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Sample records for acid hno3 ozone

  1. Antarctic ozone - Meteoric control of HNO3

    NASA Technical Reports Server (NTRS)

    Prather, Michael J.; Rodriguez, Jose M.

    1988-01-01

    Atmospheric circulation leads to an accumulation of debris from meteors in the Antarctic stratosphere at the beginning of austral spring. The major component of meteoric material is alkaline, comprised predominantly of the oxides of magnesium and iron. These metals may neutralize the natural acidity of stratospheric aerosols, remove nitric acid from the gas phase, and bond it as metal nitrates in the aerosol phase. Removal of nitric acid vapor has been previously shown to be a critical link in the photochemical depletion of ozone in the Antarctic spring, by allowing for increased catalytic loss from chlorine and bromine.

  2. Participation of HNO3 CIMS Instrument in the Sage III Ozone Loss and Validation Experiment (SOLVE)

    NASA Technical Reports Server (NTRS)

    Eisele, F. L.

    2001-01-01

    This project was part of a larger SOLVE project led by Paul Wennberg at California Institute of Technology. The work completed on this project included participating in the installation and preflight testing of a new chemical ionization mass spectrometer for measuring gas and particle phase nitric acid on the ER-2. The investigators subsequently participated in SOLVE where additional instrument improvements were made and a substantial data set was generated. The two Georgia Tech investigators that participated in this work (Fred Eisele and Dave Tanner) had previously been responsible for much of the design and construction of the ion source and mass spectrometer which would be used to measure HNO3 in SOLVE, with Caltech focusing on inlets, calibration, gas supplies/pumping computer control, and overall integration. Thus, a similar focus remained during the SOLVE measurements though all investigators worked on most if not all aspects of the instrument at some point in the mission. Some of the more interesting results from the study included measurements of nitric acid on what are thought to be 5-20 microns diameter individual particles which could supply a local mechanism for HNO3 removal, Nitric acid measurements on SOLVE were completed as a collaborative effort with a great deal of overlap between this project and the larger parent project led by Paul Wennberg. As such, the instrumentation used, its operation, and the resulting measurements are far more fully discussed in the attached report (appendix A) which describes the joint SOLVE nitric acid measurement effort.

  3. Passive sampler for measurements of atmospheric nitric acid vapor (HNO3) concentrations.

    PubMed

    Bytnerowicz, A; Padgett, P E; Arbaugh, M J; Parker, D R; Jones, D P

    2001-12-05

    Nitric acid (HNO3) vapor is an important nitrogenous air pollutant responsible for increasing saturation of forests with nitrogen and direct injury to plants. The USDA Forest Service and University of California researchers have developed a simple and inexpensive passive sampler for monitoring air concentrations of HNO3. Nitric acid is selectively absorbed on 47-mm Nylasorb nylon filters with no interference from particulate NO3-. Concentrations determined with the passive samplers closely corresponded with those measured with the co-located honeycomb annular denuder systems. The PVC protective caps of standardized dimensions protect nylon filters from rain and wind and allow for reliable measurements of ambient HNO3 concentrations. The described samplers have been successfully used in Sequoia National Park, the San Bernardino Mountains, and on Mammoth Mountain in California.

  4. The effect of nitric acid (HNO3) on growth, spectral, thermal and dielectric properties of triglycine sulphate (TGS) crystal.

    PubMed

    Parimaladevi, R; Sekar, C; Krishnakumar, V

    2010-02-01

    The effect of nitric acid (HNO(3)) addition on the growth of triglycine sulphate (TGS) crystal has been studied from the aqueous solution for various concentrations of nitric acid. Significant changes in the crystal size and morphology have been observed in all the grown samples. Single crystal and powder X-ray diffraction analyses confirm the structure and cell parameter values of pure and HNO(3) doped TGS crystals. FT-Raman and FTIR spectra confirm the characteristics absorption bands of pure and HNO(3) doped TGS crystals. The composition of TGS crystals have been confirmed by CHNS analysis. Physical properties such as thermal, dielectric and mechanical studies have been performed for the pure and HNO(3) doped TGS crystals. The dielectric constants of the crystals have been studied as a function of frequency. The results suggest that the HNO(3) is doped into TGS crystal and that the doping increases its dielectric constant.

  5. Dissociation of strong acid revisited: X-ray photoelectron spectroscopy and molecular dynamics simulations of HNO3 in water

    SciTech Connect

    Lewis, Tanza; Winter, Berndt; Stern, Abraham C.; Baer, Marcel D.; Mundy, Christopher J.; Tobias, Douglas J.; Hemminger, J. C.

    2011-08-04

    Molecular-level insight into the dissociation of nitric acid in water is obtained from photoelectron X-ray spectroscopy and first-principles molecular dynamics (MD) simulations. Our combined studies reveal surprisingly abrupt changes in solvation configurations of undissociated nitric acid at approximately 4 M concentration. Experimentally, this is inferred from N1s binding energy shifts of HNO3(aq) as a function of concentration, and is associated with variations in the local electronic structure of the nitrogen atom. It also shows up as a discontinuity in the degree of dissociation as a function of concentration, determined here from the N1s photoelectron signal intensity, which can be separately quantified for undissociated HNO3(aq) and dissociated NO3-(aq). Intermolecular interactions within the nitric acid solution are discussed on the basis of MD simulations, which reveal that molecular HNO3 interacts remarkably weakly with solvating water molecules at low concentration; around 4 M there is a turnover to a more structured solvation shell, accompanied by an increase in hydrogen bonding between HNO3 and water. We suggest that the driving force behind the more structured solvent configuration of HNO3 is the overlap of nitric acid solvent shells that sets in around 4 M concentration. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  6. Dissociation of strong acid revisited: X-ray photoelectron spectroscopy and molecular dynamics simulations of HNO3 in water.

    PubMed

    Lewis, Tanza; Winter, Bernd; Stern, Abraham C; Baer, Marcel D; Mundy, Christopher J; Tobias, Douglas J; Hemminger, John C

    2011-08-04

    Molecular-level insight into the dissociation of nitric acid in water is obtained from X-ray photoelectron spectroscopy and first-principles molecular dynamics (MD) simulations. Our combined studies reveal surprisingly abrupt changes in solvation configurations of undissociated nitric acid at approximately 4 M concentration. Experimentally, this is inferred from shifts of the N1s binding energy of HNO(3)(aq) as a function of concentration and is associated with variations in the local electronic structure of the nitrogen atom. It also shows up as a discontinuity in the degree of dissociation as a function of concentration, determined here from the N1s photoelectron signal intensity, which can be separately quantified for undissociated HNO(3)(aq) and dissociated NO(3)(-)(aq). Intermolecular interactions within the nitric acid solution are discussed on the basis of MD simulations, which reveal that molecular HNO(3) interacts remarkably weakly with solvating water molecules at low concentration; around 4 M there is a turnover to a more structured solvation shell, accompanied by an increase in hydrogen bonding between HNO(3) and water. We suggest that the driving force behind the more structured solvent configuration of HNO(3) is the overlap of nitric acid solvent shells that sets in around 4 M concentration.

  7. TES/Aura L3 Nitric Acid (HNO3) Daily V3 (TL3HNOD)

    Atmospheric Science Data Center

    2015-10-30

    ... Access: OPeNDAP Parameters:  HNO3 Volume Mixing Ratio Precision Vertical Resolution Order Data:  ... Google Earth Visualizations Giovanni Visualization - Level3 Daily Related Data:  Level 3 ...

  8. TES/Aura L3 Nitric Acid (HNO3) Daily V4 (TL3HNOD)

    Atmospheric Science Data Center

    2015-10-30

    ... Access: OPeNDAP Parameters:  HNO3 Volume Mixing Ratio Precision Vertical Resolution Order Data:  ... Google Earth Visualizations Giovanni Visualization - Level3 Daily Related Data:  Level 3 ...

  9. Mass accommodation coefficient measurements for HNO3, HCl and N2O5 on water, ice and aqueous sulfuric acid droplet surfaces

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas; Zahniser, Mark; Kolb, Charles; Watson, Lyn; Vandoren, Jane; Jayne, John; Davidovits, Paul

    1988-01-01

    Preliminary results are reported of the direct measurement of accommodation coefficients for HNO3, N2O5 and HCl on water drops, aqueous sulfuric acid drops and ice particles. The heterogeneous chemistry of these species together with ClONO2 has been implicated in the ozone depletion observed in the Antarctic stratosphere during the spring in the last eight years. The most plausible chemical mechanism involves the removal of nitrogen oxide species via condensation on ice particles in polar stratospheric clouds resulting in a increase in the active chlorine species responsible for the ozone depletion. The observation of low NO2 and high ClO densities in the Antarctic stratosphere last summer appear to be consistent with such a mechanism.

  10. Chemical Corrosion of Liquid-Phase Sintered SiC in Acidic/Alkaline Solutions Part 1. Corrosion in HNO3 Solution

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Zhang, Ming; He, Xinnong; Tang, Wenming

    2016-03-01

    The corrosion behavior of the liquid-phase sintered SiC (LPS-SiC) was studied by dipping in 3.53 mol/L HNO3 aqueous solution at room temperature and 70 °C, respectively. The weight loss, strength reduction and morphology evolution of the SiC specimens during corroding were revealed and also the chemical corrosion process and mechanism of the SiC specimens in the acidic solution were clarified. The results show that the corrosion of the LPS-SiC specimens in the HNO3 solution is selective. The SiC particles are almost free from corrosion, but the secondary phases of BaAl2Si2O8 (BAS) and Y2Si2O7 are corroded via an acid-alkali neutralization reaction. BAS has a higher corrosion rate than Y2Si2O7, resulting in the formation of the bamboo-leaf-like corrosion pits. As the SiC specimens etched in the HNO3 solution at room temperature for 75 days, about 80 μm thickness corrosion layer forms. The weight loss and bending strength reduction of the etched SiC specimens are 2.6 mg/cm2 and 52%, respectively. The corrosion of the SiC specimens is accelerated in the 70 °C HNO3 solution with a rate about five times bigger than that in the same corrosion medium at room temperature.

  11. Thermochemical Kinetics of H2O and HNO3 on crystalline Nitric Acid Hydrates (alpha-, beta-NAT, NAD) in the range 175-200 K

    NASA Astrophysics Data System (ADS)

    Rossi, Michel J.; Iannarelli, Riccardo

    2015-04-01

    The growth of NAT (Nitric Acid Trihydrate, HNO3x3H2O) and NAD (Nitric Acid Dihydrate, HNO3x2H2O) on an ice substrate, the evaporative lifetime of NAT and NAD as well as the interconversion of alpha- and beta-NAT competing with evaporation and growth under UT/LS conditions depends on the interfacial kinetics of H2O and HNO3 vapor on the condensed phase. Despite the existence of some literature results we have embarked on a systematic investigation of the kinetics using a multidiagnostic experimental approach enabled by the simultaneous observation of both the gas (residual gas mass spectrometry) as well as the condensed phase (FTIR absorption in transmission). We report on thermochemically consistent mass accommodation coefficients alpha and absolute evaporation rates Rev/molecule s-1cm-3 as a function of temperature which yields the corresponding vapor pressures of both H2O and HNO3 in equilibrium with the crystalline phases, hence the term thermochemical kinetics. These results have been obtained using a stirred flow reactor (SFR) using a macroscopic pure ice film of 1 micron or so thickness as a starting substrate mimicking atmospheric ice particles and are reported in a phase diagram specifically addressing UT (Upper Troposphere)/LS (Lower Stratosphere) conditions as far as temperature and partial pressures are concerned. The experiments have been performed either at steady-state flow conditions or in transient supersaturation using a pulsed solenoid valve in order to generate gas pulses whose decay were subsequently monitored in real time. Special attention has been given to the effect of the stainless-steel vessel walls in that Langmuir adsorption isotherms for H2O and HNO3 have been used to correct for wall-adsorption of both probe gases. Typically, the accommodation coefficients of H2O and HNO3 are similar throughout the temperature range whereas the rates of evaporation Rev of H2O are significantly larger than for HNO3 thus leading to the difference in

  12. Interhemispheric differences in polar stratospheric HNO3, H2O, ClO, and O3

    NASA Technical Reports Server (NTRS)

    Santee, M. L.; Read, W. G.; Waters, J. W.; Froidevaux, L.; Manney, G. L.; Flower, D. A.; Jarnot, R. F.; Harwood, R. S.; Peckham, G. E.

    1995-01-01

    Simultaneous global measurements of nitric acid (HNO3), water (H2O), chlorine monoxide (ClO), and ozone (O3) in the stratosphere have been obtained over complete annual cycles in both hemispheres by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite. A sizeable decrease in gas-phase HNO3 was evident in the lower stratospheric vortex over Antarctica by early June 1992, followed by a significant reduction in gas-phase H2O after mid-July. By mid-August, near the time of peak ClO, abundances of gas-phase HNO3 and H2O were extremely low. The concentrations of HNO3 and H2O over Antarctica remained depressed into November, well after temperatures in the lower stratosphere had risen above the evaporation threshold for polar stratospheric clouds, implying that denitrification and dehydration had occurred. No large decreases in either gas-phase HNO3 or H2O were observed in the 1992-1993 Arctic winter vortex. Although ClO was enhanced over the Arctic as it was over the Antarctic, Arctic O3 depletion was substantially smaller than that over Antarctica. A major factor currently limiting the formation of an Arctic ozone 'hole' is the lack of denitrification in the northern polar vortex, but future cooling of the lower stratosphere could lead to more intense denitrification and consequently larger losses of Arctic ozone.

  13. The ν_3 and ν_4 Bands of Nitric Acid (HNO_3) at 7.6 μm for Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Perrin, A.; Flaud, J. M.; Ridolfi, M.; Carlotti, M.

    2012-06-01

    Nitric acid (HNO_3) plays an important role as a reservoir molecule of the NO_x (nitrogen oxides) species in the stratosphere. The three strongest infrared bands of nitric acid are located at 11 μm (ν_5 and 2ν_9 bands), 7.6 μm (the ν_3 and ν_4 bands at 1326 and 1303 cm-1) and 5.8 μm (ν_2 band). Although two times weaker than those located at 7.6 and 5.8 μm, the 11 μm region is the only one which is used for nitric acid retrievals in the atmosphere by several satellite instruments like MIPAS (Michelson Interferometer for Passive Atmospheric Sounding on ENVISAT) or ACE-FTS (ACE Fourier transform spectrometer on SCISAT). This is because the available spectroscopic parameters for HNO_3 in the HITRAN and GEISA databases are of very good quality in this spectral region. Of the two remaining bands, the 7.6 μm one is only partly masked by water, and therefore can be used also for nitric acid retrievals in the upper stratosphere. Moreover, because of their large difference in band intensity, combining measurements at 11 μm and 7.6 μm could maximize informations on the vertical distribution of HNO_3 in the atmosphere. However at 7.6 μm the spectroscopic parameters available in the HITRAN and GEISA databases are are not so good. Indeed, these parameters originate from a list generated more than 20 years ago. The low quality of the list at 7.6 μm prevents HNO_3 retrievals and severely affects the retrievals of several species absorbing in the 7.5-7.7 μm region, like SO_2. This work is a new and more accurate investigation of the line positions and intensities for the ν_3 and ν_4 bands of nitric acid located at 1326.187 and 1303.074 cm-1). For this task, we used new infrared laboratory data combined with a new theoretical model. Examples showing substantial improvements will be given. [1] Rothman et al. J. Quant. Spectrosc. Radiat. Transf., 110, 533-572, 2009 [2] Jacquinet et al. J. Quant. Spectrosc. Radiat. Transf., 112, 2395-2445, 2011 [3] A. Perrin, O. Lado

  14. Novel polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6): Synthesis, characterization and extraction of Sr(II) in high acidity HNO3 medium.

    PubMed

    Ye, Gang; Bai, Feifei; Wei, Jichao; Wang, Jianchen; Chen, Jing

    2012-07-30

    A novel kind of polysiloxane resin functionalized with dicyclohexano-18-crown-6 (DCH18C6) was synthesized through a post-modification approach. The DCH18C6 moieties bearing amino groups were firstly prepared, followed by covalent grafting to a silica precursor P-(CH(2))(3)-Cl (Where P represents a 3-dimentional polymerized silica matrix) based on nucleophilic substitution reaction. (29)Si and (13)C solid-state NMR, FT-IR, XPS, TGA, ESEM and elemental analysis were employed to systematically characterize the structure, thermal property and surface morphology of the functionalized resin. The results indicated that the DCH18C6 ligands were successfully bonded to the polysiloxane resin with a satisfactory grafting degree (33.6wt.%). Due to the robust organosilica framework and the covalent immobilization of the ligands, the functionalized resin had excellent thermal stability and acid resistance. Batch experiments showed that the resin could effectively separate Sr(II) in high acidity mediums. The distribution coefficient (K(d)) of 43.6cm(3)/g could be achieved in 5.0mol/L HNO(3) solution. The influences of contact time and acidity of HNO(3) on the resin's extraction performance were examined. The reusability and the selectivity to Sr(II) over interference ions were investigated. The DCH18C6-functionalized resin might be potentially applied for the radiostrontium removal in the high level liquid waste (HLLW).

  15. Spectroscopic study of HNO3 dissociation on ice.

    PubMed

    Marchand, Patrick; Marcotte, Guillaume; Ayotte, Patrick

    2012-12-13

    A detailed spectroscopic study of HNO(3):H(2)O binary amorphous mixtures, and of the adsorption of HNO(3) onto ice, is reported. Using a classical optics model, the extent of intermixing and of ionic dissociation of adsorbed HNO(3), which forms a strong acid with liquid water, is determined as a function of HNO(3) coverage and temperature. Even at temperatures as low as 45 K, where intermixing is limited to at most a few molecular layers at the interface, ionic dissociation of adsorbed HNO(3) is observed to be extensive. While some amount of molecularly adsorbed HNO(3) is observed at the surface of ice at 45 K, its ionic dissociation occurs irreversibly upon heating the ice substrate to 120 K. The molecularly adsorbed state of HNO(3) is not restored upon cooling, suggesting HNO(3) is a metastable entity at the surface of ice. Therefore, despite ionic dissociation of HNO(3) being thermodynamically favored, it appears to be kinetically inhibited at the surface of amorphous solid water at temperatures below 120 K.

  16. Uptake of HNO3 on hexane and aviation kerosene soots.

    PubMed

    Talukdar, Ranajit K; Loukhovitskaya, Ekaterina E; Popovicheva, Olga B; Ravishankara, A R

    2006-08-10

    The uptake of HNO(3) on aviation kerosene (TC-1) soot was measured as a function of temperature (253-295 K) and the partial pressure of HNO(3), and the uptake of HNO(3) on hexane soot was studied at 295 K and over a limited partial pressure of HNO(3). The HNO(3) uptake was mostly reversible and did not release measurable amounts of gas-phase products such as HONO, NO(3), NO(2) or N(2)O(5). The heat of adsorption of HNO(3) on soot was dependent on the surface coverage. The isosteric heats of adsorption, Delta(0)H(isosteric), were determined as a function of coverage. Delta(0)H(isosteric) values were in the range -16 to -13 kcal mol(-1). The heats of adsorption decrease with increasing coverage. The adsorption data were fit to Freundlich and to Langmuir-Freundlich isotherms. The heterogeneity parameter values were close to 0.5, which suggested that a HNO(3) molecule can occupy two sites on the surface with or without being dissociated and that the soot surface could be nonuniform. Surface FTIR studies on the interaction of soot with HNO(3) did not reveal formation of any minor product such as organic nitrate or nitro compound on the soot surface. Using our measured coverage, we calculate that the partitioning of gas-phase nitric acid to black carbon aerosol is not a significant loss process of HNO(3) in the atmosphere.

  17. HNO3 profiles obtained during the EASOE campaign

    NASA Technical Reports Server (NTRS)

    Murcray, F. J.; Starkey, J. R.; Williams, W. J.; Matthews, W. A.; Schmidt, U.; Aimedieu, P.; Camy-Peyret, C.

    1994-01-01

    A small cryogenically cooled spectrometer system designed to obtain atmospheric emission spectra in the 7.5 micrometer to 13.0 micrometer region was flown piggyback on 9 balloon flights from ESRANGE (67.9 deg N, 21.2 deg E) during the European Arctic Stratospheric Ozone Experiment (EASOE) campaign. Initial analysis of the spectra obtained has been concentrated on obtaining HNO3 profiles for the various flights. HNO3 profiles for 17 December 1991, 9 January 1992, 22 January 1992, 5 February 1992 and 14 March 1992 are presented.

  18. First characterization and validation of FORLI-HNO3 vertical profiles retrieved from IASI/Metop

    NASA Astrophysics Data System (ADS)

    Ronsmans, Gaétane; Langerock, Bavo; Wespes, Catherine; Hannigan, James W.; Hase, Frank; Kerzenmacher, Tobias; Mahieu, Emmanuel; Schneider, Matthias; Smale, Dan; Hurtmans, Daniel; De Mazière, Martine; Clerbaux, Cathy; Coheur, Pierre-François

    2016-09-01

    Knowing the spatial and seasonal distributions of nitric acid (HNO3) around the globe is of great interest and allows us to comprehend the processes regulating stratospheric ozone, especially in the polar regions. Due to its unprecedented spatial and temporal sampling, the nadir-viewing Infrared Atmospheric Sounding Interferometer (IASI) is capable of sounding the atmosphere twice a day globally, with good spectral resolution and low noise. With the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm, we are retrieving, in near real time, columns as well as vertical profiles of several atmospheric species, among which is HNO3. We present in this paper the first characterization of the FORLI-HNO3 profile products, in terms of vertical sensitivity and error budgets. We show that the sensitivity of IASI to HNO3 is highest in the lower stratosphere (10-20 km), where the largest amounts of HNO3 are found, but that the vertical sensitivity of IASI only allows one level of information on the profile (degrees of freedom for signal, DOFS; ˜ 1). The sensitivity near the surface is negligible in most cases, and for this reason, a partial column (5-35 km) is used for the analyses. Both vertical profiles and partial columns are compared to FTIR ground-based measurements from the Network for the Detection of Atmospheric Composition Change (NDACC) to characterize the accuracy and precision of the FORLI-HNO3 product. The profile validation is conducted through the smoothing of the raw FTIR profiles by the IASI averaging kernels and gives good results, with a slight overestimation of IASI measurements in the upper troposphere/lower stratosphere (UTLS) at the six chosen stations (Thule, Kiruna, Jungfraujoch, Izaña, Lauder and Arrival Heights). The validation of the partial columns (5-35 km) is also conclusive with a mean correlation of 0.93 between IASI and the FTIR measurements. An initial survey of the HNO3 spatial and seasonal variabilities obtained from IASI

  19. Measurements of HCl and HNO3 with the new research aircraft HALO - Quantification of the stratospheric contribution to the O3 and HNO3 budget in the UT/LS

    NASA Astrophysics Data System (ADS)

    Jurkat, Tina; Kaufmann, Stefan; Voigt, Christiane; Zahn, Andreas; Schlager, Hans; Engel, Andreas; Bönisch, Harald; Dörnbrack, Andreas

    2013-04-01

    Dynamic and chemical processes modify the ozone (O3) budget of the upper troposphere/lower stratosphere, leading to locally variable O3 trends. In this region, O3 acts as a strong greenhouse gas with a net positive radiative forcing. It has been suggested, that the correlation of the stratospheric tracer hydrochloric acid (HCl) with O3 can be used to quantify stratospheric O3 in the UT/LS region (Marcy et al., 2004). The question is, whether the stratospheric contribution to the nitric acid (HNO3) budget in the UT/LS can be determined by a similar approach in order to differentiate between tropospheric and stratospheric sources of HNO3. To this end, we performed in situ measurements of HCl and HNO3 with a newly developed Atmospheric chemical Ionization Mass Spectrometer (AIMS) during the TACTS (Transport and Composition in the UTLS) / ESMVal (Earth System Model Validation) mission in August/September 2012. The linear quadrupole mass spectrometer deployed aboard the new German research aircraft HALO was equipped with a new discharge source generating SF5- reagent ions and an in-flight calibration allowing for accurate, spatially highly resolved trace gas measurements. In addition, sulfur dioxide (SO2), nitrous acid (HONO) and chlorine nitrate (ClONO2) have been simultaneously detected with the AIMS instrument. Here, we show trace gas distributions of HCl and HNO3 measured during a North-South transect from Northern Europe to Antarctica (68° N to 65° S) at 8 to 15 km altitude and discuss their latitude dependence. In particular, we investigate the stratospheric ozone contribution to the ozone budget in the mid-latitude UT/LS using correlations of HCl with O3. Differences in these correlations in the subtropical and Polar regions are discussed. A similar approach is used to quantify the HNO3 budget of the UT/LS. We identify unpolluted atmospheric background distributions and various tropospheric HNO3 sources in specific regions. Our observations can be compared to

  20. Vapor pressures of solid hydrates of nitric acid - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Worsnop, Douglas R.; Fox, Lewis E.; Zahniser, Mark S.; Wofsy, Steven C.

    1993-01-01

    Thermodynamic data are presented for hydrates of nitric acid: HNO3.H2O, HNO3.2H2O, HNO3.3H2O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO3.2H2O may be favored in polar stratospheric clouds over the slightly more stable HNO3.3H2O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO3.2H2O and HNO3.3H2O. Vapor transfer from HNO3.2H2O to HNO3.3H2O could be a key step in the sedimentation of HNO3, which plays an important role in the depletion of polar ozone.

  1. Infrared studies of sulfuric acid and its impact on polar and global ozone

    NASA Astrophysics Data System (ADS)

    Iraci, Laura Tracy

    Sulfuric acid aerosols are present throughout the lower stratosphere and play an important role in both polar and global ozone depletion. In the polar regions, stratospheric sulfate aerosols (SSAs) act as nuclei for the growth of polar stratospheric clouds (PSCs). Heterogeneous reactions can occur on these PSCs, leading to chlorine activation and catalytic ozone destruction. This thesis addresses the issue of polar ozone depletion through laboratory studies which examine the nucleation of PSCs on sulfuric acid. In addition, chemistry which occurs directly on sulfate aerosols may impact ozone at midlatitudes, and studies describing one such reaction are presented as well. To study the growth of type I PSCs on sulfuric acid, thin H2SO4 films were exposed to water and nitric acid vapors at stratospheric temperatures. Fourier transform infrared spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films which condensed. Supercooled liquid sulfuric acid films showed uptake of HNO3 to form ternary solutions, followed by crystallization of nitric acid trihydrate (NAT). When crystalline sulfuric acid tetrahydrate (SAT) films were exposed to nitric acid and water, condensation of a supercooled HNO3/H2O layer was often observed. As predicted by theory, some of the SAT crystal then dissolved, creating a ternary H2SO4/HNO3/H2O solution. From this solution, NAT nearly always crystallized, halting the phase change of sulfuric acid. If a supercooled nitric acid layer did not condense on frozen sulfuric acid, crystalline NAT was not deposited from the gas phase when SNAT/leq41. At significantly higher supersaturations, NAT could be forced to condense on sulfuric acid, regardless of its phase. Calculations of the contact parameter from experimental data indicate that m<0.79 for NAT on SAT, predicting a significant barrier to nucleation of NAT from the gas phase. While PSCs can form only in the cold polar regions of the stratosphere, sulfuric

  2. Physical chemistry of the H2SO4/HNO3/H2O system - Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Molina, M. J.; Zhang, R.; Wooldridge, P. J.; Mcmahon, J. R.; Kim, J. E.; Chang, H. Y.; Beyer, K. D.

    1993-01-01

    Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO3 hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H2SO4/H2O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO3 vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO3 and H2O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H2SO4 solutions and on solid H2SO4 hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles.

  3. Impact of future land-cover changes on HNO3 and O3 surface dry deposition

    NASA Astrophysics Data System (ADS)

    Verbeke, T.; Lathière, J.; Szopa, S.; de Noblet-Ducoudré, N.

    2015-12-01

    Dry deposition is a key component of surface-atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between the present day (2006) and the future (2050) on dry deposition velocities at the surface, with special interest for ozone (O3) and nitric acid (HNO3), two compounds which are characterized by very different physicochemical properties. The 3-D chemistry-transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections, RCPs 2.6, 4.5 and 8.5, and present-day (2007) meteorology. The 2050 RCP 8.5 vegetation distribution leads to a rise of up to 7 % (+0.02 cm s-1) in the surface deposition velocity calculated for ozone (Vd,O3) and a decrease of -0.06 cm s-1 in the surface deposition velocity calculated for nitric acid (Vd,HNO3) relative to the present-day values in tropical Africa and up to +18 and -15 %, respectively, in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land-cover change in Eurasia, Vd,HNO3 increases by up to 20 % (annual-mean value) and reduces Vd,O3 by the same magnitude in this region. When analyzing the impact of surface dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual-mean surface ozone concentration for both the RCP 8.5 and RCP 2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a

  4. Composition and freezing of aqueous H2SO4/HNO3 solutions under polar stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Beyer, K. D.; Seago, S. W.; Chang, H. Y.; Molina, M. J.

    1994-01-01

    The results of laboratory investigations of the freezing behavior of aqueous acid solutions indicate that in the stratosphere H2SO/H2O aerosol droplets would not freeze at temperatures above the ice frost point in the absence of HNO3; however, in the presence of typical levels of HNO3 liquid sulfuric acid aerosols take up significant amounts of HNO3 and H2O vapors and freeze much more readily. This is a consequence of the very rapid change in composition of the liquid droplets as the temperature drops to within two to three degrees of the equilibrium temperature at which HNO3 and H2O vapors would co-condense to form a liquid solution. In the high latitude stratosphere this HNO3/H2O 'dew point' is typically around 192-194 K at 100 mbar.

  5. Laboratory studies of HNO3/H2O mixtures at low temperatures

    NASA Technical Reports Server (NTRS)

    Hanson, David; Mauersberger, Konrad

    1988-01-01

    The possibility of stratospheric HN3 condensing out of the gas-phase at low temperatures has become important in the chemical explanations of the rapid loss of Antarctic ozone in spring. Consequently, knowledge about the behavior of the vapor pressures of water and HNO3 over HNO3/water mixtures at stratospheric temperatures is needed to determine if HNO3 could condense, and by how much the HNO3 vapor pressure could be depressed. Laboratory investigations of vapor pressures above HNO3/water mixtures are described. Vapor pressures were initially measured over liquid and frozen bulk mixtures contained in a glass still which was attached to a stainless steel vacuum chamber. The total pressure in the chamber was monitored with a precision pressure sensor, and the vapor pressures of HNO3, water and impurities were analyzed with a mass spectrometer beam system. In a second set of experiments, vapor deposits were made to produce ice and the mono- and trihydrate of HNO3. Further data and conclusions are presented.

  6. Heterogeneous reactions of NO2 and HNO3 on oxides and mineral dust: A combined laboratory and modeling study

    NASA Astrophysics Data System (ADS)

    Underwood, G. M.; Song, C. H.; Phadnis, M.; Carmichael, G. R.; Grassian, V. H.

    2001-08-01

    This study combines laboratory measurements and modeling analysis to quantify the role of heterogeneous reactions of gaseous nitrogen dioxide and nitric acid on mineral oxide and mineral dust particles in tropospheric ozone formation. At least two types of heterogeneous reactions occur on the surface of these particles. Upon initial exposure of the oxide to NO2 there is a loss of NO2 from the gas phase by adsorption on the particle surface, i.e., NO2(g) → NO2(a). As the reaction proceeds, a reduction of gaseous NO2 to NO, NO2 (g) → NO (g) is found to occur. Initial uptake coefficients γ0 for NO2 on the surface of these particles have been measured at 298 K using a Knudsen cell reactor coupled to a mass spectrometer. For the oxides studied, α,γ-Al2O3, α,γ-Fe2O3, TiO2, SiO2, CaO, and MgO, γ0 ranges from <4×10-10 for SiO2 to 2×10-5 for CaO with most values in the 10-6 range. For authentic samples of China loess and Saharan sand, similar reactivity to the oxides is observed with γ0 values of 2×10-6 and 1×10-6, respectively. For HNO3 the reactivity is 1-2 orders of magnitude higher. Using these laboratory measurements, the impact of heterogeneous reactions of NO2 and HNO3 on mineral dust in tropospheric ozone formation and on O3-precursor relationships is assessed using a time-dependent, multiphase chemistry box model. Simulations with and without heterogeneous reactions were conducted to evaluate the possible influence of these heterogeneous reactions on ambient levels. Results show that values of the initial uptake for NO2 and HNO3, adjusted for roughness effects, must be greater than 10-4 to have an appreciable impact on NOx, HNO3, and O3 concentrations for the conditions modeled here. Thus the measured uptake coefficients for NO2 on dry surfaces are just below the lower limit to have an impact on the photochemical oxidant cycle, while the heterogeneous reactivity of HNO3 is sufficiently large to have an effect. Under conditions of high mineral dust

  7. Detection of stratospheric HNO3 and NO2 response to short-term solar ultraviolet variability

    NASA Astrophysics Data System (ADS)

    Keating, G. M.; Nicholson, J., III; Brasseur, G.; de Rudder, A.; Schmailzl, U.

    1986-07-01

    It is pointed out that variations in the solar ultraviolet irradiance with a period equal to or approximately one-half of the rotation period of the sun are currently observed by satellite monitoring. Information regarding the response of stratospheric species to solar ultraviolet variability is indispensable for an understanding of the photochemical behavior of the middle atmosphere. Relations are considered between LIMS (limb infrared monitor of the stratosphere) measurements of HNO3 and NO2, and the SBUV (solar backscatter ultraviolet) measurements of short-term variations in 205-nm radiation. It is found that the response of HNO3 is much stronger than, but in the opposite sense to the ozone response, while the NO2 response is in the opposite sense to the HNO3 response. Model calculations predict large variations in HNO3 over the 11-yr solar cycle.

  8. Flow reactor and triple quadrupole mass spectrometer investigations of negative ion reactions involving nitric acid - Implications for atmospheric HNO3 detection by chemical ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Arnold, F.

    1991-07-01

    The ion-molecule reactions on which Active Chemical Ionization Mass Spectrometry (ACIMS) measurements of atmospheric nitric acid are based are presently subjected to product-ion distribution and rate coefficient measurements. The results obtained indicate that while previous stratospheric nitric acid measurements were not impared by collisional dissociation processes, these processes may have played a major role during previous tropospheric measurements: leading to an undereestimation of nitric acid concentrations. A novel ACIMS ion source has been developed in order to avoid these problems.

  9. The detection of large HNO3-containing particles in the winter Arctic stratosphere.

    PubMed

    Fahey, D W; Gao, R S; Carslaw, K S; Kettleborough, J; Popp, P J; Northway, M J; Holecek, J C; Ciciora, S C; McLaughlin, R J; Thompson, T L; Winkler, R H; Baumgardner, D G; Gandrud, B; Wennberg, P O; Dhaniyala, S; McKinney, K; Peter, T; Salawitch, R J; Bui, T P; Elkins, J W; Webster, C R; Atlas, E L; Jost, H; Wilson, J C; Herman, R L; Kleinböhl, A; von König, M

    2001-02-09

    Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These in situ observations were made over a large altitude range (16 to 21 kilometers) and horizontal extent (1800 kilometers) on several airborne sampling flights during a period of several weeks. With diameters of 10 to 20 micrometers, these sedimenting particles have significant potential to denitrify the lower stratosphere. A microphysical model of nitric acid trihydrate particles is able to simulate the growth and sedimentation of these large sizes in the lower stratosphere, but the nucleation process is not yet known. Accurate modeling of the formation of these large particles is essential for understanding Arctic denitrification and predicting future Arctic ozone abundances.

  10. Impact of future land cover changes on HNO3 and O3 surface dry deposition

    NASA Astrophysics Data System (ADS)

    Verbeke, T.; Lathière, J.; Szopa, S.; de Noblet-Ducoudré, N.

    2015-07-01

    Dry deposition is a key component of surface-atmosphere exchange of compounds, acting as a sink for several chemical species. Meteorological factors, chemical properties of the trace gas considered and land surface properties are strong drivers of dry deposition efficiency and variability. Under both climatic and anthropogenic pressure, the vegetation distribution over the Earth has been changing a lot over the past centuries, and could be significantly altered in the future. In this study, we perform a modeling investigation of the potential impact of land-cover changes between present-day (2006) and the future (2050) on dry deposition rates, with special interest for ozone (O3) and nitric acid vapor (HNO3), two compounds which are characterized by very different physico-chemical properties. The 3-D chemistry transport model LMDz-INCA is used, considering changes in vegetation distribution based on the three future projections RCPs 2.6, 4.5 and 8.5. The 2050 RCP 8.5 vegetation distribution leads to a rise up to 7 % (+0.02 cm s-1) in VdO3 and a decrease of -0.06 cm s-1 in VdHNO3 relative to the present day values in tropical Africa, and up to +18 and -15 % respectively in Australia. When taking into account the RCP 4.5 scenario, which shows dramatic land cover change in Eurasia, VdHNO3 increases by up to 20 % (annual-mean value) and reduces VdO3 by the same magnitude in this region. When analyzing the impact of dry deposition change on atmospheric chemical composition, our model calculates that the effect is lower than 1 ppb on annual mean surface ozone concentration, for both for the RCP8.5 and RCP2.6 scenarios. The impact on HNO3 surface concentrations is more disparate between the two scenarios, regarding the spatial repartition of effects. In the case of the RCP 4.5 scenario, a significant increase of the surface O3 concentration reaching locally up to 5 ppb (+5 %) is calculated on average during the June-August period. This scenario induces also an increase of

  11. Miniaturizing and automation of free acidity measurements for uranium (VI)-HNO3 solutions: Development of a new sequential injection analysis for a sustainable radio-analytical chemistry.

    PubMed

    Néri-Quiroz, José; Canto, Fabrice; Guillerme, Laurent; Couston, Laurent; Magnaldo, Alastair; Dugas, Vincent

    2016-10-01

    A miniaturized and automated approach for the determination of free acidity in solutions containing uranium (VI) is presented. The measurement technique is based on the concept of sequential injection analysis with on-line spectroscopic detection. The proposed methodology relies on the complexation and alkalimetric titration of nitric acid using a pH 5.6 sodium oxalate solution. The titration process is followed by UV/VIS detection at 650nm thanks to addition of Congo red as universal pH indicator. Mixing sequence as well as method validity was investigated by numerical simulation. This new analytical design allows fast (2.3min), reliable and accurate free acidity determination of low volume samples (10µL) containing uranium/[H(+)] moles ratio of 1:3 with relative standard deviation of <7.0% (n=11). The linearity range of the free nitric acid measurement is excellent up to 2.77molL(-1) with a correlation coefficient (R(2)) of 0.995. The method is specific, presence of actinide ions up to 0.54molL(-1) does not interfere on the determination of free nitric acid. In addition to automation, the developed sequential injection analysis method greatly improves the standard off-line oxalate complexation and alkalimetric titration method by reducing thousand fold the required sample volume, forty times the nuclear waste per analysis as well as the analysis time by eight fold. These analytical parameters are important especially in nuclear-related applications to improve laboratory safety, personnel exposure to radioactive samples and to drastically reduce environmental impacts or analytical radioactive waste.

  12. A Study on the Passivation Behavior and Semiconducting Properties of Gamma Titanium Aluminide in 0.1 N H2SO4, HNO3, and HClO4 Acidic Solutions

    NASA Astrophysics Data System (ADS)

    Memarbashi, S.; Saebnoori, E.; Shahrabi, T.

    2014-03-01

    The study focuses on the passivation behavior of single-gamma-phase titanium aluminide in acidic solutions with a particular emphasis on the role of oxidizing strength in characteristics of passive layer. The report includes potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies along with Mott-Schottky analysis in order to determine the corrosion behavior of the alloy and the semiconducting properties of the scale formed during exposure to acidic environment. Passive current density measured from potentiodynamic polarization curve, polarization resistance ( R p) estimated by EIS, defect density, and flatband potential drawn from Mott-Schottky analysis are mainly used in estimating the ability of passive film formed on alloy in protecting it against high corrosion rates in Sulfuric acid (a non-oxidizing acid), perchloric acid, and nitric acid (oxidizing acid with different oxidizing strength). The results show that passive current density ( i pass) in Sulfuric acid is 2.67 × 10-5 A cm-2, which is 2.5 and 3 times greater than the values obtained in perchloric acid ( i pass = 9.91 × 10-6) and nitric acid ( i pass = 7.98 × 10-6), respectively. EIS data reveal that the value of R p in sulfuric acid (20 kΩ cm2) is about three and five times smaller than that its value in perchloric acid and Nitric acid, respectively. Mott-Schottky analysis shows that the passive layer exhibits an n-type semiconducting characteristics irrespective of acidic environment. The greatest and the smallest values of donor density ( N D) are obtained for the passive scale formed in sulfuric acid ( N D, H2SO4 = 18.36 × 1019) and nitric acid ( N D, HNO3 = 13.13 × 1019), respectively. The report concludes that characteristics of the passive scale are directly affected by reduction potential of the acid, which is the criterion of its oxidizing strength. An increase in the oxidizing strength of the acidic solution results in formation of more protective and less

  13. Establishing a long-term, global stratospheric HNO3 data record combining UARS MLS with Aura MLS data by means of ground-based measurements

    NASA Astrophysics Data System (ADS)

    Fiorucci, I.; Muscari, G.; Froidevaux, L.; Santee, M. L.; de Zafra, R. L.

    2009-12-01

    Nitric Acid (HNO3) is a major player in processes controlling stratospheric ozone depletion. It is a primary reservoir for reactive nitrogen in the stratosphere and has a key role in both the activation and the deactivation of chlorine and bromine species. Since 1993 HNO3 observations have been carried out by means of a Ground-Based Millimeter-wave Spectrometer (GBMS) from a variety of sites in both hemispheres, at polar and mid-latitudes. The GBMS observes a cluster of weak emission lines centered at 269 GHz, with a pass band of 600 MHz and a resolution of 1 MHz. The retrieval of vertical profiles from the pressure-blended multiple line spectra is carried out with an Optimal Estimation Method. The GBMS provides HNO3 profiles from ~15 up to 50 km, with a vertical resolution of 6-8 km and a total uncertainty of ~15%. GBMS HNO3 measurements have been used within GOZCARDS (Global Ozone Chemistry and Related Trace gas Data Records for the Stratosphere), a multi-year MEaSUREs project, aimed at developing a long-term, commonly-formatted Earth system data record (ESDR) of stratospheric constituents relevant to the issues of ozone decline and expected recovery. This data record is based mainly on satellite-derived measurements. Nevertheless, ground-based observations can be critically used for assessing offsets between satellite data sets, as well as to fill gaps in temporal coverage when possible. Since the GBMS has been operated for more than 15 years (with minor instrumental upgrading), the GBMS HNO3 data record is well-suited for the GOZCARDS objectives; it offers a unique opportunity for the cross-calibration of HNO3 measurements from the NASA/JPL Microwave Limb Sounder (MLS) experiments (aboard the Upper Atmosphere Research Satellite (UARS) from 1991 to 1999, and on the Earth Observing System (EOS) Aura mission from 2004 to date). In this study we compare Aura MLS observations and GBMS HNO3 measurements obtained from the Italian Alpine station of Plateau Rosa, during

  14. Heterogeneous kinetics of H2O, HNO3 and HCl on HNO3 hydrates (α-NAT, β-NAT, NAD) in the range 175-200 K

    NASA Astrophysics Data System (ADS)

    Iannarelli, Riccardo; Rossi, Michel J.

