an offline run driven with Climatic Research Unit–National Centers for Environmental Prediction (CRU-NCEP meteorological data and (b from the same offline run in which the modelled wetland fractions are replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999–2007 is in line with other recently published estimates. There are regional differences as the unconstrained JULES inventory gives significantly higher emissions in the Amazon (by ~36 Tg CH4 yr−1 and lower emissions in other regions (by up to 10 Tg CH4 yr−1 compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2, we evaluate these JULES wetland emissions against atmospheric observations of methane. We obtain improved agreement with the surface concentration measurements, especially at high northern latitudes, compared to previous HadGEM2 runs using the wetland emission data set of Fung et al. (1991. Although the modelled monthly atmospheric methane columns reproduce the large-scale patterns in the SCIAMACHY observations, they are biased low by 50 part per billion by volume (ppb. Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE–ACE assimilated TOMCAT output results in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain the JULES

  14. Comparison of the HadGEM2 climate-chemistry model against in-situ and SCIAMACHY atmospheric methane data

    Directory of Open Access Journals (Sweden)

    G. D. Hayman

    2014-05-01

    Full Text Available Wetlands are a major emission source of methane (CH4 globally. In this study, we have evaluated wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates were investigated: (a from an offline run driven with CRU-NCEP meteorological data and (b from the same offline run in which the modelled wetland fractions were replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999–2007 is in line with other recently-published estimates. There are regional differences as the unconstrained JULES inventory gave significantly higher emissions in the Amazon and lower emissions in other regions compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2, we have evaluated these JULES wetland emissions against atmospheric observations of methane. We obtained improved agreement with the surface concentration measurements, especially at northern high latitudes, compared to previous HadGEM2 runs using the wetland emission dataset of Fung (1991. Although the modelled monthly atmospheric methane columns reproduced the large–scale patterns in the SCIAMACHY observations, they were biased low by 50 part per billion by volume (ppb. Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE–ACE assimilated TOMCAT output resulted in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain JULES-derived wetland fraction improved the description of the wetland emissions in JULES and gave a good description

  15. Comparison of the HadGEM2 climate-chemistry model against in situ and SCIAMACHY atmospheric methane data

    Science.gov (United States)

    Hayman, G. D.; O'Connor, F. M.; Dalvi, M.; Clark, D. B.; Gedney, N.; Huntingford, C.; Prigent, C.; Buchwitz, M.; Schneising, O.; Burrows, J. P.; Wilson, C.; Richards, N.; Chipperfield, M.

    2014-12-01

    Wetlands are a major emission source of methane (CH4) globally. In this study, we evaluate wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator) against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates are investigated: (a) from an offline run driven with Climatic Research Unit-National Centers for Environmental Prediction (CRU-NCEP) meteorological data and (b) from the same offline run in which the modelled wetland fractions are replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS) remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999-2007) is in line with other recently published estimates. There are regional differences as the unconstrained JULES inventory gives significantly higher emissions in the Amazon (by ~36 Tg CH4 yr-1) and lower emissions in other regions (by up to 10 Tg CH4 yr-1) compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2), we evaluate these JULES wetland emissions against atmospheric observations of methane. We obtain improved agreement with the surface concentration measurements, especially at high northern latitudes, compared to previous HadGEM2 runs using the wetland emission data set of Fung et al. (1991). Although the modelled monthly atmospheric methane columns reproduce the large-scale patterns in the SCIAMACHY observations, they are biased low by 50 part per billion by volume (ppb). Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE-ACE assimilated TOMCAT output results in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain the JULES-derived wetland

  16. Episodic perturbations of end-Permian atmosphere recorded in plant spore chemistry

    Science.gov (United States)

    Fraser, Wesley; Lomax, Barry; Beerling, David; James, David; Pyle, John; Self, Stephen; Sephton, Mark; Wellman, Charles

    2016-04-01

    The largest marine Phanerozoic extinction occurred 251 million years ago at the end of the Permian period with a contemporaneous major reorganisation of terrestrial. Previous work suggests the eruption of the Siberian Traps large igneous province could have generated substantial volumes of ozone depleting substances; the result being a partial collapse of the stratospheric ozone layer, and commensurate increase in ultraviolet-B (UV-B, 280-315nm) radiation. Increased UV-B flux would contribute additional pressures to an already stressed environment and flora and fauna. Here we present data utilising a new biogeochemical proxy for UV-B radiation to analyse clubmoss (lycophyta) megaspores to track UV-B radiation across the end-Permian interval. Our biogeochemical data when combined with published work on spore and pollen mutations suggests a highly dynamic global atmospheric system, oscillating between episodes of high and low UV-B flux, most likely driven by pulsed eruptive phases of the Siberian Traps.

  17. Climate change and atmospheric chemistry: how will the stratospheric ozone layer develop?

    Science.gov (United States)

    Dameris, Martin

    2010-10-25

    The discovery of the ozone hole over Antarctica in 1985 was a surprise for science. For a few years the reasons of the ozone hole was speculated about. Soon it was obvious that predominant meteorological conditions led to a specific situation developing in this part of the atmosphere: Very low temperatures initiate chemical processes that at the end cause extreme ozone depletion at altitudes of between about 15 and 30 km. So-called polar stratospheric clouds play a key role. Such clouds develop at temperatures below about 195 K. Heterogeneous chemical reactions on cloud particles initiate the destruction of ozone molecules. The future evolution of the ozone layer will not only depend on the further development of concentrations of ozone-depleting substances, but also significantly on climate change.

  18. Fundamental Heterogeneous Reaction Chemistry Related to Secondary Organic Aerosols (SOA) in the Atmosphere

    Science.gov (United States)

    Akimoto, H.

    2016-11-01

    Typical reaction pathways of formation of dicarboxylic acids, larger multifunctional compounds, oligomers, and organosulfur and organonitrogen compounds in secondary organic aerosols (SOA), revealed by laboratory experimental studies are reviewed with a short introduction to field observations. In most of the reactions forming these compounds, glyoxal, methyl glyoxal and related difunctional carbonyl compounds play an important role as precursors, and so their formation pathways in the gas phase are discussed first. A substantial discussion is then presented for the OH-initiated aqueous phase radical oxidation reactions of glyoxal and other carbonyls which form dicarboxylic acids, larger multifunctional compounds and oligomers, and aqueous-phase non-radical reactions which form oligomers, organosulfates and organonitrogen compounds. Finally, the heterogeneous oxidation reaction of gaseous O3, OH and NO3 with liquid and solid organic aerosols at the air-particle interface is discussed relating to the aging of SOA in the atmosphere.

  19. The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment

    DEFF Research Database (Denmark)

    Schofield, J.T.; Barnes, J.R.; Crisp, D.

    1997-01-01

    The Mars Pathfinder atmospheric structure investigation/meteorology (ASI/MET) experiment measured the vertical density, pressure, and temperature structure of the martian atmosphere from the surface to 160 km, and monitored surface meteorology and climate for 83 sols (1 sol = 1 martian day = 24...... nighttime upper atmosphere; atmospheric temperatures that are 10 to 12 degrees kelvin warmer near the surface; light slope-controlled winds; and dust devils, identified by their pressure, wind, and temperature signatures. The results are consistent with the warm, moderately dusty atmosphere seen by VL-1........7 hours). The atmospheric structure and the weather record are similar to those observed by the Viking 1 lander (VL-1) at the same latitude, altitude, and season 21 years ago, but there are differences related to diurnal effects and the surface properties of the landing site. These include a cold...