    2016-09-01

    Experiments on the title compounds have been performed using a multidiagnostic stirred-flow reactor (SFR) in which the gas phase as well as the condensed phase has been simultaneously investigated under stratospheric temperatures in the range 175-200 K. Wall interactions of the title compounds have been taken into account using Langmuir adsorption isotherms in order to close the mass balance between deposited and desorbed (recovered) compounds. Thin solid films at 1 µm typical thickness have been used as a proxy for atmospheric ice particles and have been deposited on a Si window of the cryostat, with the optical element being the only cold point in the deposition chamber. Fourier transform infrared (FTIR) absorption spectroscopy in transmission as well as partial and total pressure measurement using residual gas mass spectrometry (MS) and sensitive pressure gauges have been employed in order to monitor growth and evaporation processes as a function of temperature using both pulsed and continuous gas admission and monitoring under SFR conditions. Thin solid H2O ice films were used as the starting point throughout, with the initial spontaneous formation of α-NAT (nitric acid trihydrate) followed by the gradual transformation of α- to β-NAT at T > 185 K. Nitric acid dihydrate (NAD) was spontaneously formed at somewhat larger partial pressures of HNO3 deposited on pure H2O ice. In contrast to published reports, the formation of α-NAT proceeded without prior formation of an amorphous HNO3 / H2O layer and always resulted in β-NAT. For α- and β-NAT, the temperature-dependent accommodation coefficient α(H2O) and α(HNO3), the evaporation flux Jev(H2O) and Jev(HNO3) and the resulting saturation vapor pressure Peq(H2O) and Peq(HNO3) were measured and compared to binary phase diagrams of HNO3 / H2O in order to afford a thermochemical check of the kinetic parameters. The resulting kinetic and thermodynamic parameters of activation energies for evaporation (Eev) and

  15. Fast-response airborne in situ measurements of HNO3 during the Texas 2000 Air Quality Study

    NASA Astrophysics Data System (ADS)

    Neuman, J. A.; Huey, L. G.; Dissly, R. W.; Fehsenfeld, F. C.; Flocke, F.; Holecek, J. C.; Holloway, J. S.; Hübler, G.; Jakoubek, R.; Nicks, D. K.; Parrish, D. D.; Ryerson, T. B.; Sueper, D. T.; Weinheimer, A. J.

    2002-10-01

    Nitric acid (HNO3) was measured from an aircraft in the planetary boundary layer and free troposphere up to 7 km on 14 flights during the Texas Air Quality Study in August and September 2000. HNO3 mixing ratios were measured at 1 Hz using a fast-response chemical ionization mass spectrometer with SiF5- reagent ions. HNO3 measurement using this highly selective ion chemistry is insensitive to water vapor and is not degraded by interferences from other species. Rapid time response (1 s) was achieved using a heated Teflon inlet. In-flight standard addition calibrations from a HNO3 permeation source were used to determine the instrument sensitivity of 1.1 ± 0.1 ion counts pptv-1 s-1 over the duration of the study. Contributions to the HNO3 signal from instrument artifacts were accounted for by regularly performing in-flight instrument background checks, where HNO3 was removed from the ambient air sample by diverting the sampled air though a nylon wool scrubber. Measurement inaccuracy, which is determined from uncertainties in the standard addition calibrations, was ±10%. Measurement precision at low HNO3 levels was ±25 pptv (1σ) for the 1 Hz data and ±9 pptv for 10 s averages of the 1 s measurements. Coincident in situ measurements of other reactive nitrogen species are used to examine NOy partitioning and HNO3 formation during this month long measurement campaign. The sum of the individually measured reactive nitrogen species is shown to be in agreement with the measured NOy. HNO3 formation in plumes from electric utility power plants, urban areas, and petrochemical facilities was studied. The observed differences in the fractional contribution of HNO3 to NOy in plumes from different anthropogenic source types are discussed.

  16. Rate of reaction of OH with HNO3

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Ravishankara, A. R.; Kreutter, N. M.; Shah, R. C.; Nicovich, J. M.; Thompson, R. L.; Wuebbles, D. J.

    1981-01-01

    Measurements of the kinetics of the reaction of OH with HNO3, and mechanisms of HNO3 removal from the stratosphere, are reported. Bimolecular rate constants were determined at temperatures between 224 and 366 K by monitoring the concentrations of OH radicals produced by HNO3 photolysis and HNO3 according to their resonance fluorescence and 184.9-nm absorption, respectively. The rate constant measured at 298 K is found to be somewhat faster than previously accepted values, with a negative temperature dependence. Calculations of a one-dimensional transport-kinetic atmospheric model on the basis of the new rate constant indicate reductions in O3 depletion due to chlorofluoromethane release and NOx injection, of magnitudes dependent on the nature of the reaction products.

  17. Theoretical study of atmospheric clusters: HNO3:HCl:H2O

    NASA Astrophysics Data System (ADS)

    Gomez, P. C.; Escribano, R. M.; Galvez, O.

    2009-04-01

    Water, nitric acid and hydrogen chloride play an important role in several atmospheric processes, as individual species, and also interacting in the complex reactions related to ozone depletion in polar stratospheric clouds (PSC). The atmospheric importance of the ternary system HCl:HNO3:H2O was recognized long ago [1]. It is also known that HCl attaches to the surface of PSC particles formed by nitric acid hydrates in what can be considered the first step of the heterogeneous reactions leading to the release of the active chlorine molecule [2]. Recently, HCl was detected dissolved in liquid particles with HNO3/H2O by in situ measurements in the Artic stratosphere [3]. The study of simple models including these three species at a high level of theory can be the first step towards the understanding of all possible kinds of bonding and structures that can arise among these molecules, and can constitute the embryo of more complex mixtures with higher amounts of water or variable proportions of their constituents. This kind of calculations have been successfully performed in the past [4,5]. We present in this contribution our results on the structure and spectroscopical properties of the many different ways that these molecules can be bonded in what are predicted to be thermodynamically stable species. The calculations are performed by density functional methods (B3LYP) using Dunning's quadruple-zeta augmented correlated consisted basis sets (aug-cc-pVQZ). This work has been supported by the Spanish Ministry of Education, Projects FIS2007-61686 and CTQ2008-02578/BQU. We wish to thank also CESGA (Centro de Supercomputacion de Galicia), where some of these calculations were carried out. References: [1] O. B. Toon, P. Hamill, R. P. Turco, J. Pinto. Geophys. Res. Lett. 1986, 13, 1284. [2] Molina, M. J.; Zhang, R.; Wooldridge, P. J.; McMahon, J. R.; Kim, J. E.; Chang, H. Y.; Beyer, K. D. Science 1993, 261,1418. [3] C. Weiser, K. Mauersberger, J. Schreiner, N. Larsen, F

  18. Measurements of ozone, nitrogen dioxide, nitrous and nitric acids, and sulphur dioxide in the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Vecera, V.; Mikuska, M.; Smolik, S.; Eleftheriadis, E.; Bryant, B.; Colbeck, C.; Lazaridis, L.

    2003-04-01

    Measurements of reactive nitrogen gases (NO_2, HONO, HNO_3), as well as ozone and sulfur dioxide were made over the Aegean Sea (the R/V Agaeon) within an air mass later reaching the Finokalia (Crete) sampling site. These measurements were carried out with unique gas trace instrumentation (wet effluent and "dry" diffusion denuder techniques, a chemiluminescent detection and chemiluminescent analyzers) during special conditions. There are significant differences in pollutant concentrations between results from Finokalia and from the R/V Agaeon. While at Finokalia concentrations of nitrogen dioxide, ozone and nitric and nitrous acids changed relatively slowly, the boat data showed a number of episodes with rapid changes in reactive nitrogen compounds and ozone concentrations. These episodes were correlated with the presence of boats up wind a short distance from the R/V Agaeon. Ozone concentrations at Finokalia and on the boat typically ranged between 40--80 ppb (v/v). Ozone concentrations reached up to 88 ppb (v/v) in the open sea. Nitrogen dioxide concentrations at Finokalia were in the range 0.5--3 ppb (v/v). Typical NO_2 concentrations observed aboard the boat were 4--6 ppb (v/v) with maxima of 20--30 ppb (v/v). During "spiked" episodes, up to 200 ppb (v/v) of nitrogen dioxide was observed while ozone concurrently was dramatically depleted down to 20 ppb (v/v). Concentrations of HONO and HNO_3 at Finokalia, in general, were low, typically in the order of 0.1--0.2 ppb (v/v) for HONO and 0.05--0.1 ppb (v/v) for HNO_3. On average, concentrations of both nitric and nitrous acids in the ambient air of the Aegean Sea were typically small, below 0.05 ppt (v/v). Within the "spiked" episodes up to 33 ppb (v/v) nitric acid and up to 2.5 ppb (v/v) nitrous acid were formed. The nitric acid "dry" denuder data were on average higher than the measurements by the wet efluent diffusion denuder. The concentration of SO_2 reached up to 9.2 ppb (v/v). The work was conducted within

  19. Quantum chemical study of ternary mixtures of: HNO3:H2SO4:H2O

    NASA Astrophysics Data System (ADS)

    Verdes, M. A.; Gómez, P. C.; Gálvez, O.

    2009-04-01

    Water, nitric acid and sulfuric acid are important atmospheric species as individual species and as hydrogen-bonded aggregates involved in many physical-chemical processes both superficial and bulk. The importance of heterogeneous chemical reactions taking place on ice surfaces, either solid water or solid water plus nitric or sulfuric acid, is well established now in relation to the ozone-depleting mechanisms. Also the importance of liquid droplets formed by HNO3.H2SO4.H2O as components of PSC was soon recognized [1-3]. Finally the physical properties of finely divided aqueous systems is an interesting and active field of research in which theoretical information on the microphysical domain systems may help to understand and rationalize the wealth of experimental information. This can also be the initial step in the study of more complex mixtures with higher amounts of water or variable proportions of their constituents. This kind of calculations have been successfully performed in the past[4]. We present here our results on the structure and spectroscopic and thermodynamic properties of the energy-lowest lying structures among those thermodynamically stable formed by linking the acids plus water. The calculations have been carried out by means of DFT methods (in particular the successful B3LYP) using different basis sets that contain appropriate sets of polarization and diffuse functions up to quadruple-Z quality (Dunninǵs aug-cc-pVQZ). Careful assessment of the dependability of the methodology used has been carried out. This work has been supported by the Spanish Ministry of Education, Projects FIS2007-61686 and CTQ2008-02578/BQU References: [1] Carslaw, K. S. et al.: Geophys. Res. Lett. 21, 2479-2482, 1994 [2] Drdla, K. Et al. :Geophys. Res. Lett. 21, 2473-2478, 1994 [3] Tabazadeh, A. et al.: Geophys. Res. Lett 21, 1619-1622, 1994 [4] Escribano, R et al.: J. J. Chem. Phys A 2003, 107, 652.

  20. Nucleation and growth of HNO3-3H2O particles in the polar stratosphere

    NASA Technical Reports Server (NTRS)

    Wofsy, Steven C.; Gobbi, Gian Paolo; Salawitch, Ross J.; Mcelroy, Michael B.

    1990-01-01

    Growth of nitric acid trihydrate (NAT) particles on background stratospheric aerosols is examined for an isolated air parcel cooled at a uniform rate. During the process of nucleation, the saturation ratio of HNO3 vapor reaches a maximum value between 2 and 15, corresponding to supercooling by 1-4 K. If cooling rates exceed 0.5-1 K/day, small particles of NAT are produced. A major fraction of the available condensation nuclei is activated and removal of HNO3 by gravitational settling is slow. If cooling rates are less than 0.5-1 K/day, the number of aerosols that nucleate is reduced, leading to differential growth of large NAT particles. Observations of 5 micron radius particles in clouds at temperatures above the water frost point may reflect condensation of NAT on ice particles that fall through a column of air as it is cooled. Rapid condensation of HNO3 on ice particles is promoted by the high supersaturation attained during nucleation and maintained during subsequent cooling. This process provides a mechanism for irreversible removal of HNO3.

  1. Deposition and adsorption of the air pollutant HNO 3 vapor to soil surfaces

    NASA Astrophysics Data System (ADS)

    Padgett, Pamela E.; Bytnerowicz, Andrzej

    Deposition of nitric acid (HNO 3) vapor to soils has been evaluated in three experimental settings: (1) continuously stirred tank reactors with the pollutant added to clean air, (2) open-top chambers at high ambient levels of pollution with and without filtration reducing particulate nitrate levels, (3) two field sites with high or low pollution loads in the coastal sage plant community of southern California. The results from experiment (1) indicated that the amount of extractable NO 3- from isolated sand, silt and clay fractions increased with atmospheric concentration and duration of exposure. After 32 days, the highest absorption of HNO 3 was determined for clay, followed by silt and sand. While the sand and silt fractions showed a tendency to saturate, the clay samples did not after 32 days of exposure under highly polluted conditions. Absorption of HNO 3 occurred mainly in the top 1 mm layer of the soil samples and the presence of water increased HNO 3 absorption by about 2-fold. Experiment (2) indicated that the presence of coarse particulate NO 3- could effectively block absorption sites of soils for HNO 3 vapor. Experiment (3) showed that soil samples collected from open sites had about 2.5 more extractable NO 3- as compared to samples collected from beneath shrub canopies. The difference in NO 3- occurred only in the upper 1-2 cm as no significant differences in NO 3- concentrations were found in the 2-5 cm soil layers. Extractable NO 3- from surface soils collected from a low-pollution site ranged between 1 and 8 μg NO 3-N g -1, compared to a maximum of 42 μg NO 3-N g -1 for soils collected from a highly polluted site. Highly significant relationship between HNO 3 vapor doses and its accumulation in the upper layers of soils indicates that carefully prepared soil samples (especially clay fraction) may be useful as passive samplers for evaluation of ambient concentrations of HNO 3 vapor.

  2. Comparison of the CIBA HNO_3 model with UARS observations

    NASA Astrophysics Data System (ADS)

    Gille, J.; Bailey, P.; Massie, S.; Roche, A.; Kumer, J.; Lyjak, L.

    The CIRA HNO_3 model is based on the 7 months of data from the LIMS experiment on Nimbus 7. Now CLAES and ISAMS, two instruments on UARS, are providing further observations. Preliminary CLAES results are here compared with the CIRA model. There is agreement on the broad features of the HNO_3 distribution. CLAES data provide the first direct observations of the Northern Hemisphere summer, and of the atmosphere poleward of 64 S. Because the data are still being evaluated and improved, it is premature to draw any quantitative conclusions at this time.

  3. Uptake of HNO3 to deliquescent sea-salt particles

    NASA Astrophysics Data System (ADS)

    Guimbaud, C.; Arens, F.; Gutzwiller, L.; Gäggeler, H. W.; Ammann, M.

    2002-06-01

    The uptake of HNO3 to deliquescent airborne sea-salt particles (RH = 55%, P = 760 torr, T = 300 K) at concentrations from 2 to 575 ppbv is measured in an aerosol flow tube using 13N as a tracer. Small particles (~ 70 nm diameter) are used in order to minimize the effect of diffusion in the gas phase on the mass transfer. Below 100 ppbv, an uptake coefficient (gupt) of 0.50 ± 0.20 is derived. At higher concentrations, the uptake coefficient decreases along with the consumption of aerosol chloride. Data interpretation is further supported by using the North American Aerosol Inorganics Model (AIM), which predicts the aqueous phase activities of ions and the gas-phase partial pressures of H2O, HNO3, and HCl at equilibrium for the NaCl/HNO3/H2O system. These simulations show that the low concentration data are obtained far from equilibrium, which implies that the uptake coefficient derived is equal to the mass accommodation coefficient under these conditions. The observed uptake coefficient can serve as input to modeling studies of atmospheric sea-salt aerosol chemistry. The main sea-salt aerosol burden in the marine atmosphere is represented by coarse mode particles (> 1 mm diameter). This implies that diffusion in the gas-phase is the limiting step to HNO3 uptake until the sea-salt has been completely processed.

  4. Uptake of HNO3 on aviation kerosene and aircraft engine soot: influences of H2O or/and H2SO4.

    PubMed

    Loukhovitskaya, Ekaterina E; Talukdar, Ranajit K; Ravishankara, A R

    2013-06-13

    The uptake of HNO3 on aviation kerosene soot (TC-1 soot) was studied in the absence and presence of water vapor at 295 and 243 K. The influence of H2SO4 coating of the TC-1 soot surface on HNO3 uptake was also investigated. Only reversible uptake of HNO3 was observed. HONO and NO2, potential products of reactive uptake of HNO3, were not observed under any conditions studied here. The uptake of nitric acid increased slightly with relative humidity (RH). Coating of the TC-1 soot surface with sulfuric acid decreased the uptake of HNO3 and did not lead to displacement of H2SO4 from the soot surface. A limited set of measurements was carried out on soot generated by aircraft engine combustor (E-soot) with results similar to those on TC-1 soot. The influence of water on HNO3 uptake on E-soot appeared to be more pronounced than on TC-1 soot. Our results suggest that HNO3 loss in the upper troposphere due to soot is not significant except perhaps in aircraft exhaust plumes. Our results also suggest that HNO3 is not converted to either NO2 or HONO upon its uptake on soot in the atmosphere.

  5. Heterogeneous conversion of N2O5 to HNO3 in the post-Mount Pinatubo eruption stratosphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Abrams, M. C.; Lowes, L. L.; Zander, R.; Mahieu, E.; Goldman, A.; Ko, M. K. W.; Rodriguez, J. M.; Sze, N. D.

    1994-01-01

    Simultaneous stratospheric volume mixing ration (VMR) profiles of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) at sunrise between 25 deg N and 15 deg S latitude and profiles of HNO3 at sunset between 42 deg S and 53 deg S latitude have been derived from 0.01/cm resolution infrared solar occultation spectra recorded 9.5 months after the massive eruption of the Mount Pinatubo volcano in the Philippine Islands. The measurements were obtained by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992). The measured HNO3 VMRs are higher at all altitudes and latitudes than corresponding values measured by the limb infrared monitor of the stratosphere (LIMS) instrument during the same season in 1979, when the aerosol loading was near background levels. The largest relative increase in the HNO3 VMR occurred near the equator at 30-km altitude, where the ATMOS/ATLAS 1 values are about a factor of 2 higher than the LIMS measurements. Two-dimensional model calculations show that the increase in HNO3 and the ATMOS/ATLAS 1 measurement of a steep decrease in the N2O5 VMR below 30 km can be explained by the enhanced conversion of N2O5 to HNO3 on the surfaces of the Mount Pinatubo sulfate aerosols. Our profile results demonstrate the global impact of the N2O5 + H2O yields 2HNO3 heterogeneous reaction in altering the partitioning of stratospheric odd nitrogen after a major volcanic eruption.

  6. Heterogeneous conversion of N2O5 to HNO3 in the post-Mount Pinatubo eruption stratosphere

    NASA Astrophysics Data System (ADS)

    Rinsland, C. P.; Gunson, M. R.; Abrams, M. C.; Lowes, L. L.; Zander, R.; Mahieu, E.; Goldman, A.; Ko, M. K. W.; Rodriguez, J. M.; Sze, N. D.

    1994-04-01

    Simultaneous stratospheric volume mixing ratio (VMR) profiles of dinitrogen pentoxide (N2O5) and nitric acid (HNO3) at sunrise between 25°N and 15°S latitude and profiles of HNO3 at sunset between 42°S and 53°S latitude have been derived from 0.01 cm-1 resolution infrared solar occultation spectra ? months after the massive eruption of the Mount Pinatubo volcano in the Philippine Islands. The measurements were obtained by the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992). The measured HNO3 VMRs are higher at all altitudes and latitudes than corresponding values measured by the limb infrared monitor of the stratosphere (LIMS) instrument during the same season in 1979, when the aerosol loading was near background levels. The largest relative increase in the HNO3 VMR occurred near the equator at 30-km altitude, where the ATMOS/ATLAS 1 values are about a factor of 2 higher than the LIMS measurements. Two-dimensional model calculations show that the increase in HNO3 and the ATMOS/ATLAS 1 measurement of a steep decrease in the N2O5 VMR below 30 km can be explained by the enhanced conversion of N2O5 to HNO3 on the surfaces of the Mount Pinatubo sulfate aerosols. Our profile results demonstrate the global impact of the N2O5 + H2O → 2HNO3 heterogeneous reaction in altering the partitioning of stratospheric odd nitrogen after a major volcanic eruption.

  7. Competitive Adsorption of HNO3 and HCl On/in Water Clusters and Ice

    NASA Astrophysics Data System (ADS)

    Balci, M.; Uras-Aytemiz, N.

    2009-04-01

    Solvation and ionization of strong acids such as HX (X=Cl, Br), HNO3 etc. have been subjected to many researchers (see for example refs. 1, 2, and references therein). In this study, the competitive adsorption of two strong acids, namely, HCl and HNO3 on/in the water clusters and the surface of crystalline ice slab containing 72 water molecules were investigated at the average temperatures below 140 K. The main tool of this study is on-the-fly molecular dynamics as implemented in the density functional code QUICKSTEP (3) which is part of CP2K package (4). The small water clusters containing both HNO3 and HCl with up to five water molecules were further checked with MP2 level ab initio calculations. The results will be discussed in terms of dynamics, structures, energetics and spectroscopic perspectives. 1. Buch, V.; Sadlej, J.; Aytemiz-Uras, N.; Devlin, J. P., The Journal of Physical Chemistry A 2002, 106, 9374. 2. Escribano, R.; Couceiro, M.; Gómez, P. C.; Carrasco, E.; Moreno, M. A.; Herrero, V. J., The Journal of Physical Chemistry A 2003, 107, 651. 3. CP2K, http://cp2k.berlios.de (2000-2004). 4. VandeVondele, J.; Krack, M.; Mohamed, F.; Parrinello, M.; Chassaing, T.; Hutter, J., Comp. Phys. Comm. 2005, 167, 103. This work was supported by TUBITAK (Project number: 107T044)

  8. Transport of atmospheric NOx and HNO3 over Cape Town

    NASA Astrophysics Data System (ADS)

    Abiodun, B. J.; Ojumu, A. M.; Jenner, S.; Ojumu, T. V.

    2013-05-01

    Cape Town, the most popular tourist city in Africa, usually experiences air pollution with unpleasant odour in winter. Previous studies have associated the pollution with local emission of pollutants within the city. The present study examines the transport of atmospheric pollutants (NOx and HNO3) over South Africa and shows how the transport of pollutants from the Mpumalanga Highveld may contribute to the pollution in Cape Town. The study analysed observation data (2001-2008) from Cape Town air quality network and simulation data (2001-2004) from regional climate model (RegCM4) over southern Africa. The simulation accounts for the influence of complex topography, atmospheric condition, and atmospheric chemistry on emission and transport of pollutants over southern Africa. Flux budget analysis was used to examine whether Cape Town is a source or sink for NOx and HNO3 during the extreme pollution events. The results show that extreme pollution events over Cape Town are associated with the low-level (surface-850 hPa) transport of NOx from the Mpumalanga Highveld to Cape Town, and with a tongue of high concentration of HNO3 that extends from the Mpumalanga Highveld to Cape Town along the south coast of South Africa. The prevailing atmospheric conditions during the extreme pollution events feature an upper-level (700 hPa) anticyclonic flow over South Africa and a low-level col over Cape Town. The anticyclonic flow induces a strong subsidence motion, which prevents vertical mixing of the pollutants and caps high concentration of pollutants close to the surface as they are transported from the Mpumalanga Highveld toward Cape Town, while the col accumulates the pollutants over the city. This study shows that Cape Town can be a sink for the NOx and HNO3 during extreme pollution events and suggests that the accumulation of pollutants transported from other areas (e.g. Mpumalanga Highveld) may contribute substantially to the air pollution in Cape Town.

  9. Ground-based infrared measurements of HNO3 total column abundances - Long-term trend and variability

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Zander, R.; Demoulin, P.

    1991-01-01

    The long-term trend and variability of the total column amount of atmospheric nitric acid (HNO3) have been investigated. The study was based on time series of infrared solar absorption spectra recorded at two sites, the International Scientific Station of the Jungfraujoch (ISSJ) in the Swiss Alps (altitude 3.6 km, latitude 46.5 N, longitude 8.0 E) and the National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.1 km, latitude 31.9 N, longitude 111.6 W), Arizona. Measurements of HNO3 absorption features recorded at Kitt Peak between 1980 and 1990 and measurements of the same features in ISSJ solar spectra obtained in June 1951 and June 1986 to June 1990 provide quantitative estimates of the long-term trend in the HNO3 total vertical column. It is found that the trend deduced for each site is equal to zero within the measurement uncertainty. The modern ISSJ measurements show that the fitted trend is (-0.16 + or - 0.50) percent/yr, 2 sigma, which indicates that there has been no detectable change in HNO3 total column over three decades. The Kitt Peak measurements show marked variability in the HNO3 total column, but no obvious seasonal cycle is observed.

  10. Global sensitivity of aviation NOx effects to the HNO3-forming channel of the HO2 + NO reaction

    NASA Astrophysics Data System (ADS)

    Gottschaldt, K.; Voigt, C.; Jöckel, P.; Righi, M.; Deckert, R.; Dietmüller, S.

    2013-03-01

    The impact of a recently proposed HNO3-forming channel of the HO2 + NO reaction on atmospheric ozone, methane and their precursors is assessed with the aim to investigate its effects on aviation NOx induced radiative forcing. The first part of the study addresses the differences in stratospheric and tropospheric HOx-NOx chemistry in general, by comparing a global climate simulation without the above reaction to two simulations with different rate coefficient parameterizations for HO2 + NO → HNO3. A possible enhancement of the reaction by humidity, as found by a laboratory study, particularly reduces the oxidation capacity of the atmosphere, increasing methane lifetime significantly. Since methane lifetime is an important parameter for determining global methane budgets, this might affect estimates of the anthropogenic greenhouse effect. In the second part aviation NOx effects are isolated independently for each of the three above simulations. Warming and cooling effects of aircraft NOx emissions are both enhanced when considering the HNO3-forming channel, but the sum is shifted towards negative radiative forcing. Uncertainties associated with the inclusion of the HO2 + NO → HNO3 reaction and with its corresponding rate coefficient propagate a considerable additional uncertainty on estimates of the climate impact of aviation and on NOx-related mitigation strategies.

  11. Stratospheric Sulfuric Acid and Black Carbon Aerosol Measured During POLARIS and its Role in Ozone Chemistry

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Pueschel, R. F.; Drdla, K.; Verma, S.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosol can affect the environment in three ways. Sulfuric acid aerosol have been shown to act as sites for the reduction of reactive nitrogen and chlorine and as condensation sites to form Polar Stratospheric Clouds, under very cold conditions, which facilitate ozone depletion. Recently, modeling studies have suggested a link between BCA (Black Carbon Aerosol) and ozone chemistry. These studies suggest that HNO3, NO2, and O3 may be reduced heterogeneously on BCA particles. The ozone reaction converts ozone to oxygen molecules, while HNO3 and NO2 react to form NOx. Finally, a buildup of BCA could reduce the single-scatter albedo of aerosol below a value of 0.98, a critical value that has been postulated to change the effect of stratospheric aerosol from cooling to warming. Correlations between measured BCA amounts and aircraft usage have been reported. Attempts to link BCA to ozone chemistry and other stratospheric processes have been hindered by questions concerning the amount of BCA that exists in the stratosphere, the magnitude of reaction probabilities, and the scarcity of BCA measurements. The Ames Wire Impactors (AWI) participated in POLARIS as part of the complement of experiments on the NASA ER-2. One of our main objectives was to determine the amount of aerosol surface area, particularly BCA, available for reaction with stratospheric constituents and assess if possible, the importance of these reactions. The AWI collects aerosol and BCA particles on thin Palladium wires that are exposed to the ambient air in a controlled manner. The samples are returned to the laboratory for subsequent analysis. The product of the AWI analysis is the size, surface area, and volume distributions, morphology and elemental composition of aerosol and BCA. This paper presents results from our experiments during POLARIS and puts these measurements in the context of POLARIS and other missions in which we have participated. It describes modifications to the AWI data

  12. Efficiency enhancement of graphene/silicon-pillar-array solar cells by HNO3 and PEDOT-PSS.

    PubMed

    Feng, Tingting; Xie, Dan; Lin, Yuxuan; Zhao, Haiming; Chen, Yu; Tian, He; Ren, Tianling; Li, Xiao; Li, Zhen; Wang, Kunlin; Wu, Dehai; Zhu, Hongwei

    2012-03-21

    A single-layer graphene film was grown on copper foil by chemical vapor deposition and transferred onto a silicon-pillar-array (SPA) substrate to make a Schottky junction solar cell. The SPA substrate was specifically designed to suppress reflectance and enhance light absorption. The energy conversion efficiency of the prepared graphene/SPA solar cells achieved a maximum of 2.90% with a junction area of 0.09 cm(2). HNO(3) was employed to dope the graphene in the solar cells, and the time dependence of HNO(3) treatment on the cell performance was studied. Poly(3,4-ethylenedioxythiophene) polystyrenesulfonic acid (PEDOT-PSS) was also introduced in graphene/SPA solar cells by spin coating on top of the graphene film, and its modification on the cell performance was characterized. The results show that both HNO(3) and the PEDOT-PSS film could enhance the energy conversion efficiency of graphene/SPA solar cells.

  13. Vapour pressures of H2SO4/HNO3/HCI/HBr/H2O solutions to low stratospheric temperatures

    SciTech Connect

    Luo, B.; Carslaw, K.S.; Peter, T.; Clegg, S.L. |

    1995-02-01

    Vapor pressures of H2O, HNO3, HCl and HBr over supercooled aqueous mixtures with sulfuric acid have been calculated using an activity coefficient model, for 185 K less than T less than 235 K, 0 less than wt% (H2SO4) + wt% (HNO3) less than 70, and assuming HCl and HBr to be minor constituents. Predicted vapor pressures agree well with most laboratory data, and give confidence in the validity of the model. The results are parameterized as simple formulae, which reproduce the model results to within 40% and cover the entire stratospherically relevant range of composition and temperature.

  14. The Effects of Gaseous Ozone and Nitric Acid Deposition on two Crustose Lichen Species From Joshua Tree National Park

    NASA Astrophysics Data System (ADS)

    Hessom, Elizabeth Curie

    Lichens are dependent on atmospheric deposition for much of their water and nutrients, and due to their sensitivity to pollutants, are commonly used as bioindicators for air quality. While studies have focused on epiphytic (tree dwelling) lichens as bioindicators, virtually nothing is known about crustose (rock dwelling) lichens. The atmospheric pollutants ozone (O 3) and nitric acid (HNO3) are two major pollutants found within the Los Angeles Basin. While recent O3 research suggests it does not significantly affect lichen growth, HNO3 appears to be phytotoxic to some lichens. As both of these pollutants are deposited downwind from the L.A. basin into Joshua Tree National Park (JOTR), lichen species located in the park may provide a sensitive indicator of pollution effects. This research studied two lichen species of particular interest from Joshua Tree National Park, Lobothallia praeradiosa (Nyl.) Hafellner, and Acarospora socialis H. Magn., both of which are crustose species with unknown sensitivities to O3, as well as hypothesized and unknown sensitivities to nitrogen compounds, respectively. Little research exists for either species, possibly because of the difficulty in working with crustose lichens. This research attempted to expand the background knowledge of these species by exposing them to varying levels of O3 and HNO3, to ascertain their physiological responses. Physiological measures of chlorophyll fluorescence, dark respiration, microscopic imaging, and lichen washes (as a proxy for membrane leakage), were measured throughout the exposure period. Results indicated that both species had similar sensitivities to O3 and HNO3. Both species registered physical damage during the O3 fumigation, as well as a decrease in respiration. Neither species showed major physical damage to HNO3, but both manifested a decrease in chlorophyll fluorescence, suggesting damage to the photosynthetic systems of the algae symbiont. These results suggest that both of these

  15. Model/Data Comparisons of NO2 and HNO3

    NASA Astrophysics Data System (ADS)

    Remsberg, E. E.; Natarajan, M.; Thompson, R. E.; Gordley, L. L.

    2001-05-01

    NASA Reference Publication 1292 [Prather and Remsberg, 1993] contains reports of the stratospheric model simulations of NOy for 1980, when the effects of volcanic aerosols on the partitioning of NOy should have been minimal. Those model runs included heterogeneous chemistry on background aerosols. Model values of NO2 and HNO3 were compared with those from the archived Nimbus 7 LIMS dataset, and the models exhibited the seasonal asymmetry that was observed for the LIMS HNO3. Still there were model/data differences that did not seem to be related solely to the variations among the model transport fields. Since then, we have updated the LIMS emissivity tables (spectroscopic parameters) and developed new algorithms for retrieving the profiles of the LIMS species, and we will show that there is improved agreement between these new data and the early results from most of the models. However, because there have also been improvements since 1992 in model transport of N2O and in the relevant chemical mechanisms for the generation and partitioning of NOy, it is recommended that the various models be rerun for the 1980 case and recompared with this latest version of the LIMS dataset.

  16. Redistribution of nitric acid in the Arctic lower stratosphere during the winter of 1996-1997

    NASA Astrophysics Data System (ADS)

    Irie, H.; Koike, M.; Kondo, Y.; Bodeker, G. E.; Danilin, M. Y.; Sasano, Y.

    2001-10-01

    Vertical profiles of HNO3, N2O, O3, and the aerosol extinction coefficient at 780 nm were observed by the Improved Limb Atmospheric Spectrometer (ILAS) on board the Advanced Earth Observing Satellite (ADEOS) during the Arctic winter of 1996-1997. Irreversible redistribution of HNO3 is evaluated using HNO3-N2O and HNO3-O3 correlations. Denitrification and nitrification started to be observed just after the Arctic vortex cooled to below the ice frost point (TICE) on February 10. Trajectory analyses show that denitrification occurred only in air masses, which were once cooled to near TICE and were kept at temperatures below the nitric acid trihydrate saturation threshold continuously for more than 4 days. Such a temperature history provides the necessary conditions for nucleation and growth of particles causing denitrification. The average extent of denitrification at 19 km reached 43% at the center of the vortex, suggesting that stratospheric ozone could be affected by denitrification deep inside the vortex. Denitrification (>2 ppbv) and nitrification (>1 ppbv) covered 40±10% and 35±10% of the vortex area, respectively. Redistributed numbers of HNO3 molecules at each altitude were calculated by integrating the area-weighted changes in the HNO3 concentration. The decreases in total HNO3 concentration at 17-21 km in late February and early March agreed with the increases at 12-15 km to within 25%, confirming conservation of HNO3 during sedimentation and evaporation of HNO3-containing polar stratospheric cloud particles.

  17. BrCl production in NaBr/NaCl/HNO3/O3 solutions representative of sea-salt aerosols in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Chapman, E. G.; Barchet, W. R.; Colson, S. D.; Howd, C. D.

    Atomic bromine and chlorine liberated from sea-salt aerosol is thought to play an important role in chemistry of the marine boundary layer. Despite numerous modeling studies, no prior experimental investigations of the oxidation of halide species contained in simulated, or actual, sea-salt solutions have been performed. We present laboratory data that examines chemistry in NaBr/NaCl/HNO3/O3 solutions at 290 K. Ozonation experiments were performed by flowing ozone in air through a nitric acid/salt solution and monitoring pH with time using an ion-sensitive electrode. The rate of oxidation was observed to be first order in ozone concentration and to have a non-first order bromide concentration dependence. Ion Chromatography was used to measure both bromide disappearance as well as oxidation products formed during the course of the reactions studied. Our measurements of the oxidation rate versus ion concentration indicate that the high ionic strength present in sea-salt aerosol will possess unique kinetics different from dilute solution behavior. In addition, our results are consistent with the reaction sequence O3 + H+ + Br- → O2 + HOBr and HOBr + Cl- + H+ → BrCl + H2O. These observations support the HOBr mediated Cl- oxidation process proposed previously (Vogt et al., 1996).

  18. Kinetics of heterogeneous reaction of CaCO3 particles with gaseous HNO3 over a wide range of humidity.

    PubMed

    Liu, Y; Gibson, E R; Cain, J P; Wang, H; Grassian, V H; Laskin, A

    2008-02-21

    Heterogeneous reaction kinetics of gaseous nitric acid (HNO3) with calcium carbonate (CaCO3) particles was investigated using a particle-on-substrate stagnation flow reactor (PS-SFR). This technique utilizes the exposure of substrate deposited, isolated, and narrowly dispersed particles to a gas mixture of HNO3/H2O/N2, followed by microanalysis of individual reacted particles using computer-controlled scanning electron microscopy with energy-dispersive X-ray analysis (CCSEM/EDX). The first series of experiments were conducted at atmospheric pressure, room temperature and constant relative humidity (40%) with a median dry particle diameter of Dp = 0.85 mum, particle loading densities 2 x 104 HNO3 concentrations of 7, 14, and 25 ppb. The apparent, pseudo first-order rate constant for the reaction was determined from oxygen enrichment in individual particles as a function of particle loading. Quantitative treatment of the data using a diffusion-kinetic model yields a lower limit to the net reaction probability gammanet >/= 0.06 (x3//2). In a second series of experiments, HNO3 uptake on CaCO3 particles of the same size was examined over a wide range of relative humidity, from 10 to 80%. The net reaction probability was found to increase with increasing relative humidity, from gammanet >/= 0.003 at RH = 10% to 0.21 at 80%.

  19. The reduction of HNO3 by volatile organic compounds emitted by motor vehicles

    NASA Astrophysics Data System (ADS)

    Rutter, A. P.; Malloy, Q. G. J.; Leong, Y. J.; Gutierrez, C. V.; Calzada, M.; Scheuer, E.; Dibb, J. E.; Griffin, R. J.

    2014-04-01

    Nitric acid (HNO3) was reduced in a flow tube by volatile organic carbon compounds (VOCs) generated from engine oil vapor. The primary reaction product was believed to be HONO. The reaction was not enhanced when Teflon® Raschig rings were added to the flow tube to increase surface area, thereby showing the reaction to be homogeneous under the conditions studied. The HONO formation observed ranged between 0.1 and 0.6 ppb h-1, with a mean of 0.3 ± 0.1 ppb h-1, for typical HNO3 concentrations of 4-5 ppb and estimated concentrations of the reactive components in the engine oil vapor between 200 and 300 ppt. The observations in this study compare well to a recently published field study conducted in Houston that observed average formation rates of 0.6 ± 0.3 ppb h-1. Water vapor was found to decrease the HONO formation rate by ˜0.1 ppb h-1 for every 1% increase in the water mixing ratio.

  20. The Reduction of HNO3 to HONO by Volatile Organic Compounds Associated with Rush Hour Traffic

    NASA Astrophysics Data System (ADS)

    Rutter, A. P.; Malloy, Q.; Scheuer, E.; Gutierrez, C.; Calzada, M.; Dibb, J. E.; Griffin, R. J.

    2012-12-01

    Nitrous acid (HONO) is an important source of OH radicals in urban environments. However, the sources of HONO are not completely understood, which makes modeling urban atmospheric chemistry difficult. During a previous field study in Houston, TX a correlation was observed between increases in HONO and organic aerosol freshly emitted by motor vehicle traffic during morning rush hours (Ziemba et al., 2010). This source of HONO could not be explained by primary HONO emissions, and the hypothesis was drawn that the HONO was being formed from the reduction of HNO3 by the organic aerosols emitted by motor vehicles. To test this hypothesis, nitric acid (HNO3) was combined in a flow tube with aerosols made from automobile engine oil, which were used as a model for the organic aerosols emitted by rush hour traffic. Reduction of the HNO3 to HONO was observed, although the reaction was found to occur with the volatile organic carbon compounds (VOCs) found in the aerosol vapor, and not the particle surfaces. To explore this further Teflon raschig rings were added to the flow tube to increase surface area but the reaction was not enhanced, confirming the reaction to be homogeneous. The HONO formation observed ranged between 0.1 and 0.5 ppb hr-1 with a mean of 0.3±0.1 ppb hr-1, for typical nitric acid concentrations of 4-5 ppb and estimated concentrations of the reactive components in the engine oil vapor of between 200 and 300 ppt. The observations in this study compared well to the cited field study which observed formation rates between 0.05 and 0.5 ppb hr-1 with an average of 0.3±0.15 ppb hr-1. Water vapor was found to decrease the HONO formation rate by 0.1 ppb hr-1 for every1% of increase in the water mixing ratio. Reference Ziemba L.D., Dibb J.E., Griffin R.J., Anderson C.H., Whitlow S.I., Lefer B.L., Rappenglueck B., and Flynn J. (2010) Heterogeneous conversion of nitric acid to nitrous acid on the surface of primary organic aerosol in an urban atmosphere. Atmospheric

  1. Laboratory studies of infrared absorption by NO2 and HNO3

    NASA Technical Reports Server (NTRS)

    Murcray, D. G.; Goldman, A.; Bonomo, F.

    1975-01-01

    Data concerning the quantitative absorption in the 11 and 22 micron region by HNO3 were obtained. Results are presented indicating the temperature dependence of these bands of HNO3 vapor. The 21.8 micron absorption bands of HNO3 vapor at 40 C are discussed along with the integrated intensity and line parameters for the 6.2 micron band of NO2.

  2. Aerosol chamber study of optical constants and N2O5 uptake on supercooled H2SO4/H2O/HNO3 solution droplets at polar stratospheric cloud temperatures.

    PubMed

    Wagner, Robert; Naumann, Karl-Heinz; Mangold, Alexander; Möhler, Ottmar; Saathoff, Harald; Schurath, Ulrich

    2005-09-15

    The mechanism of the formation of supercooled ternary H(2)SO(4)/H(2)O/HNO(3) solution (STS) droplets in the polar winter stratosphere, i.e., the uptake of nitric acid and water onto background sulfate aerosols at T < 195 K, was successfully mimicked during a simulation experiment at the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. Supercooled sulfuric acid droplets, acting as background aerosol, were added to the cooled AIDA vessel at T = 193.6 K, followed by the addition of ozone and nitrogen dioxide. N(2)O(5), the product of the gas phase reaction between O(3) and NO(2), was then hydrolyzed in the liquid phase with an uptake coefficient gamma(N(2)O(5)). From this experiment, a series of FTIR extinction spectra of STS droplets was obtained, covering a broad range of different STS compositions. This infrared spectra sequence was used for a quantitative test of the accuracy of published infrared optical constants for STS aerosols, needed, for example, as input in remote sensing applications. The present findings indicate that the implementation of a mixing rule approach, i.e., calculating the refractive indices of ternary H(2)SO(4)/H(2)O/HNO(3) solution droplets based on accurate reference data sets for the two binary H(2)SO(4)/H(2)O and HNO(3)/H(2)O systems, is justified. Additional model calculations revealed that the uptake coefficient gamma(N(2)O(5)) on STS aerosols strongly decreases with increasing nitrate concentration in the particles, demonstrating that this so-called nitrate effect, already well-established from uptake experiments conducted at room temperature, is also dominant at stratospheric temperatures.

  3. Measurement of OH, H2SO4, MSA, and HNO3 Aboard the P-3B Aircraft

    NASA Technical Reports Server (NTRS)

    Eisele, F. L.

    2003-01-01

    This paper addresses the measurement of OH, H2SO4, MSA, and HNO3 aboard the P-3B aircraft under the following headings: 1) Performance Report; 2) Highlights of OH, H2SO4, and MSA Measurements Made Aboard the NASA P-3B During TRACE-P; 3) Development and characteristics of an airborne-based instrument used to measure nitric acid during the NASA TRACE-P field experiment.

  4. Model development for naphthenic acids ozonation process.

    PubMed

    Al Jibouri, Ali Kamel H; Wu, Jiangning

    2015-02-01

    Naphthenic acids (NAs) are toxic constituents of oil sands process-affected water (OSPW) which is generated during the extraction of bitumen from oil sands. NAs consist mainly of carboxylic acids which are generally biorefractory. For the treatment of OSPW, ozonation is a very beneficial method. It can significantly reduce the concentration of NAs and it can also convert NAs from biorefractory to biodegradable. In this study, a factorial design (2(4)) was used for the ozonation of OSPW to study the influences of the operating parameters (ozone concentration, oxygen/ozone flow rate, pH, and mixing) on the removal of a model NAs in a semi-batch reactor. It was found that ozone concentration had the most significant effect on the NAs concentration compared to other parameters. An empirical model was developed to correlate the concentration of NAs with ozone concentration, oxygen/ozone flow rate, and pH. In addition, a theoretical analysis was conducted to gain the insight into the relationship between the removal of NAs and the operating parameters.

  5. Freezing temperatures of H2SO4/HNO3/H2O mixtures: Implications for polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Song, Naihui

    1994-01-01

    The freezing temperatures of H2SO4/HNO3/H2O mixtures were systematically documented. Nitric acid was found to affect freezing significantly. Measurements show that nitric acid can cause substantial supercooling over a broad composition range. However, some ternary compositions, like to those in polar stratospheric clouds (PSCs), have high freezing temperatures. The freezing of PSC particles could be controlled by the temperature and vapor pressure of both nitric acid and water in a non-linear way. Formation of polar stratospheric clouds may be forecasted on the basic of conditions of temperature and vapor contents of water and nitric acid.

  6. Enhanced performance of PEDOT:PSS/n-Si hybrid solar cell by HNO3 treatment

    NASA Astrophysics Data System (ADS)

    Zhao, Haiming; Xie, Dan; Feng, Tingting; Zhao, Yuanfan; Xu, Jianlong; Li, Xinming; Zhu, Hongwei; Ren, Tianling

    2014-03-01

    In this study, a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/n-Si hybrid solar cell is fabricated via spin coating and treatment with HNO3 vapor. It is found that after the HNO3 treatment, the hybrid solar cell shows much better performance with an open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (η) of 555.34 mV, 23.61 mA/cm2, 0.54, and 8.81%, respectively. The conversion efficiency is nearly two times larger than that before HNO3 treatment. The possible reason is that HNO3 could significantly reduce the resistivity of the spin-coated PEDOT:PSS. The effect of HNO3 treatment time on the PEDOT:PSS/n-Si HSC’s performance is also investigated.

  7. Observations and Modeling of Composition of Upper Troposphere/Lower Stratosphere (UTILS): Isentropic Mixing Events and Morphology of HNO3 as Observed by HIRDLS and Comparison with Results from Global Modeling Initiative

    NASA Technical Reports Server (NTRS)

    Rodriquez, J. M.; Douglass, A.R.; Yoshida, Y.; Strahan, S.; Duncan, B.; Olsen, M.; Gille, J.; Yudin, V.; Nardi, B.

    2008-01-01

    isentropic exchange of air masses between the tropical upper troposphere and mid-latitude lowermost stratosphere (the so-called "middle world") is an important pathway for stratospheric-tropospheric exchange. A seasonal, global view of this process has been difficult to obtain, in part due to the lack of the vertical resolution in satellite observations needed to capture the laminar character of these events. Ozone observations at a resolution of about 1 km from the High Resolution Dynamic Limb Sounder (HIRDLS) on NASA's Aura satellite show instances of these intrusions. Such intrusions should also be observable in HN03 observations; however, the abundances of nitric acid could be additionally controlled by chemical processes or incorporation and removal into ice clouds. We present a systematic examination of the HIRDLS data on O3 and HNO3 to determine the seasonal and spatial characteristics of the distribution of isentropic intrusions. At the same time, we compare the observed distributions with those calculated by the Global Modeling Initiative combined tropospheric-stratospheric model, which has a vertical resolution of about I km. This Chemical Transport Model (CTM) is driven by meteorological fields obtained from the GEOS-4 system of NASA/Goddard Global Modeling and Assimilation Office (GMAO), for the Aura time period, at a vertical resolution of about 1 km. Such comparison brings out the successes and limitations of the model in representing isentropic stratospheric-tropospheric exchange, and the different processes controlling HNO3 in the UTAS.

  8. Unveiling the shape-diversified silicon nanowires made by HF/HNO3 isotropic etching with the assistance of silver.

    PubMed

    Chen, Chia-Yun; Wong, Ching-Ping

    2015-01-21

    Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag(+)-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag(+) and NO3(-) ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.

  9. Measuring tropospheric HNO3 - Problems and prospects for Nylon filter and mist chamber techniques

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

    1990-01-01

    A series of laboratory and field measurements was performed to evaluate the mist chamber technique for determining tropospheric HNO3 concentrations. Both the mist chamber and standard Nylon filter techniques exhibit high collection efficiency and excellent agreement measuring HNO3 vapors from a permeation source. When simultaneously sampling ambient air in eastern Virginia, the Nylon filter measured an average of 70 percent higher HNO3 concentration than the mist chamber technique. The results indicate that O3 causes a low-level positive artifact interference in HNO3 measurements performed with the filter technique. This O3-induced error is small, however, compared to the large difference between atmospheric HNO3 concentrations determined with the two techniques. It is hypothesized that unidentified (organic?) nitrogen species in the atmosphere react for form NO3(-) on the filter and this phenomenon may interfere with Nylon filter measurements of HNO3 vapor. These potential interferences did not appear to affect measurements of HNO3 with the mist chamber method.

  10. FTIR Spectroscopy of HNO3 and NO2 Relevant to Stratospheric Wake Analysis

    NASA Technical Reports Server (NTRS)

    Abina, Rafiu A.; Misra, Prabhakar; Okabe, Hideo; Chu, P. M.; Sams, Robert L.

    1997-01-01

    The Fourier Transform Infrared (FTIR) technique has been employed to measure absolute concentrations of nitric acid (HNO3) and nitrogen dioxide (NO2) with 1/cm resolution and an absorption pathlength of 4 m under quasi-static and flow conditions at atmospheric pressure and room temperature. Water features seen under quasi-static conditions diminished in intensity under flowing conditions. Nitric acid was observed in the 1660-1760/cm range, while nitrogen dioxide was detected both in the 1536-1660 and 1213-1400/cm ranges. Concentrations of nitrogen dioxide and nitric acid were determined to be 11.9 and 4.35 parts per million (ppm), respectively, with an uncertainty of 0.2 ppm. Experiments are underway with a 10 m cell to measure the absorption of nitric acid, water, sulfur dioxide, hydrochloric acid and ammonia on various materials such as glass, teflon, stainless steel and aluminum used for implementation of the flow system. Such materials will be used for the measurements of stratospheric trace gases by the Quartz Crystal Microbalance (QCM) and Surface Acoustic Wave (SAW) devices.

  11. Temperature dependent absorption cross-sections of HNO3 and N2O5

    NASA Technical Reports Server (NTRS)

    Rattigan, Oliver V.; Harwood, Matthew H.; Jones, Rod L.; Cox, Richard A.

    1994-01-01

    Absorption cross-sections for HNO3 and N2O5 have been measured in the wavelength region 220-450 nm, using a dual beam diode array spectrometer with a spectral resolution of 0.3 nm. The results for both compounds are in good agreement with recommended values at room temperature. However, the cross-sections of both HNO3 and N2O5 show a marked reduction with decreasing temperature in the range 295-233 K. The calculated photolysis rate of HNO3 at the low temperatures and high solar zenith angles characteristic of the polar winter and spring is significantly lower than previously estimated.

  12. Measurements of HNO3 and N2O5 using ion drift-chemical ionization mass spectrometry during the MILAGRO/MCMA-2006 campaign

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Zhang, R.; Fortner, E. C.; Volkamer, R. M.; Molina, L.; Aiken, A. C.; Jimenez, J. L.; Gaeggeler, K.; Dommen, J.; Dusanter, S.; Stevens, P. S.; Tie, X.

    2008-11-01

    An ion drift-chemical ionization mass spectrometer (ID-CIMS) was deployed in Mexico City between 7 and 31 March to measure gas-phase nitric acid (HNO3) and dinitrogen pentoxide (N2O5 during the Mexico City Metropolitan Area (MCMA)-2006 field campaign. The observation site was located at the Instituto Mexicano del Petróleo in the northern part of Mexico City urban area with major emissions of pollutants from residential, vehicular and industrial sources. Diurnally, HNO3 was less than 200 parts per trillion (ppt) during the night and early morning. The concentration of HNO3 increased steadily from around 09:00 a.m. central standard time (CST), reached a peak value of 0.5 to 3 parts per billion (ppb) in the early afternoon, and then declined sharply to less than half of the peak value near 05:00 p.m. CST. An inter-comparison between the ID-CIMS and an ion chromatograph/mass spectrometer (ICMS) showed a good agreement between the two HNO3 measurements (R2=0.75). The HNO3 mixing ratio was found to anti-correlate with submicron-sized aerosol nitrate, suggesting that the gas-particle partitioning process was a major factor in determining the gaseous HNO3 concentration. Losses by irreversible reactions with mineral dust and via dry deposition also could be important at this site. Most of the times during the MCMA 2006 field campaign, N2O5 was found to be below the detection limit (about 30 ppt for a 10 s integration time) of the ID-CIMS, because of high NO mixing ratio at the surface (>100 ppb) during the night. An exception occurred on 26 March 2006, when about 40 ppt N2O5 was observed during the late afternoon and early evening hours under cloudy conditions before the build-up of NO at the surface site. The results revealed that during the MCMA-2006 field campaign HNO3 was primarily produced from the reaction of OH with NO2 and regulated by gas/particle transfer and dry deposition. The production of HNO3 from N2O5 hydrolysis during the nighttime was small because of

  13. Unveiling the shape-diversified silicon nanowires made by HF/HNO3 isotropic etching with the assistance of silver

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Yun; Wong, Ching-Ping

    2014-12-01

    Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag+-ion containing oxidants on Si etching, we have re-examined the state-of-the-art metal-assisted chemical etching (MaCE) using HF/AgNO3 etchants. In contrast with previous reports, we found that the interplay of hole injections from Ag+ and NO3- ions to the valence band of Si collectively contributes to the unidirectional dissolution of Si. Finally, we explored the engineering of the Ag nano-seeds to regularize the orientation of the etched nanowires formed on non-Si (100) wafers, which further provides a reliable pathway for constructing the desired morphologies of one-dimensional Si nanostructures regardless of wafer orientation.Hydrofluoric (HF)/nitric (HNO3)/acetic (CH3COOH) acid, normally referred to as the HNA method, is a widely utilized technique for performing isotropic etching on silicon (Si) in industrial Si-based processing and device construction. Here, we reported a novel etching strategy based on a HF/HNO3 process with the assistance of silver (Ag) nano-seeds, offering good controllability in preparing diversified Si nanostructure arrays with particularly smooth top surfaces. The involved mechanism was visualized by systematically investigating both the time and temperature dependencies on the etching kinetics with various ratios of HF to HNO3. Moreover, by testing different Ag

  14. MIPAS database: new HNO3 line parameters at 7.6  µm validated with MIPAS satellite measurements

    NASA Astrophysics Data System (ADS)

    Perrin, Agnès; Flaud, Jean-Marie; Ridolfi, Marco; Vander Auwera, Jean; Carlotti, Massimo

    2016-05-01

    Improved line positions and intensities have been generated for the 7.6 µm spectral region of nitric acid. They were obtained relying on a recent reinvestigation of the nitric acid band system at 7.6 µm and comparisons of HNO3 volume mixing ratio profiles retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) limb emission radiances in the 11 and 7.6 µm domains. This has led to an improved database called MIPAS-2015. Comparisons with available laboratory information (individual line intensities, integrated absorption cross sections, and absorption cross sections) show that MIPAS-2015 provides an improved description of the 7.6 µm region of nitric acid. This study should help to improve HNO3 satellite retrievals by allowing measurements to be performed simultaneously in the 11 and 7.6 µm micro-windows. In particular, it should be useful to analyze existing MIPAS and IASI spectra as well as spectra to be recorded by the forthcoming Infrared Atmospheric Sounding Interferometer - New Generation (IASI-NG) instrument.

  15. Investigation of Interfacial and Bulk Dissociation of HBr, HCl, and HNO3 Using Density Functional Theory-Based Molecular Dynamics Simulations

    SciTech Connect

    Baer, Marcel; Tobias, Douglas J.; Mundy, Christopher J.

    2014-12-18

    In this study we investigate the free energy barrier associated with the dissociation of strong acids, XH (HBr, HCl and HNO3) deprotonation, and subsequent formation of ionpairs, X–___H3O+ in the vicinity of the air-water interface. We will show that the free energy for acid dissociation for HCl and HNO3 show significant differences at the air-water than under bulk solvation conditions producing a picture where at the interface associated molecular species can be stable. For the strongest acid we consider, HBr the more traditional picture of acids is preserved in the vicinity of the air-water interface. Our results have implications for our understanding of acids, and their surface tensions at the air-water interface.

  16. A role of HNO3 on transparent conducting film with single-walled carbon nanotubes.

    PubMed

    Shin, Dong-Wook; Lee, Jong Hak; Kim, Yu-Hee; Yu, Seong Man; Park, Seong-Yong; Yoo, Ji-Beom

    2009-11-25

    There is some controversy regarding the effects of HNO3 on films of single-walled carbon nanotubes (SWCNTs). In this study we examined the change in sheet resistance of an HNO3-modified SWCNT film after different drying times at 85 degrees C using various analytical techniques. The shift and suppression in the Raman spectra, bleaching of the transition peaks related to van Hove singularities and a shift in the original peak in the C 1s XPS spectra provided evidence for p-type doping. A decrease in sheet resistance was also observed in the SWCNTs films due to the removal of residual N-methylpyrrolidone solvent on the surface and bundle of SWCNTs. These results suggest that p-type doping has a larger effect on the sheet resistance than the removal of residual N-methylpyrrolidone by an HNO3 treatment.

  17. Uptake of HNO3 to Deliquescent Sea-Salt and Mineral Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Guimbaud, C.; Vlassenko, A.; Gaggeler, H.; Ammann, M.

    2002-12-01

    Uptake of HNO3 to aerosol particles is an important removal pathway of nitrogen oxides in the troposphere. Uptake of HNO3 to deliquescent sea-salt aerosol particles was studied in an aerosol flow reactor. Submicron sea-salt particles were used to avoid diffusion limitation in the gas-phase at atmospheric pressure. To overcome the sensitivity problems associated with low amount of reactants processed in such low aerosol masses, we used the short-lived radioactive tracer 13N to label the trace gas molecules at very low concentration. Uptake of HNO3 to deliquescent sea-salt particles was studied under a wide range of HNO3 concentration. Between 1 and 60 ppbv, the uptake coefficient was constant at 0.5+/-0.2 within the first few seconds, whereas at higher concentrations of about 600ppbv, the uptake coefficient rapidly dropped to 0.1 after about 1 second. This drop was due to complete release of chloride as HCl. The equilibrium conditions for these experiments were explored using the North American Aerosol Inorganics (AIM) model, which accounts for the activities of the concentrated solution of the deliquescent aerosol. It is concluded that the rates of uptake at low concentration were limited by the mass accommodation coefficient as both the diffusion in the liquid phase or the rate of release of HCl were not rate limiting. Using an identical approach, we started to investigate the uptake of HNO3 to mineral dust aerosol particles in a similar flow reactor, and first results will be presented. References Ammann, M, Using 13N as tracer in heterogeneous atmospheric chemistry experiments, Radiochim. Acta., 89, 831-838, 2001 Guimbaud, C., F., Arens, L., Gutzwiller, H.W, Gäggeler, and M. Ammann, Uptake of HNO3 to Deliquescent Sea-Salt Aerosol Particles, Atmos. Chem. Phys. Discuss., 2, 739-763, 2002

  18. Time Series of Trace Gas Profiles of O3, N2o, Ch4, Hf, Hcl, and Hno3 As Retrieved From Ground Based Ftir Observations In Winter 2000/2001 and 2001/2002 At Kiruna (sweden)

    NASA Astrophysics Data System (ADS)

    Griesfeller, A.; Blumenstock, T.; Hase, F.; Höpfner, M.; Ruhnke, R.; Arvelius, J.; Raffalski, U.; Kondo, Y.

    Atmospheric absorption spectra using the sun as the source of radiation were recorded by ground based FTIR (Fourier Transform InfraRed) spectrometers at Kiruna (Swe- den, 68N, 20E) during winter and early spring since winter 1990. Since March 1996 a Bruker 120 HR is in operation at the IRF (Swedish Institute of Space Physics). It is operated permanently and it is part of the NDSC (Network for the Detection of Strato- spheric Change). The FTIR spectra have been analyzed with the radiative transfer code KOPRA (Karlsruhe Optimized and Precise Radiative transfer Algorithm) and the re- trieval code PROFFIT (Profile Fit) using Tikhonov-Phillips approach. Zenith column amounts (ZCA) of several trace gases like O3, N2O, CH4, HF, HCl, ClONO2, NO, NO2, and HNO3 have been derived from these spectra. In case of some important species as O3, N2O, CH4, HF, HCl, and HNO3 also reasonable information on the vertical concentration profiles can be derived. Since winter 1999/2000 data analysis is performed in near real time during the campaigns. These time series of ZCA and profiles will be presented for the winters of 2000/2001 and 2001/2002 and discussed in terms of chlorine activation and deactivation, ozone loss, and sequestration of ni- tric acid in PSCs in the polar vortex. Winter 2000/2001 is of interest due to a long lasting break-up of the polar vortex. Therefore a great variability in many gases is ob- served and will be discussed. In addition the results will be compared to results from KASIMA (Karlsruhe Simulation Model of the Middle Atmosphere).

  19. HNO3 and HCl amounts over McMurdo during the spring of 1987

    NASA Technical Reports Server (NTRS)

    Murcray, Frank J.; Goldman, Aaron; Blatherwick, Ronald; Matthews, Andrew; Jones, Nicholas

    1989-01-01

    Infrared solar spectra were obtained from the ground at McMurdo, Antarctica, during September and October 1987. Absorption features due to HNO3 and HCl have been analyzed to determine the vertical column content of these compounds for the days when observations were made. The variation of these column amounts with time is presented and discussed.

  20. Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase.

    PubMed

    Bohli, Thouraya; Ouederni, Abdelmottaleb

    2016-08-01

    Recently, modification of surface structure of activated carbons in order to improve their adsorption performance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O3) and in liquid phase using nitric acid (HNO3). The activated carbon samples were characterized using N2 adsorption-desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated carbon parent (COSAC) has a high surface area of 1194 m(2)/g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a decrease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich-Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO3), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems.

  1. Observations of total RONO2 over the boreal forest: NOx sinks and HNO3 sources

    NASA Astrophysics Data System (ADS)

    Browne, E. C.; Min, K.-E.; Wooldridge, P. J.; Apel, E.; Blake, D. R.; Brune, W. H.; Cantrell, C. A.; Cubison, M. J.; Diskin, G. S.; Jimenez, J. L.; Weinheimer, A. J.; Wennberg, P. O.; Wisthaler, A.; Cohen, R. C.

    2013-01-01

    In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (ΣANs) from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questions concerning the chemical lifetime and ultimate fate of ΣANs. We present observations of nitrogen oxides and organic molecules collected over the Canadian boreal forest during the summer that show that ΣANs account for ~ 20% of total oxidized nitrogen and that their instantaneous production rate is larger than that of HNO3. This confirms the primary role of reactions producing ΣANs as a control over the lifetime of NOx (NOx = NO + NO2) in remote, continental environments. However, HNO3 is generally present in larger concentrations than ΣANs indicating that the atmospheric lifetime of ΣANs is shorter than the HNO3 lifetime. We investigate a range of proposed loss mechanisms that would explain the inferred lifetime of ΣANs finding that in combination with deposition, two processes are consistent with the observations: (1) rapid ozonolysis of isoprene nitrates where at least ~ 40% of the ozonolysis products release NOx from the carbon backbone and/or (2) hydrolysis of particulate organic nitrates with HNO3 as a product. Implications of these ideas for our understanding of NOx and NOy budget in remote and rural locations are discussed.

  2. Observations of total RONO2 over the boreal forest: NOx sinks and HNO3 sources

    NASA Astrophysics Data System (ADS)

    Browne, E. C.; Min, K.-E.; Wooldridge, P. J.; Apel, E.; Blake, D. R.; Brune, W. H.; Cantrell, C. A.; Cubison, M. J.; Diskin, G. S.; Jimenez, J. L.; Weinheimer, A. J.; Wennberg, P. O.; Wisthaler, A.; Cohen, R. C.

    2013-05-01

    In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (ΣANs) from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questions concerning the chemical lifetime and ultimate fate of ΣANs. We present observations of nitrogen oxides and organic molecules collected over the Canadian boreal forest during the summer which show that ΣANs account for ~20% of total oxidized nitrogen and that their instantaneous production rate is larger than that of HNO3. This confirms the primary role of reactions producing ΣANs as a control over the lifetime of NOx (NOx = NO + NO2) in remote, continental environments. However, HNO3 is generally present in larger concentrations than ΣANs indicating that the atmospheric lifetime of ΣANs is shorter than the HNO3 lifetime. We investigate a range of proposed loss mechanisms that would explain the inferred lifetime of ΣANs finding that in combination with deposition, two processes are consistent with the observations: (1) rapid ozonolysis of isoprene nitrates where at least ~40% of the ozonolysis products release NOx from the carbon backbone and/or (2) hydrolysis of particulate organic nitrates with HNO3 as a product. Implications of these ideas for our understanding of NOx and NOy budget in remote and rural locations are discussed.

  3. Uric acid protects erythrocytes from ozone-induced changes.

    PubMed

    Meadows, J; Smith, R C

    1987-08-01

    Uric acid effectively reduced hemolysis and methemoglobin formation in bovine and swine erythrocytes bubbled with ozone in vitro. In bovine erythrocytes, formation of thiobarbituric acid-reactive material was inhibited by uric acid, but there was little immediate protection for the swine cells. Antioxidant protection was due to preferential degradation of the uric acid by ozone. These results provide evidence to support the hypothesis that in plasma, uric acid can provide antioxidant protection for erythrocytes.

  4. Comparing data obtained from ground-based measurements of the total contents of O3, HNO3,HCl, and NO2 and from their numerical simulation

    NASA Astrophysics Data System (ADS)

    Virolainen, Ya. A.; Timofeyev, Yu. M.; Polyakov, A. V.; Ionov, D. V.; Kirner, O.; Poberovskii, A. V.; Imhasin, H. Kh.

    2016-01-01

    Chemistry climate models of the gas composition of the atmosphere make it possible to simulate both space and time variations in atmospheric trace-gas components (TGCs) and predict their changes. Both verification and improvement of such models on the basis of a comparison with experimental data are of great importance. Data obtained from the 2009-2012 ground-based spectrometric measurements of the total contents (TCs) of a number of TGCs (ozone, HNO3, HCl, and NO2) in the atmosphere over the St. Petersburg region (Petergof station, St. Petersburg State University) have been compared to analogous EMAC model data. Both daily and monthly means of their TCs for this period have been analyzed in detail. The seasonal dependences of the TCs of the gases under study are shown to be adequately reproduced by the EMAC model. At the same time, a number of disagreements (including systematic ones) have been revealed between model and measurement data. Thus, for example, the EMAC model underestimates the TCs of NO2, HCl, and HNO3, when compared to measurement data, on average, by 14, 22, and 35%, respectively. However, the TC of ozone is overestimated by the EMAC model (on average, by 12%) when compared to measurement data. In order to reveal the reasons for such disagreements between simulated and measured data on the TCs of TGCs, it is necessary to continue studies on comparisons of the contents of TGCs in different atmospheric layers.

  5. Gas phase spectroscopy of HNO3 in the region 2000-8500 cm(-1).

    PubMed

    Feierabend, K J; Havey, D K; Vaida, V

    2004-10-01

    Spectra of gas phase HNO3 were collected in the region 2000-8500 cm(-1) using Fourier-transform infrared spectroscopy. This region is dominated by the nu1 O-H stretching mode but also contains many previously unreported combination bands and overtones. This work marks the first observation of Fermi resonance the 2nu1 O-H stretching overtone. Previously unobserved bands were assigned and integrated intensities were obtained. For bands already reported in the literature, comparisons of relative intensities are presented when possible. This work gives a brief discussion on the trends in overtone intensities and on mode mixing in HNO3 in relation to previous experimental and theoretical studies.

  6. Stratospheric H2O and HNO3 profiles derived from solar occultation measurements

    NASA Astrophysics Data System (ADS)

    Fischer, H.; Fergg, F.; Rabus, D.; Burkert, P.

    1985-04-01

    Compact two-channel radiometers for solar occultation experiments have been constructed in order to measure stratospheric trace gases. The instruments can be used as filter- or correlation-type radiometers, depending on the trace gas under investigation. Within the LIMS correlative measurement program, balloon flights were performed with a payload of up to four of these two-channel radiometers. From the filter-type measurements, profiles of the trace gases H2O and HNO3 are inferred for the height region between the tropopause and the balloon float level. The data evaluation also includes a comprehensive analysis of the error sources and their effect on the accuracy of the trace gas profiles. The derived H2O and HNO3 profiles are assessed against the observations of other authors and are discussed in the light of the trace gas distributions calcualted from photochemical models.

  7. The transport of atmospheric NOx and HNO3 over Cape Town

    NASA Astrophysics Data System (ADS)

    Abiodun, B. J.; Ojumu, A. M.; Jenner, S.; Ojumu, T. V.

    2014-01-01

    Cape Town, the most popular tourist city in Africa, usually experiences air pollution with unpleasant odour in winter. Previous studies have associated the pollution with local emission of pollutants within the city. The present study examines the transport of atmospheric pollutants (NOx and HNO3) over South Africa and shows how the transport of pollutants from the Mpumalanga Highveld, a major South African industrial area, may contribute to the pollution in Cape Town. The study analysed observation data (2001-2008) from the Cape Town air-quality network and simulation data (2001-2004) from a regional climate model (RegCM) over southern Africa. The simulation accounts for the influence of complex topography, atmospheric conditions, and atmospheric chemistry on emission and transport of pollutants over southern Africa. Flux budget analysis was used to examine whether Cape Town is a source or sink for NOx and HNO3 during the extreme pollution events. The results show that extreme pollution events in Cape Town are associated with the lower level (surface - 850 hPa) transport of NOx from the Mpumalanga Highveld to Cape Town, and with a tongue of high concentration of HNO3 that extends from the Mpumalanga Highveld to Cape Town along the south coast of South Africa. The prevailing atmospheric conditions during the extreme pollution events feature an upper-level (700 hPa) anticyclone over South Africa and a lower-level col over Cape Town. The anticyclone induces a strong subsidence motion, which prevents vertical mixing of the pollutants and caps high concentration of pollutants close to the surface as they are transported from the Mpumalanga Highveld toward Cape Town. The col accumulates the pollutants over the city. This study shows that Cape Town can be a sink for the NOx and HNO3 during extreme pollution events and suggests that the accumulation of pollutants transported from other areas (e.g. the Mpumalanga Highveld) may contribute to the air pollution in Cape Town.

  8. Coupled Variations in HNO3 and Soluble Gas Phase Chloride in the Houston Region

    NASA Astrophysics Data System (ADS)

    Dibb, J. E.; Corr, C. A.; Lefer, B. L.; Flynn, J. H.

    2010-12-01

    The University of New Hampshire mist chamber/ion chromatography (MC/IC) system was operated on the north Moody Tower as part of the Study of Houston Atmospheric and Radical Precursors (SHARP) during April-May, 2009. The MC/IC system provided 5-minute resolution measurements of HONO, HNO3, and soluble gas phase chloride (soluble Cl-) throughout the intensive campaign. Several other papers in this session discuss the HONO results, here we focus on HNO3, and soluble Cl-. These gases were highly correlated on short (minutes to hours time scales) throughout the SHARP campaign but anticorrelated when binned by broad wind direction sectors. Peak mixing ratios of HNO3, occurred during transport from the north and east and minima were observed under southerly flow, with the opposite true for soluble Cl-, yet strong correlation from sample to sample and diurnally were observed regardless of wind direction. It should be noted that the mixing ratios of soluble Cl- are substantial in Houston. Even during intervals with sustained northerly flow (relatively low Cl-) daytime maxima routinely exceeded 1 ppbv. Similar observations made during TexAQS 2006 on the Moody Tower and the NOAA vessel Ronald H Brown indicate that abundant soluble Cl-, linked with HNO3, by processes not yet understood, is characteristic of the Houston-Galveston Bay region during both spring and summer. Limited data on bulk aerosol composition at Moody Tower suggest that displacement of HCl from sea salt is not sufficient to account for all of the soluble Cl- observed in Houston.

  9. Simulations of the Vertical Redistribution of HNO3 by NAT or NAD PSCs: The Sensitivity to the Number of Cloud Particles Formed and the Cloud Lifetime

    NASA Technical Reports Server (NTRS)

    Jensen, Eric J.; Tabazadeh, Azadeh; Drdla, Katja; Toon, Owen B.; Gore, Warren J. (Technical Monitor)

    2000-01-01

    Recent satellite and in situ measurements have indicated that limited denitrification can occur in the Arctic stratosphere. In situ measurements from the SOLVE campaign indicate polar stratospheric clouds (PSCs) composed of small numbers (about 3 x 10^ -4 cm^-3) of 10-20 micron particles (probably NAT or NAD). These observations raise the issue of whether low number density NAT PSCs can substantially denitrify the air with reasonable cloud lifetimes. In this study, we use a one dimensional cloud model to investigate the verticle redistribution of HNO3 by NAT/NAD PSCs. The cloud formation is driven by a temperature oscillation which drops the temperature below the NAT/NAD formation threshold (about 195 K) for a few days. We assume that a small fraction of the available aerosols act as NAT nuclei when the saturation ratio of HNO3 over NAT(NAD) exceeds 10(l.5). The result is a cloud between about 16 and 20 km in the model, with NAT/NAD particle effective radii as large as about 10 microns (in agreement with the SOLVE data). We find that for typical cloud lifetimes of 2-3 days or less, the net depletion of HNO3 is no more than 1-2 ppbv, regardless of the NAT or NAD particle number density. Repeated passes of the air column through the cold pool build up the denitrification to 3-4 ppbv, and the cloud altitude steadily decreases due to the downward transport of nitric acid. Increasing the cloud lifetime results in considerably more effective denitrification, even with very low cloud particle number densities. As expected, the degree of denitrification by NAT clouds is much larger than that by NAD Clouds. Significant denitrification by NAD Clouds is only possible if the cloud lifetime is several days or more. The clouds also cause a local maximum HNO3 mixing ratio at cloud base where the cloud particles sublimate.

  10. Measurements of NO2, SO2, NH3, HNO3 and O3 in West African urban environments

    NASA Astrophysics Data System (ADS)

    Adon, Marcellin; Yoboué, Véronique; Galy-Lacaux, Corinne; Liousse, Catherine; Diop, Babakar; Doumbia, El Hadji Thierno; Gardrat, Eric; Ndiaye, Seydi Ababacar; Jarnot, Christian

    2016-06-01

    In this paper, we present the measurements of atmospheric gas concentrations of NO2, SO2, NH3, HNO3, and O3 performed at two traffic sites in the context of the POLCA (Pollution of African Capitals) program. These gases were measured using a passive sampling technique from Jan. 2008 to Dec. 2009 at Dakar and from Jun. 2008 to Dec. 2009 at Bamako. In addition, during these periods there were two intensive measurement campaigns (from 19 Jan. to 2 Feb. 2009 at Bamako and from 30 Nov. to 13 Dec. 2009 at Dakar) where real-time active analysers were used to measure NO2 and SO2. Results show that Dakar has a pollution level for NO2 and SO2 higher than that of Bamako, whereas it is lower for NH3 concentrations. Monthly values of NO2 range between 21.1 and 43.5 ppb in Dakar with an annual mean concentration of 31.7 ppb (59.6 μg/m3). NO2 values in Bamako are 9.4-22.6 ppb with a mean of 16.2 ppb. At Dakar, the mean annual NO2 limit value (21.3 ppb or 40 μg/m3) recommended by the World Health Organization (WHO) is widely exceeded. The mean annual concentration of SO2 is 15.9 ppb in Dakar and 3.6 ppb in Bamako. These differences may be explained by different sources of traffic between Bamako (with mainly gasoline vehicles) and Dakar (with mainly diesel vehicles). The annual mean NH3 concentration is about two times higher in Bamako (46.7 ppb) than in Dakar (21.1 ppb). In addition to other possible sources, we assume that the ammonia from domestic fires and uncontrolled garbage incineration may have more influence at Bamako than at Dakar. The mean annual concentrations of HNO3 and O3 are 1.3 ppb and 7.7 ppb in Dakar and 0.6 ppb and 5.1 ppb in Bamako, respectively. Seasonal variation in measured gas concentrations are low in Bamako and more pronounced in Dakar, except for HNO3 and NH3. At Dakar, NO2 and SO2 daily mean concentrations are higher during the weekdays than on weekends, when urban activities are reduced, whereas at Bamako, no significant difference was observed

  11. Ozone and the peroxidation of polyunsaturated fatty acids in vivo

    SciTech Connect

    Goheen, S.C.; O'Rourke, L.; Larkin, E.C.

    1986-06-01

    Two experiments were carried out to determine whether ozone causes significant oxidation of pulmonary polyunsaturated fatty acids in vivo. These involved ad libitum and pair-feeding. In the first experiment, rats were fed fat-free diets and exposed to ozone for 0, 1, 2, and 4 weeks. Lung and liver fatty acids were analyzed to determine if the rats exposed to ozone lost essential fatty acids more rapidly than those exposed to filtered air. In the second experiment, rats were divided into four groups. Two of these groups were fed fat-free diets, and two were fed diets containing essential fatty acids. Rats from the two diet groups (one of each type) were exposed to ozone, while the remaining two groups were exposed to filtered air. In the second experiment, rats were pair-fed. The amounts of lung and liver fatty acids were relatively uninfluenced by breathing ozone. Results from these experiments demonstrate that in the lung, the polyunsaturated fatty acids, linoleic and arachidonic acids, appear to be oxidized by filtered air and ozone at essentially the same rate.

  12. Photocatalytic ozonation of phenolic wastewaters: Syringic acid, tyrosol and gallic acid.

    PubMed

    Gimeno, Olga; Fernandez, Lidia A; Carbajo, Maria; Beltran, Fernando; Rivas, Javier

    2008-01-01

    The photocatalytic ozonation of a mixture of 3 phenols (gallic acid, tyrosol and syringic acid) has been conducted under different operating conditions. The individual adsorption of the phenol type compounds onto titanium dioxide (photocatalyst) has been first evaluated. Equilibrium conditions are attained in less than an hour while the isotherm curves reveal that adsorption intensity increases in order: syringic acid < tyrosol < gallic acid. When the photocatalytic ozonation is applied, an optimum in titanium dioxide concentration is experienced (1.5 g L(-1)). Direct comparison of the photocatalytic ozonation to other less sophisticated oxidation systems (i.e., single ozonation, catalytic ozonation, photo-ozonation, etc.) indicates a higher efficiency of the former in terms of ozone uptake.

  13. Inactivation of H1N1 viruses exposed to acidic ozone water

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Lee, Kwang H.; Seong, Baik L.

    2009-10-01

    The inactivation of H1N1 viruses upon exposure to acidic ozone water was investigated using chicken allantoic fluids of different dilutions, pH values, and initial ozone concentrations. The inactivation effect of the acidic ozone water was found to be stronger than the inactivation effect of the ozone water combined with the degree of acidity, indicating a synergic effect of acidity on ozone decay in water. It is also shown that acidic ozone water with a pH value of 4 or less is very effective means of virus inactivation if provided in conjunction with an ozone concentration of 20 mg/l or higher.

  14. Composition-dependent freezing nucleation rates for HNO3/H2O aerosols resembling gravity-wave-perturbed stratospheric particles

    NASA Astrophysics Data System (ADS)

    Prenni, Anthony J.; Onasch, Timothy B.; Tisdale, Robert T.; Siefert, Ronald L.; Tolbert, Margaret A.

    1998-11-01

    Laboratory measurements are presented for the freezing kinetics of H2O/HNO3 aerosols over the temperature range of 188-204 K. For 2:1 H2O:HNO3 aerosols crystallizing to NAD we observed a maximum nucleation rate of J = 9.3×109 cm-3 s-1 at 194 K. This temperature is between the glass point of 161 K [Ji et al., 1993] and the melting point of 235.5 K [Ji et al., 1996]. This can be compared to a previous measurement of J = 6.7×109 cm-3 s-1 at 193 K [Disselkamp et al., 1996] and lower temperature measurements of J ≈ 1010-1012 cm-3 s-1 at 178.8 - 175.8 K [Bertram and Sloan, 1998a]. Measured nucleation rates decrease as the aerosol becomes dilute, but NAD formation is still observable for 2.5:1 H2O:HNO3 at temperatures near 195 K. In contrast, freezing of 3:1 H2O:HNO3 aerosol was not observed for constant temperature experiments throughout this temperature range, yielding an upper limit of J<1.5×109 cm-3 s-1. This is the lowest experimental value determined for 3:1 H2O:HNO3 freezing rates at these temperatures. From the measured freezing rates and knowledge of the free energy of diffusion the average interfacial free energy for NAD in a 2:1 H2O:HNO3 solution was determined to be σ = 25.2 ergs cm-2. A limit for the interfacial free energy was placed on 3:1 H2O:HNO3 particles, for which freezing was not observed. These data imply that if aerosols reach compositions more concentrated than 3:1 H2O:HNO3 in the atmosphere, NAD may play a role in polar stratospheric cloud formation.

  15. Simultaneous ozonation kinetics of phenolic acids present in wastewaters

    SciTech Connect

    Benitez, F.J.; Beltran-Heredia, J.; Acero, J.L.; Pinilla, M.L.

    1996-12-31

    Among the several chemical processes conducted for the removal of organic matter present in wastewaters coming from some agro-industrial plants (wine distilleries, olive oil mills, etc), the oxidation by ozone has shown a great effectiveness in the destruction of specially refractory pollutants: it is demonstrated that the biodegradability of those wastewaters increases aflcer an ozonation pretreatment. Their great pollutant character is imputed to the presence of some organic compounds, like phenols and polyphenols, which are toxic and inhibit the latter biological treatments. In this research, a competitive kinetic procedure reported by Clurol and Nekouinaini is applied to determine the degradation rate constants by ozone of several phenolic acids which are present in the wastewaters from the olive oil obtaining process. The resulting kinetic expressions for the ozonation reactions are useful for the successful design and operation of ozone reactors in water and wastewaters treatment plants.

  16. Investigation of catalytic reduction and filter techniques for simultaneous measurements of NO, NO2, and HNO3 in the stratosphere

    NASA Technical Reports Server (NTRS)

    Wendt, J.; Fabian, Peter; Flentje, G.; Kourtidis, K.

    1994-01-01

    A concept for measuring stratospheric NOy-species is presented which utilizes the catalytic reduction of NO2 and HNO3 over heated metal catalysts and the chemisorption of HNO3 on Nylon. Using the Max Planck Institute for Aeronomy (MPAE) chemiluminescent balloon-borne sonde, stratospheric NO and NO2 profiles have been measured since 1983. NO is detected by chemiluminescence produced in reaction with O3 while NO2 needs first to be converted to NO over a heated stainless steel catalyst. To improve this technique for simultaneously measuring HNO3, the catalytic reduction of NO2 and HNO3 over several metal catalysts and the chemisorption of NO2 and HNO3 on Nylon have been investigated in laboratory tests. The results of these tests under simulated stratospheric conditions are presented in detail in this paper. They demonstrate that the simultaneous measurement of NO, NO2 and HNO3 is indeed possible with the combination of stainless steel or Au as a catalyst and a nylon filter.

  17. Removal of oxalic acid, oxamic acid and aniline by a combined photolysis and ozonation process.

    PubMed

    Orge, C A; Faria, J L; Pereira, M F R

    2015-01-01

    Aniline (ANL), an aromatic amine, oxalic acid (OXA) and oxamic acid (OMA), short-chain carboxylic acids, were chosen as model organic pollutants for testing the combined effect of neat photolysis and ozonation in the treatment of aqueous effluents. In order to better understand the results, single ozonation and neat photolysis were also carried out. OXA has a high refractory character relatively to single ozonation and neat photolysis only accounted for 26% conversion of OXA after 2 h of reaction. On the other hand, OXA complete degradation was observed in less than an hour when ozone and light were used simultaneously. Despite OMA, a compound never studied before by a combined ozonation and photolysis treatment, being highly refractory to oxidation, more than 50% was removed by photo-ozonation after 3 h of reaction. In the case of ANL, both single ozonation and photo-ozonation resulted in 100% removal in a short reaction period due to the high reactivity of ozone to attack this type of molecules; however, only the combined method leads to efficient mineralization (89%) after 3 h of reaction. A significant synergetic effect was observed in the degradation of the selected contaminants by the simultaneous use of ozone and light, since the mineralization rate of combined method is higher than the sum of the mineralization rates of the individual treatments. The promising results observed in the degradation of the selected contaminants are paving the way to the application of photo-ozonation in the treatment of wastewater containing this type of pollutants.