  20. Identification of the biologically active liquid chemistry induced by a nonthermal atmospheric pressure plasma jet.

    Science.gov (United States)

    Wende, Kristian; Williams, Paul; Dalluge, Joe; Gaens, Wouter Van; Aboubakr, Hamada; Bischof, John; von Woedtke, Thomas; Goyal, Sagar M; Weltmann, Klaus-Dieter; Bogaerts, Annemie; Masur, Kai; Bruggeman, Peter J

    2015-06-06

    The mechanism of interaction of cold nonequilibrium plasma jets with mammalian cells in physiologic liquid is reported. The major biological active species produced by an argon RF plasma jet responsible for cell viability reduction are analyzed by experimental results obtained through physical, biological, and chemical diagnostics. This is complemented with chemical kinetics modeling of the plasma source to assess the dominant reactive gas phase species. Different plasma chemistries are obtained by changing the feed gas composition of the cold argon based RF plasma jet from argon, humidified argon (0.27%), to argon/oxygen (1%) and argon/air (1%) at constant power. A minimal consensus physiologic liquid was used, providing isotonic and isohydric conditions and nutrients but is devoid of scavengers or serum constituents. While argon and humidified argon plasma led to the creation of hydrogen peroxide dominated action on the mammalian cells, argon-oxygen and argon-air plasma created a very different biological action and was characterized by trace amounts of hydrogen peroxide only. In particular, for the argon-oxygen (1%), the authors observed a strong negative effect on mammalian cell proliferation and metabolism. This effect was distance dependent and showed a half life time of 30 min in a scavenger free physiologic buffer. Neither catalase and mannitol nor superoxide dismutase could rescue the cell proliferation rate. The strong distance dependency of the effect as well as the low water solubility rules out a major role for ozone and singlet oxygen but suggests a dominant role of atomic oxygen. Experimental results suggest that O reacts with chloride, yielding Cl2(-) or ClO(-). These chlorine species have a limited lifetime under physiologic conditions and therefore show a strong time dependent biological activity. The outcomes are compared with an argon MHz plasma jet (kinpen) to assess the differences between these (at least seemingly) similar plasma sources.

  1. ATR-FTIR Spectroscopy in the Undergraduate Chemistry Laboratory: Part II--A Physical Chemistry Laboratory Experiment on Surface Adsorption

    Science.gov (United States)

    Schuttlefield, Jennifer D.; Larsen, Sarah C.; Grassian, Vicki H.

    2008-01-01

    Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is a useful technique for measuring the infrared spectra of solids and liquids as well as probing adsorption on particle surfaces. The use of FTIR-ATR spectroscopy in organic and inorganic chemistry laboratory courses as well as in undergraduate research was presented…

  2. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2010-01-01

    kinetics analysis indicate that the formation and removal processes of H2O2 may be different from those of MHP and PAA. (iv Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  3. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2009-10-01

    analysis reveals that a possible unknown pathway results in the significant removal of H2O2 and the extent of H2O2 undergoing this pathway needs a further study. (iv Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  4. A STUDY ON LEGIONELLA PNEUMOPHILA, WATER CHEMISTRY, AND ATMOSPHERIC CONDITIONS IN COOLING TOWERS AT THE SAVANNAH RIVER SITE

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.; Brigmon, R.

    2009-10-20

    elevated Legionella concentrations when the dew point temperature was high--a summertime occurrence. However, analysis of the three years of Legionella monitoring data of the 14 different SRS Cooling Towers demonstrated that elevated concentrations are observed at all temperatures and seasons. The objective of this study is to evaluate the ecology of L. pneumophila including serogroups and population densities, chemical, and atmospheric data, on cooling towers at SRS to determine whether relationships exist among water chemistry, and atmospheric conditions. The goal is to more fully understand the conditions which inhibit or encourage L. pneumophila growth and supply this data and associated recommendations to SRS Cooling Tower personnel for improved management of operation. Hopefully this information could then be used to help control L. pneumophila growth more effectively in SRS cooling tower water.

  5. Balloon UV Experiments for Astronomical and Atmospheric Observations

    CERN Document Server

    Sreejith, A G; Sarpotdar, Mayuresh; Nirmal, K; Ambily, S; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

    2016-01-01

    The ultraviolet (UV) window has been largely unexplored through balloons for astronomy. We discuss here the development of a compact near-UV spectrograph with ?ber optics input for balloon ights. It is a modi?ed Czerny-Turner system built using o?-the-shelf components. The system is portable and scalable to di?erent telescopes. The use of re ecting optics reduces the transmission loss in the UV. It employs an image-intensi?ed CMOS sensor, operating in photon counting mode, as the detector of choice. A lightweight pointing system developed for stable pointing to observe astronomical sources is also discussed, together with the methods to improve its accuracy, e.g. using the in-house build star sensor and others. Our primary scienti?c objectives include the observation of bright Solar System objects such as visible to eye comets, Moon and planets. Studies of planets can give us valuable information about the planetary aurorae, helping to model and compare atmospheres of other planets and the Earth. The other ma...

  6. Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis.

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, Gabor A.; Li, Yimin

    2009-11-21

    Experimental discoveries followed by theoretical interpretations that pave the way of further advances by experimentalists is a developing pattern in modern surface chemistry and catalysis. The revolution of modern surface science started with the development of surface-sensitive techniques such as LEED, XPS, AES, ISS and SIMS, in which the close collaboration between experimentalists and theorists led to the quantitative determination of surface structure and composition. The experimental discovery of the chemical activity of surface defects and the trends in the reactivity of transitional metals followed by the explanations from the theoretical studies led to the molecular level understanding of active sites in catalysis. The molecular level knowledge, in turn, provided a guide for experiments to search for new generation of catalysts. These and many other examples of successes in experiment-and-theory-combined studies demonstrate the importance of the collaboration between experimentalists and theorists in the development of modern surface science.

  7. Results from solar, atmospheric and K2K experiments and future possibilities with T2K

    Indian Academy of Sciences (India)

    Takaaki Kajita

    2006-10-01

    Recent results from solar, reactor, atmospheric and long baseline (K2K) experiments are discussed. With the improved data statistics and analyses, our knowledge on the neutrino masses and mixing angles are steadily improving. T2K is the next generation neutrino oscillation experiment between J-PARC in Tokai and Super-Kamiokande. This experiment will start in 2009. This experiment is expected to improve the current knowledge on the neutrino masses and mixings substantially.

  8. Biogenic non-methane hydrocarbons (NMHC). Nature`s contribution to regional and global atmospheric chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Klockow, D.; Hoffman, T. [Inst. of Spectrochemistry and Applied Spectroscopy, Dortmund (Germany)

    1995-12-31

    Terrestrial vegetation provides an important source of volatile hydrocarbons, especially isoprene, monoterpenes and in addition possibly sesquiterpenes as well as oxygenated compounds. Although there exist considerable uncertainties in the estimation of the magnitude of these biogenic NMHC emissions, it is generally accepted that the majority of global NMHC release is from natural and not from anthropogenic sources. Taking into consideration the high reactivity of the mostly unsaturated biogenic emissions, their impact on tropospheric processes can be assumed to be of great importance. Together with anthropogenic NO{sub x} emissions, the highly reactive natural alkenes can act as precursors in photochemical oxidant formation and contribute to regional-scale air pollution. Their oxidation in the atmosphere and the subsequent gas-to-particle conversion of the products lead to the formation of organic aerosols. Because of the formation of phytotoxic compounds, the interaction of the biogenic hydrocarbons with ozone inside or outside the leaves and needles of plants has been suggested to play a role in forest decline. (author)

  9. Palmitic Acid on Salt Subphases and in Mixed Monolayers of Cerebrosides: Application to Atmospheric Aerosol Chemistry

    Directory of Open Access Journals (Sweden)

    Ellen M. Adams

    2013-10-01

    Full Text Available Palmitic acid (PA has been found to be a major constituent in marine aerosols, and is commonly used to investigate organic containing atmospheric aerosols, and is therefore used here as a proxy system. Surface pressure-area isotherms (π-A, Brewster angle microscopy (BAM, and vibrational sum frequency generation (VSFG were used to observe a PA monolayer during film compression on subphases of ultrapure water, CaCl2 and MgCl2 aqueous solutions, and artificial seawater (ASW. π-A isotherms indicate that salt subphases alter the phase behavior of PA, and BAM further reveals that a condensation of the monolayer occurs when compared to pure water. VSFG spectra and BAM images show that Mg2+ and Ca2+ induce ordering of the PA acyl chains, and it was determined that the interaction of Mg2+ with the monolayer is weaker than Ca2+. π-A isotherms and BAM were also used to monitor mixed monolayers of PA and cerebroside, a simple glycolipid. Results reveal that PA also has a condensing effect on the cerebroside monolayer. Thermodynamic analysis indicates that attractive interactions between the two components exist; this may be due to hydrogen bonding of the galactose and carbonyl headgroups. BAM images of the collapse structures show that mixed monolayers of PA and cerebroside are miscible at all surface pressures. These results suggest that the surface morphology of organic-coated aerosols is influenced by the chemical composition of the aqueous core and the organic film itself.