  18. [Characteristics of acid red 3R wastewater treatment by ozone microbubbles].

    PubMed

    Zhang, Jing; Du, Ya-Wei; Liu, Xiao-Jing; Zhou, Yu-Wen; Liu, Chun; Yang, Jing-Liang; Zhang, Lei

    2015-02-01

    The application of microbubble technology for ozonation wastewater treatment could enhance ozone mass transfer, improve ozonation performance and increase ozone utilization efficiency. The ozone microbubbles were used to treat synthetic acid red 3R wastewater in the present study, and compared to ozone conventional bubbles. The ozone mass transfer and ozonation characteristics of acid red 3R were investigated when ozone microbubbles and ozone conventional bubbles were applied. The results confirmed the enhanced ozone mass transfer using microbubbles. The ozone mass transfer coefficient using microbubbles was 3.6 times higher than that using conventional bubbles under the same conditions. Simultaneously, the ozone decomposition coefficient using microbubbles was 6.2 times higher than that using conventional bubbles, which would be favorable for *OH generation. The ozonation rate and mineralization efficiency of acid red 3R could be improved significantly using ozone microbubbles. A TOC removal efficiency of 78.0% was achieved using ozone microbubbles, which was about 2 times higher than that using ozone conventional bubbles. The ozone utilization efficiency using microbubbles was much higher that using conventional bubbles during ozonation treatment of acid red 3R. The average ozone utilization efficiencies were 97.8% and 69.3% when microbubbles and conventional bubbles were used, respectively. The oxidative ability of ozone microbubbles could be increased by enhancing *OH generation, and as a result, the oxidative reaction of degradation intermediates was accelerated by ozone microbubbles. Especially, the mineralization ability of small organic acid intermediates using ozone microbubbles was about 1.6 times higher than that using ozone conventional bubbles.

  19. Increase in the ozone decay time in acidic ozone water and its effects on sterilization of biological warfare agents.

    PubMed

    Uhm, Han S; Hong, Yi F; Lee, Han Y; Park, Yun H

    2009-09-15

    The sterilization properties of ozone in acidic water are investigated in this study. Acidification of water increases the ozone decay time by several times compared to the decay time in neutral water, thereby enhancing the sterilization strength of ozone in acidic water. A simple analytical model involving the viable microbial counts after contact with acidic ozone water was derived, and a sterilization experiment was conducted on bacterial cells using the acidic ozone water. The acidic ozone water was found to kill very effectively endospores of Bacillus atrophaeus ATCC 9372, thereby demonstrating the potential for disinfection of a large surface area in a very short time and for reinstating the contaminated environment as free from toxic biological agents.

  20. The determination of HNO3 column amounts from tunable diode laser heterodyne spectrometer spectra taken at Jungfruajoch, Switzerland

    NASA Technical Reports Server (NTRS)

    Fogal, P. F.; Murcray, D. G.; Martin, N. A.; Swann, N. R.; Woods, P. T.; Mcelroy, C. T.

    1994-01-01

    In May of 1991 a tunable diode laser heterodyne spectrometer built by the National Physical Laboratory was operated at the International Scientific Station of the Jungfraujoch (46.5 deg N, 8.0 deg E, altitude 3.56 km). Nitric acid spectra in the region of 868 wavenumbers were recorded at sunset and sunrise on two separate days at a resolution of 0.0013 wavenumbers with a signal-to-noise ratio of approximately 130:1. A vertical column amount of HNO3 of 1.61 x 10(exp 16) molecules/sq cm was determined using an atmospheric transmission model developed at the University of Denver. The mean of a number of mid-latitude, northern hemisphere profiles was used as the initial profile for the inversion. A comparison of different initial profiles provides information on the sensitivity of the retrieved column amount of 1.61 x 10(exp 16) molecules/sq cm lies within the range of values published in the World Meteorological Organization Report no. 16 (1986), but is considerably larger than the value of (0.99 - 1.29) x 10(exp 16) reported by Rinsland et al. (1991) for June during the period 1986 to 1990.

  1. The effect of HNO3 on morphology, phase transformation, and luminescence properties of LaPO4:Eu3+ phosphors

    NASA Astrophysics Data System (ADS)

    Zhou, Ruisen; Lv, Meng; Li, Xia

    2016-01-01

    LaPO4:Eu3+ powders with different morphologies were hydrothermally constructed by adjusting the amount of HNO3 without using a catalyst, surfactant, or template. The as-prepared products were characterized by photoluminescence spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), infrared (IR) spectra, and X-ray photoelectron spectroscopy. The SEM study revealed that the amount of HNO3 played a crucial role in the morphology of the final products. The XRD results indicated that the as-prepared samples were in the monoclinic phase when 3 mL of HNO3 was used. The HR-TEM micrographs and SAED results demonstrated that the prepared nanorods were single and crystalline in nature with HNO3, and that they grew preferentially along the [0 1 2] direction. The emission spectra showed that the LaPO4:Eu3+ samples had the strongest emission intensity when prepared with HNO3.

  2. Determination of total fluoride in HF/HNO3/H2SiF6 etch solutions by new potentiometric titration methods.

    PubMed

    Weinreich, Wenke; Acker, Jörg; Gräber, Iris

    2007-03-30

    In the photovoltaic industry the etching of silicon in HF/HNO(3) solutions is a decisive process for cleaning wafer surfaces or to produce certain surface morphologies like polishing or texturization. With regard to cost efficiency, a maximal utilisation of etch baths in combination with highest quality and accuracy is strived. To provide an etch bath control realised by a replenishment with concentrated acids the main constituents of these HF/HNO(3) etch solutions including the reaction product H(2)SiF(6) have to be analysed. Two new methods for the determination of the total fluoride content in an acidic etch solution based on the precipitation titration with La(NO(3))(3) are presented within this paper. The first method bases on the proper choice of the reaction conditions, since free fluoride ions have to be liberated from HF and H(2)SiF(6) at the same time to be detected by a fluoride ion-selective electrode (F-ISE). Therefore, the sample is adjusted to a pH of 8 for total cleavage of the SiF(6)(2-) anion and titrated in absence of buffers. In a second method, the titration with La(NO(3))(3) is followed by a change of the pH-value using a HF resistant glass-electrode. Both methods provide consistent values, whereas the analysis is fast and accurate, and thus, applicable for industrial process control.

  3. Uric acid protects membranes and linolenic acid from ozone-induced oxidation.

    PubMed

    Meadows, J; Smith, R C; Reeves, J

    1986-05-29

    Aqueous preparations of linolenic acid, bovine serum albumin, and bovine erythrocyte membrane fragments were bubbled with ozone in the presence or absence of uric acid. Ozonation of the membrane fragments or the bovine serum albumin did not result in protein degradation. After 15 min of ozonation, the absorbance of the thiobarbituric acid-reactive material increased by 0.34 in the linolenic acid preparation and by 0.08 in the suspension of membrane fragments. In the presence of uric acid, these changes in absorbance were reduced to 0.14 for the fatty acid and to 0.01 for the membrane fragments. This result indicates that uric acid protects lipids from ozone-induced oxidation.

  4. Modified HNO3 seasonality in volcanic layers of a polar ice core - Snow-pack effect or photochemical perturbation?

    NASA Technical Reports Server (NTRS)

    Laj, Paolo; Palais, Julie M.; Gardner, James E.; Sigurdsson, Haraldur

    1993-01-01

    Changes in atmospheric HNO3 chemistry following the Laki (1783), Tambora (1815), and Katmai (1912) volcanic eruptions are presently investigated in view of a central Greenland ice core's chemical composition. Attention is given to the concentration of several cations and anions, using ion chromatography. Following the eruptions, the ratio of winter to summer depositions of NO3(-) was significantly higher than during nonvolcanic periods. While this may be due to ice pack effects, it is proposed that large concentrations of the stratospheric H2SO4 particles ejected by the volcanoes favored HNO3 removal during Arctic winter.

  5. Spectrometric analysis of process etching solutions of the photovoltaic industry--determination of HNO3, HF, and H2SiF6 using high-resolution continuum source absorption spectrometry of diatomic molecules and atoms.

    PubMed

    Bücker, Stefan; Acker, Jörg

    2012-05-30

    The surface of raw multicrystalline silicon wafers is treated with HF-HNO(3) mixtures in order to remove the saw damage and to obtain a well-like structured surface of low reflectivity, the so-called texture. The industrial production of solar cells requires a consistent level of texturization for tens of thousands of wafers. Therefore, knowing the actual composition of the etch bath is a key element in process control in order to maintain a certain etch rate through replenishment of the consumed acids. The present paper describes a novel approach to quantify nitric acid (HNO(3)), hydrofluoric acid (HF), and hexafluosilicic acid (H(2)SiF(6)) using a high-resolution continuum source graphite furnace absorption spectrometer. The concentrations of Si (via Si atom absorption at the wavelength 251.611 nm, m(0),(Si)=130 pg), of nitrate (via molecular absorption of NO at the wavelength 214.803 nm, [Formula: see text] ), and of total fluoride (via molecular absorption of AlF at the wavelength 227.46 nm, m(0,F)=13 pg) were measured against aqueous standard solutions. The concentrations of H(2)SiF(6) and HNO(3) are directly obtained from the measurements. The HF concentration is calculated from the difference between the total fluoride content, and the amount of fluoride bound as H(2)SiF(6). H(2)SiF(6) and HNO(3) can be determined with a relative uncertainty of less than 5% and recoveries of 97-103% and 96-105%, respectively. With regards to HF, acceptable results in terms of recovery and uncertainty are obtained for HF concentrations that are typical for the photovoltaic industry. The presented procedure has the unique advantage that the concentration of both, acids and metal impurities in etch solutions, can be routinely determined by a single analytical instrument.

  6. Condensed Acids In Antartic Stratospheric Clouds

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Snetsinger, K. G.; Toon, O. B.; Ferry, G. V.; Starr, W. L.; Oberbeck, V. R.; Chan, K. R.; Goodman, J. K.; Livingston, J. M.; Verma, S.; Fong, W.

    1992-01-01

    Report dicusses nitrate, sulfate, and chloride contents of stratospheric aerosols during 1987 Airborne Antarctic Ozone Experiment. Emphasizes growth of HNO3*3H2O particles in polar stratospheric clouds. Important in testing theories concerning Antarctic "ozone hole".

  7. Measurements of Nitric Acid and Aerosol Species Aboard the NASA DC-8 Aircraft During the SASS OZone and Nitrogen Oxide Experiment (SONEX)

    NASA Technical Reports Server (NTRS)

    Talbot, Robert W.; Dibb, Jack E.

    1999-01-01

    The SASS Ozone and Nitrogen Oxides Experiment (SONEX) over the north Atlantic during October/November 1997 offered an excellent opportunity to examine the budget of total reactive nitrogen (NO(y)) in the upper troposphere (8 - 12 km altitude). The median measured NO(y) mixing ratio was 425 parts per trillion by volume (pptv). Two different methods were used to measure HNO3: (1) the mist chamber technique and, (2) chemical ionization mass spectrometry. Two merged data sets using these HNO3 measurements were used to calculate NO(y) by summing the reactive nitrogen species (a combination of measured plus modeled results) and comparing the resultant values to measured NO(y) (gold catalytic reduction method). Both comparisons showed good agreement in the two quantities (slope greater than 0.9 and r(sup 2) greater than 0.9). Thus, the total reactive nitrogen budget in the upper troposphere over the North Atlantic can be explained in a general manner as a simple mixture of NO(x). (NO + NO2), HNO3, and PAN. Median values of NO(x)/NO(y) were approx. = 0.25, HNO3/NO(y) approx. = 0.35 and PAN/NO(y) approx. = 0.17. Particulate NO3 and alkyl nitrates together composed less than 10% of NO(y), while model estimated HNO4 averaged 12%.

  8. Measurements of Nitric Acid and Aerosol Species Aboard the NASA DC-8 Aircraft During the SASS Ozone and Nitrogen Oxide Experiment (SONEX)

    NASA Technical Reports Server (NTRS)

    Talbot, Robert W.; Dibb, Jack E.

    1999-01-01

    The SASS Ozone and Nitrogen Oxides Experiment (SONEX) over the North Atlantic during October/November 1997 offered an excellent opportunity to examine the budget of total reactive nitrogen (NO(sub y)) in the upper troposphere (8 - 12 km altitude). The median measured NO(sub y) mixing ratio was 425 parts per trillion by volume (pptv). Two different methods were used to measure HNO3: (1) the mist chamber technique and, (2) chemical ionization mass spectrometry. Two merged data sets using these HNO3 measurements were used to calculate NO(sub y) by summing the reactive nitrogen species (a combination of measured plus modeled results) and comparing the resultant values to measured NO(sub y) (gold catalytic reduction method). Both comparisons showed good agreement in the two quantities (slope > 0.9 and r(exp 2) > 0.9). Thus, the total reactive nitrogen budget in the upper troposphere over the North Atlantic can be explained in a general manner as a simple mixture of NO(sub x). (NO + NO2), HNO3, and PAN. Median values of NO(sub x)/NO(sub y) were approximately equal to 0.25, HNO3/NO(sub y) were approximately equal to 0.35 and Peroxyacetyl Nitrate (PAN)/NO(sub y) were approximately equal to 0. 17. Particulate NO3 and alkyl nitrates together composed <10 % of NO(sub y), while model estimated HNO4 averaged 12%.

  9. Modification of active and porous sublayers of aged polyamide/polysulfone composite membranes due to HNO3 treatment: effect of treatment time.

    PubMed

    Benavente, J; Vázquez, M I; de Lara, R

    2006-05-01

    Changes in electrical and transport parameters for aged composite polyamide/polysulfone membrane samples (PAC) and their porous support layers (PSU) as a result of chemical treatment (immersion in 1 M HNO3 solution) at four different times (12 h < or = t < or = 72 h) have been obtained. Salt permeability, ion transport number, and membrane electrical resistance for the treated samples were determined from salt diffusion, membrane potential, and impedance spectroscopy measurements, which were carried out with the membranes in contact with NaCl solutions at different concentrations and compared with those determined for fresh and aged nontreated samples. Results show the strong effect of aging on membrane parameters, particularly the decrease in salt permeability (P(s)) and the increase in membrane electrical resistance (R(m)), while ion transport number is hardly affected by aging, chemical treatment, or treatment time. Results show how the compaction of the porous structure causes by aging (dried membrane matrix structure) can be partially reduced by HNO3 treatment, and they also allow the estimation of 24-h treatment as the optimum time (higher salt permeability and lower membrane electrical resistance), mainly for the polysulfone support layer. The use of equivalent circuits in the analysis of impedance spectroscopy data allows separate estimation of the electrical resistance associated with each sublayer of the composite PAC membrane samples. On the other hand, chemical changes in the active top layer of the PAC membrane (polyamide active layer) were obtained from XPS analysis, which show some modifications in the atomic concentration percentages of the polyamide characteristic elements as a result of acidic treatment time, which are more significant after 72-h acidic immersion.

  10. Laboratory Investigations of Heterogeneous Chemistry Important to Ozone Depletion in the Stratosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Renyi

    Results of laboratory investigations of heterogeneous chemistry important to ozone depletion in the stratosphere are presented. Thermodynamic properties (such as melting points, enthalpies of fusion, etc.) for acids which are present in the stratosphere (HCl, HNO_3 , and H_2SO_4 ) are studied using laboratory-assembled apparatus of electrical conductivity and differential thermal analysis and using a commercial differential scanning calorimeter (DSC). Vapor pressures and infrared spectra of liquid and supercooled solutions, and of liquid-solid and solid -solid coexistence mixtures for the HCl/H_2 O and H_2SO_4 /H_2O binary systems are investigated. Equilibrium constants and standard enthalpies of formation for the pure crystalline hydrates of those acids as well as their corresponding liquid compositions are determined from the vapor pressure and calorimetric data. A theoretical approach, which allows determination of vapor pressures for two adjacent hydrates in thermodynamic equilibrium and for the coexistence systems involving a hydrate and ice in a binary system, is presented in terms of chemical equilibrium principles and compared with the experimental data for thermodynamic consistence. Vapor pressures of HNO_3 and HCl over H_2SO_4 /HNO_3/H_2 O and H_2SO_4 /HCl/H_2O solutions as well as over H_2SO_4/HNO _3/HCl/H_2O solutions are also measured in order to predict incorporation of stratospheric acids into the background sulfate aerosols. From the data, the Henry's law solubility constants for those systems are determined and the equilibrium compositions of aqueous stratospheric aerosols are predicted as a function of ambient temperature and mixing ratios of H_2 O and HNO_3. The results indicate that at the low temperatures characteristic of the stratosphere at high latitudes in the winter and spring, the HNO_3 content reaches levels of the order of 10% wt in the background sulfate aerosols. The results also reveal that the amount of dissolved HCl in the

  11. Determination of trace elements in foods by HCl-HNO3 leaching and flame atomic absorption spectroscopy.

    PubMed

    Puchyr, R F; Shapiro, R

    1986-01-01

    Aluminum, iron, tin, zinc, calcium, magnesium, nickel, copper, chromium, cadmium, and potassium in foods can be extracted by HCl-HNO3 leaching and determined quantitatively using flame atomic absorption spectroscopy (AAS), with recoveries ranging from 90 to 110%. Thirty to 40 samples of almost any type of food sample can be analyzed routinely for 2 elements in 4-5 h. In contrast, one or 2 days are required when a wet-ash or dry-ash technique is used. Extraction consists of weighing 2-10 g samples into 125 mL Erlenmeyer flasks, adding 20 mL concentrated HCl-HNO3 (9 + 1), then heating in a 82- 93 degrees C water bath for 30 min. After cooling, samples are diluted to volume in 50 mL Nessler tubes and then filtered through No. 541 or 540 Whatman paper. The filtrate is analyzed directly by AAS.

  12. Study on the kinetics and transformation products of salicylic acid in water via ozonation.

    PubMed

    Hu, Ruikang; Zhang, Lifeng; Hu, Jiangyong

    2016-06-01

    As salicylic acid is one of widely used pharmaceuticals, its residue has been found in various environmental water systems e.g. wastewater, surface water, treated water and drinking water. It has been reported that salicylic acid can be efficiently removed by advanced oxidation processes, but there are few studies on its transformation products and ozonation mechanisms during ozonation process. The objective of this study is to characterize the transformation products, investigate the degradation mechanisms at different pH, and propose the ozonation pathways of salicylic acid. The results showed that the rate of degradation was about 10 times higher at acidic condition than that at alkaline condition in the first 1 min when 1 mg L(-1) of ozone solution was added into 1 mg L(-1) of salicylic acid solution. It was proposed that ozone direct oxidation mechanism dominates at acidic condition, while indirect OH radical mechanism dominates at alkaline condition. A two stages pseudo-first order reaction was proposed at different pH conditions. Various hydroxylation products, carbonyl compounds and carboxylic acids, such as 2,5-dihydroxylbenzoic acid, 2,3-dihydroxylbenzoic acid, catechol, formaldehyde, glyoxal, acetaldehyde, maleic acid, acetic acid and oxalic acid etc. were identified as ozonation transformation products. In addition, acrylic acid was identified, for the first time, as ozonation transformation products through high resolution liquid chromatography-time of flight mass spectrometer. The information demonstrated in this study will help us to better understand the possible effects of ozonation products on the water quality. The degradation pathways of salicylic acid by ozonation in water sample were proposed. As both O3 and OH radical were important in the reactions, the degradation pathways of salicylic acid by ozonation in water sample were proposed at acidic and basic conditions. To our knowledge, there was no integrated study reported on the ozonation of

  13. HNO3, N2O5 and CIONO2 Enhancements after the October-November 2003 Solar Proton Events

    NASA Technical Reports Server (NTRS)

    Lopez-Puertas, M.; Funke, B.; Gil-Lopez, S.; Tsidu, G. Mengistu; Fischer, H.; Jackman, C. H.

    2005-01-01

    The large solar storm in October-November 2003 produced enormous amounts of high-energy protons which reached the Earth and penetrated into the middle atmosphere in the polar regions. At this time, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the Environmental Satellite (ENVISAT) was observing the atmosphere in the 6-68 km altitude range. MIPAS observed significant enhancements of the NO(y) components HNO3, N2O5 and CIONO2 in the Northern polar stratosphere after the intense solar proton events. Two distinct HNO3 enhancements were observed. An instantaneous increase of 1-2 ppbv was observed immediately after the SPEs and is attributed to gas-phase chemistry: NO2 + OH + M yields HNO3 + M, accelerated by SPE-produced excess OH. A very large second increase of 1- 5 ppbv started around 10 November and lasted until the end of December. It is attributed to NO(x) (NO+NO2) produced in the mesosphere during the major SPEs in late October/early November and then transported downwards during November and December, partially converted to N2O5 in the upper stratosphere, which finally formed HNO3 via ion cluster reactions. N2O5 was observed to increase by 0.1-0.4 ppbv 1-3 days after the major SPEs and reached down to 30 km altitude. A second, more pronounced N2O5 enhancement of up to 1.2 ppbv at 40 km appeared about 12-13 days after the major SPEs. With a delay of 1-2 days after the major SPEs CIONO2 increased by up to 0.4 ppbv (40%) at 32 km altitude. NO(y) enhancements in the Southern hemisphere were generally less pronounced.

  14. Ozone

    MedlinePlus

    ... reactive form of oxygen. In the upper atmosphere, ozone forms a protective layer that shields us from the sun’s ultraviolet rays. At ground level, ozone is a harmful air pollutant and a primary ...

  15. Coupled aerosol-chemical modeling of UARS HNO3 and N2O5 measurements in the Arctic upper stratosphere

    NASA Astrophysics Data System (ADS)

    Bekki, S.; Chipperfield, M. P.; Pyle, J. A.; Remedios, J. J.; Smith, S. E.; Grainger, R. G.; Lambert, A.; Kumer, J. B.; Mergenthaler, J. L.

    1997-04-01

    Gas-phase photochemical models do not account for the formation of a secondary altitude HNO3 maximum in the upper stratosphere at high latitudes during winter, suggesting that some processes are missing in the currently accepted chemistry of reactive nitrogen species [Kawa et al, 1995]. Heterogeneous chemistry on aerosol particles had been discounted as the cause because the aerosol surface area is expected to be very low at these altitudes. We have coupled a sulphate aerosol microphysical model to a chemical transport model to investigate this model deficiency in the Arctic during January 1992. The aerosol model predicts the formation of small sulphate particles at 1100 K. Comparisons with cryogenic limb array etalon spectrometer (CLAES) HNO3 and improved stratospheric and mesospheric sounder (ISAMS) N2O5 observations show that the heterogeneous conversion of N2O5 to HNO3 on the modeled small sulphate particles can account for some of the unexpected features seen in Upper Atmosphere Research Satellite (UARS) observations.

  16. Ozone

    MedlinePlus

    Ozone is a gas. It can be good or bad, depending on where it is. "Good" ozone occurs naturally about 10 to 30 miles above ... the sun's ultraviolet rays. Part of the good ozone layer is gone. Man-made chemicals have destroyed ...

  17. Gas chromatography-mass spectrometry profile of urinary organic acids of Wistar rats orally treated with ozonized unsaturated triglycerides and ozonized sunflower oil.

    PubMed

    Jardines, Daniel; Correa, Teresa; Ledea, Oscar; Zamora, Zullyt; Rosado, Aristides; Molerio, Jesús

    2003-01-15

    The main products in the ozonolysis of unsaturated triglycerides or vegetable oils are peroxides, aldehydes, Criegee ozonides and carboxylic acids. Some of these compounds are present in different concentrations in the biological fluids. The aim of this work is to study, using gas chromatography-mass spectrometry (GC-MS), the organic acid excretion in urine of rats orally treated with ozonized sunflower oil (OSO), ozonized triolein or ozonized trilinolein. Oral administration of OSO to Wistar rats has produced changes in the urinary content of dicarboxylic organic acids. Among others heptanedioic (pimelic acid) and nonanedioic acids (azelaic acid) were the major increased dicarboxylic acids found. The urinary dicarboxylic acid profiles of rats which received ozonized triolein only showed an increase in heptanedioic and nonanedioic acids. However, when ozonized trilinolein is applied, the profile is similar to that obtained when OSO is administered. A biochemical mechanism is proposed to explain the formation of dicarboxylic acids from ozonated unsaturated triglycerides.

  18. Analysis of the ν 8+ ν 9Band of HNO 3, Line Positions and Intensities, and Resonances Involving the v6= v7= 1 Dark State

    NASA Astrophysics Data System (ADS)

    Perrin, A.; Flaud, J.-M.; Keller, F.; Goldman, A.; Blatherwick, R. D.; Murcray, F. J.; Rinsland, C. P.

    1999-03-01

    Using a high-resolution (R= 0.0025 cm-1) Fourier transform spectrum of nitric acid recorded at room temperature in the 1100-1240 cm-1region, it has been possible to perform a more extended analysis of the ν8+ ν9band of HNO3centered at 1205.7075 cm-1. As in a recent analysis of this band [W. F. Wang, P. P. Ong, T. L. Tan, E. C. Looi, and H. H. Teo,J. Mol. Spectrosc.183, 407-413 (1997)], the Hamiltonian used for the line positions calculation takes into account, for the upper state, the ΔK= ±2 anharmonic resonance linking the rotational levels of thev8=v9= 1 "bright" vibrational state and those of the "dark"v6=v7= 1 vibrational state. More than 4800 lines were assigned in the ν8+ ν9band, which involve significantly higher rotational quantum numbers than in previous works. On the other hand, and surprisingly as compared to previous studies, the ν8+ ν9band appears to be a hybrid band. In fact, nonnegligibleB-type transitions could be clearly identified among the much strongerA-type lines. Accordingly, a set of individual line intensities were measured for lines of both types and were introduced in a least-squares fit to get theA- andB-type components of the transition moment operator. Finally, a synthetic spectrum of the 8.3-μm region of HNO3has been generated, using for the line positions and line intensities the Hamiltonian constants and the expansion of the transition moment operator which were determined in this work. In this way, theB-type and theA-type components of the ν8+ ν9band appear to contribute for about {1}/{4} and {3}/{4}, respectively, to the total band intensity.

  19. Lifetime Extension of Cirrus Cloud Ice Particles upon Contamination with HCl and HNO3 under conditions of the Upper Troposphere and Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Rossi, Michel J.; Delval, Christophe

    2016-04-01

    Ice particles in the Upper Troposphere/Lower Stratosphere (UT/LS) are the seat of heterogeneous chemical processes that are important in polar ozone chemistry. Estimated evaporative lifetimes of typical pure ice particles of a few micrometers radius in Cirrus clouds are on the order of a minute or so at 80% relative humidity, too short to allow significant heterogeneous processing. We took this as a motivation to systematically measure absolute rates of evaporation and condensation of H2O in 1 to 2 micrometer thick ice films taken as proxies for small atmospheric ice particles under controlled conditions of HCl and HNO3 trace gas contamination. We have used a multidiagnostic reaction vessel equipped with residual gas mass spectrometry (MS), FTIR absorption spectroscopy in transmission and a quartz crystal microbalance (QCMB) in order to simultaneously observe both the gas and condensed phases under relevant atmospheric conditions. The rates (Rev(H2O)) or fluxes of evaporation (Jev(H2O)) of H2O from thin ice films contaminated by a measured amount of HCl in the range of 10% of a formal monolayer to 20 formal monolayers decreased by factors of between 2 and 50 depending on parameters such as temperature of deposition (Tdep), rate (RHCl) and dose (NHCl) of contaminant doping. Experiments with HCl fell into two categories as far as the decrease of Jev with the average mole fraction of contaminant (χHCl) in the remaining ice slab was concerned: one group where Jev(H2O) decreased gradually after pure ice evaporated, and another group where Jev(H2O) abruptly changes with χHCl after evaporation of excess ice. FTIR spectroscopy revealed an unknown, yet crystalline form of HCl hydrate upon HCl doping that does not correspond to a known crystalline hydrate. Of importance is the observation, that the equilibrium vapor pressure of these contaminated ices correspond to that of pure ice even after evaporation of excess ice at the characteristic rate of pure ice evaporation

  20. Analysis of seasonal variation of stratospheric nitric acid

    NASA Astrophysics Data System (ADS)

    Gruzdev, A. N.

    1998-11-01

    Data from the draft COSPAR reference model for stratospheric nitric acid (HNO3) are analysed. Eight months of LIMS HNO3 measurements allow the analysis of dynamics of regimes associated with the annual HNO3 maximum followed by the HNO3 decrease in the Northern Hemisphere and the annual HNO3 minimum followed by the HNO3 increase in the Southern Hemisphere. The HNO3 minimum is noted earlier (in November) in the Southern Hemisphere subtropical upper stratosphere, from where the regime of minimum HNO3 values propagates to the southern high-latitude middle stratosphere, and then (in Austral summer) the equatorward propagation of the regime is observed, with a persistent downward component. The regime of the HNO3 annual maximum in the Northern Hemisphere propagates from the Arctic lower stratosphere (in autumn) and from the tropical middle stratosphere (in late summer), so that in the mid-latitude middle stratosphere the downward propagation of the regime is observed. Evolution of areas with HNO3 increase and decrease by 1 ppbv against the January HNO3 distribution quantifies intensity of the HNO3 decrease in winter-spring in the Northern Hemisphere and the HNO3 increase in Austral summer-autumn in the Southern Hemisphere.

  1. The mid-IR Absorption Cross Sections of α- and β-NAT (HNO3 · 3H2O) in the range 170 to 185 K and of metastable NAD (HNO3 · 2H2O) in the range 172 to 182 K

    NASA Astrophysics Data System (ADS)

    Iannarelli, R.; Rossi, M. J.

    2015-11-01

    Growth and Fourier transform infrared (FTIR) absorption in transmission of the title nitric acid hydrates have been performed in a stirred flow reactor (SFR) under tight control of the H2O and HNO3 deposition conditions affording a closed mass balance of the binary mixture. The gas and condensed phases have been simultaneously monitored using residual gas mass spectrometry and FTIR absorption spectroscopy, respectively. Barrierless nucleation of the metastable phases of both α-NAT (nitric acid trihydrate) and NAD (nitric acid dihydrate) has been observed when HNO3 was admitted to the SFR in the presence of a macroscopic thin film of pure H2O ice of typically 1 µm thickness. The stable β-NAT phase was spontaneously formed from the precursor α-NAT phase through irreversible thermal rearrangement beginning at 185 K. This facile growth scheme of nitric acid hydrates requires the presence of H2O ice at thicknesses in excess of approximately hundred nanometers. Absolute absorption cross sections in the mid-IR spectral range (700-4000 cm-1) of all three title compounds have been obtained after spectral subtraction of excess pure ice at temperatures characteristic of the upper troposphere/lower stratosphere. Prominent IR absorption frequencies correspond to the antisymmetric nitrate stretch vibration (ν3(NO3-)) in the range 1300 to 1420 cm-1 and the bands of hydrated protons in the range 1670 to 1850 cm-1 in addition to the antisymmetric O-H stretch vibration of bound H2O in the range 3380 to 3430 cm-1 for NAT.

  2. The Relative Roles of RONO2 and HNO3 as Sinks of NOX in the Denver Metropolitan Region and Colorado's Front Range

    NASA Astrophysics Data System (ADS)

    Sparks, T.; Ebben, C. J.; Wooldridge, P. J.; Cohen, R. C.

    2015-12-01

    Measurements of HNO3, total RONO2, NOX, and other relevant species, acquired during the DISCOVER-AQ and FRAPPE field campaigns in the Northern Front Range of Colorado during July-August 2014, are used to assess our understanding of the relative roles of RONO2 and HNO3 formation as sinks of NOX. Although HNO3 production was dominant in the region, RONO2 production was often of order 1/3 of the NOX sink. As NOX emissions decrease, our results indicate RONO2­ chemistry will be increasingly important to descriptions of the chemistry in the region.

  3. [Catalytic ozonation by ceramic honeycomb for the degradation of oxalic acid in aqueous solution].

    PubMed

    Zhao, Lei; Sun, Zhi-Zhong; Ma, Jun

    2007-11-01

    Comparative experiments for the degradation of oxalic acid in aqueous solution were carried out in the three processes of ozonation alone, ceramic honeycomb-catalyzed ozonation and ceramic honeycomb adsorption. The results show that the degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation, ozonation alone and ceramic honeycomb adsorption systems are 37.6%, 2.2% and 0.4%, and the presence of ceramic honeycomb catalyst significantly improves the degradation rate of oxalic acid compared to the results from non-catalytic ozonation and adsorption. With the addition of tert-butanol, the degradation rates of oxalic acid in catalytic ozonation system decrease by 24.1%, 29.0% and 30.1%, respectively, at the concentration of 5, 10 and 15 mg x L(-1). This phenomenon indicates that ceramic honeycomb-catalyzed ozonation for the degradation of oxalic acid in aqueous solution follows the mechanism of *OH oxidation, namely the heterogeneous surface of catalyst enhances the initiation of *OH. The results of TOC analysis demonstrate that the process of ceramic honeycomb-catalyzed ozonation can achieve the complete mineralization level without the formation of intermediary degradation products. The experimental results suggest that the reaction temperature has positive relationship with the degradation rate of oxalic acid. The degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation system are 16.4%, 37.6%, 61.3% and 68.2%, at the respective reaction temperature of 10, 20, 30 and 40 degrees C.

  4. Quantum yields for OH production from 193 and 248 nm photolysis of HNO3 and H2O2

    NASA Astrophysics Data System (ADS)

    Schiffman, A.; Nelson, D. D., Jr.; Nesbitt, D. J.

    1993-05-01

    Flash kinetic spectroscopy in a flow tube is used to measure at room temperature the absolute yields for OH production from 193 and 248 nm photolysis of HNO3 and H2O2. The OH radicals are produced by excimer laser photolysis and probed via direct absorption of high resolution tunable IR laser light. The results indicate quantum yields for both precursors at both wavelengths which are less than the maximum possible values of 1 for H2O2. The present measurements are discussed in light of contrasting results suggested from other work.

  5. Heterogeneous conversion of N2O5 to HNO3 on background stratospheric aerosols - Comparisons of model results with data

    NASA Astrophysics Data System (ADS)

    Considine, David B.; Douglass, Anne R.; Stolarski, Richard S.

    1992-02-01

    The effects of heterogeneous processing by a parameterized lower stratospheric sulfate aerosol layer on model calculations were examined using a 2D photochemical model. Model results were compared with zonally averaged LIMS data on HNO3 and NO2 and in situ measurements of NO, NO(y), and ClO, taken by the ER-2 aircraft. The results obtained are contradictory: some comparisons favor heterogeneous chemistry, and some do not. It is suggested that the assumptions made to parameterize the sulfate aerosol chemistry result in a rate of heterogeneous processing that is too vigorous.

  6. Laboratory measurements of heterogeneous reactions on sulfuric acid surfaces

    NASA Technical Reports Server (NTRS)

    Williams, Leah R.; Manion, Jeffrey A.; Golden, David M.; Tolbert, Margaret A.

    1994-01-01

    Increasing evidence from field, modeling, and laboratory studies suggests that heterogeneous reactions on stratospheric sulfate aerosol particles may contribute to global ozone depletion. Using a Knudsen cell reactor technique, the authors have studied the uptake, reactivity, and solubility of several trace atmospheric species on cold sulfuric acid surfaces representative of stratospheric aerosol particles. The results suggest that the heterogeneous conversion of N2O5 to HNO3 is fast enough to significantly affect the partitioning of nitrogen species in the global stratosphere and thus contribute to global ozone depletion. The hydrolysis of ClONO2 is slower and unlikely to be important under normal conditions at midlatitudes. The solubilities of HCl and HNO3 in sulfuric acid down to 200 K were found to be quite low. For HCl, this means that little HCl is available for reaction on the surfaces of stratospheric sulfate aerosol particles. The low solubility of HNO3 means that this product of heterogeneous reactions will enter the gas phase, and the denitrification observed in polar regions is unlikely to occur in the global stratosphere.

  7. Effects of acid fog and ozone on conifers. Final report

    SciTech Connect

    Bytnerowicz, A.; Olszyk, D.M.; Takemoto, B.K.; McCool, P.M.; Musselman, R.C.

    1989-05-01

    This study evaluated the effects of acidic fog (pH 2.0, 3.0, or 4.0) on the physiological, biochemical, and growth responses of two coniferous tree species (Pinus ponderosa and Abies concolor), and determined if exposure to acidic fog predisposed the tree seedlings to the phytotoxic effects of ozone (O{sub 3}). Results provide evidence that the growth and metabolic responses of two coniferous tree species could be altered by multiple applications of acidic fog, and by exposure to ambient O{sub 3}. In general, the alterations were slight to modest, which may be attributed to the low degree of stress severity, and the slow rate of tree growth. The findings indicate that exposure to acidic fog followed by O{sub 3} does not cause detectable changes in conifer seedling growth within a single-growing season. Nevertheless, it is clear that acidic fog and O{sub 3} cause temporal alterations in seedling physiology and biochemistry.

  8. Wastewater disinfection alternatives: chlorine, ozone, peracetic acid, and UV light.

    PubMed

    Mezzanotte, V; Antonelli, M; Citterio, S; Nurizzo, C

    2007-11-01

    Disinfection tests were carried out at pilot scale to compare the disinfection efficiency of ozone, sodium hypochlorite (NaOCl), peracetic acid (PAA), and UV irradiation. Total coliforms, fecal coliforms, and Escherichia coli were monitored as reference microorganisms. Total heterotrophic bacteria (THB) were also enumerated by cytometry. At similar doses, NaOCl was more effective than PAA, and its action was less affected by contact time. The results obtained by ozonation were comparable for total coliforms, fecal coliforms, and E. coli. On the contrary, some differences among the three indicators were observed for NaOCl, PAA, and UV. Differences increased with increasing values of the disinfectant concentration times contact time (C x t) and were probably the result of different initial counts, as total coliforms include fecal coliforms, which include E. coli. The UV irradiation lead to complete E. coli removals, even at low doses (10 to 20 mJ/cm2). Total heterotrophic bacteria appeared to be too wide a group to be a good disinfection indicator; no correlation was found among THB inactivation, dose, and contact time.

  9. Removal of nalidixic acid and its degradation products by an integrated MBR-ozonation system.

    PubMed

    Pollice, A; Laera, G; Cassano, D; Diomede, S; Pinto, A; Lopez, A; Mascolo, G

    2012-02-15

    Chemical-biological degradation of a widely spread antibacterial (nalidixic acid) was successfully obtained by an integrated membrane bioreactor (MBR)-ozonation process. The composition of the treated solution simulated the wastewater from the production of the target pharmaceutical, featuring high salinity and a relevant concentration of sodium acetate. Aim of treatment integration was to exploit the synergistic effects of chemical oxidation and bioprocesses, by adopting the latter to remove most of the COD and the ozonation biodegradable products. Integration was achieved by placing ozonation in the recirculation stream of the bioreactor effluent. The recirculation flow rate was three-fold the MBR feed, and the performance of the integrated system was compared to the standard polishing configuration (single ozonation step after the MBR). Results showed that the introduction of the ozonation step did not cause relevant drawbacks to both biological and filtration processes. nalidixic acid passed undegraded through the MBR and was completely removed in the ozonation step. Complete degradation of most of the detected ozonation products was better achieved with the integrated MBR-ozonation process than using the sequential treatment configuration, i.e. ozone polishing after MBR, given the same ozone dosage.

  10. Reactive nitrogen partitioning and its relationship to winter ozone events in Utah

    NASA Astrophysics Data System (ADS)

    Wild, R. J.; Edwards, P. M.; Bates, T. S.; Cohen, R. C.; de Gouw, J. A.; Dubé, W. P.; Gilman, J. B.; Holloway, J.; Kercher, J.; Koss, A. R.; Lee, L.; Lerner, B. M.; McLaren, R.; Quinn, P. K.; Roberts, J. M.; Stutz, J.; Thornton, J. A.; Veres, P. R.; Warneke, C.; Williams, E.; Young, C. J.; Yuan, B.; Zarzana, K. J.; Brown, S. S.

    2016-01-01

    High wintertime ozone levels have been observed in the Uintah Basin, Utah, a sparsely populated rural region with intensive oil and gas operations. The reactive nitrogen budget plays an important role in tropospheric ozone formation. Measurements were taken during three field campaigns in the winters of 2012, 2013 and 2014, which experienced varying climatic conditions. Average concentrations of ozone and total reactive nitrogen were observed to be 2.5 times higher in 2013 than 2012, with 2014 an intermediate year in most respects. However, photochemically active NOx (NO + NO2) remained remarkably similar all three years. Nitric acid comprised roughly half of NOz ( ≡ NOy - NOx) in 2013, with nighttime nitric acid formation through heterogeneous uptake of N2O5 contributing approximately 6 times more than daytime formation. In 2012, N2O5 and ClNO2 were larger components of NOz relative to HNO3. The nighttime N2O5 lifetime between the high-ozone year 2013 and the low-ozone year 2012 is lower by a factor of 2.6, and much of this is due to higher aerosol surface area in the high-ozone year of 2013. A box-model simulation supports the importance of nighttime chemistry on the reactive nitrogen budget, showing a large sensitivity of NOx and ozone concentrations to nighttime processes.

  11. Complexes of HNO3 and NO3 - with NO2 and N2O4, and their potential role in atmospheric HONO formation.

    PubMed

    Kamboures, Michael A; Raff, Jonathan D; Miller, Yifat; Phillips, Leon F; Finlayson-Pitts, Barbara J; Gerber, R Benny

    2008-10-21

    Calculations were performed to determine the structures, energetics, and spectroscopy of the atmospherically relevant complexes (HNO(3)).(NO(2)), (HNO(3)).(N(2)O(4)), (NO(3)(-)).(NO(2)), and (NO(3)(-)).(N(2)O(4)). The binding energies indicate that three of the four complexes are quite stable, with the most stable (NO(3)(-)).(N(2)O(4)) possessing binding energy of almost -14 kcal mol(-1). Vibrational frequencies were calculated for use in detecting the complexes by infrared and Raman spectroscopy. An ATR-FTIR experiment showed features at 1632 and 1602 cm(-1) that are attributed to NO(2) complexed to NO(3)(-) and HNO(3), respectively. The electronic states of (HNO(3)).(N(2)O(4)) and (NO(3)(-)).(N(2)O(4)) were investigated using an excited state method and it was determined that both complexes possess one low-lying excited state that is accessible through absorption of visible radiation. Evidence for the existence of (NO(3)(-)).(N(2)O(4)) was obtained from UV/vis absorption spectra of N(2)O(4) in concentrated HNO(3), which show a band at 320 nm that is blue shifted by 20 nm relative to what is observed for N(2)O(4) dissolved in organic solvents. Finally, hydrogen transfer reactions within the (HNO(3)).(NO(2)) and (HNO(3)).(N(2)O(4)) complexes leading to the formation of HONO, were investigated. In both systems the calculated potential profiles rule out a thermal mechanism, but indicate the reaction could take place following the absorption of visible radiation. We propose that these complexes are potentially important in the thermal and photochemical production of HONO observed in previous laboratory and field studies.

  12. Kinetics of electron attachment to OH and HNO3 and mutual neutralization of Ar+ with NO2- and NO3- at 300 and 500 K

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, A. A.

    2012-03-01

    The electron attachment rate constant to nitric acid (HNO3) has been measured in a flowing afterglow-Langmuir probe (FALP) apparatus at 300 and 500 K using three independent methods: the traditional FALP technique of monitoring electron depletion, "one-gas" VENDAMS (variable electron and neutral density attachment mass spectrometry), and "two-gas" VENDAMS. The three measurements are in agreement with a 300 K weighted average of 1.4 ± 0.3 × 10-7 cm3 s-1, 2 to 10 times higher than previously reported values. Attachment is primarily dissociative yielding NO2- as previously reported, but for the first time a small endothermic channel to produce OH- was also observed at 500 K. From the one-gas VENDAMS data, associative attachment to the OH produced in the primary attachment was found to occur with an effective two body rate constant of 1.2 ± _{0.7}^3 × 10-11 cm3 s-1 at 300 K, the first reported rate constant for this radical species. Finally, ion-ion neutralization rate constants of NO2- and NO3- with Ar+ were determined to be 5.2 ± _{2.5}^{1.5} × 10-8 and 4.5 ± 2.5 × 10-8 cm3 s-1 at 300 K, respectively.

  13. Kinetics of electron attachment to OH and HNO3 and mutual neutralization of Ar+ with NO2(-) and NO3(-) at 300 and 500 K.

    PubMed

    Shuman, Nicholas S; Miller, Thomas M; Viggiano, A A

    2012-03-28

    The electron attachment rate constant to nitric acid (HNO(3)) has been measured in a flowing afterglow-Langmuir probe (FALP) apparatus at 300 and 500 K using three independent methods: the traditional FALP technique of monitoring electron depletion, "one-gas" VENDAMS (variable electron and neutral density attachment mass spectrometry), and "two-gas" VENDAMS. The three measurements are in agreement with a 300 K weighted average of 1.4 ± 0.3 × 10(-7) cm(3) s(-1), 2 to 10 times higher than previously reported values. Attachment is primarily dissociative yielding NO(2)(-) as previously reported, but for the first time a small endothermic channel to produce OH(-) was also observed at 500 K. From the one-gas VENDAMS data, associative attachment to the OH produced in the primary attachment was found to occur with an effective two body rate constant of 1.2±(0.7) (3)×10(-11) cm(3) s(-1) at 300 K, the first reported rate constant for this radical species. Finally, ion-ion neutralization rate constants of NO(2)(-) and NO(3)(-) with Ar(+) were determined to be 5.2±(2.5) (1.5) × 10(-8) and 4.5 ± 2.5 × 10(-8) cm(3) s(-1) at 300 K, respectively.

  14. Fatty acids and ultrastructure of ozone-exposed Aleppo pine (Pinus halepensis Mill.) needles.

    PubMed

    Anttonen, S; Herranen, J; Peura, P; Kärenlampi, L

    1995-01-01

    Fifteen or 18-month-old Aleppo pine seedlings were fumigated with different concentrations and doses of ozone over a period of 2-16 days in controlled-environmental growth chambers. The total fatty acid content and ultrastructure of the current year needles were subsequently analysed. In acute, high concentration exposures, significant reductions in the levels of linolenic acid were detected. Increases in myristic or palmitic acid were common in needles exposed to lower concentrations of ozone. Ultrastructural studies revealed reductions in chloroplast size and a darkening of stroma at low ozone exposures while at high concentrations disruption of the chloroplast membranes was also identified.

  15. Modeling aqueous ozone/UV process using oxalic acid as probe chemical.

    PubMed

    Garoma, Temesgen; Gurol, Mirat D

    2005-10-15

    A kinetic model that describes the removal of organic pollutants by an ozone/UV process is described. Oxalic acid, which reacts with a very low rate constant with ozone and relatively high rate constant with hydroxyl radical (OH*), was used as the probe chemical to model the process. The model was verified by experimental data on concentrations of oxalic acid and hydrogen peroxide (H202) under various experimental conditions, i.e., ozone gas dosage, UV light intensity, and varying oxalic acid concentrations.

  16. Kinetics of the reaction between ozone and phenolic acids present in agro-industrial wastewaters.

    PubMed

    Beltran-Heredia, J; Torregrosa, J; Dominguez, J R; Peres, J A

    2001-03-01

    The kinetics of the ozonation of three phenolic acids is investigated from ozone absorption experiments in a semi-continuous reactor. After the evaluation of stoichiometric ratios for the individual reactions between ozone and each phenolic acid, the oxidation of p-hydroxybenzoic acid by ozone is performed in a first stage. The influence of the operating variables on the degradation process is established, and the application of a mass transfer with chemical reaction model based on the film theory leads to the determination of the reaction orders and kinetic rate constants. The experimental absorption rates obtained agree well with those calculated theoretically. In the second stage, a mixture of ferulic acid (4-hydroxy-3-methoxycinnamic acid), beta-resorcylic acid (2,4-dihydroxybenzoic acid) and p-hydroxybenzoic acid is ozonated under different experimental conditions. The kinetic study is performed by means of a competitive method that takes p-hydroxybenzoic acid as reference compound. The application of this model allows to determine the kinetic rate constants for each compound, which are correlated as a function of pH and temperature. The results obtained support that the kinetic regime of absorption is fast and pseudo-first order with respect to ozone, a condition required by the competitive method used.

  17. A theoretical investigation of gaseous absorption by water droplets from SO2-HNO3-NH3-CO2-HCl mixtures

    NASA Technical Reports Server (NTRS)

    Adewuyi, Y. G.; Carmichael, G. R.

    1982-01-01

    A physical-chemical model is developed and used to investigate gaseous absorption by water droplets from trace gas mixtures. The model is an extension of that of Carmichael and Peters (1979) and includes the simultaneous absorption of SO2, NH3, HNO3, CO2, and HCl. Gas phase depletion is also considered. Presented results demonstrate that the absorption behavior of raindrops is strongly dependent on drop size, fall distance, trace gas concentrations, and the chemical and physical properties of the constituents of the mixture. In addition, when gas phase depletion is considered, the absorption rates and equilibrium values are also dependent on the precipitation rate itself. Also, the trace constituents liquid phase concentrations may be a factor of six or more lower when gas depletion is considered then when the depletion is ignored. However, the hydrogen ion concentration may be insensitive to the gas phase depletion.

  18. Effects of ozone and acid aerosol exposures on surfactant-associated protein A in the lung

    SciTech Connect

    Su, W.Y.

    1993-01-01

    This study examined the effect of ozone and/or acid aerosol exposure on the level of surfactant associated protein A (SP-A), its gene expression and functionality in the lung. Guinea pigs were exposed to (1) a single exposure to 0.2 to 0.8 ppm ozone for 6 hr and sacrificed at 0 to 120 hr postexposure, (2) 0.8 ppm ozone, 6 hr/day for 3 to 5 days and sacrificed immediately postexposure, or (3) 0.8 ppm ozone, 600 [mu]g/m[sup 3] sulfuric acid, or ozone plus acid for 6 hr and sacrificed at 72 hr postexposure. The concentration of SP-A was determined by ELISA in lavage fluid, lavage cell pellets, and lung tissue compartments. SP-A gene expression was examined in lung tissue by Northern and slot blot analysis. Effect of ozone exposure on functionality of surfactant was tested by its ability to modulate phagocytic cell respiratory burst in a luminol-amplified chemiluminescence (CL) assay of phagocytic cells simulated by PMA or opsonized-zymosan. There were isolated, but significant, changes in SP-A concentrations in the lavage cell and the lavage fluid compartments at 24 and 48 hr after single exposure to 0.8 ppm ozone, respectively. Exposure to ozone and ozone plus acid also slightly increased total SP-A level in the lung. No change in SP-A gene expression was detected under the exposure conditions examined. However, surfactant from ozone exposed animals significantly enhanced CL response of phagocytic cells stimulated by either PMA or opsonized-zymosan. Blocking of the enhancement of CL by a rabbit anti-human SP-A antibody strongly suggested that SP-A may contribute in the altered respiratory burst of phagocytic cells induced by surfactant from ozone exposed animals.

  19. Foliar nutrient status of Pinus ponderosa exposed to ozone and acid rain

    SciTech Connect

    Anderson, P.D.; Houpis, J.L.J. )

    1991-05-01

    A direct effect of foliar exposure to acid rain may be increased leaching of nutrient elements. Ozone exposure, through degradation of the cuticle and cellular membranes, may also result in increased nutrient leaching. To test these hypotheses, the foliar concentrations of 13 nutrient elements were monitored for mature branches of three clones of Pinus ponderosa exposed to ozone and/or acid rain. The three clones represented three distinct levels of phenotypic vigor. Branches were exposed to charcoal filtered, ambient, or 2 x ambient concentrations of ozone and received no acid rain (NAP), pH 5.1 rain (5.1), or pH 3.0 (3.0) rain. Following 10 months of continuous ozone exposure and 3 months of weekly rain applications, the concentrations of P and Mg differed significantly among rain treatments with a ranking of: 5.1 < NAP < 3.0. The S concentration increased with rain application regardless of pH. For the clones of moderate and low vigor, the concentration of N decreased with increasing rain acidity. There was no evidence of significant ozone or ozone x acid rain response. Among the three families, high phenotypic vigor was associated with significantly greater concentrations of N, P, K, Mg, B and An. These results indicate generally negligible leaching as a result of exposure to acid rain and/or ozone for one growing season. Increases in foliar concentrations of S, Mg and P are possibly the result of evaporative surface deposition from the rain solution.

  20. Kinetics of the Reactions of F((sup 2)P) and Cl((sup 2)P) with HNO3

    NASA Technical Reports Server (NTRS)

    Wine, P. H.; Wells, J. R.; Nicovich, J. M.

    1997-01-01

    The kinetics of the reactions of HNO3 with fluorine (k(sub 1)) and Chlorine (k(sub 2)) atoms have been studied by using a time-resolved long-path laser absorption technique to monitor the appearance of product NO3 radicals following 351-nm pulsed laser photolysis of X2/HNO3/He mixtures (X = F,Cl). Absolute rate coefficients for the F((sup 2)P) + HNO reaction have been determined over the temperature range 260-373 K. Between 260 and 320 K, the data are adequately represented by the Arrhenius expression k(sub 1)(T) = (6.0 +/- 2.6) x 10(exp -12) exp[(40 +/- 120)/T]cu cm/(molecule.s). Between 335 and 373 K, the rate coefficient is found to be (2.0 +/- 0.3) x 10(exp -11)cu cm/(molecule.s) independent of temperature. The observed temperature dependence suggests that reaction proceeds via competing direct abstraction and complex pathways. No NO3 production was observed in the experiments with X equals Cl, thus establishing that k(sub 2)(298 K) is less than 2 x 10(exp -16) cu cm/(molecule.s). The Cl((sup 2)P) + HNO reaction was also investigated by using a pulsed laser photolysis-resonance fluorescence technique to monitor the decay of Cl((sup 2)P). Upper limit values for k(sub 2) obtained from these experiments, in units of 10(exp -16)cu cm/(molecule.s), are 13 at 298 K and 10 at 400 K.

  1. Balloon profiles of stratospheric NO2 and HNO3 for testing the heterogeneous hydrolysis of N2O5 on sulfate aerosols

    NASA Technical Reports Server (NTRS)

    Webster, C. R.; May, R. D.; Allen, M.; Jaegle, L.; Mccormick, M. P.

    1994-01-01

    Simultaneous in situ measurements of stratospheric NO2, HNO3, HCl, and CH4 from 34 to 24 km were made in August 1992 from Palestine, Texas, using the Balloon-borne Laser In-Situ Sensor (BLISS) tunable diode laser spectrometer. Although the measurements of NO2, HNO3, and NO2/HNO3 agree well with gas-phase model calculations near 34 km where Stratospheric Aerosol and Gas Experiment (SAGE) 2 data show little sulfate aerosol, this is not true at the lower altitudes where SAGE 2 shows high aerosol loadings. At 24 km the BLISS NO2 and HNO3 measurements are 70% lower and 50% higher, respectively, than the gas phase model predictions, with a measured NO2/HNO3 ratio 5 times smaller. When the heterogeneous hydrolysis of N2O5 and ClONO2 on sulfate aerosol of surface area densities matching the SAGE 2 measurements is added to the model, good agreement with the BLISS measurements is found over the whole altitude range.

  2. Azo dye Acid Red 27 decomposition kinetics during ozone oxidation and adsorption processes.

    PubMed

    Beak, Mi H; Ijagbemi, Christianah O; Kim, Dong S

    2009-05-01

    To elucidate the effects of ozone dosage, catalysts, and temperature on azo dye decomposition rate in treatment processes, the decomposition kinetics of Acid Red 27 by ozone was investigated. Acid Red 27 decomposition rate followed the first-order reaction with complete dye discoloration in 20 min of ozone reaction. The dye decay rate increases as ozone dosage increases. Using Mn, Zn and Ni as transition metal catalysts during the ozone oxidation process, Mn displayed the greatest catalytic effect with significant increase in the rate of decomposition. The rate of decomposition decreases with increase in temperature and beyond 40 degrees C, increase in decomposition rate was followed by a corresponding increase in temperature. The FT-IR spectra in the range of 1,000-1,800 cm(-1) revealed specific band variations after the ozone oxidation process, portraying structural changes traceable to cleavage of bonds in the benzene ring, the sulphite salt group, and the C-N located beside the -N = N- bond. From the (1)H-NMR spectra, the breaking down of the benzene ring showed the disappearance of the 10 H peaks at 7-8 ppm, which later emerged with a new peak at 6.16 ppm. In a parallel batch test of azo dye Acid Red 27 adsorption onto activated carbon, a low adsorption capacity was observed in the adsorption test carried out after three minutes of ozone injection while the adsorption process without ozone injection yielded a high adsorption capacity.

  3. Laboratory studies of chemical and photochemical processes relevant to stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Zahniser, Mark S.; Nelson, David D.; Worsnop, Douglas R.; Kolb, Charles E.

    1994-01-01

    The purpose of this project is to reduce the uncertainty in several key gas-phase kinetic processes which impact our understanding of stratospheric ozone. The main emphasis of this work is on measuring rate coefficients and product channels for reactions of HO(sub x) and NO(sub x) species in the temperature range 200 K to 240 K relevant to the lower stratosphere. Other areas of study have included infrared spectroscopic studies of the HO2 radical, measurements of OH radical reactions with alternative fluorocarbons, and determination of the vapor pressures of nitric acid hydrates under stratospheric conditions. The results of these studies will improve models of stratospheric ozone chemistry and predictions of perturbations due to human influences. In this annual report, we focus on our recent accomplishments in the quantitative spectroscopy of the HO2 radical. This report details the measurements of the broadening coefficients for the v(sub 2) vibrational band. Further measurements of the vapor pressures of nitric acid hydrates relevant to the polar stratospheric cloud formation indicate the importance of metastable crystalline phases of H2SO4, HNO3, and H2O. Large particles produced from these metastable phases may provide a removal mechanism for HNO3 in the polar stratosphere.

  4. Ozonation of azo dyes (Orange II and Acid Red 27) in saline media.

    PubMed

    Silva, Alessandra C; Pic, Jean Stephane; Sant'Anna, Geraldo L; Dezotti, Marcia

    2009-09-30

    Ozonation of two azo dyes was investigated in a monitored bench scale bubble column reactor (8.5-L), varying liquid media salt content (0, 1, 40 and 100 g L(-1), NaCl). In experiments with Orange II pH was varied (5, 7.5 and 9) but ozonation of Acid Red 27 was performed at pH 7.5. Ozone self-decomposition rate-constant increased with salt concentration. Color removal was very effective and fast achieved under all experimental conditions. For the two azo dyes tested, more than 98% of color intensity was removed in 30-min ozonation assays. However, only partial mineralization of azo dyes (45%-Orange II; 20%-Acid Red 27) was attained in such experiments. The degree of mineralization (TOC removal) was negatively affected by salt concentration. Biodegradation assays conducted by respirometry revealed the inhibitory effect of dye degradation products formed during ozonation.

  5. Jasmonic acid signaling modulates ozone-induced hypersensitive cell death.

    PubMed

    Rao, M V; Lee, H; Creelman, R A; Mullet, J E; Davis, K R

    2000-09-01

    Recent studies suggest that cross-talk between salicylic acid (SA)-, jasmonic acid (JA)-, and ethylene-dependent signaling pathways regulates plant responses to both abiotic and biotic stress factors. Earlier studies demonstrated that ozone (O(3)) exposure activates a hypersensitive response (HR)-like cell death pathway in the Arabidopsis ecotype Cvi-0. We now have confirmed the role of SA and JA signaling in influencing O(3)-induced cell death. Expression of salicylate hydroxylase (NahG) in Cvi-0 reduced O(3)-induced cell death. Methyl jasmonate (Me-JA) pretreatment of Cvi-0 decreased O(3)-induced H(2)O(2) content and SA concentrations and completely abolished O(3)-induced cell death. Cvi-0 synthesized as much JA as did Col-0 in response to O(3) exposure but exhibited much less sensitivity to exogenous Me-JA. Analyses of the responses to O(3) of the JA-signaling mutants jar1 and fad3/7/8 also demonstrated an antagonistic relationship between JA- and SA-signaling pathways in controlling the magnitude of O(3)-induced HR-like cell death.

  6. Removal of dicyclohexyl acetic acid from aqueous solution using ultrasound, ozone and their combination.

    PubMed

    Kumar, Pardeep; Headley, John; Peru, Kerry; Bailey, Jon; Dalai, Ajay

    2014-01-01

    Naphthenic acids are a complex mixture of organic components, some of which include saturated alkyl-substituted cycloaliphatic carboxylic acids and acyclic aliphatic acids. They are naturally found in hydrocarbon deposits like oil sand, petroleum, bitumen and crude oil. In this study, the oxidation of a relatively high molecular weight naphthenic acid (Dicyclohexyl acetic acid) was investigated using ozonation, ultrasonication and hydrogen peroxide alone and their combinations. Effects on oxidation of dicyclohexyl acetic acid (DAA) were measured for different concentrations of ozone ranging between 0.7 to 3.3 mg L(-1) and pH in the range 6 to 10. Ultrasonication and hydrogen peroxide alone were not effective to oxidize dicyclohexyl acetic acid, but combining ultrasonication with H2O2 had a significant effect on oxidation of dicyclohexyl acetic acid with maximum removal reaching to 84 ± 2.2% with 81 ± 2.1% reduction in chemical oxygen demand (COD). Synergistic effects were observed for combining ultrasonication with ozonation and resulted in 100% DAA removal with 98 ± 0.8% reduction in COD within 15 min at 3.3 mg L(-1) ozone concentration and 130 Watts ultrasonication power. The reaction conditions obtained for the maximum oxidation of DAA and COD removal were used for the degradation of naphthenic acids mixture extracted from oil sands process water (OSPW). The percentage oxidation of NAs mixture extracted from OSPW was 89.3 ± 1.1% in ozonation and combined ozonation and ultrasonication, but COD removal observed was 65 ± 1.2% and 78 ± 1.4% for ozonation and combined ozonation and ultrasonication treatments, respectively.

  7. Environmental Externalities in Electric Power Markets: Acid Rain, Urban Ozone, and Climate Change

    EIA Publications

    1995-01-01

    This article discusses the emissions resulting from the generation of electricity by utilities and their role in contributing to the environmental problems of acid rain, urban ozone, and climate change.

  8. The impact of high altitude aircraft on the ozone layer in the stratosphere

    NASA Technical Reports Server (NTRS)

    Tie, Xue XI; Brasseur, Guy; Lin, Xing; Friedlingstein, P.; Granier, Claire; Rasch, Philip

    1994-01-01

    The paper discusses the potential effects on the ozone layer of gases released by the engines of proposed high altitude supersonic aircraft. The major problem arises from the emissions of nitrogen oxides which have the potential to destroy significant quantities of ozone in the stratosphere. The magnitude of the perturbation is highly dependent on the cruise altitude of the aircraft. Furthermore, the depletion of ozone is substantially reduced when heterogeneous conversion of nitrogen oxides into nitric acid on sulfate aerosol particles is taken into account in the calculation. The sensitivity of the aerosol load on stratospheric ozone is investigated. First, the model indicates that the aerosol load induced by the SO2 released by aircraft is increased by about 10-20% above the background aerosols at mid-high latitude of the Northern Hemisphere at 15 km for the NASA emission scenario A (the NASA emission scenarios are explained in Tables I to III). This increase in aerosol has small effects on stratospheric ozone. Second, when the aerosol load is increased following a volcanic eruption similar to the eruption of El Chichon (Mexico, April 1982), the ozone column in spring increases by as much as 9% in response to the injection of NOx from the aircraft with the NASA emission scenario A. Finally, the modeled suggests that significant ozone depletion could result from the formation of additional polar stratospheric clouds produced by the injection of H2O and HNO3 by the aircraft engines.

  9. Ozone

    SciTech Connect

    Not Available

    1988-06-01

    The author discusses the debate over whether concern about a hole in the ozone layer in Antarctic is real or science fiction. There is a growing consensus that efforts must be taken to protect the ozone layer. The issue now is not whether chlorofluorocarbons (CFCs) should be controlled and regulated but how much and how soon. The United States has urged that the production of dangerous CFCs, and any other chemicals that affect the ozone layer, be restricted immediately to current levels and that their use be reduced 95 percent over the next decade. The American position was too strong for many European nations and the Japanese. Negotiations at an international conference on the matter broke down. The breakdown is due in part to a more acute concern for environmental matters in the United States than exists in many countries. Meanwhile CFCs are linked to another environmental problem that equally threatens the world - the Greenhouse Effect. The earth is in a natural warming period, but man could be causing it to become even warmer. The Greenhouse Effect could have a catastrophic impact on mankind, although nothing has been proven yet.

  10. Economic assessment of acid deposition and ozone damage on the San Joaquin Valley agriculture. Final report

    SciTech Connect

    Howitt, R.

    1993-02-01

    The California Agricultural Resources Model (CARM) was used to estimate the economic impact of acidic deposition and ozone on crops in the San Joaquin Valley. Data on ozone exposure-crop response and agricultural markets are used in the CARM to estimate the potential economic benefits of an improvement in air quality. The study focused on the economic impact of two ozone reduction scenarios in agricultural regions of California. The CARM projected that if growing season concentrations of ozone were reduced to 0.04 ppm, annual benefits to consumers (higher availability and lower prices) and producers (higher production and lower production costs) would be approximately $489 million. In comparison, the benefit projected if statewide levels of ozone were uniformly reduced to 0.025 ppm was approximately $1.5 billion. Although the 0.025 ppm scenario is unlikely, the economic benefits were estimated to be correspondingly large.

  11. Kinetics of heterogeneous reaction of ozone with linoleic acid and its dependence on temperature, physical state, RH, and ozone concentration.

    PubMed

    Zeng, Guang; Holladay, Sara; Langlois, Danielle; Zhang, Yunhong; Liu, Yong

    2013-03-07

    Heterogeneous reaction between ozone and linoleic acid (LA) thin film was investigated by a flow reactor coupled to attenuated total reflection infrared spectroscopy (FR-ATR-IR) over wide ranges of temperature, relative humidity (RH), and ozone concentration under atmospheric pressure condition. Pseudo-first-order rate constants kapp and overall reactive uptake coefficients γ were acquired on the basis of changes in absorbance from peaks located near 1743, 1710, 1172, and 1110 cm(-1), which can be assigned to C═O in ester, C═O in acid, and C-C and C-O stretching modes, respectively. Results showed that the kapp and γ increased nearly by a factor of 6 with increasing temperatures from 258 to 314 K. It was noted the temperature effect on the reaction kinetics was much more pronounced at lower temperatures. Such behavior can be explained by a change in the physical state of LA at lower temperatures. In addition, kapp and γ were enhanced by 2-fold as the RH increased from 0 to 80%. Moreover, the effect of ozone concentration on the reaction kinetics was reported for the first time. kapp was found to display a Langmuir-Hinshelwood dependence on ozone concentration with KO3 = (1.146 ± 0.017) × 10(-15) molecules cm(-3) and k[S] = 0.0522 ± 0.0004 s(-1), where KO3 is a parameter that describes the partitioning of ozone to the thin film surface, and k[S] is the maximum pseudo-first-order coefficient at high ozone concentration. Furthermore, yields and hygroscopic properties of reaction products were also investigated by FTIR spectroscopy. The intensity ratio of two C═O stretching bands, A1743/A1710, which was utilized as an indicator of the product yields, increased sharply with increasing temperatures in the lower temperature region (258-284 K), and then remained nearly constant in the higher temperature region (284-314 K). The product yields showed no significant variation with RH, for the intensity ratio of A1743/A1710 barely changed in the wide RH range 0

  12. Influence of ozone and paracetic acid disinfection on adhesion of resilient liners to acrylic resin

    PubMed Central

    2016-01-01

    PURPOSE The aim of this study was to evaluate the effect of paracetic acid (PAA) and ozone disinfection on the tensile bond strength (TBS) of silicone-based resilient liners to acrylic resins. MATERIALS AND METHODS One hundred and twenty dumbbell shaped heat-polymerized acrylic resins were prepared. From the mid segment of the specimens, 3 mm of acrylic were grinded off and separated parts were reattached by resilient liners. The specimens were divided into 2 control (control1, control7) and 4 test groups of PAA and ozone disinfection (PAA1, PAA7, ozone1 and ozone7; n=10). While control groups were immersed in distilled water for 10 min (control1) and 7 days (control7), test groups were subjected to PAA (16 g/L) or ozone rich water (4 mg/L) for 1 cycle (10 min for PAA and 60 min for ozone) per day for 7 days prior to tensile tests. Measurements of the TBS were analyzed using 3-way ANOVA and Tukey's HSD test. RESULTS Adhesive strength of Mollosil decreased significantly by application of ozone disinfection. PAA disinfection had no negative effect on the TBS values of Mollosil and Molloplast B to acrylic resin. Single application of ozone disinfection did not have any negative effect on TBS values of Molloplast B, but prolonged exposure to ozone decreased its adhesive strength. CONCLUSION The adhesion of resilient liners to acrylic was not adversely affected by PAA disinfection. Immersion in ozonated water significantly decreased TBS of Mollosil. Prolonged exposure to ozone negatively affects adhesion of Molloplast B to denture base materials. PMID:27555898

  13. Single-step microwave digestion with HNO(3) alone for determination of trace elements in coal by ICP spectrometry.

    PubMed

    Wang, Jie; Nakazato, Tetsuya; Sakanishi, Kinya; Yamada, Osamu; Tao, Hiroaki; Saito, Ikuo

    2006-02-28

    A microwave digestion method with HNO(3) alone was conducted at a temperature as high as 250 degrees C for determination of 19 trace elements (Li, Be, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Cd, Cs, Ba, Hg, and Pb) in coal jointly by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and flow injection ICP-MS (FI-ICP-MS). The validity of determination was assessed by using three standard coals, SRM 1632c, BCR 180, and SARM 19. It was found that the high-temperature digestion led to an extensive decomposition of the organic matrix and clay in coal, and no dissolved and solid carbon remained in the final solution after evaporation. Good recoveries were observed for all trace elements in three coals, with the exception of V, Rb, and Cs in high-ash SARM 19. Additionally, FI-ICP-MS combined with the present digestion without evaporation pretreatment was proved to be a rapid and efficient approach for determination of ultra-trace elements such as Se, Cd, and Hg in coal.

  14. Uptake of HNO3 to deliquescent sea-salt particles: a study using the short-lived radioactive isotope tracer 13N

    NASA Astrophysics Data System (ADS)

    Guimbaud, C.; Arens, F.; Gutzwiller, L.; Gäggeler, H. W.; Ammann, M.

    2002-10-01

    The uptake of HNO3 to deliquescent airborne sea-salt particles (RH = 55%, P = 760 torr, T = 300 K) at concentrations from 2 to 575 ppbv is measured in an aerosol flow tube using 13N as a tracer. Small particles ( 70 nm diameter) are used in order to minimize the effect of diffusion in the gas phase on the mass transfer. Below 100 ppbv, an uptake coefficient (gupt) of 0.50 ± 0.20 is derived. At higher concentrations, the uptake coefficient decreases along with the consumption of aerosol chloride. Data interpretation is further supported by using the North American Aerosol Inorganics Model (AIM), which predicts the aqueous phase activities of ions and the gas-phase partial pressures of H2O, HNO3, and HCl at equilibrium for the NaCl/HNO3/H2O system. These simulations show that the low concentration data are obtained far from equilibrium, which implies that the uptake coefficient derived is equal to the mass accommodation coefficient under these conditions. The observed uptake coefficient can serve as input to modeling studies of atmospheric sea-salt aerosol chemistry. The main sea-salt aerosol burden in the marine atmosphere is represented by coarse mode particles (> 1 µm diameter). This implies that diffusion in the gas-phase is the limiting step to HNO3 uptake until the sea-salt has been completely processed.

  15. Stratospheric HNO3 measurements from 0.002/cm resolution solar occultation spectra and improved spectroscopic line parameters in the 5.8-micron region

    NASA Astrophysics Data System (ADS)

    Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, D. G.; Rinsland, C. P.; Flaud, J.-M.; Camy-Peyret, C.

    1992-02-01

    Very-high-resolution FWHM solar-occultation spectra are investigated with a balloon-borne interferometer using revised spectroscopic line parameters for HNO3, O3, and H2O. The O3 and H2O data are evaluated to determine their capacity for interference in the HNO3 line which is studied in the nu sub 2 band at 5.8 microns. The line parameters developed with the stratospheric data are compared to data based on a HITRAN compilation as well as laboratory spectra with a 0.002/cm resolution. The line list is calculated and shown to include J and Ka transitions which improve the line parameters for HNO3 by accounting for the weaker absorption features in the stratospheric spectra. The stratospheric HNO3 profile developed analytically is compared to those based on reported measurements, and the one developed with the stratospheric solar spectra is found to be consistent with the measurements and confirm inherent measurement biases.

  16. Intercomparison of Clean Air Status and Trends Network (CASTNET) NO3 - and HNO3 Measurements with Data from Other Monitoring Programs

    EPA Science Inventory

    The EPA Clean Air Status and Trends Network (CASTNET) utilizes an open face filter pack system to measure concentrations of atmospheric sulfur and nitrogen species. The purpose of this study was to estimate the uncertainty in seasonal and annual concentrations of HNO3, NO3 - , ...

  17. Stratospheric HNO3 measurements from 0.002/cm resolution solar occultation spectra and improved spectroscopic line parameters in the 5.8-micron region

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Kosters, J. J.; Murcray, D. G.; Rinsland, C. P.; Flaud, J.-M.; Camy-Peyret, C.

    1992-01-01

    Very-high-resolution FWHM solar-occultation spectra are investigated with a balloon-borne interferometer using revised spectroscopic line parameters for HNO3, O3, and H2O. The O3 and H2O data are evaluated to determine their capacity for interference in the HNO3 line which is studied in the nu sub 2 band at 5.8 microns. The line parameters developed with the stratospheric data are compared to data based on a HITRAN compilation as well as laboratory spectra with a 0.002/cm resolution. The line list is calculated and shown to include J and Ka transitions which improve the line parameters for HNO3 by accounting for the weaker absorption features in the stratospheric spectra. The stratospheric HNO3 profile developed analytically is compared to those based on reported measurements, and the one developed with the stratospheric solar spectra is found to be consistent with the measurements and confirm inherent measurement biases.

  18. Adaptation to multiday ozone exposure is associated with a sustained increase of bronchoalveolar uric acid.

    PubMed

    Kirschvink, Nathalie; Fiévez, Laurence; Bureau, Fabrice; Degand, Guy; Maghuin-Rogister, Guy; Smith, Nicola; Art, Tatiana; Lekeux, Pierre

    2002-01-01

    The phenomenon of ozone tolerance is described, but the underlying mechanisms remain unknown. We tested whether adaptation to multiday ozone exposure was related to an upregulated pulmonary antioxidant defence. Six calves were exposed to 0.75 ppm ozone, 12 h day(-1) for seven consecutive days. Pulmonary function tests and bronchoalveolar lavage (BAL) were performed before, after the first (D1), third (D3) and seventh (D7) exposure. Differential cell count, total proteins, 8-epi-PGF2alpha, glutathione and uric acid were determined in BAL. Dynamic lung compliance and arterial oxygen tension were significantly decreased and lung oedema impaired pulmonary function on D1. By repeating ozone exposures, progressive functional adaptation occurred. Ozone induced a significant increase of BAL neutrophil percentage on D1. On D3 and D7, neutrophil percentage was progressively decreased, but remained significantly elevated. BAL total proteins were significantly increased on D1 and decreased progressively until D7. 8-Epi-PGF2alpha was significantly increased on D1 and was returned to baseline on D3 and D7, whilst glutathione significantly increased on D3 and returned to baseline on D7. Uric acid was increased ten-fold on D1. On D3, uric acid was increased six-fold and was persistently elevated at D7. This study suggests that ozone adaptation of functional and inflammatory variables is accompanied with sustained BAL uric acid elevation.

  19. Measurements of HNO3 and N2O5 using Ion drift - Chemical Ionization Mass Spectrometry during the MCMA - 2006 Campaign

    NASA Astrophysics Data System (ADS)

    Zheng, J.; Zhang, R.; Fortner, E. C.; Molina, L.; Aiken, A. C.; Jimenez, J. L.; Gäggeler, K.; Dommen, J.; Dusanter, S.; Stevens, P. S.; Tie, X.

    2008-03-01

    An ion drift - chemical ionization mass spectrometry (ID-CIMS) was deployed in Mexico City between 5 and 31 March to measure HNO3 and N2O5 during the 2006 Mexico City Metropolitan Area (MCMA) field campaign. The observation site, T0, was located at the Instituto Mexicano del Petróleo at the center of the Mexico City Basin with major emissions of pollutants from both domestic and industrial sources. Diurnally, HNO3 was less than 200 parts per trillion (ppt) during the night and in the early morning, increased steadily from around 09:00 a.m. central standard time (CST), reached a peak value of 0.5 to 3 parts per billion (ppb) in the early afternoon, and declined sharply to less than half of the peak value near 05:00 p.m. CST. An inter-comparison between the ID-CIMS and an ion chromatograph/mass spectrometer (ICMS) showed a good correlation in the HNO3 measurements (R2=0.75). The HNO3 mixing ratio was found to anti-correlate with aerosol nitrate, suggesting that the gaseous HNO3 concentration was controlled by the gas-particle partitioning process. During most times of the MCMA 2006 field campaign, N2O5 was found to be under the detection limit (about 20 ppt for a 10 s integration time) of the ID-CIMS, because of high NO mixing ratio (>100 ppb) during the night. With one exception on 26 March 2006, about 40 ppt N2O5 was observed during the late afternoon and early evening hours under a cloudy condition, before NO built up at the surface site. The results revealed that during the 2006 MCMA field campaign HNO3 was primarily produced by the reaction of OH with NO2 and regulated by gas/particle partitioning, and HNO3 production from N2O5 hydrolysis during the nighttime was small because of high NO and low O3 concentrations near the surface.

  20. Acid mist and ozone effects on the leaf chemistry of two western conifer species

    NASA Technical Reports Server (NTRS)

    Westman, Walter E.; Temple, Patrick J.

    1989-01-01

    The effects of ozone and acid-mist exposures on the leaf chemistry of Jeffrey pine and giant sequoia seedlings grown in filtered-air greenhouses were investigated. Acid-mist treatments (pH 4.1, 3.4, 2.7, or 2.0) were administered for 3 h, and ozone exposures (0, 0.10, and 0.20 microliter/liter), which followed acid-mist treatments, for 4 h, each for three days a week for six to nine weeks. It was found that seedlings were more susceptible to acid-mist and acid mist/ozone combinations, than to ozone alone. Acid mist treatment resulted in higher levels of nitrogen and sulfur (both present in acid mist) as well as Na. Leaves of giant sequoia exhibited increased K and decreased Mn, while Jeffrey pine showed increases in Fe and Mn. In sequoia leaves, concentrations of Ca, Mg, and Ba decreased. Acid treatment also reduced chlorophyll b concentrations in both conifer species. Extensive changes induced by acid mist are consistent with earlier observations of changes in spectral reflectance of conifer seedlings observed after three weeks of fumigation.

  1. Ozonation kinetics of phenolic acids present in wastewaters from olive oil mills

    SciTech Connect

    Benitez, F.J.; Beltran-Heredia, J.; Acero, J.L.; Pinilla, M.L.

    1997-03-01

    A kinetic study of the degradation by ozone of eight phenolic acids present in wastewaters from olive oil mills has been performed by using a competition kinetic method. The selected phenolic acids are: caffeic, p-coumaric, syringic, vanillic, 3,4,5-trimethoxybenzoic, veratric, p-hydroxy-benzoic, and protocatechuic. The influence of the operating variables (temperature, pH, and ozone partial pressure in the gas stream) is established, and the stoichiometric ratios for the individual direct reactions between ozone and each acid are determined. Once the reaction rate constants are evaluated, they are correlated as a function of temperature and pH into kinetic expressions which are provided for every phenolic acid. The global process occurs in the fast and pseudo-first-order kinetic regime of absorption, a condition required by the competition model to be used.

  2. Corrosion of Type 7075-T73 Aluminum in a 10% HNO3 + Fe2(SO4)3 Deoxidizer Solution

    NASA Astrophysics Data System (ADS)

    Savas, Terence P.; Earthman, James C.

    2009-03-01

    Localized corrosion damage in Type 7075-T73 aluminum was investigated for a HNO3 + Fe2(SO4)3 deoxidizer solution which is frequently used for surface pretreatment prior to anodizing. The corrosion damage was quantified in the time domain using the electrochemical noise resistance ( Rn) and in the frequency domain using the spectral noise impedance ( Rsn). The Rsn was derived from an equivalent electrical circuit model that represented the corrosion cell implemented in the present study. These data are correlated to scanning electron microscopy (SEM) examinations and corresponding statistical analysis based on digital image analysis of the corroded surfaces. Other data used to better understand the corrosion mechanisms include the open circuit potential (OCP) and coupling-current time records. Based on statistical analysis of the pit structures for 600 and 1200 s exposures, the best fit was achieved with a 3-paramater lognormal distribution. It was observed for the 1200 s exposure that a small population of pits continued to grow beyond a threshold critical size of 10 μm. In addition, significant grain boundary attack was observed after 1200 s exposure. These data are in good agreement with the electrochemical data. Specifically, the Rn was computed to be 295 and 96 Ω-cm2 for 600 and 1200 s exposures, respectively. The calculated value of Rsn, theoretically shown to be equal to Rn in the low frequency limit, was higher than Rn for a 1200 s exposure period. However, better agreement between the Rn and Rsn was found for frequencies above 0.01 Hz. Experimental results on the measurement performance for potassium chloride (KCl) saturated double-junction Ag/AgCl and single-junction Hg/Hg2Cl2 reference electrodes in the low-pH deoxidizer solution are also compared.

  3. Preparation of low-molecular-weight hyaluronic acid by ozone treatment.

    PubMed

    Wu, Yue

    2012-06-20

    Recently, low-molecular-weight hyaluronic acid has been reported to have novel features, such as free radical scavenging activities, antioxidant activities, promotion of excisional wound healing, etc. In the present work, degradation of native hyaluronic acid by ozone treatment was performed for preparation of low-molecular-weight hyaluronic acid. The molecular weight of native hyaluronic acid was reduced from 1535 to 87 kDa for 120 min at 40°C. The rate of reduction of molecular weight was 94.33%. The FT-IR, 13C NMR, and UV-vis spectra suggested that there was no obvious modification of chemical structure of low-molecular-weight hyaluronic acid. The use of degradation of native hyaluronic acid by ozone treatment can be a useful alternative for production of low-molecular-weight hyaluronic acid.

  4. Effect of fatty acid coatings on ozone uptake to deliquesced KI/NaCl aerosol particles

    NASA Astrophysics Data System (ADS)

    Ammann, M.; Rouvière, A.

    2009-12-01

    Phase transfer kinetics of gas phase oxidants may limit oxidative aging of aerosol particles. The aim of this work is to study the role of amphiphilic organic aerosol constituents on the kinetics of phase transfer of gaseous species to the bulk aqueous phase. The effect of (C9-C20) fatty acid surfactants on the phase transfer of ozone to deliquesced potassium iodide and sodium chloride have been investigated. Some other experiments of ozone uptake have been performed with different mixtures and proportions of fatty acids. The kinetic experiments were performed in an aerosol flow tube at room temperature and atmospheric pressure. To obtain deliquesced inorganic particles, the relative humidity was adjusted in the range of 75% to 80%. It is shown that the fatty acids in monolayer quantities may substantially inhibit the phase transfer of ozone to deliquesced particles. The results showed that especially the C15-C20 limit the mass transfer of ozone to the aqueous phase, whereby the magnitude of this effect was following the monolayer properties of the fatty acids. It was also possible to determine a resistance of such films to the transfer of ozone to the bulk phase.

  5. Degradation of dichloroacetic acid in homogeneous aqueous media employing ozone and UVC radiation.

    PubMed

    Lovato, María Eugenia; Martín, Carlos A; Cassano, Alberto E

    2011-03-02

    A tentative workable mechanism for dichloroacetic acid decomposition (DCA) in aqueous media employing ozone and UVC radiation has been developed. All experiments were made in a homogeneous medium under assured kinetic control regime. Under no circumstances did a headspace exist in the reactor volume. The starting point of the reaction with UVC radiation was always under the prerequisite of a confirmed state of initial equilibrium conditions for the mixture water-ozone-oxygen at 20 °C. The explored variables were: (i) DCA initial concentration, (ii) ozone concentration and (iii) fluence rate at the reactor window. The model comprises three parallel reactions: (1) direct photolysis, (2) direct ozonation and (3) ozone + UVC degradation. Complete DCA removal was achieved, and the mass balance, considering DCA disappearance and chloride ion formation, closed within very small error. The combination of ozone and UVC radiation produces a significant amount of hydrogen peroxide as an important reaction by-product. The direct photolysis can be well represented with a six step reaction sequence. The direct ozonation mechanism comprises 22 steps and, with the entire set of kinetic constants completed in this work, it is independent of the reaction pH in the range from 3 to 6.3. Lastly, the associated use of ozone and UVC radiation becomes necessary to consider the existence of radiation absorption by three species, namely DCA, ozone and hydrogen peroxide. The developed system, including the three parallel reactions, led to the proposal of a 37 step reaction mechanism. Finally the reaction kinetics, the mass balances and the radiation field corresponding to this complex system were rigorously modeled and the most significant features of the mathematical representation are briefly described. The simulation results rendered from this model agree very well with the measured experimental data. This outcome will be essential for deriving a complete reactor model that must be

  6. Identification of the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch in stratospheric solar occultation spectra

    NASA Technical Reports Server (NTRS)

    Perrin, A.; Flaud, J.-M.; Camy-Peyret, C.; Goldman, A.; Rinsland, C. P.; Gunson, M. R.