  10. Experimental simulation of negative ion chemistry in Martian atmosphere using ion mobility spectrometry-mass spectrometry

    Science.gov (United States)

    Sabo, Martin; Lichvanová, Zuzana; Orszagh, Juraj; Mason, Nigel; Matejčík, Štefan

    2014-08-01

    We have studied the formation of negative ions in a negative Corona Discharge (CD) fed by CO2/N2 mixtures (with 0, 2, 4, 6, 8, 10% N2) using the technique of ion mobility spectrometry-orthogonal acceleration time of flight mass spectrometry (IMS-oaTOF). The composition of the negative ions was found to be dependent on the initial gas composition, the gas flow regime, the concentrations of neutral reactive species formed in the discharge and the trace amounts on water in the gases were found to play an important role in the negative ions formation. In a pure CO2 discharge operating under standard gas flow conditions of IMS (associated with strong interaction of ions with neutral reactive species formed in discharge) the ions CO3 - (H2O) and CO4 -(H2O) dominated the measured negative ion spectrum while in CO2/N2 mixtures NO3 -(H2O) n , NO3 -(HNO3) ( n = 0, 1) ions prevailed. In the case of reverse gas flow regime (low interaction of ions with neutral reactive species formed in discharge), the negative ions detected were O2 -(H2O) n , and O2 -.CO2(H2O) n both in pure CO2 and N2/CO2 mixtures. The spectra of negative ions recorded for a gas mixture containing 4% N2 in CO2 were compared with theoretical predictions of negative ion composition in the lower atmosphere of Mars.

  11. Downward transport of ozone rich air and implications for atmospheric chemistry in the Amazon rainforest

    Science.gov (United States)

    Gerken, Tobias; Wei, Dandan; Chase, Randy J.; Fuentes, Jose D.; Schumacher, Courtney; Machado, Luiz A. T.; Andreoli, Rita V.; Chamecki, Marcelo; Ferreira de Souza, Rodrigo A.; Freire, Livia S.; Jardine, Angela B.; Manzi, Antonio O.; Nascimento dos Santos, Rosa M.; von Randow, Celso; dos Santos Costa, Patrícia; Stoy, Paul C.; Tóta, Julio; Trowbridge, Amy M.

    2016-01-01

    From April 2014 to January 2015, ozone (O3) dynamics were investigated as part of GoAmazon 2014/5 project in the central Amazon rainforest of Brazil. Just above the forest canopy, maximum hourly O3 mixing ratios averaged 20 ppbv (parts per billion on a volume basis) during the June-September dry months and 15 ppbv during the wet months. Ozone levels occasionally exceeded 75 ppbv in response to influences from biomass burning and regional air pollution. Individual convective storms transported O3-rich air parcels from the mid-troposphere to the surface and abruptly enhanced the regional atmospheric boundary layer by as much as 25 ppbv. In contrast to the individual storms, days with multiple convective systems produced successive, cumulative ground-level O3 increases. The magnitude of O3 enhancements depended on the vertical distribution of O3 within storm downdrafts and origin of downdrafts in the troposphere. Ozone mixing ratios remained enhanced for > 2 h following the passage of storms, which enhanced chemical processing of rainforest-emitted isoprene and monoterpenes. Reactions of isoprene and monoterpenes with O3 are modeled to generate maximum hydroxyl radical formation rates of 6 × 106 radicals cm-3s-1. Therefore, one key conclusion of the present study is that downdrafts of convective storms are estimated to transport enough O3 to the surface to initiate a series of reactions that reduce the lifetimes of rainforest-emitted hydrocarbons.

  12. Interaction of pollution plumes and discontinuous fields in atmospheric chemistry models

    Science.gov (United States)

    Santillana, Mauricio; Brenner, Michael P.; Rastigeyev, Yevgeniy; Jacob, Daniel J.

    2010-11-01

    Atmospheric pollutants originate from concentrated sources such as cities, power plants, and biomass fires. They are injected in the troposphere where eddies and convective motions of various scales act to shear and dilute the pollution plumes as they are advected downwind. Despite this shear and dilution, observations from aircraft, sondes, and satellites show that pollution plumes in the remote free troposphere can preserve their identity as well-defined layers for a week or more as they are transported on intercontinental scales. This structure cannot be reproduced in the standard Eulerian chemical transport models used for global modeling of tropospheric composition, instead, the plumes dissipate far too quickly. In this work, we study how the structure of plumes is modified when they cross discontinuities arising for example: from the moving day-night boundaries or from abrupt unresolved horizontal temperature changes (for example in horizontal ocean-land or ocean-ice transitions). Chemical reactions within the plumes depend strongly on photon availability and temperature, and thus, discontinuities in these variables lead to discontinuous changes in reaction rate constants.

  13. Characterization of vehicle emissions in São Paulo and the impacts on atmospheric chemistry and secondary aerosol formation

    Science.gov (United States)

    Ferreira De Brito, J.; Godoy, M.; Godoy, J.; Varanda Rizzo, L.; Artaxo, P.

    2012-12-01

    Megacities emissions are increasingly becoming a global issue, where emissions from the transportation sector play an important role. São Paulo, located in Southeast of Brazil, is a megacity with a population of 18 million people, 7 million cars and large-scale industrial emissions. As a result of the vehicular and industrial emissions, the air quality in São Paulo is considered one of the worst worldwide. Despite the large impact on human health and atmospheric chemistry/dynamics, many uncertainties are found on gas- and particulate matter vehicular emission factors and their following atmospheric processes, e.g. secondary organic aerosol formation. Due to the uniqueness of the vehicular fuel in Brazil, largely based on ethanol use, such characterization currently holds further uncertainties. To improve the understanding of the role of this unique emission pattern, we are running a source apportionment study in São Paulo. One of the goals of this study is a quantitative aerosol source apportionment focused on vehicular emissions, including ethanol and gasohol (both fuels used by light-duty vehicles) and diesel (heavy-duty vehicles). Whereas the latter shows usually much higher emission factors compared with ethanol or gasohol, heavy-duty vehicles have increasingly limited access within the São Paulo city limits, thus increasing the importance of light duty vehicles on air quality degradation. This study comprises four sampling sites, where trace elements and organic aerosol are being measured for PM2.5 and PM10 along with real-time NOx, ozone, PM10 and CO measurements. Aerosol optical properties and size distribution are being measured on a rotation basis between sampling stations. Furthermore, a Proton-Transfer-Reaction Mass Spectrometer (PTR-MS) and an Aerosol Chemical Speciation Monitor (ACSM) are used to real-time VOC analysis and aerosol composition, respectively. Results show aerosol number concentrations ranging between 10^4 and 3.10^4 cm-3, mostly

  14. Atmospheric methane and carbon dioxide from SCIAMACHY satellite data: initial comparison with chemistry and transport models

    Directory of Open Access Journals (Sweden)

    M. Buchwitz

    2004-11-01

    Full Text Available The remote sensing of the atmospheric greenhouse gases methane (CH4 and carbon dioxide (CO2 in the troposphere from instrumentation aboard satellites is a new area of research. In this manuscript, results obtained from observations of the up-welling radiation in the near-infrared by SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY, which flies on board ENVISAT, are presented. Vertical columns of CH4, CO2 and oxygen (O2 have been retrieved and the (air or O2-normalized CH4 and CO2 column amounts, the dry air column averaged mixing ratios XCH4 and XCO2 derived. In this manuscript the first results, obtained by using the version 0.4 of the Weighting Function Modified (WFM DOAS retrieval algorithm applied to SCIAMACHY data, are described and compared with global models. This is an important step in assessing the quality and information content of the data products derived from SCIAMACHY observations. This study investigates the behaviour of CO2 and CH4 in the period from January to October 2003. The SCIAMACHY greenhouse gas column amounts and their mixing ratios for cloud free scenes over land are shown to be in reasonable agreement with models. Over the ocean, as a result of the lower surface spectral reflectance and resultant low signal to noise with the exception of sun glint conditions, the accuracy of the individual data products is poorer. The measured methane column amounts agree with the model columns within a few percent. The inter-hemispheric difference of the methane mixing ratios, determined from single day cloud free measurements over land, is in the range 30–110 ppbv and in reasonable agreement with the corresponding model data (48–71 ppbv. For the set of individual measurements the standard deviations of the difference with respect to the models are in the range ~100

  15. Prospects for simulating macromolecular surfactant chemistry at the ocean-atmosphere boundary

    Science.gov (United States)

    Elliott, S.; Burrows, S. M.; Deal, C.; Liu, X.; Long, M.; Ogunro, O.; Russell, L. M.; Wingenter, O.