    1994-01-01

    The spectroscopic identification for the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch at 830.4/cm is reported based on 0.01/cm resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025/cm resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(exp -18)/cm/mol/sq cm at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated.

  7. Comparison of correlative data with HNO3 version 7 from the CLAES instrument deployed on the NASA Upper Atmosphere Research Satellite

    NASA Astrophysics Data System (ADS)

    Kumer, J. B.; Mergenthaler, J. L.; Roche, A. E.; Nightingale, R. W.; Ely, G. A.; Uplinger, W. G.; Gille, J. C.; Massie, S. T.; Bailey, P. L.; Gunson, M. R.; Abrams, M. C.; Toon, G. C.; Sen, B.; Blavier, J.-F.; Stachnik, R. A.; Webster, C. R.; May, R. D.; Murcray, D. G.; Murcray, F. J.; Goldman, A.; Traub, W. A.; Jucks, K. W.; Johnson, D. G.

    1996-04-01

    The cryogenic limb array etalon spectrometer (CLAES) aboard UARS made near-global measurements of HNO3 and 388 days from January 9, 1992, to April 25, 1993, have been processed to data version 7 (V7). Results from UARS instruments, including CLAES, the improved stratospheric and mesospheric sounder, and the microwave limb sounder, provide the first near-global documentation of the evolution of denitrification in the Antarctic 1992 winter and spring vortex. We provide a description of the CLAES HNO3 V7 quality that includes comparisons with correlative measurements to assess overall quality, accuracy, and precision. Correlative profiles of volume mixing ratio (vmr) included those obtained by the space shuttle deployed ATMOS in two missions, March-April 1992 and April 1993, data from a variety of balloon-borne instruments at midlatitude (11 profiles), and in high-latitude northern winter (six profiles), and LIMS data. In general, the CLAES V7 HNO3 maximum values of vmr were of the order of 6-15% less than correlative for CLAES values ≤8 parts per billion by volume (ppbv). However, when CLAES peak vmr values were 10 to 13 ppbv, then CLAES values exceeded correlative by 0-7%. The comparisons were within the combined instrumental error estimates, or observed measurement variability, for the large majority of comparisons. As discussed, the retrieval of future versions will utilize updated spectral parameters and will also correct for a small uncompensated drift in radiometric calibration that occurred in the latter part of the mission. This is expected to improve the comparisons in the ≤8 ppbv range, perhaps at the expense of those in the ≥8 ppbv range. The data obtained January 9 to April 15, 1992, in comparison with data obtained January 9 to April 15, 1993, reveal strikingly evident 1-year period deseasonalized trends on a global basis. These trends agree quantitatively with available correlative data suitable for trend analysis. These include ATMOS in the

  8. Uptake of ozone to mixed sodium bromide/ citric acid solutions

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Tao; Steimle, Emilie; Bartels-Rausch, Thorsten; Kato, Shunsuke; Lampimäki, Markus; Brown, Matthew; van Bokhoven, Jeroen; Nolting, Frithjof; Kleibert, Armin; Türler, Andreas; Ammann, Markus

    2013-04-01

    Sea-salt solution - air interfaces play an important role in the chemistry of the marine boundary layer. The reaction of ozone (O3) with bromide is of interest in the context of formation of photolabile halogens (Br2, BrCl) in the marine boundary layer. Recent experiments have suggested that the bromide oxidation rate is related to the surface concentration of bromide [1] and inversely related to the gas phase concentration of O3, an indication for a precursor mediated reaction at the surface [2]. So far, the effect of organics (such as those occurring at the ocean surface or in marine aerosols) on the reaction of O3 with bromide aerosols has not been studied yet. In our study we investigate the uptake kinetics of O3 to a mixed solution of sodium bromide (NaBr) and citric acid (CA), which represents highly oxidized organic compounds present in the environment, with a well-established coated wall flow tube technique, which leads to exposure of the film to O3 allowing the heterogeneous reactions to take place and the loss of O3 being measured. The results indicate that the uptake of O3 to the films with the higher bromide concentrations (0.34M and 4M) is independent of the gas phase concentration and roughly consistent with uptake limited by reaction in the bulk. For the lower bromide concentration (84mM), however, we observe a trend of the uptake coefficient to decrease with increasing O3 concentration, indicating an increasing importance of a surface reaction. In an attempt to constrain the kinetic data, we employed X-ray photoelectron spectroscopy (XPS) to get insight into the surface composition of the aqueous solution - air interface. Previous XPS studies have shown that halide ion concentrations are enhanced at the aqueous solution air interface [3-4], which likely promotes the surface reactions of bromide or iodide with O3. A first XPS study of ternary solutions of KI with butanol indicated the importance of specific interactions of the cation with the alcohol

  9. Catalytic ozonation of fenofibric acid over alumina-supported manganese oxide.

    PubMed

    Rosal, Roberto; Gonzalo, María S; Rodríguez, Antonio; García-Calvo, Eloy

    2010-11-15

    The catalytic ozonation of fenofibric acid was studied using activated alumina and alumina-supported manganese oxide in a semicontinuous reactor. The rate constants at 20°C for the non-catalytic reaction of fenofibric acid with ozone and hydroxyl radicals were 3.43±0.20 M(-1) s(-1) and (6.55±0.33)×10(9) M(-1) s(-1), respectively. The kinetic constant for the catalytic reaction between fenofibric acid and hydroxyl radicals did not differ significantly from that of homogeneous ozonation, either using Al(2)O(3) or MnO(x)/Al(2)O(3). The results showed a considerable increase in the generation of hydroxyl radicals due to the use of catalysts even in the case of catalytic runs performed using a real wastewater matrix. Both catalysts promoted the decomposition of ozone in homogeneous phase, but the higher production of hydroxyl radicals corresponded to the catalyst with more activity in terms of ozone decomposition. We did not find evidence of the catalysts having any effect on rate constants, which suggests that the reaction may not involve the adsorption of organics on catalyst surface.

  10. Extraction of Pd(II), Rh(III) and Ru(III) from HNO(3) aqueous solution to betainium bis(trifluoromethanesulfonyl)imide ionic liquid.

    PubMed

    Sasaki, Kotoe; Takao, Koichiro; Suzuki, Tomoya; Mori, Takahiro; Arai, Tsuyoshi; Ikeda, Yasuhisa

    2014-04-21

    Extraction efficiencies of Pd(ii), Rh(iii), and Ru(iii) from HNO3(aq) to [Hbet][Tf2N] were demonstrated, i.e., Pd(ii) is the most extractable, Rh(iii) is medium extractable, and Ru(iii) is the least extractable. The extraction seems to proceed through coordination of betaine to the metal ions and the cation exchange of the formed complex with H(+).

  11. Complexation of mercury(II) with 1-Phenyl-2,3-dimethylpyrazoline-5-thione in 0.1 mol/L HNO3 at 273-338 K

    NASA Astrophysics Data System (ADS)

    Beknazarova, N. S.; Shoalifov, Dzh. O.; Amindzhanov, A. A.; Safarmamadov, S. M.

    2016-12-01

    The complexation of mercury(II) with 1-phenyl-2,3-dimethylpyrazoline-5-thione is studied by means of potentiometry in 0.1 mol/L HNO3 at 273-338 K. The composition of the complexes is determined and their stepwise stability constants are calculated. A pattern is found in altering the stepwise stability constants as the temperature and number of attached 1-phenyl-2,3-dimethylpyrazoline-5-thione molecules rise.

  12. Polar processing in a split vortex: early winter Arctic ozone loss in 2012/13

    NASA Astrophysics Data System (ADS)

    Manney, G. L.; Lawrence, Z. D.; Santee, M. L.; Livesey, N. J.; Lambert, A.; Pitts, M. C.

    2015-02-01

    A sudden stratospheric warming (SSW) in early January 2013 caused the polar vortex to split. After the lower stratospheric vortex split on 8 January, the two offspring vortices - one over Canada and the other over Siberia - remained intact, well-confined, and largely at latitudes that received sunlight until they reunited at the end of January. As the SSW began, temperatures abruptly rose above chlorine activation thresholds throughout the lower stratosphere. The vortex was very disturbed prior to the SSW, and was exposed to much more sunlight than usual in December 2012 and January 2013. Aura Microwave Limb Sounder (MLS) nitric acid (HNO3) data and observations from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) indicate extensive polar stratospheric cloud (PSC) activity, with evidence of PSCs containing solid nitric acid trihydrate particles during much of December 2012. Consistent with the sunlight exposure and PSC activity, MLS observations show that chlorine monoxide (ClO) became enhanced early in December. Despite the cessation of PSC activity with the onset of the SSW, enhanced vortex ClO persisted until mid-February, indicating lingering chlorine activation. The smaller Canadian offspring vortex had lower temperatures, lower HNO3, lower hydrogen chloride (HCl), and higher ClO in late January than the Siberian vortex. Chlorine deactivation began later in the Canadian than in the Siberian vortex. HNO3 remained depressed within the vortices after temperatures rose above the PSC existence threshold, and passive transport calculations indicate vortex-averaged denitrification of about 4 ppbv; the resulting low HNO3 values persisted until the vortex dissipated in mid-February. Consistent with the strong chlorine activation and exposure to sunlight, MLS measurements show rapid ozone loss commencing in mid-December and continuing through January. Lagrangian transport estimates suggest ~ 0.7-0.8 ppmv (parts per million by volume) vortex

  13. The role of ion-molecule reactions in the conversion of N2O5 to HNO3 in the stratosphere

    NASA Astrophysics Data System (ADS)

    Bohringer, H.; Fahey, D. W.; Fehsenfeld, F. C.; Ferguson, E. E.

    1983-02-01

    The role of several ion-molecule reactions in the conversion of N2O5 to HNO3 was investigated. In the proposed conversion, an N2O5 molecule would react with an H2O molecule clustered to an inert ion to produce two HNO3 molecules. Subsequent clustering of an H2O molecule to the inert ion would make the reaction catalytic. If such an ion-catalyzed conversion of N2O5 to HNO3 occurs, it would probably play a role in the stratospheric chemistry at high latitudes in winter. Reaction rate constant measurements made in a flowing afterglow apparatus flor hydrated H3O(+), H(+)(CH3CN)m(m equals 1,2,3), and several negative ions reacting with N2O5 are presented. Slow rate constants were found for these ions for hydration levels that are predominant in the stratosphere. With the known stratospheric ion density, these slow rate constants preclude significant N2O5 conversion by ion-molecule reactions.

  14. Composites of manganese oxide with carbon materials as catalysts for the ozonation of oxalic acid.

    PubMed

    Orge, C A; Órfão, J J M; Pereira, M F R

    2012-04-30

    Manganese oxide and manganese oxide-carbon composites were prepared and tested as catalysts for the removal of oxalic acid by ozonation. Their performances were compared with the parent carbon material (activated carbon or carbon xerogel) used to prepare the composites. Oxalic acid degradation by carbon materials is slower than that attained with manganese oxide or manganese oxide-carbon composites. A complete degradation after 90 and 45 min of reaction was obtained for carbon materials and for the catalysts containing manganese, respectively. The ozonation in the presence of the prepared composites are supposed to occur mainly by surface reactions, following a direct oxidation mechanism by molecular ozone and/or surface oxygenated radicals.

  15. Removal of dichloroacetic acid from drinking water by using adsorptive ozonation.

    PubMed

    Gu, Li; Yu, Xin; Xu, Jinli; Lv, Lu; Wang, Qing

    2011-07-01

    Chloroacetic acids, formed during the disinfection process in potable water production, are considered to pose a potential risk to human health. This article deals with dichloroacetic acid (DCAA) removal from drinking water by using a process of bentonite based adsorptive ozonation. This process is formed by combined addition of ozone, bentonite and Fe(3+). During the reaction, DCAA is removed by the joint effect of adsorption, ozonation and catalytic oxidation. In addition, under the effect of the adsorption, natural organic matters (NOM) can be adsorbed onto the bentonite surface, resulting in a reduced scavenging effect toward HO· radicals, and hence eliminate the negative effect of NOM on DCAA removal. At the initial stage of the reaction, Fe(3+) is rapidly hydrolyzed to polycations and adsorbed onto the bentonite surface or into its structural layers. This positively charges the surface of the bentonite and increases its surface area, resulting in a strong adsorption of HA or DCAA. Furthermore, Fe(3+) catalyzes ozone decomposition to form HO· thus further improving the efficiency. The adsorptive ozonation has been shown to be potentially advantageous in destruction of toxic, dissolved pollutants in drinking water, and appears to have great potential for a wide range of treatment applications.

  16. Student Teacher Understanding of the Greenhouse Effect, Ozone Layer Depletion, and Acid Rain.

    ERIC Educational Resources Information Center

    Dove, Jane

    1996-01-01

    Describes the results of a survey designed to ascertain details of student teachers' knowledge and misconceptions about the greenhouse effect, acid rain, and ozone layer depletion. Results indicate familiarity with the issues but little understanding of the concepts involved and many commonly held misconceptions. (JRH)

  17. Acid mist and ozone effects on the leaf chemistry of two western conifer species.

    PubMed

    Westman, W E; Temple, P J

    1989-01-01

    Seedlings of Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were more susceptible to leaf chemical changes following exposure to acid mist (pH 3.4-2.0) or acid mist/ozone combinations, than to ozone alone (0.1-0.2 microl/litre), when plants were exposed to alternating doses of these pollutants for 6-9 weeks. Under acid mist treatment, leaves exhibited higher levels of nitrogen and sulfur, two elements applied in acid mist. In addition, levels of foliar sodium, and, in the case of giant sequia, potassium, as well, increased under acid mist treatment. Iron and manganese were also mobilized, resulting in significant increases in these elements in pine, and decreases in manganese in giant sequoia foliage. The acid treatment also reduced chlorophyll b concentrations in pine, and, to a less significant extent, in giant sequoia. Calcium, magnesium, barium and strontium were differentially accumulated in giant sequoia compared to Jeffrey pine. Under acid mist treatment, all of these elements (except strontium) declined in concentration in giant sequoia, with calcium showing the most significant trend. The more extensive changes in leaf chemistry induced by acid mist are consistent with earlier observations of significant changes in spectral reflectance of these seedlings after 3 weeks of fumigation. Limited foliage samples collected from these two species in 1985 and 1986 in Sequoia/Kings Canyon National Parks in the southern Sierra Nevada do not in themselves indicate any clearcut or severe effects of ozone alone on leaf chemistry of these species, but a mild influence of nitrate-laden acid deposition, possibly in combination with ozone, is consistent with the rise in nitrogen and lignin levels in Jeffrey pine on sites observed to have moderate visible injury symptoms. No firm conclusions about effects of pollutants on leaf chemistry in these field sites is possible without further study.

  18. Laboratory simulations of the interaction between ozone and chloroacetic acids in the conditions close to stratospheric

    NASA Astrophysics Data System (ADS)

    Strokova, N. E.; Savilov, S. V.; Morozov, I. I.; Yagodovskaya, T. V.; Lunin, V. V.

    2015-01-01

    The interaction between ozone and mono-, di-, and trichloroacetic acids are studied using a flow vacuum gas discharge setup in a regime close to stratospheric conditions (in the temperature range of 77 to 250 K, at pressures of 10-3 to 0 Torr, and in the presence of ice). The interaction between ozone and trichloroacetic acid starts at 77 K, while interaction with monochloroacetic acid begins when the temperature is raised to 200 K. The reactions are assumed to proceed via different mechanisms: chlorine oxides of different composition are the reaction products, as is shown using low-temperature IR spectroscopy. Preliminary adsorption of the acids on a surface of ice raises the temperature of interaction to 190 K.

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

    NASA Technical Reports Server (NTRS)

    Stevens, Robert K.

    1991-01-01

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

  20. Synergistic effect of the combination of immobilized TiO2, UVA and ozone on the decomposition of dichloroacetic acid.

    PubMed

    Mehrjouei, Mohammad; Müller, Siegfried; Möller, Detlev

    2012-01-01

    The performance of a heterogeneous photocatalytic ozonation system (TiO(2)/UVA/O(3)) was evaluated on the degradation and mineralization of dichloroacetic acid as a contaminant in aqueous solutions by means of a planar reactor. The commercial product "Pilkington Active™ glass" was used as the immobilized TiO(2) photocatalyst and it was irradiated by near UV light in this study. The synergistic interaction between ozone and the photoactivated TiO(2) surface was discussed and highlighted. Furthermore, the influences of initial concentration and temperature on the degradation rate of dichloroacetic acid and the ozone consumption level during the oxidation process were investigated. The concentrations of dichloroacetic acid and chloride anions produced during degradation were measured using ion chromatography. The mineralization of dichloroacetic acid was evaluated by Total Organic Carbon (TOC) measurements. The degradation of dichloroacetic acid by photocatalytic ozonation showed good agreement with the kinetics of first-order reactions with respect to dichloroacetic acid.

  1. Carboxylic acids in secondary aerosols from oxidation of cyclic monoterpenes by ozone

    SciTech Connect

    Glasius, M.; Lahaniati, M.; Calogirou, A.; Di Bella, D.; Jensen, N.R.; Hjorth, J.; Kotzias, D.; Larsen, B.R.

    2000-03-15

    A series of smog chamber experiments have been conducted in which five cyclic monoterpenes were oxidized by ozone. The evolved secondary aerosol was analyzed by GC-MS and HPLC-MS for nonvolatile polar oxidation products with emphasis on the identification of carboxylic acids. Three classes of compounds were determined at concentration levels corresponding to low percentage molar yields: i.e., dicarboxylic acids, oxocarboxylic acids, and hydroxyketocarboxylic acids. Carboxylic acids are highly polar and have lower vapor pressures than their corresponding aldehydes and may thus play an important role in secondary organic aerosol formation processes. The most abundant carboxylic acids were the following: cis-pinic acid AB1(cis-3-carboxy-2,2-dimethylcyclobutylethanoic acid) from {alpha} and {beta}-pinene; cis-pinonic acid A3 (cis-3-acetyl-2,2-dimethylcyclobutylethanoic acid) and cis-10-hydroxypinonic acid Ab6 (cis-2,2-dimethyl-3-hydroxyacetylcyclobutyl-ethanoic acid) from {alpha}-pinene and {beta}-pinene; cis-3-caric acid C1 (cis-2,2-dimethyl-1,3-cyclopropyldiethanoic acid), cis-3-caronic acid C3 (2,2-dimethyl-3-(2-oxopropyl)cyclopropanylethanoic acid), and cis-10-hydroxy-3-caronic acid C6 (cis-2,2-dimethyl-3(hydroxy-2-oxopropyl)cyclopropanylethanoic acid) from 3-carene; cis-sabinic acid S1 (cis-2-carboxy-1-isopropylcyclopropylethanoic acid) from sabinene; limonic acid L1 (3-isopropenylhexanedioic acid), limononic acid L3 (3-isopropenyl-6-oxo-heptanoic acid), 7-hydroxy-limononic acid L6 (3-isopropenyl-7-hydroxy-6-oxoheptanoic acid), and 7-hydroxylimononic acid Lg{prime} (7-hydroxy-3-isopropenyl-6-oxoheptanoic acid) from limonene.

  2. Uptake of CO2, SO2, HNO3 and HCl on calcite (CaCO3) at 300 K: mechanism and the role of adsorbed water.

    PubMed

    Santschi, Ch; Rossi, M J

    2006-06-01

    All experimental observations of the uptake of the four title compounds on calcite are consistent with the presence of a reactive bifunctional surface intermediate Ca(OH)(HCO3) that has been proposed in the literature. The uptake of CO2 and SO2 occurs on specific adsorption sites of crystalline CaCO3(s) rather than by dissolution in adsorbed water, H2O(ads). SO2 primarily interacts with the bicarbonate moiety whereas CO2, HNO3 and HCl all react first with the hydroxyl group of the surface intermediate. Subsequently, the latter two react with the bicarbonate group to presumably form Ca(NO3)2 and CaCl2.2H2O. The effective equilibrium constant of the interaction of CO2 with calcite in the presence of H2O(ads) is kappa = deltaCO2/(H2O(ads)[CO2]) = 1.62 x 10(3) bar(-1), where CO2 is the quantity of CO2 adsorbed on CaCO3. The reaction mechanism involves a weakly bound precursor species that is reversibly adsorbed and undergoes rate-controlling concurrent reactions with both functionalities of the surface intermediate. The initial uptake coefficients gamma0 on calcite powder depend on the abundance of H2O(ads) under the present experimental conditions and are on the order of 10(-4) for CO2 and 0.1 for SO2, HNO3 and HCl, with gamma(ss) being significantly smaller than gamma0 for HNO3 and HCl, thus indicating partial saturation of the uptake. At 33% relative humidity and 300 K there are 3.5 layers of H2O adsorbed on calcite that reduce to a fraction of a monolayer of weakly and strongly bound water upon pumping and/or heating.

  3. One-pot room-temperature conversion of cyclohexane to adipic acid by ozone and UV light.

    PubMed

    Hwang, Kuo Chu; Sagadevan, Arunachalam

    2014-12-19

    Nitric acid oxidation of cyclohexane accounts for ~95% of the worldwide adipic acid production and is also responsible for ~5 to 8% of the annual worldwide anthropogenic emission of the ozone-depleting greenhouse gas nitrous oxide (N2O). Here we report a N2O-free process for adipic acid synthesis. Treatment of neat cyclohexane, cyclohexanol, or cyclohexanone with ozone at room temperature and 1 atmosphere of pressure affords adipic acid as a solid precipitate. Addition of acidic water or exposure to ultraviolet (UV) light irradiation (or a combination of both) dramatically enhances the oxidative conversion of cyclohexane to adipic acid.

  4. Polar processing in a split vortex: Arctic ozone loss in early winter 2012/2013

    NASA Astrophysics Data System (ADS)

    Manney, G. L.; Lawrence, Z. D.; Santee, M. L.; Livesey, N. J.; Lambert, A.; Pitts, M. C.

    2015-05-01

    A sudden stratospheric warming (SSW) in early January 2013 caused the Arctic polar vortex to split and temperatures to rapidly rise above the threshold for chlorine activation. However, ozone in the lower stratospheric polar vortex from late December 2012 through early February 2013 reached the lowest values on record for that time of year. Analysis of Aura Microwave Limb Sounder (MLS) trace gas measurements and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) polar stratospheric cloud (PSC) data shows that exceptional chemical ozone loss early in the 2012/13 Arctic winter resulted from a unique combination of meteorological conditions associated with the early-January 2013 SSW: unusually low temperatures in December 2012, offspring vortices within which air remained well isolated for nearly 1 month after the vortex split, and greater-than-usual vortex sunlight exposure throughout December 2012 and January 2013. Conditions in the two offspring vortices differed substantially, with the one overlying Canada having lower temperatures, lower nitric acid (HNO3), lower hydrogen chloride, more sunlight exposure/higher ClO in late January, and a later onset of chlorine deactivation than the one overlying Siberia. MLS HNO3 and CALIPSO data indicate that PSC activity in December 2012 was more extensive and persistent than at that time in any other Arctic winter in the past decade. Chlorine monoxide (ClO, measured by MLS) rose earlier than previously observed and was the largest on record through mid-January 2013. Enhanced vortex ClO persisted until mid-February despite the cessation of PSC activity when the SSW started. Vortex HNO3 remained depressed after PSCs had disappeared; passive transport calculations indicate vortex-averaged denitrification of about 4 parts per billion by volume. The estimated vortex-averaged chemical ozone loss, ~ 0.7-0.8 parts per million by volume near 500 K (~21 km), was the largest December/January loss in the MLS

  5. Reactive nitrogen, ozone, and nitrate aerosols observed in the Arctic stratosphere in January 1990

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Aimedieu, P.; Koike, M.; Iwasaka, Y.; Newman, P. A.; Schmidt, U.; Matthews, W. A.; Hayashi, M.; Sheldon, W. R.

    1992-01-01

    Ozone mixing ratios in the vicinity of the 525-K potential temperature surface in January and early February of 1990 were observed to decrease sharply across the edge of the vortex boundary, where the vortex position was estimated from Ertel's potential vorticity. The changes in NO(y) mixing ratio with respect to altitude measured on January 18 and 31 were quite well correlated with those of ozone between 15 and 24 km, indicating that NO(y) also had a large gradient across the edge of the vortex. This is interpreted as being mainly due to the significant denitrification that occurred inside the vortex. The total amount of gas and particulate phase HNO3 was close to the NO(y) amount at the altitude of the 22- to 23-km region, suggesting that the conversion of non-HNO3 reactive nitrogen to HNO3 had occurred with a PSC.

  6. Relating physical state and reactivity: humidity dependent ozone uptake on tannic and shikimic acid

    NASA Astrophysics Data System (ADS)

    Steimer, S.; Huisman, A.; Krieger, U.; Lampimäki, M.; Marcolli, C.; Peter, T.; Ammann, M.

    2012-04-01

    Atmospheric aerosols are an important focus of environmental research due to their effect on climate and human health. Recent findings show that organic aerosol particles are capable of forming amorphous solids and semi-solids under atmospheric conditions [1]. Such particles should be highly viscous, leading to low diffusivity within the bulk. This would then slow down eventual chemical reactions in the bulk, thereby increasing the lifetime of the organic compounds involved. First indications of such behavior were recently shown for the reaction of thin protein films with ozone [2]. To investigate the influence of the physical state on the reactivity of atmospherically relevant compounds, the uptake of ozone on two different organics was measured using a coated wall flow tube system. The investigated organic compounds are tannic acid, which is a proxy for atmospheric polyphenolic materials, and shikimic acid, a constituent of biomass burning aerosols. The viscosity of the organic film was adjusted by varying the humidity of the system, assuming a correlation between the two parameters due to water acting as a plasticizer. The investigated humidity range was 0% - 95% RH for tannic and 0% - 92% RH for shikimic acid. It was found that both of the compounds show a long term uptake of ozone which lasts for more than 20 h. The uptake coefficient is clearly humidity dependent and increases by close to two orders of magnitude between driest and wettest conditions. At a given humidity, shikimic acid is the more reactive compound. The measured humidity dependence supports the hypothesis that the uptake coefficient is a strong function of the diffusion coefficient of ozone in the organic film. 1. Virtanen, A., et al., An amorphous solid state of biogenic secondary organic aerosol particles. Nature, 2010. 467(7317): p. 824-827. 2. Shiraiwa, M., et al., Gas uptake and chemical aging of semisolid organic aerosol particles. Proceedings of the National Academy of Sciences of the

  7. Modulations of stratospheric ozone by volcanic eruptions

    NASA Technical Reports Server (NTRS)

    Blanchette, Christian; Mcconnell, John C.

    1994-01-01

    We have used a time series of aerosol surface based on the measurements of Hofmann to investigate the modulation of total column ozone caused by the perturbation to gas phase chemistry by the reaction N2O5(gas) + H2O(aero) yields 2HNO3(gas) on the surface of stratospheric aerosols. We have tested a range of values for its reaction probability, gamma = 0.02, 0.13, and 0.26 which we compared to unperturbed homogeneous chemistry. Our analysis spans a period from Jan. 1974 to Oct. 1994. The results suggest that if lower values of gamma are the norm then we would expect larger ozone losses for highly enhanced aerosol content that for larger values of gamma. The ozone layer is more sensitive to the magnitude of the reaction probability under background conditions than during volcanically active periods. For most conditions, the conversion of NO2 to HNO3 is saturated for reaction probability in the range of laboratory measurements, but is only absolutely saturated following major volcanic eruptions when the heterogeneous loss dominates the losses of N2O5. The ozone loss due to this heterogeneous reaction increases with the increasing chlorine load. Total ozone losses calculated are comparable to ozone losses reported from TOMS and Dobson data.

  8. Trajectory Studies of Large HNO3-Containing PSC Particles in the Arctic: Evidence for the Role of NAT

    NASA Technical Reports Server (NTRS)

    McKinney, K. A.; Wennberg, P. O.; Dhaniyala, S.; Fahey, D. W.; Northway, M. J.; Kuenzi, K. F.; Kleinboehl, A.; Sinnhuber, M.; Kuellmann, H.; Bremer, H.; Mahoney, M. J.; Bui, T. P.

    2004-01-01

    Large (5 to >20 micron diameter) nitric-acid-containing polar stratospheric cloud (PSC) particles were observed in the Arctic stratosphere during the winter of 1999-2000. We use a particle growth and sedimentation model to investigate the environment in which these particles grew and the likely phase of the largest particles. Particle trajectory calculations show that, while simulated nitric acid dihydrate (NAD) particle sizes are significantly smaller than the observed maximum particle sizes, nitric acid trihydrate (NAT) particle trajectories are consistent with the largest observed particle sizes.

  9. Influence of monolayer amounts of HNO3 on the evaporation rate of H2O over ice in the range 179 to 208 K: a quartz crystal microbalance study.

    PubMed

    Delval, Christophe; Rossi, Michel J

    2005-08-18

    The evaporation flux J(ev) of H2O from thin H2O ice films containing between 0.5 and 7 monolayers of HNO3 has been measured in the range 179 to 208 K under both molecular and stirred flow conditions in isothermal experiments. FTIR absorption of the HNO3/H2O condensate revealed the formation of metastable alpha-NAT (HNO(3).3H2O) converting to stable beta-NAT at 205 K. After deposition of HNO3 for 16-80 s on a 1 mum thick pure ice film at a deposition rate in the range (6-60) x 10(12) molecules s(-1) the initial evaporative flux J(ev)(H2O) was always that of pure ice. J(ev)(H2O) gradually decreased with the evaporation of H2O and the concomitant increase of the average mole fraction of HNO3, chi(HNO3), indicating the presence of an amorphous mixture of H2O/HNO3 that is called complexed or (c)-ice whose vapor pressure is that of pure ice. The final value of J(ev) was smaller by factors varying from 2.7 to 65 relative to pure ice. Depending on the doping conditions and temperature of the ice film the pure ice thickness d(D) of the ice film for which J(ev) < 0.85J(ev)(pure ice) varied between 130 and 700 nm compared to the 1000 nm thick original ice film at 208 and 191 K, respectively, in what seems to be an inverse temperature dependence. There exist three different types of H2O molecules under the present experimental conditions, namely (a) free H2O corresponding to pure ice, (b) complexed H2O or c-ice, and (c) H2O molecules originating from the breakup of NAT or amorphous H2O/HNO3 mixtures. The significant decrease of J(ev)(H2O) with increasing chi(HNO3) leads to an increase of the evaporative lifetime of atmospheric ice particles in the presence of HNO3 and may help explain the occurrence of persistent and/or large contaminated ice particles at certain atmospheric conditions.

  10. Carryover effects of acid rain and ozone on the physiology of multiple flushes of loblolly pine seedlings. [Pinus taeda L

    SciTech Connect

    Sasek, T.W.; Richardson, C.J.; Fendick, E.A.; Bevington, S.R. ); Kress, L.W. )

    1991-09-01

    The effects of acid rain and ozone exposure on loblolly pine (Pinus taeda L.) seedlings in the Piedmont of North Carolina were assessed over two exposure seasons (1987-1988). Direct effects and carryover effects of long-term exposure on the photosynthetic potential and photopigment concentrations of different needle age-classes were studied. Three half-sib families were grown in open-top field chambers and exposed two acid rain treatments and five ozone exposures delivered in proportion to ambient concentrations in a complete factorial design. Ozone significantly affected photosynthesis but there were no statistically significant effects of acid rain nor any ozone {times} acid rain interactions. In 1987, photosynthesis of the 1987 first-flush progressively diverged among the ozone treatments except between charcoal-filtered and nonfiltered air (NF). At the end of the first season, photosynthesis was reduced 24% at 1.5{times} compared to CF and more than 80% at 2.25{times} and 3.0{times}. Chlorophyll and carotenoid concentrations were similarly reduced at elevated ozone exposures. In 1988, photosynthesis of the 1987 first-flush in the elevated ozone treatments remained lower. Early in the second season, the 1988 first-flush had a 25% to 50% lower photosynthetic potential at 2.25{times} and 3.0{times} compared to CF. This carryover effect on the photosynthetic potential before significant cumulative exposure was progressively smaller in the later 1988 flushes. In the late season flushes in the highest ozone treatments, photosynthesis was significantly higher than in the lower ozone treatments.

  11. Decomposition of two haloacetic acids in water using UV radiation, ozone and advanced oxidation processes.

    PubMed

    Wang, Kunping; Guo, Jinsong; Yang, Min; Junji, Hirotsuji; Deng, Rongsen

    2009-03-15

    The decomposition of two haloacetic acids (HAAs), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), from water was studied by means of single oxidants: ozone, UV radiation; and by the advanced oxidation processes (AOPs) constituted by combinations of O(3)/UV radiation, H(2)O(2)/UV radiation, O(3)/H(2)O(2), O(3)/H(2)O(2)/UV radiation. The concentrations of HAAs were analyzed at specified time intervals to elucidate the decomposition of HAAs. Single O(3) or UV did not result in perceptible decomposition of HAAs within the applied reaction time. O(3)/UV showed to be more suitable for the decomposition of DCAA and TCAA in water among the six methods of oxidation. Decomposition of DCAA was easier than TCAA by AOPs. For O(3)/UV in the semi-continuous mode, the effective utilization rate of ozone for HAA decomposition decreased with ozone addition. The kinetics of HAAs decomposition by O(3)/UV and the influence of coexistent humic acids and HCO(3)(-) on the decomposition process were investigated. The decomposition of the HAAs by the O(3)/UV accorded with the pseudo-first-order mode under the constant initial dissolved O(3) concentration and fixed UV radiation. The pseudo-first-order rate constant for the decomposition of DCAA was more than four times that for TCAA. Humic acids can cause the H(2)O(2) accumulation and the decrease in rate constants of HAAs decomposition in the O(3)/UV process. The rate constants for the decomposition of DCAA and TCAA decreased by 41.1% and 23.8%, respectively, when humic acids were added at a concentration of 1.2mgTOC/L. The rate constants decreased by 43.5% and 25.9%, respectively, at an HCO(3)(-) concentration of 1.0mmol/L.

  12. Catalytic ozonation of oxalic acid using carbon nanofibres on macrostructured supports.

    PubMed

    Restivo, J; Órfão, J J M; Pereira, M F R; Vanhaecke, E; Rönning, M; Iouranova, T; Kiwi-Minsker, L; Armenise, S; Garcia-Bordejé, E

    2012-01-01

    Carbon nanofibres (CNFs) were grown on different macrostructured supports such as cordierite monoliths, carbon felts and sintered metal fibres. The resulting composites exhibited excellent resistance to attrition/corrosion and its porosity is mainly due to mesoporous structures. The CNF/structured materials were tested in the ozonation of oxalic acid in a conventional semi-batch reactor after being crushed to powder form, and in a newly designed reactor that may operate in semi-batch or continuous operation. The CNFs supported on the different structured materials exhibited high catalytic activity in the mineralization of oxalic acid.

  13. Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers.

    PubMed

    Burkey, Kent O; Neufeld, Howard S; Souza, Lara; Chappelka, Arthur H; Davison, Alan W

    2006-10-01

    Cutleaf coneflower (Rudbeckia laciniata L.), crown-beard (Verbesina occidentalis Walt.), and tall milkweed (Asclepias exaltata L.) are wildflower species native to Great Smoky Mountains National Park (U.S.A.). Natural populations of each species were analyzed for leaf ascorbic acid (AA) and dehydroascorbic acid (DHA) to assess the role of ascorbate in protecting the plants from ozone stress. Tall milkweed contained greater quantities of AA (7-10 micromol g(-1) fresh weight) than crown-beard (2-4 micromol g(-1) fresh weight) or cutleaf coneflower (0.5-2 micromol g(-1) fresh weight). DHA was elevated in crown-beard and cutleaf coneflower relative to tall milkweed suggesting a diminished capacity for converting DHA into AA. Tall milkweed accumulated AA in the leaf apoplast (30-100 nmol g(-1) fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AA was not present in the leaf apoplast of either crown-beard or cutleaf coneflower. Unidentified antioxidant compounds were present in the leaf apoplast of all three species. Overall, distinct differences in antioxidant metabolism were found in the wildflower species that corresponded with differences in ozone sensitivity.

  14. Uptake of Nitric Acid, Dinitrogen Pentoxide, Ozone and The Nitrate Radical On A Single Liquid Drop

    NASA Astrophysics Data System (ADS)

    Schütze, M.; Herrmann, H.

    A novel technique for the investigation of uptake processes on gas-liquid interfaces will be presented. It allows the generation and analysis of single liquid drops inside a flow tube reactor. The in situ analysis of the drop is performed by broad band UV-VIS absorption spectroscopy. Using this set-up the uptake of nitric acid and dinitrogen pentoxide on pure water was measured by monitoring the occurrence of the nitrate band centered at a wavelength of 300 nm. The uptake of ozone on NaI solutions of various concentrations was followed by the formation of the triiodide ion which is a product of the oxidation of iodide by ozone. Using aqueous solutions of the dye Alizarin Red S, the uptake of the nitrate radical could be quantified. In order to extract information on fundamental parameters, e.g. the mass accommo- dation coefficients (= a) of the species, a computer model is applied. It solves the diffusion equation for the transport of gas phase species to the interface numerically. The result is a separation of the influence of this process on the rate of the overall uptake process. The mass accommodation coefficients a > 0.03, a = 0.011 and a > 0.02 were obtained for nitric acid, dinitrogen pentoxide and ozone, respectively.

  15. Involvement of abscisic acid in ozone-induced puerarin production of Pueraria thomsnii Benth. suspension cell cultures.

    PubMed

    Sun, Lina; Su, Hu; Zhu, Yun; Xu, Maojun

    2012-01-01

    Exposure to ozone induced a rapid increase in the levels of the sesquiterpene phytohormone abscisic acid (ABA) and the isoflavone puerarin in suspension cell cultures of Pueraria thomsnii Benth. The observed increases in ABA and puerarin were dependent on the concentration of ozone applied to P. thomsnii cell cultures. In order to examine the role of ABA in ozone-induced puerarin production, cell suspensions were pretreated with the ABA biosynthetic inhibitor fluridone. Following ozone exposure, fluridone treatment suppressed ABA accumulation suggesting ABA was normally synthesized de novo through the carotenoid pathway. Fluridone also blocked ozone-induced puerarin production, which could be reversed through application of exogenous ABA. However, in the absence of ozone, ABA itself had no effect on puerarin accumulation in the suspension cells. Taken together, the data indicate that ozone is an efficient elicitor of puerarin production and may be particularly applicable for improving puerarin production in plant cell cultures. Furthermore, we demonstrate that ABA is one factor associated with ozone-induced puerarin production in P. thomsnii cell cultures.

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

    NASA Technical Reports Server (NTRS)

    Talbot, Robert W.; Dibb, Jack E.

    2004-01-01

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

  17. Calculation of the solubility diagrams in the system Ca(OH) 2-H 3PO 4-KOH-HNO 3-CO 2-H 2O

    NASA Astrophysics Data System (ADS)

    Vereecke, Guy; Lemaître, Jacques

    1990-09-01

    A computer program has been developed for calculating the solubility isotherms of sparingly soluble calcium phosphates (including octacalcium phosphate and β-tricalcium phosphate) and calcite in the system Ca(OH) 2-H 3PO 4-KOH-HNO 3-CO 2-H 2O. It allows the influence of such parameters as temperature, pH, partial CO 2 pressure and ionic strength to be investigated. The calculation process takes into account the effects of ion-pair formation and ionic strength. Selected solubility isotherms are presented and compared to literature data. The influence of temperature, Ca/P ratio, ionic strength and CO 2 pressure on the stability isotherms of hydroxyapatite and dicalcium phosphate are discussed in detail.

  18. HCl Vapour Pressures and Reaction Probabilities for ClONO2 + HCl on Liquid H2SO4-HNO3-HCl-H20 Solutions

    NASA Technical Reports Server (NTRS)

    Elrod, M. J.; Koch, R. E.; Kim, J. E.; Molina, M. J.

    1995-01-01

    Henry's Law solubility constants for HCl have been measured for liquid H2SO4-HNO3-HCl-H2O solutions; the results are in good agreement with predictions from published semiempirical models. The ClONO2 + HCl reaction on the surfaces of such solutions with compositions simulating those of stratospheric aerosols has been investigated; as the composition changes following the temperature drop characteristic of the high-latitude stratosphere the reaction probability gamma increases rapidly. Furthermore, the gamma values remain essentially unchanged when HN03 uptake is neglected; the controlling factor appears to be the solubility of HCl. These results corroborate our earlier suggestion that supercooled liquid sulfate aerosols promote chlorine activation at low temperatures as efficiently as solid polar stratospheric cloud particles.

  19. Phase Equilibria of H2SO4, HNO3, and HCl Hydrates and the Composition of Polar Stratospheric Clouds

    NASA Technical Reports Server (NTRS)

    Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

    1995-01-01

    Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

  20. Phase equilibria of H2SO4, HNO3, and HCl hydrates and the composition of polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Wooldridge, Paul J.; Zhang, Renyi; Molina, Mario J.

    1995-01-01

    Thermodynamic properties and phase equilibria behavior for the hydrates and coexisting pairs of hydrates of common acids which exist in the stratosphere are assembled from new laboratory measurements and standard literature data. The analysis focuses upon solid-vapor and solid-solid-vapor equilibria at temperatures around 200 K and includes new calorimetric and vapor pressure data. Calculated partial pressures versus 1/T slopes for the hydrates and coexisting hydrates agree well with experimental data where available.

  1. Development of an in situ measurement system of particulate nitrate using the scrubber difference and the NO-ozone chemiluminescence method

    NASA Astrophysics Data System (ADS)

    Sadanaga, Y.; Yuba, A.; Takami, A.; Imabayashi, H.; Suzue, T.; Kimoto, H.; Kimoto, T.; Takeda, Y.; Sera, T.; Kawakami, J.; Norimichi, T.; Hatakeyama, S.; Bandow, H.