    2014-05-01

    Biogenic lipids and polymers are surveyed for their ability to adsorb at the water-air interfaces associated with bubbles, marine microlayers and particles in the overlying boundary layer. Representative ocean biogeochemical regimes are defined in order to estimate local concentrations for the major macromolecular classes. Surfactant equilibria and maximum excess are then derived based on a network of model compounds. Relative local coverage and upward mass transport follow directly, and specific chemical structures can be placed into regional rank order. Lipids and denatured protein-like polymers dominate at the selected locations. The assigned monolayer phase states are variable, whether assessed along bubbles or at the atmospheric spray droplet perimeter. Since oceanic film compositions prove to be irregular, effects on gas and organic transfer are expected to exhibit geographic dependence as well. Moreover, the core arguments extend across the sea-air interface into aerosol-cloud systems. Fundamental nascent chemical properties including mass to carbon ratio and density depend strongly on the geochemical state of source waters. High surface pressures may suppress the Kelvin effect, and marine organic hygroscopicities are almost entirely unconstrained. While bubble adsorption provides a well-known means for transporting lipidic or proteinaceous material into sea spray, the same cannot be said of polysaccharides. Carbohydrates tend to be strongly hydrophilic so that their excess carbon mass is low despite stacked polymeric geometries. Since sugars are abundant in the marine aerosol, gel-based mechanisms may be required to achieve uplift. Uncertainties distill to a global scale dearth of information regarding two dimensional kinetics and equilibria. Nonetheless simulations are recommended, to initiate the process of systems level quantification.

  16. Prospects for Simulating Macromolecular Surfactant Chemistry at the Ocean-Atmosphere Boundary

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, S.; Burrows, Susannah M.; Deal, C.; Liu, Xiaohong; Long, M.; Ogunro, O.; Russell, Lynn M.; Wingenter, O.

    2014-05-01

    Biogenic lipids and polymers are surveyed for their ability to adsorb at the water-air interfaces associated with bubbles, marine microlayers and particles in the overlying boundary layer. Representative ocean biogeochemical regimes are defined in order to estimate local concentrations for the major macromolecular classes. Surfactant equilibria and maximum excess are then derived based on a network of model compounds. Relative local coverage and upward mass transport follow directly, and specific chemical structures can be placed into regional rank order. Lipids and denatured protein-like polymers dominate at the selected locations. The assigned monolayer phase states are variable, whether assessed along bubbles or at the atmospheric spray droplet perimeter. Since oceanic film compositions prove to be irregular, effects on gas and organic transfer are expected to exhibit geographic dependence as well. Moreover, the core arguments extend across the sea-air interface into aerosol-cloud systems. Fundamental nascent chemical properties including mass to carbon ratio and density depend strongly on the geochemical state of source waters. High surface pressures may suppress the Kelvin effect, and marine organic hygroscopicities are almost entirely unconstrained. While bubble adsorption provides a well-known means for transporting lipidic or proteinaceous material into sea spray, the same cannot be said of polysaccharides. Carbohydrates tend to be strongly hydrophilic so that their excess carbon mass is low despite stacked polymeric geometries. Since sugars are abundant in the marine aerosol, gel-based mechanisms may be required to achieve uplift. Uncertainties in the surfactant logic distill to a global scale dearth of information regarding two dimensional kinetics and equilibria. Nonetheless simulations are recommended, to initiate the process of systems level quantification.

  17. Electronic Transitions as a Probe of Tetrahedral versus Octahedral Coordination in Nickel(II) Complexes: An Undergraduate Inorganic Chemistry Experiment.

    Science.gov (United States)

    Filgueiras, Carlos A. L.; Carazza, Fernando

    1980-01-01

    Discusses procedures, theoretical considerations, and results of an experiment involving the preparation of a tetrahedral nickel(II) complex and its transformation into an octahedral species. Suggests that fundamental aspects of coordination chemistry can be demonstrated by simple experiments performed in introductory level courses. (Author/JN)

  18. A Precise, Simple, and Low-Cost Experiment to Determine the Isobaric Expansion Coefficient for Physical Chemistry Students

    Science.gov (United States)

    Pe´rez, Eduardo

    2015-01-01

    The procedure of a physical chemistry experiment for university students must be designed in a way that the accuracy and precision of the measurements is properly maintained. However, in many cases, that requires costly and sophisticated equipment not readily available in developing countries. A simple, low-cost experiment to determine isobaric…

  19. Development and Implementation of a Simple, Engaging Acid Rain Neutralization Experiment and Corresponding Animated Instructional Video for Introductory Chemistry Students

    Science.gov (United States)

    Rand, Danielle; Yennie, Craig J.; Lynch, Patrick; Lowry, Gregory; Budarz, James; Zhu, Wenlei; Wang, Li-Qiong

    2016-01-01

    Here we describe an acid rain neutralization laboratory experiment and its corresponding instructional video. This experiment has been developed and implemented for use in the teaching laboratory of a large introductory chemistry course at Brown University. It provides a contextually relevant example to introduce beginner-level students with…

  20. Characterization of High Explosives and Other Energetic Compounds by Computational Chemistry and Molecular Modeling: Experiments for Undergraduate Curriculum

    Science.gov (United States)

    Bumpus, John A.; Lewis, Anne; Stotts, Corey; Cramer, Christopher J.

    2007-01-01

    Experiments suited for the undergraduate instructional laboratory in which the heats of formation of several aliphatic and aromatic compounds are calculated, are described. The experiments could be used to introduce students to commercially available computational chemistry and its thermodynamics, while assess and compare the energy content of…

  1. Identification of Copper(II) Complexes in Aqueous Solution by Electron Spin Resonance: An Undergraduate Coordination Chemistry Experiment.

    Science.gov (United States)

    Micera, G.; And Others

    1984-01-01

    Background, procedures, and results are provided for an experiment which examines, through electron spin resonance spectroscopy, complex species formed by cupric and 2,6-dihydroxybenzoate ions in aqueous solutions. The experiment is illustrative of several aspects of inorganic and coordination chemistry, including the identification of species…

  2. Synthesis of 10-Ethyl Flavin: A Multistep Synthesis Organic Chemistry Laboratory Experiment for Upper-Division Undergraduate Students

    Science.gov (United States)

    Sichula, Vincent A.

    2015-01-01

    A multistep synthesis of 10-ethyl flavin was developed as an organic chemistry laboratory experiment for upper-division undergraduate students. Students synthesize 10-ethyl flavin as a bright yellow solid via a five-step sequence. The experiment introduces students to various hands-on experimental organic synthetic techniques, such as column…

  3. Electrochemistry of (Dihapto-Buckminster-Fullerene) Pentacarbonyl Tungsten(0): An Experiment for the Inorganic Chemistry Laboratory, Part III

    Science.gov (United States)

    Igartua-Nieves, Elvin; Ocasio-Delgado, Yessenia; Rivera-Pagan, Jose; Cortes-Figueroa, Jose E.

    2007-01-01

    Cyclic voltammetry experiments on [60]fullerene, (C[subscript 60]), and (dihapto-[60]fullerene) pentacarbonyl tungsten(0), ([eta][superscript 2]-C[subscript 60])W(CO)[subscript 5], constitute an educational experiment for the inorganic chemistry laboratory with a primary objective to teach the chemical interpretation of a voltammogram, in…

  4. Will atmospheric neutrino experiment at Hyper-Kamiokande see non-standard interaction effects?

    CERN Document Server

    Yasuda, Osamu

    2016-01-01

    In this talk we discuss the possibility to test the hypothesis, which has been proposed to explain the tension between the mass-squared differences of the solar neutrino and KamLAND experiments by the non-standard flavor-dependent interaction in neutrino propagation, with the atmospheric neutrino observations at the future Hyper-Kamiokande experiment.

  5. Compilation and analyses of emissions inventories for NOAA`s atmospheric chemistry project. Progress report, August 1997

    Energy Technology Data Exchange (ETDEWEB)

    Benkovitz, C.M.; Mubaraki, M.A.

    1997-09-01

    Global inventories of anthropogenic emissions of oxides of nitrogen (NO{sub x}) for circa 1985 and 1990 and Non-Methane Volatile Organic Compounds (NMVOCs) for circa 1990 have been compiled by this project. Work on the inventories has been carried out under the umbrella of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry (IGAC) Program. The 1985 NO{sub x} inventory was compiled using default data sets of global emissions that were refined via the use of more detailed regional data sets; this inventory is being distributed to the scientific community at large as the GEIA Version 1A inventory. Global emissions of NO{sub x} for 1985 are estimated to be 21 Tg N y{sup -1}, with approximately 84% originating in the Northern Hemisphere. The 1990 inventories of NO{sub x} and NMVOCs were compiled using unified methodologies and data sets in collaboration with the Netherlands National Institute of Public Health and Environmental Protection (Rijksinstituut Voor Volksgezondheid en Milieuhygiene, RIVM) and the Division of Technology for Society of the Netherlands Organization for Applied Scientific Research, (IMW-TNO); these emissions will be used as the default estimates to be updated with more accurate regional data. The NMVOC inventory was gridded and speciated into 23 chemical categories.