    2008-12-01

    An in situ nitric acid analyzer has been newly designed. Its operation is based on measuring the concentration difference between gaseous HNO3-surubbed NOy and NOy scrubbing gaseous HNO3 and particles. NOy is measured by an NO-ozone chemiluminescent detector equipped with a heated molybdenum catalyst. Gaseous HNO3 and particles were scrubbed by using an annular denuder coated with NaCl and Teflon fiber filter, respectively. The reduction efficiencies (RE) of sodium nitrate by a molybdenum catalyst were measured. NaNO3 particles with 3-μm diameters were reduced to NO quantitatively by a molybdenum catalyst. However, the RE decreased with particle diameter to 49.3±9.1% (1σ) for NaNO3 particles with 9-μm diameter. Meanwhile, quantitative reduction was observed for NaNO3/NaCl particles regardless of particle diameter. The RE was 92.6±2.8% (1σ) for NaNO3/NaCl particles even as large as 12-μm diameter. The decrease of the RE with particle diameter for NaNO3 is caused by the nitrate concentrations rather than particle diameter. An intercomparison of particulate nitrate between this instrument and the R&P 8400N nitrate monitor was performed at the National Institute for Environmental Studies Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS), Okinawa, Japan. The correlation plot shows that the concentrations observed by this instrument were about 20% higher than those obtained the R&P nitrate monitor. This result is qualitatively reasonable because this instrument measures TSP nitrate while the R&P nitrate monitor observes PM10 nitrate.

  2. LIMS Instrument Package (LIP) balloon experiment: Nimbus 7 satellite correlative temperature, ozone, water vapor, and nitric acid measurements

    NASA Technical Reports Server (NTRS)

    Lee, R. B., III; Gandrud, B. W.; Robbins, D. E.; Rossi, L. C.; Swann, N. R. W.

    1982-01-01

    The Limb Infrared Monitor of the Stratosphere (LIMS) LIP balloon experiment was used to obtain correlative temperature, ozone, water vapor, and nitric acid data at altitudes between 10 and 36 kilometers. The performance of the LIMS sensor flown on the Nimbus 7 Satellite was assessed. The LIP consists of the modified electrochemical concentration cell ozonesonde, the ultraviolet absorption photometric of ozone, the water vapor infrared radiometer sonde, the chemical absorption filter instrument for nitric acid vapor, and the infrared radiometer for nitric acid vapor. The limb instrument package (LIP), its correlative sensors, and the resulting data obtained from an engineering and four correlative flights are described.

  3. Inferring Ozone Production in an Urban Atmosphere using Measurements of Peroxynitric Acid

    NASA Technical Reports Server (NTRS)

    Spencer, K. M.; McCabe, D. C.; Crounse, J. D.; Olson, J. R.; Crawford, J. H.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Cantrell, C. A.; Anderson, R. S.; Mauldin, R. L.; Wennberg, P. O.

    2009-01-01

    Observations of peroxynitric acid (HO2NO2) obtained simultaneously with those of NO and NO2 provide a sensitive measure of the ozone photochemical production rate. We illustrate this technique for constraining the ozone production rate with observations obtained from the NCAR C-130 aircraft platform during the Megacity Initiative: Local and Global Research Observations (MILAGRO) intensive in Mexico during the spring of 2006. Sensitive and selective measurements of HO2NO2 were made in situ using chemical ionization mass spectrometry (CIMS). Observations were compared to modeled HO2NO2 concentrations obtained from the NASA Langley highly-constrained photochemical time-dependent box model. The median observed-to-calculated ratio of HO2NO2 is 1.18. At NOx levels greater than 15 ppbv, the photochemical box model underpredicts observations with an observed-to-calculated ratio of HO2NO2 of 1.57. As a result, we find that at high NOx, the ozone production rate calculated using measured HO2NO2 is faster than predicted using accepted photochemistry. Inclusion of an additional HOx source from the reaction of excited state NO2 with H2O or reduction in the rate constant of the reaction of OH with NO2 improves the agreement.

  4. Disinfection efficiency of peracetic acid, UV and ozone after enhanced primary treatment of municipal wastewater.

    PubMed

    Gehr, Ronald; Wagner, Monika; Veerasubramanian, Priya; Payment, Pierre

    2003-11-01

    The City of Montreal Wastewater Treatment Plant uses enhanced physicochemical processes (ferric and/or alum coagulation) for suspended solids and phosphorus removal. The objective of this study was to assess the ability of peracetic acid (PAA), UV, or ozone to inactivate the indicator organisms fecal coliforms, Enterococci, MS-2 coliphage, or Clostridium perfringens in the effluent from this plant. PAA doses to reach the target fecal coliform level of 9000 CFU/100mL exceeded 6 mg/L; similar results were obtained for enterococci, and no inactivation of Clostridium perfringens was observed. However a 1-log reduction of MS-2 occurred at PAA doses of 1.5 mg/L and higher. It was expected that this effluent would have a high ozone demand, and would require relatively high UV fluences, because of relatively high effluent COD, iron and suspended solids concentrations, and low UV transmittance. This was confirmed herein. For UV, the inactivation curve for fecal coliforms showed the typical two-stage shape, with the target of 1000 CFU/100 mL (to account for photoreactivation) occurring in the asymptote zone at fluences >20 mJ/cm(2). In contrast, inactivation curves for MS-2 and Clostridium perfringens were linear. Clostridium perfringens was the most resistant organism. For ozone, inactivation was already observed before any residuals could be measured. The transferred ozone doses to reach target fecal coliform levels ( approximately 2-log reduction) were 30-50 mg/L. MS-2 was less resistant, but Clostridium perfringens was more resistant than fecal coliforms. The different behaviour of the four indicator organisms studied, depending on the disinfectant, suggests that a single indicator organism might not be appropriate. The required dose of any of the disinfectants is unlikely to be economically viable, and upstream changes to the plant will be needed.

  5. Effect of the interaction between dye and acetic acid on the decomposition of Basic Green 4 with additive by ozone.

    PubMed

    Pérez, Arizbeth A; Poznyak, Tatiana I; Chairez, Jorge I

    2014-01-01

    This research investigated the ozonation of Basic Green 4 (BG4) under the presence of acetic acid (AA). This acid is used as a textile additive for many industrial dyes derived from triphenylmethane. Determining the effect of this additive on discoloration, degradation dynamics, and final by-product distribution is the main objective of this study. The reaction system was the ozonation of a dye solution in co-solvents. This solution (dye and AA) was considered a simplified version of real BG4 dyeing wastewaters supplied with additives. The dye concentration was set to 50, 150, and 250 mg/L without pH adjustment (pH = 3). This low value was forced by the AA. Ozonation reaction with dye was mainly done by a direct molecular mechanism. The discoloration dynamics of BG4 without and with the additive were determined by ultraviolet and visible wavelength spectroscopy. The dye decomposition and the intermediate and final product formation-decomposition dynamics were followed by high-performance liquid chromatography. The effects of AA in the ozonation results were significant in the following ways: 1) a possible complex, formed between AA and the dye, changed ozone consumption; 2) the presence of additive decelerated the dye discoloration and decomposition; and 3) the number of by-products was dissimilar in both systems, with and without the additive the ozonation. The accumulation of organic acids with low molecular weight was determined in both systems, with and without the additive. Only one by-product was obtained in ozonation when AA participated in the reactor. A possible reaction mechanism is proposed for the system dye-AA-ozone.

  6. Naphthenic acids speciation and removal during petroleum-coke adsorption and ozonation of oil sands process-affected water.

    PubMed

    Gamal El-Din, Mohamed; Fu, Hongjing; Wang, Nan; Chelme-Ayala, Pamela; Pérez-Estrada, Leonidas; Drzewicz, Przemysław; Martin, Jonathan W; Zubot, Warren; Smith, Daniel W

    2011-11-01

    The Athabasca Oil Sands industry produces large volumes of oil sands process-affected water (OSPW) as a result of bitumen extraction and upgrading processes. Constituents of OSPW include chloride, naphthenic acids (NAs), aromatic hydrocarbons, and trace heavy metals, among other inorganic and organic compounds. To address the environmental issues associated with the recycling and/or safe return of OSPW into the environment, water treatment technologies are required. This study examined, for the first time, the impacts of pretreatment steps, including filtration and petroleum-coke adsorption, on ozonation requirements and performance. The effect of the initial OSPW pH on treatment performance, and the evolution of ozonation and its impact on OSPW toxicity and biodegradability were also examined. The degradation of more than 76% of total acid-extractable organics was achieved using a semi-batch ozonation system at a utilized ozone dose of 150 mg/L. With a utilized ozone dose of 100 mg/L, the treated OSPW became more biodegradable and showed no toxicity towards Vibrio fischeri. Changes in the NA profiles in terms of carbon number and number of rings were observed after ozonation. The filtration of the OSPW did not improve the ozonation performance. Petroleum-coke adsorption was found to be effective in reducing total acid-extractable organics by a 91%, NA content by an 84%, and OSPW toxicity from 4.3 to 1.1 toxicity units. The results of this study indicate that the combination of petroleum-coke adsorption and ozonation is a promising treatment approach to treat OSPW.

  7. Ozone sensitivity in hybrid poplar correlates with insensitivity to both salicylic acid and jasmonic acid. The role of programmed cell death in lesion formation.

    PubMed

    Koch, J R; Creelman, R A; Eshita, S M; Seskar, M; Mullet, J E; Davis, K R

    2000-06-01

    Our earlier studies demonstrated that the ozone-sensitive hybrid poplar clone NE-388 displays an attenuated level of ozone-, wound-, and phytopathogen-induced defense gene expression. To determine if this reduced gene activation involves signal transduction pathways dependent on salicylic acid (SA) and/or jasmonic acid (JA), we compared the responses of NE-388 and an ozone-tolerant clone, NE-245, to these signal molecules. JA levels increased in both clones in response to ozone, but only minimal increases in SA levels were measured for either clone. Treatment with SA and methyl jasmonate induced defense gene expression only in NE-245, indicating that NE-388 is insensitive to these signal molecules. DNA fragmentation, an indicator of programmed cell death (PCD), was detected in NE-245 treated with either ozone or an avirulent phytopathogen, but was not detected in NE-388. We conclude that these clones undergo two distinct mechanisms of ozone-induced lesion formation. In NE-388, lesions appear to be due to toxic cell death resulting from a limited ability to perceive and subsequently activate SA- and/or JA-mediated antioxidant defense responses. In NE-245, SA-dependent PCD precedes lesion formation via a process related to the PCD pathway activated by phytopathogenic bacteria. These results support the hypothesis that ozone triggers a hypersensitive response.

  8. Degradation of 17beta-estradiol in aqueous solution by ozonation in the presence of manganese(II) and oxalic acid.

    PubMed

    Jiang, Liying; Zhang, Lu; Chen, Jianmeng; Ji, Hong

    2013-01-01

    Natural estrogens, such as 17beta-estradiol (E2), are the main substances responsible for estrogenic activity found in domestic sewage. In the work described herein, the degradation of E2 has been investigated by single ozonation and catalytic ozonation in the presence of manganese ion (Mn2+) and oxalic acid. The presence of Mn2+ and oxalic acid in the ozonation processes significantly improved the E2 degradation and, hence, the reduction of estrogenic activity in aqueous solution. The addition of Mn2+ and oxalic acid produced many more hydroxyl radicals in the catalytic ozonation system than in the single ozonation system. Oxidation products formed during ozonation of E2 have been identified by means of gas chromatography-mass spectrometry (GC-MS), on the basis of which a possible reaction pathway for E2 degradation by ozonation is proposed. E2 was first oxidized to hydroxyl-semiquinone isomers, and these were subsequently degraded to low molecular weight compounds such as oxalic acid and malonic acid. The latter were easily oxidized by ozone to form carbon dioxide (CO2). The results demonstrate that the ozonation-Mn(2+)-oxalic acid system may serve as a powerful tool for removing E2, and the addition of Mn2+ and oxalic acid is favourable for the complete removal of estrogenic activity induced by steroid estrogens in aqueous solution.

  9. A role for oxalic acid generation in ozone-induced signallization in Arabidopis cells.

    PubMed

    Tran, Daniel; Kadono, Takashi; Molas, Maria Lia; Errakhi, Rafik; Briand, Joël; Biligui, Bernadette; Kawano, Tomonori; Bouteau, François

    2013-03-01

    Ozone (O(3) ) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O(3) results in ascorbate-derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca(2+) concentration, generation of reactive oxygen species and cell death. We confirmed that O(3) reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O(3) -induced signalling pathways that trigger programmed cell death.

  10. In-situ measurements of chlorine activation, nitric acid redistribution and ozone depletion in the Antarctic lower vortex aboard the German research aircraft HALO during TACTS/ESMVal

    NASA Astrophysics Data System (ADS)

    Jurkat, Tina; Voigt, Christiane; Kaufmann, Stefan; Schlage, Romy; Gottschaldt, Klaus-Dirk; Ziereis, Helmut; Hoor, Peter; Bozem, Heiko; Müller, Stefan; Zahn, Andreas; Schlager, Hans; Oelhaf, Hermann; Sinnhuber, Björn-Martin; Dörnbrack, Andreas

    2016-04-01

    In-situ measurements of stratospheric chlorine compounds are rare and exhibit the potential to gain insight into small scale mixing processes where stratospheric air masses of different origin and history interact. In addition, the relationship with chemically stable trace gases helps to identify regions that have been modified by chemical processing on polar stratospheric clouds. To this end, in-situ measurements of ClONO2, HCl, HNO3, NOy, N2O and O3 have been performed in the Antarctic Polar Vortex in September 2012 aboard the German research aircraft HALO (High Altitude and Long Rang research aircraft) during the TACTS/ESMVal (Transport and Composition in the UTLS/Earth System Model Validation) mission. With take-off and landing in Capetown, HALO sampled vortex air with latitudes down to 65°S, at altitudes between 8 and 14.3 km and potential temperatures between 340 and 390 K. Before intering the vortex at 350 K potential temperature, HALO additionally sampled mid-latitude stratospheric air. The trace gas distributions at the edge of the Antarctic polar vortex show distinct signatures of processed upper stratospheric vortex air and chemically different lower stratospheric / upper tropospheric air. Diabatic descend of the vortex transports processed air into the lower stratosphere. Here small scale filaments of only a few kilometers extension form at the lower vortex boundary due to shear stress, ultimately leading to transport and irreversible mixing. Comparison of trace gas relationships with those at the beginning of the polar winter reveals substantial chlorine activation, ozone depletion de- and renitrification with high resolution. Furthermore, the measurements are compared to the chemistry climate models EMAC and supported by ECMWF analysis. Finally, we compare the Antarctic measurements with new measurements of ClONO2, HCl and HNO3 aboard HALO obtained during the Arctic mission POLSTRACC (POLar STratosphere in a Changing Climate) based in Kiruna (Sveden

  11. 3D Flower-like β-MnO2/Reduced Graphene Oxide Nanocomposites for Catalytic Ozonation of Dichloroacetic Acid

    PubMed Central

    Li, Gang; Li, Kezheng; Liu, Aijuan; Yang, Ping; Du, Yukou; Zhu, Mingshan

    2017-01-01

    Considering the potential use of manganese oxide based nanocomposite in catalytic ozonation of water contaminant, we report unique three-dimensional (3D) nanoarchitectures composed of β-MnO2 and reduced graphene oxide (RGO) for catalytic ozonation of dichloroacetic acid (DCAA) from drinking water. The catalytic results show that the 3D β-MnO2/RGO nanocomposites (FMOG) can be used as efficient and stable ozonation catalysts to eliminate DCAA from water. The probable mechanism of catalytic ozonation was also proposed by detecting intermediates using gas chromatography-mass spectrometry. This result likely paves a facile avenue and initiates new opportunities for the exploration of heterogeneous catalysts for the removal of disinfection by-products from drinking water.

  12. 3D Flower-like β-MnO2/Reduced Graphene Oxide Nanocomposites for Catalytic Ozonation of Dichloroacetic Acid

    NASA Astrophysics Data System (ADS)

    Li, Gang; Li, Kezheng; Liu, Aijuan; Yang, Ping; Du, Yukou; Zhu, Mingshan

    2017-03-01

    Considering the potential use of manganese oxide based nanocomposite in catalytic ozonation of water contaminant, we report unique three-dimensional (3D) nanoarchitectures composed of β-MnO2 and reduced graphene oxide (RGO) for catalytic ozonation of dichloroacetic acid (DCAA) from drinking water. The catalytic results show that the 3D β-MnO2/RGO nanocomposites (FMOG) can be used as efficient and stable ozonation catalysts to eliminate DCAA from water. The probable mechanism of catalytic ozonation was also proposed by detecting intermediates using gas chromatography-mass spectrometry. This result likely paves a facile avenue and initiates new opportunities for the exploration of heterogeneous catalysts for the removal of disinfection by-products from drinking water.

  13. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    NASA Astrophysics Data System (ADS)

    Stemmler, K.; Vlasenko, A.; Guimbaud, C.; Ammann, M.

    2008-01-01

    Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3), an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g). The uptake coefficient was reduced by a factor of 5-50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond) had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15), which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12) and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  14. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    NASA Astrophysics Data System (ADS)

    Stemmler, K.; Vlasenko, A.; Guimbaud, C.; Ammann, M.

    2008-09-01

    Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3), an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g). The uptake coefficient was reduced by a factor of 5 50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond) had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15), which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12) and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  15. Strong wintertime ozone events in the Upper Green River Basin, Wyoming

    NASA Astrophysics Data System (ADS)

    Rappenglück, B.; Ackermann, L.; Alvarez, S.; Golovko, J.; Buhr, M.; Field, R.; Soltis, J.; Montague, D. C.; Hauze, B.; Adamson, S.; Risch, D.; Wilkerson, G.; Bush, D.; Stoeckenius, T.; Keslar, C.

    2013-07-01

    During recent years, elevated ozone (O3) values have been observed repeatedly in the Upper Green River Basin (UGRB), Wyoming during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1 h average up to 166 ppbv). Intensive Operational Periods (IOPs) of ambient monitoring were performed which included comprehensive surface and boundary layer measurements. On IOP days, maximum O3 values are restricted to a very shallow surface layer. Low wind speeds in combination with low mixing layer heights (~50 m a.g.l. around noontime) are essential for accumulation of pollutants within the UGRB. Air masses contain substantial amounts of reactive nitrogen (NOx) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days in the morning hours in particular, reactive nitrogen (up to 69%), aromatics and alkanes (~10-15%; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. Measurements at the Boulder monitoring site during these time periods under SW wind flow conditions show the lowest NMHC/NOx ratios (~50), reflecting a relatively low NMHC mixture, and a change from a NOx-limited regime towards a NMHC limited regime as indicated by photochemical indicators, e.g. O3/NOy, O3/NOz, and O3/HNO3 and the EOR (Extent of Reaction). OH production on IOP days is mainly due to nitrous acid (HONO). Until noon on IOP days, HONO photolysis contributes between 74-98% of the entire OH-production. Ozone photolysis (contributing 2-24%) is second to HONO photolysis. However, both reach about the same magnitude in the early afternoon (close to 50%). Photolysis of formaldehyde (HCHO) is not important (2-7%). High HONO levels (maximum hourly median on IOP days: 1096 pptv) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow surface. HONO is most likely formed through (i) abundant nitric acid (HNO3

  16. Oxidation of Co(II) by ozone and reactions of Co(III) in solutions of sulfuric acid

    NASA Astrophysics Data System (ADS)

    Levanov, A. V.; Isaikina, O. Ya.; Lunin, V. V.

    2016-12-01

    Reactions of the oxidation of bivalent cobalt ions by ozone, of the spontaneous decomposition of trivalent cobalt, and of interactions between Co(III) and chloride ions in solutions of sulfuric acid are studied. The order and rate constant of the process of decomposition of Co(III) are determined. Information on the kinetics of the interaction between Co(III) and Cl- is obtained. Kinetic patterns of the accumulation of Co(III) during the ozonation of solutions of CoSO4 in sulfuric acid are explained. Molar absorption coefficients of Co(III) and Co2+ ions in the visible range of wavelengths are determined.

  17. Coal desulfurization in oxidative acid media using hydrogen peroxide and ozone: a kinetic and statistical approach

    SciTech Connect

    F.R. Carrillo-Pedroza; A. Davalos Sanchez; M. Soria-Aguilar; E.T. Pecina Trevino

    2009-07-15

    The removal of pyritic sulfur from a Mexican sub-bituminous coal in nitric, sulfuric, and hydrochloric acid solutions was investigated. The effect of the type and concentration of acid, in the presence of hydrogen peroxide and ozone as oxidants, in a temperature range of 20-60{sup o}C, was studied. The relevant factors in pyrite dissolution were determined by means of the statistical analysis of variance and optimized by the response surface method. Kinetic models were also evaluated, showing that the dissolution of pyritic sulfur follows the kinetic model of the shrinking core model, with diffusion through the solid product of the reaction as the controlling stage. The results of statistical analysis indicate that the use of ozone as an oxidant improves the pyrite dissolution because, at 0.25 M HNO{sub 3} or H{sub 2}SO{sub 4} at 20{sup o}C and 0.33 g/h O{sub 3}, the obtained dissolution is similar to that of 1 M H{sub 2}O{sub 2} and 1 M HNO{sub 3} or H{sub 2}SO{sub 4} at 40{sup o}C. 42 refs., 9 figs., 3 tabs.

  18. Oxidations of organic matter present in the phosphoric acid 54% by the ozone: characterization of groups carbonyls upstream and downstream of the ozonation

    NASA Astrophysics Data System (ADS)

    Linda, D.; Louati, A.; Chtara, C.; Kabadou, A.

    2012-02-01

    This study was focused on the oxidation of organic matter in phosphoric acid 54% by ozone. In order to understand the mechanisms involved in this process, the identification of this matter upstream and downstream of the ozonation was necessary. For the identification, after an extraction by a mixture (dichloro-methanol), the organic phase was divided into two parts: the residue and the extract:-The residue was studied by infrared spectroscopy Fourier Transform (IR-TF). It contains Kérogène which is a mixture of saturated hydrocarbons with high molecular weights. The absorption bands of the FT-IR showed that the residue contains also quantities of amino that correspond to the remains of dinoflagellate cysts, which are abundant in sediments.-The extract has been the subject of a detailed study by, chromatography on silica column, IR-TF spectroscopy and CG-SM. The passage of this extract on a silica column yielded two fractions (saturated fraction and polar fraction). Both of these fractions were analyzed by CG-SM. The yield of the reduction of the organic matter content in the phosphoric acid 54% could not exceed 29%. Therefore, we can conclude that the reduction in the rate of organic matter remains limited by the fact that some compounds are inert towards ozone.

  19. Electrons Mediate the Gas-Phase Oxidation of Formic Acid with Ozone.

    PubMed

    van der Linde, Christian; Tang, Wai-Kit; Siu, Chi-Kit; Beyer, Martin K

    2016-08-26

    Gas-phase reactions of CO3 (.-) with formic acid are studied using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Signal loss indicates the release of a free electron, with the formation of neutral reaction products. This is corroborated by adding traces of SF6 to the reaction gas, which scavenges 38 % of the electrons. Quantum chemical calculations of the reaction potential energy surface provide a reaction path for the formation of neutral carbon dioxide and water as the thermochemically favored products. From the literature, it is known that free electrons in the troposphere attach to O2 , which in turn transfer the electron to O3 . O3 (.-) reacts with CO2 to form CO3 (.-) . The reaction reported here formally closes the catalytic cycle for the oxidation of formic acid with ozone, catalyzed by free electrons.

  20. Evaluation of ozonation technique for pesticide residue removal and its effect on ascorbic acid, cyanidin-3-glucoside, and polyphenols in apple (Malus domesticus) fruits.

    PubMed

    Swami, Saurabh; Muzammil, Raunaq; Saha, Supradip; Shabeer, Ahammed; Oulkar, Dasharath; Banerjee, Kaushik; Singh, Shashi Bala

    2016-05-01

    Ozonated water dip technique was evaluated for the detoxification of six pesticides, i.e., chlorpyrifos, cypermethrin, azoxystrobin, hexaconazole, methyl parathion, and chlorothalonil from apple fruits. Results revealed that ozonation was better than washing alone. Ozonation for 15 min decreased residues of the test pesticides in the range of from 26.91 to 73.58%, while ozonation for 30 min could remove the pesticide residues by 39.39-95.14 % compared to 19.05-72.80 % by washing. Cypermethrin was the least removed pesticide by washing as well as by ozonation. Chlorothalonil, chlorpyrifos, and azoxystrobin were removed up to 71.45-95.14 % in a 30-min ozonation period. In case of methyl parathion removal, no extra advantage could be obtained by ozonation. The HPLC analysis indicated that ozonation also affected adversely the ascorbic acid and cyanidin-3-glucoside content of apples. However, 11 polyphenols studied showed a mixed trend. Gallic acid, 3,4-dihydroxybenzoic acid, catechin, epicatechin, p-coumaric acid, quercetin-3-O-glucoside, quercetin, and kaempferol were found to decrease while syringic acid, rutin, and resveratrol were found to increase in 30-min ozonation.

  1. Characterization of ferromagnetic sludge-based activated carbon and its application in catalytic ozonation of p-chlorobenzoic acid.

    PubMed

    Lu, Siying; Liu, Yongze; Feng, Li; Sun, Zhongen; Zhang, Liqiu

    2017-03-09

    In order to solve the separation problem of powdered sludge-based activated carbon (SAC), a series of novel ferromagnetic sludge-based activated carbons (FMSACs, with different iron content 2.3, 4.3, and 9.5 wt%) with a good magnetic separation ability were prepared through co-precipitation method in this study. The structure and physicochemical properties of FMSACs and their catalytic ozonation performance on the removal of p-chlorobenzoic acid (p-CBA) were investigated. The saturation magnetization (Ms) of FMSACs was determined in the range of 0.3674-5.7992 emu g(-1), and experiments confirmed that these FMSACs could be easily separated by magnetic fields. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis indicated that magnetite and maghemite were the main magnetic phases in FMSACs. Comparing with ozonation alone and SAC catalytic ozonation, the presence of 2.3 wt% - FMSAC improved the degradation of p-CBA during catalytic ozonation from 44 and 70 to 80%. The tertiary butanol inhibition experiment indicated that FMSACs catalytic ozonation process followed hydroxyl radical reaction mechanism. Furthermore, after six repetitive catalytic ozonation runs, 2.3 wt% - FMSAC still showed relatively high catalytic activity for the removal of p-CBA. Consequently, the novel FMSACs with magnetic separation ability and catalytic performance provide a practical pathway for the sludge utilization.

  2. The use of artificial neural network for modeling the decolourization of acid orange 7 solution of industrial by ozonation process

    NASA Astrophysics Data System (ADS)

    Fatimah, S.; Wiharto, W.

    2017-02-01

    Acid Orange 7 (AO7) is one of the synthetic dye in the dyeing process in the textile industry. The use of this dye can produce wastewater which will be endangered if not treated well. Ozonation method is one technique to solve this problem. Ozonation is a waste processing techniques using ozone as an oxidizing agent. Variables used in this research is the ozone concentration, the initial concentration of AO7, temperature, and pH. Based on the experimental result that the optimum value decolourization percentage is 80% when the ozone concentration is 560 mg/L, the initial concentration AO7 is 14 mg/L, the temperature is 390 °C, and pH is 7,6. Decolourization efficiency of experimental results and predictions successfully modelled by the neural network architecture. The data used to construct a neural network architecture quasi newton one step secant as many as 31 data. A comparison between the predicted results of the designed ANN models and experiment was conducted. From the modeling results obtained MAPE value of 0.7763%. From the results of this artificial neural network architecture obtained the optimum value decolourization percentage in 80,64% when the concentration of ozone is 550 mg/L, the initial concentration AO7 is 11 mg/L, the temperature is 41 °C, and the pH is 7.9.

  3. Reaction mechanism and metal ion transformation in photocatalytic ozonation of phenol and oxalic acid with Ag(+)/TiO2.

    PubMed

    Chen, Yingying; Xie, Yongbing; Yang, Jun; Cao, Hongbin; Zhang, Yi

    2014-03-01

    Photocatalytic ozonation of phenol and oxalic acid (OA) was conducted with a Ag(+)/TiO2 catalyst and different pathways were found for the degradation of different compounds. Ag(+) greatly promoted the photocatalytic degradation of contaminants due to its role as an electron scavenger. It also accelerated the removal rate of OA in ozonation and the simultaneous process for its complex reaction with oxalate. Phenol could be degraded both in direct ozonation and photolysis, but the TOC removal rates were much higher in the simultaneous processes due to the oxidation of hydroxyl radicals resulting from synergetic effects. The sequence of photo-illumination and ozone exposure in the combined process showed quite different effects in phenol degradation and TOC removal. The synergetic effects in different combined processes were found to be highly related to the properties of the target pollutants. The color change of the solution and TEM result confirmed that Ag(+) was easily reduced and deposited on the surface of TiO2 under photo-illumination, and dissolved again into solution in the presence of ozone. This simple cycle of enrichment and distribution of Ag(+) can greatly benefit the design of advanced oxidation processes, in which the sequences of ozone and photo-illumination can be varied according to the needs for catalyst recycling and the different properties of pollutants.

  4. Reduction of PCDDs/PCDFs in MSWI fly ash using microwave peroxide oxidation in H2SO4/HNO3 solution.

    PubMed

    Chang, Yu-Min; Dai, Wen-Chien; Tsai, Kao-Shen; Chen, Shiao-Shing; Chen, Jyh-Herng; Kao, Jimmy C M

    2013-05-01

    Microwave peroxide oxidation (MPO) is an energy-efficient and low GHG emission technology to destroy the hazardous organic compounds in solid waste. The objective of this paper is to explore the reduction feasibility of PCDDs/Fs in MSWI fly ash using the MPO in H2SO4/HNO3 solution. Nearly all PCDDs/Fs, 99% in the original fly ash, can be reduced in 120min at the temperature of 150°C using the MPO treatment. It was also found that a change occurred in the content distribution profiles of 17 major PCDD/F congeners before and after MPO treatment. This provides the potential to reduce the actual PCDDs/Fs content more than I-TEQ contents of PCDDs/Fs. The percentile distribution profile has a tendency of higher chlorinated PCDDs/Fs moving to the lower ones. It concludes that a significant reduction efficiency of I-TEQ toxicity was achieved and showed sufficient reduction of toxic level to lower than 1.0ngI-TEQ(gdw)(-1). The treatment temperature would be a critical factor facilitating the dissolution because higher temperature leads more inorganic salt (parts of fly ash) dissolution. Some problems caused by the MPO method are also delineated in this paper.

  5. Effects of ozone and simulated acid rain on birch seedling growth and formation of ectomycorrhizae.

    PubMed

    Keane, K D; Manning, W J

    1988-01-01

    Four-week-old paper birch (Betula papyrifera Marsh.) seedlings, inoculated or non-inoculated with the ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker & Couch and grown in steamed or non-steamed soil, were exposed to ozone (O(3)) and/or simulated acid rain (SAR). Plants were exposed to O(3) for 7 h per day on 5 days per week for 12 weeks. O(3) concentrations were maintained between 0.06 and 0.08 ppm. SAR was applied 10 min per day on 2 days per week. O(3), SAR, soil regime and mycorrhizal treatment did not significantly affect any of the measured variables. Interactions between O(3) and SAR, SAR and mycorrhizal treatment, soil regime and mycorrhizal treatment and ozone and soil regime had significant effects. Treatment of seedlings with pH 3.5 SAR caused increases in growth which were more apparent in birch exposed to O(3). Mucorrhizal treatment caused increased growth in non-steamed soil, while growth appeared to decrease in steamed soil. Birch seedlings grew much better in steamed soil. The implications of increased growth in steamed soil may demonstrate the importance of looking at the secondary effects of pollutants on soil-borne organisms.

  6. Conversion of iodide to hypoiodous acid and iodine in aqueous microdroplets exposed to ozone.

    PubMed

    Pillar, Elizabeth A; Guzman, Marcelo I; Rodriguez, Jose M

    2013-10-01

    Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O3) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O3 and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O3 at variable iodide (I(-)) concentration (0.010-100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates and products expected in sea spray for low tropospheric [O3]. The ultrafast oxidation of I(-) by O3 at the air-water interface of microdroplets is evidenced by the appearance of hypoiodous acid (HIO), iodite (IO2(-)), iodate (IO3(-)), triiodide (I3(-)), and molecular iodine (I2). Mass spectrometry measurements reveal an enhancement (up to 28%) in the dissolution of gaseous O3 at the gas-liquid interface when increasing the concentration of NaI or NaBr from 0.010 to 100 μM. The production of iodine species such as HIO and I2 from NaI aerosolized solutions exposed to 50 ppbv O3 can occur at the air-water interface of sea spray, followed by their transfer to the gas-phase, where they contribute to the loss of tropospheric ozone.

  7. Examining the Impact of Nitrous Acid Chemistry on Ozone and PM over the Pearl River Delta Region

    EPA Science Inventory

    The impact of nitrous acid (HONO) chemistry on regional ozone and particulate matter in Pearl River Delta region was investigated using the community multiscale air quality (CMAQ) modeling system and the CB05 mechanism. Model simulations were conducted for a ten-day period in Oct...

  8. CO-EXPOSURE OF HUMAN AIRWAY EPITHELIAL CELLS TO OZONE AND PARTICULATE MATTER: EFFECTS ON ARACHIDONIC ACID METABOLISM

    EPA Science Inventory

    Co-exposure of human airway epithelial cells to ozone and particulate matter: effects on arachidonic acid metabolism.

    D. Stamm1, L. Dailey2, M.C. Madden2
    1 University of North Carolina-Chapel Hill, School of Medicine
    2 U.S. EPA, ORD, NHEERL, HSD, Chapel Hill, NC, USA...

  9. An investigation of the effects of simulated acid rain and elevated ozone on the physiology of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings and mature trees

    SciTech Connect

    Momen, B.

    1993-12-31

    This study investigated the combined effects of simulated acid rain and ozone on foliar water relations, carbon and nitrogen contents, gas exchange, and respiration of ponderosa pine seedlings and mature trees grown in the field at the USDA Forest Service Tree Improvement Center in Chico, California. Acid rain levels (pH 5.1 and 3) were applied weekly on foliage only, from January to April, 1992. Plants were exposed to ozone levels (ambient and twice ambient) during the day only, from August to December, 1990, and from September to November, 1992. Results suggested that elevated ozone, particularly in combination with strong acid, caused osmotic adjustment that may benefit plants during drought. The observed effects of pollutants are similar to the reported effects of drought on plant water relations. Elevated ozone decreased foliar nitrogen content and thus increased the C:N ratio, particularly in seedlings. Stomatal conductance was not affected by pollutants but net photosynthesis was decreased by elevated ozone, especially in mature trees. The greater sensitivity of net photosynthesis of mature trees to elevated ozone was contrary to all other plant characteristics investigated. Elevated ozone increased seedling respiration. Under controlled, temperature, light, and vapor pressure deficit conditions, net photosynthesis responded positively to increases in plant age, light intensity, and rain pH, but negatively to increases in tissue age, heat, and ozone concentration. Overall results indicated that acid rain and elevated ozone declined the carbon pool of ponderosa pine due to increased respiration and decreased net photosynthesis. Pollutant effects were more profound in mid-summer when ozone concentrations were highest. On many occasions the effects of acid rain and ozone levels interacted. Seedlings were more sensitive to pollutants than mature trees.

  10. Efficacy of Nucleic Acid Probes for Detection of Poliovirus in Water Disinfected by Chlorine, Chlorine Dioxide, Ozone, and UV Radiation

    PubMed Central

    Moore, Norman J.; Margolin, Aaron B.

    1994-01-01

    MilliQ water was inoculated with poliovirus type 1 strain LSc-1 and was treated with disinfectants, including chlorine, chlorine dioxide, ozone, and UV light. No relationship between probes and plaque assays were seen, demonstrating that viral nucleic acids were not destroyed. These findings suggest that nucleic acid probes cannot distinguish between infectious and noninfectious viruses and cannot be used in the evaluation of treated waters. PMID:16349448

  11. The effect of heat treatment on the corrosion resistance of 440C stainless steel in 20% HNO3 + 2.5% Na2Cr2O7 solution

    NASA Astrophysics Data System (ADS)

    Savas, Terence P.; Wang, Allen Yi-Lan; Earthman, James C.

    2003-04-01

    The effect of heat treatment on the corrosion resistance of 440C stainless steel was investigated in a 20% HNO3 + 2.5% Na2Cr2O7 solution using electrochemical noise (ECN) measurements, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) examinations. The noise resistance ( Rn), which has been found to be inversely related to the localized corrosion rate, was measured to be 5.7E + 08 Ω-cm2, 4.2E + 08 Ω-cm2, and 3.7E + 04 Ω-cm2 for the oil-quenched, air-quenched, and vacuum furnace cooled (VFC) samples, respectively, after 1200 s exposures. The Rn for all heat treat conditions stabilized within a range of 1.0E + 07 Ω-cm2 to 3.2E + 08 Ω-cm2 after 2 h exposures. The EIS response showed a polarization resistance ( R p) on the order of 6.6E + 04 Ω-cm2, 5.3E + 04 Ω-cm2, and 1.1E + 04 Ω-cm2 for the oil-quenched, air-quenched, and VFC samples, respectively, after 2 h exposures. The EIS data are in good agreement with ECN data and indicate that after longer exposures, general corrosion mechanisms dominate and the corrosion rates are comparable. SEM examinations of specimens subjected to 1200 s exposures revealed that severity of pitting and intergranular corrosion damage was consistent with trends in the Rn data. Specifically, the electrochemical noise data as well as SEM examinations of specimens revealed a higher localized corrosion resistance of the hardened specimens during the early stages of passivation. This greater resistance to localized corrosion can be attributed to an increased stability of the natural passive film resulting from a higher concentration of chromium atoms in solution for the martensite phase.

  12. Simulating the phase partitioning of NH3, HNO3, and HCl with size-resolved particles over northern Colorado in winter

    NASA Astrophysics Data System (ADS)

    Kelly, James T.; Baker, Kirk R.; Nolte, Christopher G.; Napelenok, Sergey L.; Keene, William C.; Pszenny, Alexander A. P.

    2016-04-01

    Numerical modeling of inorganic aerosol processes is useful in air quality management, but comprehensive evaluation of modeled aerosol processes is rarely possible due to the lack of comprehensive datasets. During the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) campaign in February and March 2011, the phase partitioning of soluble trace gases with size-resolved particles and related meteorological conditions were measured continuously at a site in Colorado about 33 km north of Denver. These size-resolved measurements of particulate SO42-, NH4+, NO3-, Cl-, Na+, Ca2+, Mg2+, and K+ and inorganic gases are used here to assess the ability of a continental U.S. modeling platform to simulate the gas-particle partitioning of NH3, HNO3, and HCl at this location. Modeling is based on the Community Multiscale Air Quality (CMAQ) model with 12 km horizontal resolution. Baseline, sensitivity, and source apportionment simulations are conducted to fully characterize the model predictions. Considering the limitations in representing regional terrain features in the national 12 km modeling, predictions agree reasonably well with measured concentrations and gas-particle partitioning at this location. However, the median sum of NH4+ and NH3 is underpredicted in the baseline simulation by a factor of four suggesting a need for improved bottom-up NH3 emissions inventories in this area. The median sum of Cl- and HCl is underpredicted by a factor of 2.8, while levels of Ca2+, Mg2+, and K+ are overpredicted. Improvements in windblown and fugitive dust emissions may improve and/or better constrain these predictions. Mass size distributions for inorganic particle constituents are generally simulated well, although the modeled fine particle mode is shifted to slightly larger diameters relative to measurements. Source apportionment modeling estimates of source sector and boundary contributions to air quality at the site are provided.

  13. Long-term trends and weekday-to-weekend differences in ozone, its precursors, and other secondary pollutants in Atlanta, Georgia

    NASA Astrophysics Data System (ADS)

    Pollack, I. B.; Ryerson, T. B.; Baumann, K.; Edgerton, E. S.; De Gouw, J. A.; Gilman, J.; Graus, M.; Holloway, J.; Lerner, B. M.; Neuman, J. A.; Roberts, J. M.; Veres, P. R.; Warneke, C.; Trainer, M.; Parrish, D. D.

    2013-12-01

    In an environment rich in biogenic volatile organic compounds (VOCs), decreasing concentrations of ozone (-1.3 % yr-1) and other secondary pollutants (-8.2 % yr-1 for nitric acid, HNO3; and -7.9 % yr-1 for peroxyacetyl nitrate, PAN) in Atlanta, Georgia over the past fifteen years are primarily attributed to decreases in local emissions of nitrogen oxides (NOx=NO+NO2). Large reductions in abundances of NOx in the Southeast U.S. over the years (-8.0 % yr-1 for total reactive nitrogen, NOy) are the direct result of control strategies implemented to reduced emissions from electric-power generation plants and on-road motor vehicles. Here, we compile an extensive historical data set of trace gas measurements spanning fifteen years between 1998 and 2013 from a surface monitoring network site in downtown Atlanta (i.e. the SEARCH network Jefferson Street site) and research aircraft (e.g. the 2013 Southeast Atmosphere Study and 1999 Southern Oxidants Study aboard the NOAA P-3 aircraft). With this data set we confirm and extend long-term trends and weekday-to-weekend differences in ozone, its precursors, and other secondary pollutants during summertime in Atlanta. Long-term changes in abundances and enhancement ratios of secondary oxidation products indicate changes in pollutant formation chemistry in Atlanta resulting from the significant decrease in NOx precursor emissions over the past fifteen years. The most noteworthy changes include: 1) an increase in enhancement ratios of odd oxygen (Ox=O3+NO2) to (PAN+HNO3) of +5.5 % yr-1 indicating an increase in ozone production efficiency by a factor of 2 over the fifteen year period, 2) no significant change in the fraction of oxidized NOx out of NOy over time indicating little change in the extent of photochemical processing of the NOx emissions, and 3) a flip in observed ozone concentrations from higher average ozone on weekends to higher average ozone on weekdays after 2004. The observations for Atlanta will also be contrasted

  14. The impact of ice uptake of nitric acid on atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    von Kuhlmann, R.; Lawrence, M. G.