  6. ATMOSPHERIC CHEMISTRY FOR ASTROPHYSICISTS: A SELF-CONSISTENT FORMALISM AND ANALYTICAL SOLUTIONS FOR ARBITRARY C/O

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Kevin; Tsai, Shang-Min [University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012, Bern (Switzerland); Lyons, James R., E-mail: kevin.heng@csh.unibe.ch [Arizona State University, School of Earth and Space Exploration, Bateman Physical Sciences, Tempe, AZ 85287-1404 (United States)

    2016-01-10

    We present a self-consistent formalism for computing and understanding the atmospheric chemistry of exoplanets from the viewpoint of an astrophysicist. Starting from the first law of thermodynamics, we demonstrate that the van’t Hoff equation (which describes the equilibrium constant), Arrhenius equation (which describes the rate coefficients), and procedures associated with the Gibbs free energy (minimization, rescaling) have a common physical and mathematical origin. We address an ambiguity associated with the equilibrium constant, which is used to relate the forward and reverse rate coefficients, and restate its two definitions. By necessity, one of the equilibrium constants must be dimensionless and equate to an exponential function involving the Gibbs free energy, while the other is a ratio of rate coefficients and must therefore possess physical units. We demonstrate that the Arrhenius equation takes on a functional form that is more general than previously stated without recourse to tagging on ad hoc functional forms. Finally, we derive analytical models of chemical systems, in equilibrium, with carbon, hydrogen, and oxygen. We include acetylene and are able to reproduce several key trends, versus temperature and carbon-to-oxygen ratio, published in the literature. The rich variety of behavior that mixing ratios exhibit as a function of the carbon-to-oxygen ratio is merely the outcome of stoichiometric book-keeping and not the direct consequence of temperature or pressure variations.

  7. New experience in atmospheric monitoring in Moscow city on the base of WSN technology

    Science.gov (United States)

    Asavin, Alex; Litvinov, Artur; Baskakov, Sergey; Chesalova, Elena

    2016-04-01

    The aim of this report is to present the gas emission of H2 in the general composition of atmospheric pollution of Moscow city. We start the project at the beginning of 2015 year in two Moscow academicals organization -Vernadsky Institute of Geochemistry and Analytical Chemistry and Moscow Geological State Museum. One place is in the center of Moscow, near the Kremlin and other one is in the most clear zone of Moscow - Moscow State University place, Vorobyevy Mountains (high point of Moscow). We plan to compare these regions by the concentration of H2 and other gases (CH4, SO2) for green gas pollution. Application network of monitoring is composed of gas sensors (H2, CH4), complex autonomous equipment for measurement temperature, pressure, humidity and network of telecommunications (used ZigBee protocol). Our project offer the technical solutions for monitoring network on the base of WSN (wireless sensor network) technology and the high-sensitive sensors of hydrogen and methane, software and electronic equipment with a transmitter network. This work is the first project in Russia. Gas sensors for monitoring system were developed on the base of MIS-structures (metal-insulator-semiconductor). MIS-sensors are suitable for measuring the concentrations of the following gases: hydrogen, hydrogen sulphide, nitrogen dioxide, ethylmercaptan, chlorine and ammonia. The basis of the sensor is MIS - structure Pd-Ta2O5-SiO2-Si,), which capacitance changes when reaction with gases occurs. The sensor fabrication technology is based on the microelectronics device fabrication technologies and the thin film laser deposition technique. Sensor can be used for measuring the concentration of any gas among noted before, in ambient temperature range -30..+40°C and RH 30-90% (30°C).Three gas sensors with analog interface were made for our experimental monitoring system. Original calibration was made using calibration by special standard mixture of H2 and atmosphere. There are 10-15 points

  8. Atmospheric discharges from nuclear facilities during decommissioning: German experiences

    Energy Technology Data Exchange (ETDEWEB)

    Braun, H.; Goertz, R.; Weil, L.

    1997-08-01

    In Germany, a substantial amount of experience is available with planning, licensing and realization of decommissioning projects. In total, a number of 18 nuclear power plants including prototype facilities as well as 6 research reactors and 3 fuel cycle facilities have been shut down finally and are at different stages of decommissioning. Only recently the final {open_quotes}green field{close_quotes} stage of the Niederaichbach Nuclear Power Plant total dismantlement project has been achieved. From the regulatory point of view, a survey of the decommissioning experience in Germany is presented highlighting the aspects of production and retention of airborne radioactivity. Nuclear air cleaning technology, discharge limits prescribed in licences and actual discharges are presented. As compared to operation, the composition of the discharged radioactivity is different as well as the off-gas discharge rate. In practically all cases, there is no significant amount of short-lived radionuclides. The discussion further includes lessons learned, for example inadvertent discharges of radionuclides expected not to be in the plants inventory. It is demonstrated that, as for operation of nuclear power plants, the limits prescribed in the Ordinance on Radiological Protection can be met using existing air cleaning technology, Optimization of protection results in public exposures substantially below the limits. In the frame of the regulatory investigation programme a study has been conducted to assess the airborne radioactivity created during certain decommissioning activities like decontamination, segmentation and handling of contaminated or activated parts. The essential results of this study are presented, which are supposed to support planning for decommissioning, for LWRs, Co-60 and Cs-137 are expected to be the dominant radionuclides in airborne discharges. 18 refs., 2 figs., 1 tab.

  9. Five-year record of atmospheric precipitation chemistry in urban Beijing, China

    Science.gov (United States)

    Yang, F.; Tan, J.; Shi, Z. B.; Cai, Y.; He, K.; Ma, Y.; Duan, F.; Okuda, T.; Tanaka, S.; Chen, G.

    2012-02-01

    To investigate the chemical characteristics of precipitation in the polluted urban atmosphere in Beijing and possible mechanisms influencing their variations, a total of 131 event-based precipitation samples were collected from March 2001 to August 2005. The concentrations of major ions in the samples were analyzed by using ion chromatography. Intermediate pH (6.1-7.3) was recorded in approximately two-thirds of the precipitation samples and acidic pH (4.2-5.6) in only 16% of the samples. However, the precipitation acidity was on the growth track and the process was likely being accelerated. SO42-, NO3-, NH4+, and Ca2+ were the most abundant ions in the precipitations, with their single volume-weighted mean (VWM) concentration all above 100 μeq l-1. The two major anions and two major cations accounted for more than 80% of total anionic and cationic mass, respectively. The VWM SO42- concentration decreased by 13% compared to that during 1995-1998, much less than the 58% reduction in the annual average SO2 concentration from 1998 to 2005 in Beijing. What seems more counterintuitive is that the VWM NO3- concentration nearly doubled over the period although the annual average NO2 concentration decreased by 5% from 1998 to 2005. These results imply that the conversion of gaseous precursors to acid compounds and/or the regional transport were reinforced over the decade. The average ratio of neutralizing potential to acidifying potential (i.e. NP/AP) was as high as 1.2 but experienced an evident decline trend. This was mainly ascribed to reduced input of NH4+ and Ca2+ and increased input of NO3-. Furthermore, the equivalent mass ratio of NO3- to non-sea-salt SO42- presented an increasing trend over the study period, suggesting that the contribution of NO3- to the precipitation acidity increased in recent years. However, the mean ratio was only 0.37 ± 0.11 in the study period, which is significantly lower than those reported in some metropolitan areas in developed

  10. New insights into prebiotic chemistry from Stanley Miller's spark discharge experiments.

    Science.gov (United States)

    Bada, Jeffrey L

    2013-03-07

    1953 was a banner year for biological chemistry: The double helix structure of DNA was published by Watson and Crick, Sanger's group announced the first amino acid sequence of a protein (insulin) and the synthesis of key biomolecules using simulated primordial Earth conditions has demonstrated by Miller. Miller's studies in particular transformed the study of the origin of life into a respectable field of inquiry and established the basis of prebiotic chemistry, a field of research that investigates how the components of life as we know it can be formed in a variety of cosmogeochemical environments. In this review, I cover the continued advances in prebiotic syntheses that Miller's pioneering work has inspired. The main focus is on recent state-of-the-art analyses carried out on archived samples of Miller's original experiments, some of which had never before been analyzed, discovered in his laboratory material just before his death in May 2007. One experiment utilized a reducing gas mixture and an apparatus configuration (referred to here as the "volcanic" apparatus) that could represent a water-rich volcanic eruption accompanied by lightning. Another included H(2)S as a component of the reducing gas mixture. Compared to the limited number of amino acids Miller identified, these new analyses have found that over 40 different amino acids and amines were synthesized, demonstrating the potential robust formation of important biologic compounds under possible cosmogeochemical conditions. These experiments are suggested to simulate long-lived volcanic island arc systems, an environment that could have provided a stable environment for some of the processes thought to be involved in chemical evolution and the origin of life. Some of the alternatives to the Miller-based prebiotic synthesis and the "primordial soup" paradigm are evaluated in the context of their relevance under plausible planetary conditions.

  11. Land cover change impacts on atmospheric chemistry: simulating projected large-scale tree mortality in the United States

    Science.gov (United States)

    Geddes, Jeffrey A.; Heald, Colette L.; Silva, Sam J.; Martin, Randall V.

    2016-02-01

    Land use and land cover changes impact climate and air quality by altering the exchange of trace gases between the Earth's surface and atmosphere. Large-scale tree mortality that is projected to occur across the United States as a result of insect and disease may therefore have unexplored consequences for tropospheric chemistry. We develop a land use module for the GEOS-Chem global chemical transport model to facilitate simulations involving changes to the land surface, and to improve consistency across land-atmosphere exchange processes. The model is used to test the impact of projected national-scale tree mortality risk through 2027 estimated by the 2012 USDA Forest Service National Insect and Disease Risk Assessment. Changes in biogenic emissions alone decrease monthly mean O3 by up to 0.4 ppb, but reductions in deposition velocity compensate or exceed the effects of emissions yielding a net increase in O3 of more than 1 ppb in some areas. The O3 response to the projected change in emissions is affected by the ratio of baseline NOx : VOC concentrations, suggesting that in addition to the degree of land cover change, tree mortality impacts depend on whether a region is NOx-limited or NOx-saturated. Consequently, air quality (as diagnosed by the number of days that 8 h average O3 exceeds 70 ppb) improves in polluted environments where changes in emissions are more important than changes to dry deposition, but worsens in clean environments where changes to dry deposition are the more important term. The influence of changes in dry deposition demonstrated here underscores the need to evaluate treatments of this physical process in models. Biogenic secondary organic aerosol loadings are significantly affected across the US, decreasing by 5-10 % across many regions, and by more than 25 % locally. Tree mortality could therefore impact background aerosol loadings by between 0.5 and 2 µg m-3. Changes to reactive nitrogen oxide abundance and partitioning are also locally

  12. The Mars Environmental Compatibility Assessment (MECA) Wet Chemistry Experiment on the Mars 2001 Lander

    Science.gov (United States)

    Grannan, S. M.; Meloy, T. P.; Hecht, H.; Anderson, M. S.; Buehler, M.; Frant, M.; Kounaves, S. P.; Manatt, K. S.; Pike, W. T.; Schubert, W.

    1999-01-01

    The Mars Environmental Compatibility Assessment (MECA) is an instrument suite that will fly on the Mars Surveyor 2001 Lander Spacecraft. MECA is sponsored by the Human Exploration and Development of Space (HEDS) program and will evaluate potential hazards that the dust and soil of Mars might present to astronauts and their equipment on a future human mission to Mars. Four elements constitute the integrated MECA payload: a microscopy station, patch plates, an electrometer, and the wet chemistry experiment (WCE). The WCE is the first application of electrochemical sensors to study soil chemistry on another planetary body, in addition to being the first measurement of soil/water solution properties on Mars. The chemical composition and properties of the watersoluble materials present in the Martian soil are of considerable interest to the planetary science community because characteristic salts are formed by the water-based weathering of rocks, the action of volcanic gases, and biological activity. Thus the characterization of water-soluble soil materials on Mars can provide information on the geochemical history of the planet surface. Additional information is contained in the original extended abstract.

  13. Atmospheric methane and carbon dioxide from SCIAMACHY satellite data: initial comparison with chemistry and transport models

    Directory of Open Access Journals (Sweden)

    M. Buchwitz

    2005-01-01

    Full Text Available The remote sensing of the atmospheric greenhouse gases methane (CH4 and carbon dioxide (CO2 in the troposphere from instrumentation aboard satellites is a new area of research. In this manuscript, results obtained from observations of the up-welling radiation in the near-infrared by SCIAMACHY on board ENVISAT are presented. Vertical columns of CH4, CO2 and oxygen (O2 have been retrieved and the (air or O2-normalised CH4 and CO2 column amounts, the dry air column averaged mixing ratios XCH4 and XCO2 derived. In this manuscript the first results, obtained by using the version 0.4 of the Weighting Function Modified (WFM DOAS retrieval algorithm applied to SCIAMACHY data, are described and compared with global models. For the set of individual cloud free measurements over land the standard deviation of the difference with respect to the models is in the range ~100–200 ppbv (5–10% for XCH4 and ~14–32 ppmv (4–9% for XCO2. The inter-hemispheric difference of the methane mixing ratio, as determined from single day data, is in the range 30–110 ppbv and in reasonable agreement with the corresponding model data (48–71 ppbv. The weak inter-hemispheric difference of the CO2 mixing ratio can also be detected with single day data. The spatiotemporal pattern of the measured and the modelled XCO2 are in reasonable agreement. However, the amplitude of the difference between the maximum and the minimum for SCIAMACHY XCO2 is about ±20 ppmv which is about a factor of four larger than the variability of the model data which is about ±5 ppmv. More studies are needed to explain the observed differences. The XCO2 model field shows low CO2 concentrations beginning of January 2003 over a spatially extended CO2 sink region located in southern tropical/sub-tropical Africa. The SCIAMACHY data also show low CO2 mixing ratios over this area. According to the model the sink region becomes a source region about six months later and exhibits higher mixing ratios

  14. Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

    Science.gov (United States)

    Yin, Jun; Haggerty, Roy; Stoliker, Deborah L.; Kent, Douglas B.; Istok, Jonathan D.; Greskowiak, Janek; Zachara, John M.

    2011-01-01

    In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry.

  15. Normal and Inverse Ferrite Spinels: A Set of Solid State Chemistry Related Experiments.

    Science.gov (United States)

    Chaumont, C.; Burgard, M.

    1979-01-01

    Presents one of the themes of a French chemistry college laboratory course, which concerns the field of solid state chemistry and is focused on the study of the cation distribution in the case of certain spinel ferrites. (HM)

  16. Reducing cognitive load in the chemistry laboratory by using technology-driven guided inquiry experiments

    Science.gov (United States)

    Hubacz, Frank, Jr.

    The chemistry laboratory is an integral component of the learning experience for students enrolled in college-level general chemistry courses. Science education research has shown that guided inquiry investigations provide students with an optimum learning environment within the laboratory. These investigations reflect the basic tenets of constructivism by engaging students in a learning environment that allows them to experience what they learn and to then construct, in their own minds, a meaningful understanding of the ideas and concepts investigated. However, educational research also indicates that the physical plant of the laboratory environment combined with the procedural requirements of the investigation itself often produces a great demand upon a student's working memory. This demand, which is often superfluous to the chemical concept under investigation, creates a sensory overload or extraneous cognitive load within the working memory and becomes a significant obstacle to student learning. Extraneous cognitive load inhibits necessary schema formation within the learner's working memory thereby impeding the transfer of ideas to the learner's long-term memory. Cognitive Load Theory suggests that instructional material developed to reduce extraneous cognitive load leads to an improved learning environment for the student which better allows for schema formation. This study first compared the cognitive load demand, as measured by mental effort, experienced by 33 participants enrolled in a first-year general chemistry course in which the treatment group, using technology based investigations, and the non-treatment group, using traditional labware, investigated identical chemical concepts on five different exercises. Mental effort was measured via a mental effort survey, a statistical comparison of individual survey results to a procedural step count, and an analysis of fourteen post-treatment interviews. Next, a statistical analysis of achievement was

  17. Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation historical and projected changes

    OpenAIRE

    J.-F. Lamarque; Dentener, F.; Mcconnell, J.; C.-U. Ro; M. Shaw; Vet, R.; D. Bergmann; Cameron-Smith, P.; Doherty, R.; Faluvegi, G.; Ghan, S. J.; B. Josse; Lee, Y. H.; I. A. MacKenzie; Plummer, D.

    2013-01-01

    We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice-core measurements. We use a new dataset of wet deposition for 2000–2002 based on critical assessment of the quality of existing regional network data. We show that for present-day (year 2000 ACCMIP time-slice...

  18. Multi-model mean nitrogen and sulfur deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): evaluation of historical and projected future changes

    OpenAIRE

    Lamarque, J.-F.; Dentener, F.; Mcconnell, J.; Ro, C.-U.; M. Shaw; Vet, R.; D. Bergmann; Cameron-Smith, P.; Dalsoren, S.; Doherty, R.; Faluvegi, G.; Ghan, S. J.; B. Josse; Lee, Y. H.; I. A. MacKenzie

    2013-01-01

    We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice core measurements. We use a new dataset of wet deposition for 2000–2002 based on critical assessment of the quality of existing regional network data. We show that for present day (year 2000...

  19. Implementation of the chemistry module MECCA (v2.5 in the modal aerosol version of the Community Atmosphere Model component (v3.6.33 of the Community Earth System Model

    Directory of Open Access Journals (Sweden)

    M. S. Long

    2012-06-01

    Full Text Available A coupled atmospheric chemistry and climate system model was developed using the modal aerosol version of the National Center for Atmospheric Research Community Atmosphere Model (modal-CAM and the Max Planck Institute for Chemistry's Module Efficiently Calculating the Chemistry of the Atmosphere (MECCA to provide enhanced resolution of multiphase processes, particularly those involving inorganic halogens, and associated impacts on atmospheric composition and climate. Three Rosenbrock solvers (Ros-2, Ros-3, RODAS-3 were tested in conjunction with the basic load balancing options available to modal CAM (1 to establish an optimal configuration of the implicitly-solved multiphase chemistry module that maximizes both computational speed and repeatability of Ros-2 and RODAS-3 results versus Ros-3, and (2 to identify potential implementation strategies for future versions of this and similar coupled systems. RODAS-3 was faster than Ros-2 and Ros-3 with good reproduction of Ros-3 results, while Ros-2 was both slower and substantially less reproducible relative to Ros-3 results. Modal-CAM with MECCA chemistry was a factor of 15 slower than modal-CAM using standard chemistry. MECCA chemistry integration times demonstrated a systematic frequency distribution for all three solvers, and revealed that the change in run-time performance was due to a change in the frequency distribution chemical integration times; the peak frequency was similar for all solvers. This suggests that efficient chemistry-focused load-balancing schemes can be developed that rely on the parameters of this frequency distribution.

  20. Introductory Chemistry: A Molar Relaxivity Experiment in the High School Classroom.

    Science.gov (United States)

    Dawsey, Anna C; Hathaway, Kathryn L; Kim, Susie; Williams, Travis J

    2013-07-09

    Dotarem and Magnevist, two clinically available magnetic resonance imaging (MRI) contrast agents, were assessed in a high school science classroom with respect to which is the better contrast agent. Magnevist, the more efficacious contrast agent, has negative side effects because its gadolinium center can escape from its ligand. However, Dotarem, though a less efficacious contrast agent, is a safer drug choice. After the experiment, students are confronted with the FDA warning on Magnevist, which enabled a discussion of drug efficacy versus safety. We describe a laboratory experiment in which NMR spin lattice relaxation rate measurements are used to quantify the relaxivities of the active ingredients of Dotarem and Magnevist. The spin lattice relaxation rate gives the average amount of time it takes the excited nucleus to relax back to the original state. Students learn by constructing molar relaxivity curves based on inversion recovery data sets that Magnevist is more relaxive than Dotarem. This experiment is suitable for any analytical chemistry laboratory with access to NMR.

  1. New molecular species of potential interest to atmospheric chemistry: isomers on the [H, S2, Br] potential energy surface.

    Science.gov (United States)

    de Oliveira-Filho, Antonio Gustavo S; Aoto, Yuri Alexandre; Ornellas, Fernando R

    2009-02-19

    This work reports a state-of-the-art theoretical characterization of four new sulfur-bromine species and five transition states on the [H, S(2), Br] potential energy surface. Our highest level theoretical approach employed the method coupled cluster singles and doubles with perturbative contributions of connected triples, CCSD(T), along with the series of correlation-consistent basis sets and with extrapolation to the complete basis set (CBS) limit in the optimization of the geometrical parameters and to quantify the energetic quantities. The structural and vibrational frequencies here reported are unique and represent the most accurate investigation to date of these species. The global minimum corresponds to a skewed structure HSSBr with a disulfide bond; this is followed by a pyramidal-like structure, SSHBr, 18.85 kcal/mol above the minimum. Much higher in energy, we found another skewed structure, HSBrS (50.29 kcal/mol), with one S-Br dative-type bond, and another pyramidal-like one, HBrSS (109.80 kcal/mol), with two S-Br dative-type bonds. The interconversion of HSSBr into SSHBr can occur via a transfer of either the hydrogen or the bromine atom but involves a very high barrier of about 43 kcal/mol. These molecules are potentially a new route of coupling the sulfur and bromine chemistry in the atmosphere, and conditions of high concentration of H(2)S like in volcanic eruptions might contribute to their formation. We note that HSSBr can act as a reservoir molecule for the reaction between the radicals HSS and Br. Also, an assessment of the methods DFT/B3LYP/CBS and MP2/CBS relative to CCSD(T)/CBS provides insights on the expected performance of these methods on the characterization of polysulfides and also of more complex systems containing disulfide bridges.

  2. The Chemistry Experiment Skills Competition to the Innovation and Chemistry Experiment Skills of Undergraduates%实验技能大赛对大学生化学实验技能培养及创新

    Institute of Scientific and Technical Information of China (English)

    赵祥华; 周莉; 王莉敏

    2016-01-01

    围绕实验技能大赛对大学生化学实验技能培养和创新展开简单论述,对当今大学生实验技能薄弱现状作出了具体分析,从化学实验技能大赛的形式以及竞赛在实验技能培养和创新中的作用两个方面作出了全面阐述。实践证明:开展实验技能大赛有利于促进学生化学实验技能的提高、激发学生的学习兴趣并能培养学生的创新能力。%Chemistry experiment skills competition for the innovation and chemistry experiment skills of undergraduates was discussed. A concrete analysis was made on the weak present situation of college students experiment skill, and a comprehensive elaboration about the form of the chemical experiment competition and its function in the training of innovation and chemistry experiment skills of undergraduates. The practice proved that it was beneficial to university students for the improvement of their chemical experiment skills, stimulation of their interests and cultivation of their innovation ability by carrying out experiment skill competition.

  3. Detecting Complex Organic Compounds Using the SAM Wet Chemistry Experiment on Mars

    Science.gov (United States)

    Freissinet, C.; Buch, A.; Glavin, D. P.; Brault, A.; Eigenbrode, J. L.; Kashyap, S.; Martin, M. G.; Miller, K.; Mahaffy, P. R.; Team, M.

    2013-12-01

    The search for organic molecules on Mars can provide important first clues of abiotic chemistry and/or extinct or extant biota on the planet. Gas Chromatography Mass Spectrometry (GC-MS) is currently the most relevant space-compatible analytical tool for the detection of organic compounds. Nevertheless, GC separation is intrinsically restricted to volatile molecules, and many molecules of astrobiological interest are chromatographically refractory or polar. To analyze these organics such as amino acids, nucleobases and carboxylic acids in the Martian regolith, an additional derivatization step is required to transform them into volatile derivatives that are amenable to GC analysis. As part of the Sample Analysis at Mars (SAM) experiment onboard Mars Science Laboratory (MSL) Curiosity rover, a single-step protocol of extraction and chemical derivatization with the silylating reagent N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA) has been developed to reach a wide range of astrobiology-relevant refractory organic molecules (Mahaffy et al. 2012; Stalport et al. 2012). Seven cups in the SAM instrument are devoted to MTBSTFA derivatization. However, this chemical reaction adds a protective silyl group in place of each labile hydrogen, which makes the molecule non-identifiable in common mass spectra libraries. Therefore, we have created an extended library of mass spectra of MTBSTFA derivatized compounds of interest, considering their potential occurrence in Mars soils. We then looked specifically for MTBSTFA derivatized compounds using the existing and the newly created library, in various Mars analog soils. To enable a more accurate interpretation of the in situ derivatization GC-MS results that will be obtained by SAM, the lab experiments were performed as close as possible to the SAM flight instrument experimental conditions. Our first derivatization experiments display promising results, the laboratory system permitting an extraction and detection

  4. Water physics and chemistry data from bottle casts from the GERDA as part of the Rosenstiel School of Marine and Atmospheric Science (RSMAS) project from 20 July 1955 to 29 May 1957 (NODC Accession 7000057)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water physics and chemistry data were collected from bottle casts from the GERDA from 20 July 1955 to 29 May 1957. Data were collected as part of the Rosenstiel...

  5. Atmospheric Chemistry of Hydrocarbon Fuels. Volume I. Experiments, Results, and Discussion.

    Science.gov (United States)

    1981-11-01

    STATEMENT (ol the abstract entered In Block 20, Il different from Report) 18. SUPPLEMENTARY NOTES Availability of this report is specified on verso of...alkane 0.03 CIH30 n-terradecane 0.05 C 15H32 n-pentadecane 0.08 aMore than one compound. 21 TABLE 7. ORGANIC COMPOUNDS IDENTIFIED BY GC-MS IN UNLEADED

  6. CTD and Water Chemistry data of the Eastern Pacific Redox Experiment of May - June 2000 (NODC Accession 0000833)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Eastern Pacific Redox Experiment (EPREX) took place 24 May to 28 June 2000 on the R/V Roger Revelle. The first station was at the Hawaii Ocean Time Series...

  7. Preparation and Reactions of the 1,1-Dithiolato Complexes of Ni(II). An Undergraduate Coordination Chemistry Experiment.

    Science.gov (United States)

    Ballester, L.; Perpinan, M. F.

    1988-01-01

    Described is an undergraduate coordination chemistry experiment that enables students to relate concepts developed in class about the stereochemistry and coordination numbers to the interpretation of the electronic and infrared spectra and their magnetic behavior. Indicates that thermal decomposition and x-ray diffraction studies can also be…

  8. An Advanced Analytical Chemistry Experiment Using Gas Chromatography-Mass Spectrometry, MATLAB, and Chemometrics to Predict Biodiesel Blend Percent Composition

    Science.gov (United States)

    Pierce, Karisa M.; Schale, Stephen P.; Le, Trang M.; Larson, Joel C.

    2011-01-01

    We present a laboratory experiment for an advanced analytical chemistry course where we first focus on the chemometric technique partial least-squares (PLS) analysis applied to one-dimensional (1D) total-ion-current gas chromatography-mass spectrometry (GC-TIC) separations of biodiesel blends. Then, we focus on n-way PLS (n-PLS) applied to…

  9. Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

    Science.gov (United States)

    Najarian, Maya L.; Chinni, Rosemarie C.

    2013-01-01

    This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

  10. Synthesis of Hollow Gold-Silver Alloyed Nanoparticles: A "Galvanic Replacement" Experiment for Chemistry and Engineering Students

    Science.gov (United States)

    Jenkins, Samir V.; Gohman, Taylor D.; Miller, Emily K.; Chen, Jingyi

    2015-01-01

    The rapid academic and industrial development of nanotechnology has led to its implementation in laboratory teaching for undergraduate-level chemistry and engineering students. This laboratory experiment introduces the galvanic replacement reaction for synthesis of hollow metal nanoparticles and investigates the optical properties of these…

  11. Improving Critical Thinking "via" Authenticity: The CASPiE Research Experience in a Military Academy Chemistry Course

    Science.gov (United States)

    Chase, A. M.; Clancy, H. A.; Lachance, R. P.; Mathison, B. M.; Chiu, M. M.; Weaver, G. C.

    2017-01-01

    Course-based undergraduate research experiences (CUREs) can introduce many students to authentic research activities in a cost-effective manner. Past studies have shown that students who participated in CUREs report greater interest in chemistry, better data collection and analysis skills, and enhanced scientific reasoning compared to traditional…

  12. Using an Advanced Computational Laboratory Experiment to Extend and Deepen Physical Chemistry Students' Understanding of Atomic Structure

    Science.gov (United States)

    Hoffman, Gary G.

    2015-01-01

    A computational laboratory experiment is described, which involves the advanced study of an atomic system. The students use concepts and techniques typically covered in a physical chemistry course but extend those concepts and techniques to more complex situations. The students get a chance to explore the study of atomic states and perform…

  13. iPads in the Science Laboratory: Experience in Designing and Implementing a Paperless Chemistry Laboratory Course

    Science.gov (United States)

    Hesser, Tiffany L.; Schwartz, Pauline M.

    2013-01-01

    In the fall of 2012, 20 General Chemistry Honors students at the University of New Haven were issued the new iPad 3 to incorporate these devices both in the classroom and the laboratory. This paper will focus on the integration of the iPad into the laboratory curriculum while creating a paperless experience, an environment where no paper would…

  14. Drug Synthesis and Analysis on a Dime: A Capstone Medicinal Chemistry Experience for the Undergraduate Biochemistry Laboratory

    Science.gov (United States)

    Streu, Craig N.; Reif, Randall D.; Neiles, Kelly Y.; Schech, Amanda J.; Mertz, Pamela S.

    2016-01-01

    Integrative, research-based experiences have shown tremendous potential as effective pedagogical approaches. Pharmaceutical development is an exciting field that draws heavily on organic chemistry and biochemistry techniques. A capstone drug synthesis/analysis laboratory is described where biochemistry students synthesize azo-stilbenoid compounds…

  15. Binary Solid-Liquid Phase Diagram of Phenol and t-Butanol: An Undergraduate Physical Chemistry Experiment

    Science.gov (United States)

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen

    2014-01-01

    The determination of the solid-liquid phase diagram of a binary system is always used as an experiment in the undergraduate physical chemistry laboratory courses. However, most phase diagrams investigated in the lab are simple eutectic ones, despite the fact that complex binary solid-liquid phase diagrams are more common. In this article, the…

  16. [60]Fullerene Displacement from (Dihapto-Buckminster-Fullerene) Pentacarbonyl Tungsten(0): An Experiment for the Inorganic Chemistry Laboratory, Part II

    Science.gov (United States)

    Cortes-Figueroa, Jose E.; Moore-Russo, Deborah A.

    2006-01-01

    The kinetics experiments on the ligand-C[subscript 60] exchange reactions on (dihapto-[60]fullerene) pentacarbonyl tungsten(0), ([eta][superscript 2]-C[subscript 60])W(CO)[subscript 5], form an educational activity for the inorganic chemistry laboratory that promotes graphical thinking as well as the understanding of kinetics, mechanisms, and the…

  17. Removal of Aromatic Pollutant Surrogate from Water by Recyclable Magnetite-Activated Carbon Nanocomposite: An Experiment for General Chemistry

    Science.gov (United States)

    Furlan, Ping Y.; Melcer, Michael E.

    2014-01-01

    A general chemistry laboratory experiment using readily available chemicals is described to introduce college students to an exciting class of nanocomposite materials. In a one-step room temperature synthetic process, magnetite nanoparticles are embedded onto activated carbon matrix. The resultant nanocomposite has been shown to combine the…

  18. Extraction and [superscript 1]H NMR Analysis of Fats from Convenience Foods: A Laboratory Experiment for Organic Chemistry

    Science.gov (United States)

    Hartel, Aaron M.; Moore, Amy C.

    2014-01-01

    The extraction and analysis of fats from convenience foods (crackers, cookies, chips, candies) has been developed as an experiment for a second-year undergraduate organic chemistry laboratory course. Students gravimetrically determine the fat content per serving and then perform a [superscript 1]H NMR analysis of the recovered fat to determine the…

  19. The Quantitative Resolution of a Mixture of Group II Metal Ions by Thermometric Titration with EDTA. An Analytical Chemistry Experiment.

    Science.gov (United States)

    Smith, Robert L.; Popham, Ronald E.

    1983-01-01

    Presents an experiment in thermometric titration used in an analytic chemistry-chemical instrumentation course, consisting of two titrations, one a mixture of calcium and magnesium, the other of calcium, magnesium, and barium ions. Provides equipment and solutions list/specifications, graphs, and discussion of results. (JM)

  20. Sol-Gel Synthesis of a Biotemplated Inorganic Photocatalyst: A Simple Experiment for Introducing Undergraduate Students to Materials Chemistry

    Science.gov (United States)

    Boffa, Vittorio; Yue, Yuanzheng; He, Wen

    2012-01-01

    As part of a laboratory course, undergraduate students were asked to use baker's yeast cells as biotemplate in preparing TiO[subscript 2] powders and to test the photocatalytic activity of the resulting materials. This laboratory experience, selected because of the important environmental implications of soft chemistry and photocatalysis, provides…