    2006-01-01

    The potential impact of the uptake of HNO3 on ice on the distribution of NOy species, ozone and OH has been assessed using the global scale chemistry-transport model MATCH-MPIC. Assuming equilibrium uptake according to dissociative Langmuir theory results in significant reductions of gas phase HNO3. Comparison to a large set of observations provides support that significant uptake of HNO3 on ice is occurring, but the degree of the uptake cannot be inferred from this comparison alone. Sensitivity simulations show that the uncertainties in the total amount of ice formation in the atmosphere and the actual expression of the settling velocity of ice particles only result in small changes in our results. The largest uncertainty is likely to be linked to the actual theory describing the uptake process and the value of the initial uptake coefficient. The inclusion of non-methane hydrocarbon chemistry partially compensates for the absence of HNO3 uptake on ice when this is neglected in the model. The calculated overall effect on upper tropospheric ozone concentrations and the tropospheric methane lifetime are moderate to low. These results support a shift in the motivation for future experimental and theoretical studies of HNO3-ice interaction towards the role of HNO3 in hydrometeor surface physics.

  15. The impact of ice uptake of nitric acid on atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    von Kuhlmann, R.; Lawrence, M. G.

    2005-08-01

    The potential impact of the uptake of HNO3 on ice on the distribution of NOy species, ozone and OH has been assessed using the global scale chemistry-transport model MATCH-MPIC. Assuming equilibrium uptake according to dissociative Langmuir theory results in significant reductions of gas phase HNO3. Comparison to a large set of observations provides support that significant uptake of HNO3 on ice is occurring, but the degree of the uptake cannot be inferred from this comparison alone. Sensitivity simulations show that the uncertainties in the total amount of ice formation in the atmosphere and the actual expression of the settling velocity of ice particles only result in small changes in our results. The largest uncertainty is likely to be linked to the actual theory describing the uptake process. The inclusion of non-methane hydrocarbon chemistry buffers the overall effect of neglected uptake of HNO3 on ice. The calculated overall effect on upper tropospheric ozone concentrations and the tropospheric methane lifetime are moderate to low. These results support a shift in the motivation for future experimental and theoretical studies of HNO3-ice interaction towards the role of HNO3 in hydrometeor surface physics.

  16. The potential for ozone depletion in the Arctic polar stratosphere

    NASA Technical Reports Server (NTRS)

    Brune, W. H.; Anderson, J. G.; Toohey, D. W.; Fahey, D. W.; Kawa, S. R.; Poole, L. R.

    1991-01-01

    The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (CHl and ClONO2) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl2O2 thoroughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO3, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15 percent at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8 percent losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50 percent over the next two decades, ozone losses recognizable as an ozone hole may well appear.

  17. The potential for ozone depletion in the arctic polar stratosphere.

    PubMed

    Brune, W H; Anderson, J G; Toohey, D W; Fahey, D W; Kawa, S R; Jones, R L; McKenna, D S; Poole, L R

    1991-05-31

    The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HCl and ClONO(2)) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl(2)O(2) throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO(3), and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear.

  18. On the export of reactive nitrogen from Asia: NOx partitioning and effects on ozone

    NASA Astrophysics Data System (ADS)

    Bertram, T. H.; Perring, A. E.; Wooldridge, P. J.; Dibb, J.; Avery, M. A.; Cohen, R. C.

    2013-05-01

    The partitioning of reactive nitrogen (NOy was measured over the remote North Pacific during spring 2006. Aircraft observations of NO, NO2, total peroxy nitrates (ΣPNs), total alkyl and multi-functional nitrates (ΣANs) and nitric acid (HNO3, made between 25° and 55° N, confirm a controlling role for peroxyacyl nitrates in NOx production in aged Asian outflow. ΣPNs account for more than 60% of NOy above 5 km, while thermal dissociation limits their contribution to less than 10% in the lower troposphere. Using simultaneous observations of NOx, ΣPNs, ΣANs, HNO3 and average wind speed, we calculate the flux of reactive nitrogen through the meridional plane of 150° W (between 20° and 55° N) to be 0.007 ± 0.002 Tg N day-1, which provides an upper limit of 23 ± 6.5% on the transport efficiency of NOy from East Asia. Observations of NOx, and HOx are used to constrain a 0-D photochemical box model for the calculation of net photochemical ozone production or tendency (Δ O3) as a function of aircraft altitude and NOx concentrations. The model analysis indicates that the photochemical environment of the lower troposphere (altitude < 6 km) over the north Pacific is one of net O3 destruction, with an experimentally determined crossover point between net O3 destruction and net O3 production of 60 pptv NOx. Qualitative indicators of integrated net O3 production derived from simultaneous measurements of O3 and light alkanes (Parrish et al., 1992), also indicate that the north Pacific is, on average, a region of net O3 destruction.

  19. Free fatty acids degradation in grease trap purification using ozone bubbling and sonication

    NASA Astrophysics Data System (ADS)

    Piotr Kwiatkowski, Michal; Satoh, Saburoh; Fukuda, Shogo; Yamabe, Chobei; Ihara, Satoshi; Nieda, Masanori

    2013-02-01

    The oil and fat were treated at first by only ozone bubbling and it was confirmed that the collection efficiency of them became 98.4% when the aeration was used. It showed that the aeration method in a grease trap cleared the standard value of 90% and there was no worry on the oil and fat outflow from a grease trap. The characteristics of sonication process were studied for free fatty acids degradation. The free saturated fatty acids are the most hard-degradable compounds of the fats, oils and greases (FOGs) in the grease trap. The influence of various parameters such as immersion level of an ultrasound probe in the liquid and bubbling of various gases (Ar, O2, air, O3) on the sonochemical and energy efficiency of the sonication process was investigated. The most effective degradation treatment method for saturated free fatty acids was the combination of sonication and low flow rate argon bubbling. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  20. WACCM-D—Improved modeling of nitric acid and active chlorine during energetic particle precipitation

    NASA Astrophysics Data System (ADS)

    Andersson, M. E.; Verronen, P. T.; Marsh, D. R.; Päivärinta, S.-M.; Plane, J. M. C.

    2016-09-01

    Observations have shown that a number of neutral minor species are affected by energetic particle precipitation (EPP) and ion chemistry (IC) in the polar regions. However, to date the complexity of the ion chemistry below the mesopause (i.e., in the D region ionosphere) has restricted global models to simplified EEP/IC parameterizations which are unable to reproduce some important effects, e.g., the increase of mesospheric nitric acid (HNO3). Here we use WACCM-D, a variant of the Whole Atmosphere Community Climate Model which includes a selected set of D region ion chemistry designed to produce the observed effects of EPP/IC. We evaluate the performance of EPP/IC modeling by comparing WACCM-D results for the January 2005 solar proton event (SPE) to those from the standard WACCM and Aura/Microwave Limb Sounder (MLS) and SCISAT/Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) observations. The results indicate that WACCM-D improves the modeling of HNO3, HCl, ClO, OH, and NOx during the SPE. Northern Hemispheric HNO3 from WACCM-D shows an increase by 2 orders of magnitude at 40-70 km compared to WACCM, reaching 2.6 ppbv, in agreement with the observations. For HCl and ClO, the improvement is most pronounced in the Southern Hemisphere at 40-50 km where WACCM-D predicts a decrease of HCl and increase of ClO by 1.6% and 10%, respectively, similar to MLS data. Compared to WACCM, WACCM-D produces 25-50% less OH and 30-130% more NOx at 70-85 km which leads to better agreement with the observations. Although not addressed here, longer-term NOx impact of ion chemistry could be important for polar stratospheric ozone and middle atmospheric dynamics.

  1. How do background ozone concentrations affect the biosynthesis of rosmarinic acid in Melissa officinalis?

    PubMed

    Döring, Anne S; Pellegrini, Elisa; Della Batola, Michele; Nali, Cristina; Lorenzini, Giacomo; Petersen, Maike

    2014-03-01

    Lemon balm (Melissa officinalis; Lamiaceae) plants were exposed to background ozone (O3) dosages (80ppb for 5h), because high background levels of O3 are considered to be as harmful as episodic O3 peaks. Immediately at the end of fumigation the plants appeared visually symptomless, but necrotic lesions were observed later. The biosynthesis of rosmarinic acid (RA) comprises eight enzymes, among them phenylalanine ammonia-lyase (PAL), 4-coumarate:coenzyme A ligase (4CL), tyrosine aminotransferase (TAT) and rosmarinic acid synthase (RAS). The transcript levels of these genes have been investigated by quantitative RT-PCR. There was a quick up-regulation of all genes at 3h of O3 exposure, but at 24h from beginning of exposure (FBE) only RAS and PAL were up-regulated. The specific activity of RAS was closely correlated with a decrease of RA concentration in lemon balm leaves. The specific activity of PAL increased at 12h FBE to 163% in comparison to control levels. This work provides insight into the effect of O3 stress on the formation of the main phenolic ingredient of the pharmaceutically important plant M. officinalis.

  2. SMILES zonal and diurnal variation climatology of stratospheric and mesospheric trace gasses: O3, HCl, HNO3, ClO, BrO, HOCl, HO2, and temperature

    NASA Astrophysics Data System (ADS)

    Kreyling, Daniel; Sagawa, Hideo; Wohltmann, Ingo; Lehmann, Ralph; Kasai, Yasuko

    2013-10-01

    We present a climatology of the diurnal variation of short-lived atmospheric compounds, such as ClO, BrO, HO2, and HOCl, as well as longer-lived species: O3, the hydrogen chloride isotopes H35Cl and H37Cl, and HNO3. Measurements were taken by the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES). This spectrally resolving radiometer, with very low observation noise and altitude range from the lower stratosphere to the lower thermosphere (20-100km), was measuring vertical profiles of absorption spectra along a non-sun-synchronous orbit, thus observing at all local times. We used the retrieved volume mixing ratio profiles to compile climatologies that are a function of pressure, a horizontal coordinate (latitude or equivalent latitude), and a temporal coordinate (solar zenith angle or local solar time). The main product presented are climatologies with a high resolution of the temporal coordinate (diurnal variation climatologies). In addition, we provide climatologies with a high resolution of the horizontal coordinate (zonal climatologies).The diurnal variation climatologies are based on data periods of 2 months and the zonal climatologies on monthly data periods. Consideration of the SMILES time-space sampling patterns with respect to the averaging coordinates is a key issue for climatology creation, especially in case of diurnal variation climatologies. Biases induced by inhomogeneous sampling are minimized by carefully choosing the size of averaging bins. The sampling biases of the diurnal variation climatology of ClO and BrO are investigated in a comparison of homogeneously sampled model data versus SMILES-sampled model data from the stratospheric Lagrangian chemistry and transport model Alfred Wegener Institute Lagrangian Chemisrty/Transport System. In most cases, the relative sampling error is in the range of 0-20%. The strongest impact of sampling biases is found where the species' temporal gradients are strongest (mostly at sunrise and sunset

  3. A heterogeneous chemistry model for acid rain`s effect on ozone

    SciTech Connect

    Ye, Tao

    1995-11-01

    A computer model for simulating heterogeneous reactions in cloud is developed to determine the S(IV) species` effect on ozone. Crutzen claims that NO{sub x}, HO{sub x} families and H{sub 2}CO in the troposphere can decrease ozone by 5 to 10%. However, is this claim valid for a SO{sub x} polluted atmosphere? The SO{sub x} family reacts with the ozone destroyers. These reactions seem to be significant enough to reduce the H{sub 2}CO`s destructive effect on ozone.

  4. Quantifying foliar responses of white ash to ozone and simulated acid precipitation: An assessment proposal for forest exposure studies. Forest Service research paper. (Final)

    SciTech Connect

    Dochinger, L.S.; Jensen, K.F.

    1990-04-01

    Seedlings populations represent an important linkage for assessing the effect of air pollution on forests. The study examines the foliar responses of white ash seedlings to ozone and acid precipitation as a means of identifying atmospheric deposition effects on forests.

  5. Removal of aqueous oxalic acid by heterogeneous catalytic ozonation with MnOx/sewage sludge-derived activated carbon as catalysts.

    PubMed

    Huang, Yuanxing; Sun, Yaru; Xu, Zhihua; Luo, Mengyu; Zhu, Chunlei; Li, Liang

    2017-01-01

    MnOx/sewage sludge-derived activated carbon (MnOx/SAC) was prepared as catalysts to improve the performance of aqueous oxalic acid degradation by ozonation. The results indicated that MnOx/SAC had excellent catalytic activity in mineralization of oxalic acid during heterogeneous catalytic ozonation process. MnOx/SAC with a manganese load of 30% exhibited the strongest catalytic activity under the condition of solution pH3.5, which enhanced the oxalic acid removal from 10.3% to 92.2% in 60min compared with that treated by ozone alone. Increase of catalyst dosage and aqueous ozone concentration was advantageous for oxalic acid removal from water. On the basis of catalyst characterization analysis and the observation of inhibitory effect induced by higher pH, less catalyst dosage as well as the presence of hydroxyl radical scavenger, it was deduced that the reaction mechanism involved both hydroxyl radicals attack and surface reactions.

  6. Influence of polar stratospheric clouds on the depletion of Antarctic ozone

    NASA Technical Reports Server (NTRS)

    Salawitch, Ross J.; Wofsy, Steven C.; Mcelroy, Michael B.

    1988-01-01

    Precipitation of nitrate in polar stratospheric clouds (PSCs) can provide a significant sink for Antarctic stratospheric odd nitrogen. It is argued that the depth of the Ozone Hole is sensitive to the occurrence of temperatures below about 196 K. An increase in the prevalence of temperatures below 196 K would enhance ozone loss by increasing the spatial extent and persistence of PSCs, and by decreasing the level of HNO3 that remains following PSC evaporation. Concentrations of halogen gases in the 1960s and earlier were insufficient to support major ozone loss, even if thermal conditions were favorable.

  7. Light-induced multiphase chemistry of gas phase ozone on aqueous pyruvic and oxalic acids: Aerosol chamber study

    NASA Astrophysics Data System (ADS)

    Gligorovski, S.; Grgic, I.; Net, S.; Böge, O.; Iinuma, Y.; Kahnt, A.; Scheinhardt, S.; Herrmann, H.; Wortham, H.

    2010-12-01

    The light-absorbing organic compounds present in and on condensed aerosol particles interacting with trace gases such as ozone can initiate a new and potentially important photo-induced multiphase chemistry. However, investigations of light induced multiphase processes are very scarce at present. We have launched the idea of pyruvic acid (PA) acting as a photosensitizer in the multiphase reactions between gas-phase ozone and aqueous oxalic acid (OA). The performed photochemical batch experiments yielded a complex suite of organic molecules which resulted primarily from the oligomerization of OA/PA and subsequent reactions, including decarboxylation and cycloadition (Grgic et al., 2010). In the atmosphere, pyruvic acid will always be accompanied by other carboxylic acids (and also other organics) which are constituents of either aerosol particles or aqueous droplets the effects of a possible photochemistry triggered by pyruvic acid should be experimentally studied in depth and under natural conditions as far as possible. Hence, in a very recent study experiments in the aerosol chamber facility LEAK at IFT, Leipzig, were performed to verify the influence of pyruvic on the multiphase (photo)oxidation of oxalic acid. The aim of these experiments was to study the multiphase photo-induced oxidation reactions with airborne deliquescent particles to demonstrate the applicability of the reactions mentioned above under more realistic conditions than in a batch reactor. State of the art sampling and analytical tools were applied for the analysis of the ongoing chamber runs and the formed particulate products which include denuder sampling, carbonyl compound derivatisation, PTR-MS measurements, GC-MS measurements and HPLC-MS and CE-MS for the particle phase. First results from these joint complex chamber experiments will be presented and discussed. Reference: Grgić I., Nieto-Gligorovski L.I., Net S., Temime-Roussel B., Gligorovski S., Wortham H. Light induced multiphase

  8. Measurements of tropospheric nitric acid over the Western United States and Northeastern Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Lebel, P. J.; Huebert, B. J.; Schiff, H. I.; Vay, S. A.; Vanbramer, S. E.; Hastie, D. R.

    1990-01-01

    Over 240 measurements of nitric acid (HNO3) were made in the free troposphere as well as in the boundary layer. Marine HNO3 measurement results were strikingly similar to results from GAMETAG and other past atmospheric field experiments. The marine boundary layer HNO3 average, 62 parts-per-trillion by volume (pptv), was 1/3 lower than the marine free tropospheric average, 108 pptv, suggesting that the boundary layer is a sink for tropospheric nitric acid, probably by dry deposition. Nitric acid measurements on a nighttime continental flight gave a free tropospheric average of 218 pptv, substantially greater than the daytime continental free tropospheric 5-flight average of 61 pptv. However, the nighttime results may be influenced by highly convective conditions that existed from thunderstorms in the vicinity during that night flight. The continental boundary layer HNO3 average of 767 pptv is an order of magnitude greater than the free tropospheric average, indicating that the boundary layer is a source of free tropospheric HNO3. The distribution of continental boundary layer HNO3 data, from averages of 123 over rural Nevada and Utah to 1057 pptv in the polluted San Joaquin Valley of California suggest a close tie between boundary layer HNO3 and anthropogenic activity.

  9. Improvements in the profiles and distributions of nitric acid and nitrogen dioxide with the LIMS version 6 dataset

    NASA Astrophysics Data System (ADS)

    Remsberg, E.; Natarajan, M.; Marshall, T.; Gordley, L. L.; Thompson, R. E.; Lingenfelser, G.

    2010-02-01

    The quality of the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) nitric acid (HNO3) and nitrogen dioxide (NO2) profiles and distributions of 1978/1979 is described after their processing with an updated, Version 6 (V6) algorithm and subsequent archival in 2002. Estimates of the precision and accuracy of both of those species are developed and provided herein. The character of the V6 HNO3 profiles is relatively unchanged from that of the earlier LIMS Version 5 (V5) profiles, except in the upper stratosphere where the interfering effects of CO2 are accounted for better with V6. The accuracy of the retrieved V6 NO2 is also significantly better in the middle and upper stratosphere, due to improvements in its spectral line parameters and in the reduced biases for the accompanying V6 temperature and water vapor profiles. As a result of these important updates, there is better agreement with theoretical calculations for profiles of the HNO3/NO2 ratio, day-to-night NO2 ratio, and with estimates of the production of NO2 in the mesosphere and its descent to the upper stratosphere during polar night. The improved precisions and more frequent retrievals of the profiles along the LIMS orbit tracks provide for better continuity and detail in map analyses of these two species on pressure surfaces. It is judged that the chemical effects of the oxides of nitrogen on ozone can be examined quantitatively throughout the stratosphere with the LIMS V6 data, and that the findings will be more compatible with those obtained from measurements of the same species from subsequent satellite sensors.

  10. Improvements in the profiles and distributions of nitric acid and nitrogen dioxide with the LIMS version 6 dataset

    NASA Astrophysics Data System (ADS)

    Remsberg, E.; Natarajan, M.; Marshall, B. T.; Gordley, L. L.; Thompson, R. E.; Lingenfelser, G.

    2010-05-01

    The quality of the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) nitric acid (HNO3) and nitrogen dioxide (NO2) profiles and distributions of 1978/1979 are described after their processing with an updated, Version 6 (V6) algorithm and subsequent archival in 2002. Estimates of the precision and accuracy of both of those species are developed and provided herein. The character of the V6 HNO3 profiles is relatively unchanged from that of the earlier LIMS Version 5 (V5) profiles, except in the upper stratosphere where the interfering effects of CO2 are accounted for better with V6. The accuracy of the retrieved V6 NO2 is also significantly better in the middle and upper stratosphere, due to improvements in its spectral line parameters and in the reduced biases for the accompanying V6 temperature and water vapor profiles. As a result of these important updates, there is better agreement with theoretical calculations for profiles of the HNO3/NO2 ratio, day-to-night NO2 ratio, and with estimates of the production of NO2 in the mesosphere and its descent to the upper stratosphere during polar night. In particular, the findings for middle and upper stratospheric NO2 should also be more compatible with those obtained from more recent satellite sensors because the effects of the spin-splitting of the NO2 lines are accounted for now with the LIMS V6 algorithm. The improved precisions and more frequent retrievals of the LIMS profiles along their orbit tracks provide for better continuity and detail in map analyses of these two species on pressure surfaces. It is judged that the chemical effects of the oxides of nitrogen on ozone can be studied quantitatively throughout the stratosphere with the LIMS V6 data.

  11. Description of data on the Nimbus 7 LIMS map archive tape: ozone and nitric acid

    SciTech Connect

    Remsberg, E.E.; Kurzeja, R.J.; Haggard, K.V.; Russell, J.M. III; Gordley, L.L.

    1986-12-01

    The Nimbus 7 Limb infrared monitor of the stratosphere (LIMS) data set has been processed into a Fourier coefficient representation with a Kalman filter algorithm applied to profile data at individual latitudes and pressure levels. The algorithm produces synoptic data at noon Greenwich Mean Time (GMT) from the asynoptic orbital profiles. This form of the data set is easy to use and is appropriate for time series analysis and further data manipulation and display. Ozone and nitric acid results are grouped together in this report because the LIMS vertical field of views (FOV's) and analysis characteristics for these species are similar. A comparison of the orbital input data with mixing ratios derived from Kalman filter coefficients indicates errors in mixing ratio of generally less than 5 percent, with 15 percent being a maximum error. The high quality of the mapped data was indicated by coherence of both the phases and the amplitudes of waves with latitude and pressure. Examples of the mapped fields are presented, and details are given concerning the importance of diurnal variations, the removal of polar stratospheric cloud signatures, and the interpretation of bias effects in the data near the tops of profiles.

  12. Description of data on the Nimbus 7 LIMS map archive tape: Ozone and nitric acid

    NASA Technical Reports Server (NTRS)

    Remsberg, E. E.; Kurzeja, R. J.; Haggard, K. V.; Russell, J. M., III; Gordley, L. L.

    1986-01-01

    The Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) data set has been processed into a Fourier coefficient representation with a Kalman filter algorithm applied to profile data at individual latitudes and pressure levels. The algorithm produces synoptic data at noon Greenwich Mean Time (GMT) from the asynoptic orbital profiles. This form of the data set is easy to use and is appropriate for time series analysis and further data manipulation and display. Ozone and nitric acid results are grouped together in this report because the LIMS vertical field of views (FOV's) and analysis characteristics for these species are similar. A comparison of the orbital input data with mixing ratios derived from Kalman filter coefficients indicates errors in mixing ratio of generally less than 5 percent, with 15 percent being a maximum error. The high quality of the mapped data was indicated by coherence of both the phases and the amplitudes of waves with latitude and pressure. Examples of the mapped fields are presented, and details are given concerning the importance of diurnal variations, the removal of polar stratospheric cloud signatures, and the interpretation of bias effects in the data near the tops of profiles.

  13. The effects of sequential exposure to acidic fog and ozone on pulmonary function in exercising subjects

    SciTech Connect

    Aris, R.; Christian, D.; Sheppard, D.; Balmes, J.R. )

    1991-01-01

    In Southern California coastal regions, morning fog is often acidified by the presence of nitric acid (HNO{sub 3}). Peak exposure to ozone (O{sub 3}) usually occurs in the afternoon and evening, after the fog has dissipated. To determine whether fog containing HNO{sub 3} might enhance pulmonary responses to O{sub 3}, we studied a group of healthy, athletic subjects selected for lung function sensitivity to O{sub 3}. On 3 separate days, the subjects exercised for 2 h in atmospheres containing HNO{sub 3} fog (0.5 mg/ml), H{sub 2}O fog, or clean, filtered air. After a 1-h break, they exercised for an additional 3 h in an atmosphere containing 0.20 ppm O{sub 3}. Surprisingly, the mean O{sub 3}-induced decrements in FEV1 and FVC were smaller after exercise in each fog-containing atmosphere than they were after exercise in clean, filtered air. The mean (+/- SEM) O{sub 3}-induced decrements in FEV1 were 26.4 +/- 5.3% after air, 17.1 +/- 3.7% after H{sub 2}O fog, and 18.0 +/- 4.3% after HNO{sub 3} fog, and in FVC they were 19.9 +/- 4.7% after air, 13.6 +/- 2.8% after H{sub 2}O fog, and 13.6 +/- 4.2% after HNO{sub 3} fog.

  14. Effects of ozone and peroxyacetyl nitrate on polar lipids and fatty acids in leaves of morning glory and kidney bean. [Pharbitis nil; Phaseolus vulgaris

    SciTech Connect

    Nouchi, Isamu; Toyama, Susumu Ochanomizu Univ., Tokyo )

    1988-07-01

    To compare the effects of ozone and peroxyacetyl nitrate (PAN) on leaf lipids, fatty acids and malondialdehyde (MDA), morning glory (Pharbitis nil Choisy cv Scarlet O'Hara) and kidney bean (Phaseolus vulgaris L. cv Gintebo) plants were exposed to either ozone (0.15 microliter per liter for 8 hours) or PAN (0.10 microliter per liter for up to 8 hours). Ozone increased phospholipids in morning glory and decreased in kidney bean at the initial stage (2-4 hours) of exposure, while it scarcely changed glycolipids, the unsaturated fatty acids, and MDA in both plants. A large reduction of glycolipids occurred 1 day after ozone exposure in both plants. PAN caused marked drops in phospholipids and glycolipids in kidney bean at relatively late stage (6-8 hours) of exposure, while it increased phosphatidic acid and decreased the unsaturated fatty acids, an increase which was accompanied by a large increase in MDA. These results suggest that ozone may not directly oxidize unsaturated fatty acids at the initial stage of exposure, but may alter polar lipid metabolism, particularly phospholipids. On the other hand, PAN may abruptly and considerably degrade phospholipids and glycolipids by peroxidation or hydrolysis at the late stage of exposure. The present study shows that ozone and PAN affect polar lipids in different manners.

  15. Analysis of Strong Wintertime Ozone Events in an Area of Extensive Oil and Gas Extraction

    NASA Astrophysics Data System (ADS)

    Rappenglück, Bernhard; Ackermann, Luis; Alvarez, Sergio; Golovko, Julia; Buhr, Martin; Field, Robert; Soltis, Jeff; Montague, Derek C.; Hauze, Bill; Scott, Adamson; Risch, Dan; Wilkerson, George; Bush, David; Stoeckenius, Till; Keslar, Cara

    2015-04-01

    During recent years, elevated ozone (O3) values have been observed repeatedly in the Upper Green River Basin (UGRB), Wyoming during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1-hour average up to 166 ppbv). Intensive Observational Periods (IOPs) were performed which included comprehensive surface and boundary layer measurements. Low windspeeds in combination with low mixing layer heights (~50 m agl) are essential for accumulation of pollutants. Air masses contain substantial amounts of reactive nitrogen (NOx) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days in the morning hours reactive nitrogen (up to 69%), then aromatics and alkanes (each ~10-15%; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. This time frame largely coincides with lowest NMHC/NOx ratios (~50), reflecting a relatively low NMHC mixture, and a change from a NOx-limited regime towards a NMHC limited regime. OH production on IOP days is mainly due to nitrous acid (HONO). On a 24-hr basis and as determined for a measurement height of 1.80 m above the surface HONO photolysis on IOP days can contribute ~83% to OH production on average, followed by alkene ozonolysis (~9%). Photolysis by ozone and HCHO photolysis contributes about 4% each to hydroxyl formation. High HONO levels (maximum hourly median on IOP days: 1,096 pptv) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow surface. HONO is most likely formed through (i) abundant nitric acid (HNO3) produced in atmospheric oxidation of NOx, deposited onto the snow surface and undergoing photo-enhanced heterogeneous conversion to HONO and (ii) combustion related emission of HONO. HONO production is confined to the lowermost 10 m of the boundary layer. HONO, serves as the most important precursor for OH, strongly enhanced due to

  16. Retrospective bioindication of stratospheric ozone and ultraviolet radiation using hydroxycinnamic acid derivatives of herbarium samples of an aquatic liverwort.

    PubMed

    Otero, Saúl; Núñez-Olivera, Encarnación; Martínez-Abaigar, Javier; Tomás, Rafael; Huttunen, Satu

    2009-01-01

    We analyzed bulk UV absorbance of methanolic extracts and levels of five UV-absorbing compounds (hydroxycinnamic acid derivatives) in 135 herbarium samples of the liverwort Jungermannia exsertifolia subsp. cordifolia from northern Europe. Samples had been collected in 1850-2006 (96% in June-August). Both UV absorbance and compound levels were correlated positively with collection year. p-Coumaroylmalic acid (C1) was the only compound showing a significant (and negative) correlation with stratospheric ozone and UV irradiance in the period that real data of these variables existed. Stratospheric ozone reconstruction (1850-2006) based on C1 showed higher values in June than in July and August, which coincides with the normal monthly variation of ozone. Combining all the data, there was no long-term temporal trend from 1850 to 2006. Reconstructed UV showed higher values in June-July than in August, but again no temporal trend was detected in 1918-2006 using the joint data. This agrees with previous UV reconstructions.

  17. Toxicity on aquatic organisms exposed to secondary effluent disinfected with chlorine, peracetic acid, ozone and UV radiation.

    PubMed

    da Costa, Juliana Berninger; Rodgher, Suzelei; Daniel, Luiz Antonio; Espíndola, Evaldo Luiz Gaeta

    2014-11-01

    The toxic potential of four disinfectant agents (chlorine, ozone, peracetic acid and UV radiation), used in the disinfection of urban wastewater, was evaluated with respect to four aquatic organisms. Disinfection assays were carried out with wastewater from the city of Araraquara (São Paulo State, Brazil), and subsequently, toxicity bioassays were applied in order to verify possible adverse effects to the cladocerans (Ceriodaphnia silvestrii and Daphnia similis), midge larvae Chironomus xanthus and fish (Danio rerio). Under the experimental conditions tested, all the disinfectants were capable of producing harmful effects on the test organisms, except for C. xanthus. The toxicity of the effluent to C. silvestrii was observed to increase significantly as a result of disinfection using 2.5 mg L(-1) chlorine and 29.9 mg L(-1) ozone. Ozonation and chlorination significantly affected the survival of D. similis and D. rerio, causing mortality of 60 to 100 % in comparison to the non-disinfected effluent. In experiments with effluent treated with peracetic acid (PAA) and UV radiation, a statistically significant decrease in survival was only detected for D. rerio. This investigation suggested that the study of the ideal concentrations of disinfectants is a research need for ecologically safe options for the treatment of wastewater.

  18. Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices

    PubMed Central

    Vellayappan, Muthu Vignesh; Muhamad, Ida Idayu

    2016-01-01

    Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE) and nitric acid (HNO3) treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO3 decreased. Surface of mPE and HNO3 treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P < 0.05) for HNO3 treated mPE. Hemolysis assay and platelet adhesion of the treated surface resulted in the lysis of red blood cells and platelet adherence, respectively indicating improved hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO3 treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO3 treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc. PMID:26819837

  19. An evaluation of the regional acid deposition model surface module for ozone uptake at three sites in the San Joaquin Valley of California

    NASA Technical Reports Server (NTRS)

    Massman, W. J.; Pederson, J.; Delany, A.; Grantz, D.; Hertog, G. Den; Neumann, H. H.; Oncley, S. P.; Pearson, R., Jr.; Shaw, R. H.

    1994-01-01

    Plants and soils act as major sinks for the destruction of tropospheric ozone, especially during daylight hours when plant stomata open and are thought to provide the dominant pathway for the uptake of ozone. The present study, part of the California Ozone Deposition Experiment, compares predictions of the regional acid deposition model ozone surface conductance module with surface conductance data derived from eddy covariance measurements of ozone flux taken at a grape, a cotton, and a grassland site in the San Joaquin Valley of California during the summer of 1991. Results indicate that the model (which was developed to provide long-term large-area estimates for the eastern United States) significantly overpredicts the surface conductance at all times of the day for at least two important types of plant cover of the San Joaquin Valley and that it incorrectly partitions the ozone flux between transpiring and nontranspiring components of the surface at the third site. Consequently, the model either overpredicts or inaccurately represents the observed deposition velocities. Other results indicate that the presence of dew does not reduce the rate of ozone deposition, contradicting to model assumptions, and that model assumptions involving the dependency of stomata upon environmental temperature are unnecessary. The effects of measurement errors and biases, arising from the presence of the roughness sublayer and possible photochemical reactions, are also discussed. A simpler model for ozone surface deposition (at least for the San Joaquin Valley) is proposed and evaluated.

  20. Concurrent removal of humic acid and o-dichlorobenzene in drinking water by combined ozonation and bentonite coagulation process.

    PubMed

    Gu, Li; Zhang, Xingwang; Lei, Lecheng; Liu, Xianjun

    2009-01-01

    Combined ozonation and bentonite coagulation process (COBC) was investigated as a method of concurrently removing humic acid (HA) and o-dichlorobenzene (DCB) from drinking water. In this process, HA and DCB were removed by joint effect of catalytic ozonation and bentonite coagulation. HA removal was highly dependent on the coagulation process while DCB removal was dependent on the oxidation process in COBC. Iron in solution not only acted as a coagulant, but also promoted the formation of HO, which is effective in destroying aromatic chemicals. Bentonite in COBC improved the coagulation process, resulting in an enhancement in the treating efficiency. COBC is proved to be potentially advantageous on dissolved pollutants in drinking water, and appears to have great potential for a wide range of practical applications.

  1. Applying model simulation and photochemical indicators to evaluate ozone sensitivity in southern Taiwan.

    PubMed

    Peng, Yen-Ping; Chen, Kang-Shin; Wang, Hsin-Kai; Lai, Chia-Hsiang; Lin, Ming-Hsun; Lee, Cheng-Haw

    2011-01-01

    Ozone sensitivity was investigated using CAMx simulations and photochemical indicator ratios at three sites (Pingtung City, Chao-Chou Town, and Kenting Town) in Pingtung County in southern Taiwan during 2003 and 2004. The CAMx simulations compared fairly well with the hourly concentrations of ozone. Simulation results also showed that Pingtung City was mainly a volatile organic compounds (VOC)-sensitive regime, while Chao-Chou Town was either a VOC-sensitive or a NOx-sensitive regime, depending on the seasons. Measurements of three photochemical indicators (H2O2, HNO3, and NOy) were conducted, and simulated three transition ranges of H2O2/HNO3 (0.5-0.8), O3/HNO3 (10.3-16.2) and O3/NOy (5.7-10.8) were adopted to assess the ozone sensitive regime at the three sites. The results indicated that the three transition ranges yield consistent results with CAMx simulations at most times at Pingtung City. However, both VOC-sensitive and NOx-sensitive regimes were important at the rural site Chao-Chou Town. Kenting Town, a touring site at the southern end of Taiwan, was predominated by a NOx-sensitive regime in four seasons.

  2. Chemical nature and immunotoxicological properties of arachidonic acid degradation products formed by exposure to ozone.

    PubMed Central

    Madden, M C; Friedman, M; Hanley, N; Siegler, E; Quay, J; Becker, S; Devlin, R; Koren, H S

    1993-01-01

    Ozone (O3) exposure in vivo has been reported to degrade arachidonic acid (AA) in the lungs of rodents. The O3-degraded AA products may play a role in the responses to this toxicant. To study the chemical nature and biological activity of O3-exposed AA, we exposed AA in a cell-free, aqueous environment to air, 0.1 ppm O3, or 1.0 ppm O3 for 30-120 min. AA exposed to air was not degraded. All O3 exposures degraded > 98% of the AA to more polar products, which were predominantly aldehydic substances (as determined by reactivity with 2,4-dinitrophenylhydrazine and subsequent separation by HPLC) and hydrogen peroxide. The type and amount of aldehydic substances formed depended on the O3 concentration and exposure duration. A human bronchial epithelial cell line (BEAS-2B, S6 subclone) exposed in vitro to either 0.1 ppm or 1.0 ppm O3 for 1 hr produced AA-derived aldehydic substances, some of which eluted with similar retention times as the aldehydic substances derived from O3 degradation of AA in the cell-free system. In vitro, O3-degraded AA induced an increase in human peripheral blood polymorphonuclear leukocyte (PMN) polarization, decreased human peripheral blood T-lymphocyte proliferation in response to mitogens, and decreased human peripheral blood natural killer cell lysis of K562 target cells. The aldehydic substances, but not hydrogen peroxide, appeared to be the principal active agents responsible for the observed effects. O3-degraded AA may play a role in the PMN influx into lungs and in decreased T-lymphocyte mitogenesis and natural killer cell activity observed in humans and rodents exposed to O3. PMID:8354202

  3. Chemical nature and immunotoxicological properties of arachidonic acid degradation products formed by exposure to ozone

    SciTech Connect

    Madden, M.C.; Friedman, M.; Hanley, N.; Siegler, E.; Quay, J.; Becker, S.; Devlin, R.; Koren, H.S. )

    1993-06-01

    Ozone (O3) exposure in vivo has been reported to degrade arachidonic acid (AA) in the lungs of rodents. The O3-degraded AA products may play a role in the responses to this toxicant. To study the chemical nature and biological activity of O3-exposed AA, we exposed AA in a cell-free, aqueous environment to air, 0.1 ppm O3, or 1.0 ppm O3 for 30-120 min. AA exposed to air was not degraded. All O3 exposures degraded > 98% of the AA to more polar products, which were predominantly aldehydic substances (as determined by reactivity with 2,4-dinitrophenylhydrazine and subsequent separation by HPLC) and hydrogen peroxide. The type and amount of aldehydic substances formed depended on the O3 concentration and exposure duration. A human bronchial epithelial cell line (BEAS-2B, S6 subclone) exposed in vitro to either 0.1 ppm or 1.0 ppm O3 for 1 hr produced AA-derived aldehydic substances, some of which eluted with similar retention times as the aldehydic substances derived from O3 degradation of AA in the cell-free system. In vitro, O3-degraded AA induced an increase in human peripheral blood polymorphonuclear leukocyte (PMN) polarization, decreased human peripheral blood T-lymphocyte proliferation in response to mitogens, and decreased human peripheral blood natural killer cell lysis of K562 target cells. The aldehydic substances, but not hydrogen peroxide, appeared to be the principal active agents responsible for the observed effects. O3-degraded AA may play a role in the PMN influx into lungs and in decreased T-lymphocyte mitogenesis and natural killer cell activity observed in humans and rodents exposed to O3.

  4. Heterogeneous chemistry related to Antarctic ozone depletion: Reaction of ClONO2 and N2O5 on ice surfaces

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Rossi, Michel J.; Golden, David M.

    1988-01-01

    Laboratory studies of heterogeneous reactions of possible importance for Antarctic ozone depletion were performed. In particular, the reactions of chlorine nitrate (ClONO2) and dinitrogen pentoxide (N2O5) were investigated on ice and HCl/ice surfaces. These reactions occur on the surfaces of polar stratospheric clouds (PSCs) over Antarctica. One reaction transforms the stable chlorine reservoir species (ClONO2 and HCl) into photochemically active chlorine in the form of HOCl and Cl2. Condensation of HNO3 in the reactions removes odd nitrogen from the stratosphere, a requirement in nearly all models of Antarctic ozone depletion. Other reactions may also be important for Antarctic ozone depletion. Like the reactions of chlorine nitrate, these reactions deplete odd nitrogen through HNO3 condensation. In addition, one reaction converts a stable chlorine reservior species (HCl) into photochemically active chlorine (ClNO2). These reactions were studied with a modified version of a Knudsen cell flow reactor.

  5. Heterogeneous chemistry in the troposphere: The nitric acid "renoxification"

    NASA Astrophysics Data System (ADS)

    Rivera-Figueroa, Armando M.

    2005-07-01

    . Therefore, the chemistry elucidated by these experiments may help to resolve some discrepancies between model-predicted ozone and field observations in polluted urban atmospheres. The heterogeneous hydrolysis of NO2 under dark and light (400 ≤ gamma ≤ 500 nm) conditions, and pre-treating the silica surface with HNO3, as an important pathway for the production of HNO3(ads) was investigated. HNO3 remains surface-adsorbed, and hence available to further react with atmospheric species, such as NO. In the presence of light, the decay of HNO3(ads) was observed. Additionally, NO2 hydrolysis has been shown to slow down when occurring on acidified surfaces.

  6. Experimental and theoretical studies of the interaction of gas phase nitric acid and water with a self-assembled monolayer.

    PubMed

    Moussa, S G; Stern, A C; Raff, J D; Dilbeck, C W; Tobias, D J; Finlayson-Pitts, B J

    2013-01-14

    Nitric acid in air is formed by atmospheric reactions of oxides of nitrogen and is removed primarily through deposition to surfaces, either as the gas or after conversion to particulate nitrate. Many of the surfaces and particles have organic coatings, but relatively little is known about the interaction of nitric acid with organic films. We report here studies of the interaction of gaseous HNO(3) with a self-assembled monolayer (SAM) formed by reacting 7-octenyltrichlorosilane [H(2)C=CH(CH(2))(6)SiCl(3)] with the surface of a germanium infrared-transmitting attenuated total reflectance (ATR) crystal that was coated with a thin layer of silicon oxide (SiO(x)). The SAM was exposed at 298 ± 2 K to dry HNO(3) in a flow of N(2), followed by HNO(3) in humid N(2) at a controlled relative humidity (RH) between 20-90%. For comparison, similar studies were carried out using a similar crystal without the SAM coating. Changes in the surface were followed using Fourier transform infared spectroscopy (FTIR). In the case of the SAM-coated crystal, molecular HNO(3) and smaller amounts of NO(3)(-) ions were observed on the surface upon exposure to dry HNO(3). Addition of water vapor led to less molecular HNO(3) and more H(3)O(+) and NO(3)(-) complexed to water, but surprisingly, molecular HNO(3) was still evident in the spectra up to 70% RH. This suggests that part of the HNO(3) observed was initially trapped in pockets within the SAM and shielded from water vapor. After increasing the RH to 90% and then exposing the film to a flow of dry N(2), molecular nitric acid was regenerated, as expected from recombination of protons and nitrate ions as water evaporated. The nitric acid ultimately evaporated from the film. On the other hand, exposure of the SAM to HNO(3) and H(2)O simultaneously gave only hydronium and nitrate ions. Molecular dynamics simulations of defective SAMs in the presence of HNO(3) and water predict that nitric acid intercalates in defects as a complex with a

  7. Protective effect of Mn(III)-desferrioxamine B upon oxidative stress caused by ozone and acid rain in the Brazilian soybean cultivar Glycine max "Sambaiba".

    PubMed

    Esposito, Jéssica Bordotti Nobre; Esposito, Breno Pannia; Azevedo, Ricardo Antunes; Cruz, Luciano Soares; da Silva, Luzimar Campos; de Souza, Silvia Ribeiro

    2015-04-01

    This study aimed to investigate the effects of the Mn complex (Mn(III)-desferrioxamine B (MnDFB)) on oxidative stress in the Brazilian soybean cultivar Glycine max "Sambaiba" following exposure to ozone and acid rain. We determined the suitable dose of MnDFB to apply to G. max seedlings using a dose-response curve. The highest superoxide dismutase (SOD) activity and Mn content in leaves were found upon the application of 8 μM MnDFB. Thus, G. max seedlings pretreated with 8 μM MnDFB were individually exposed to ozone and acid rain simulated. Pretreatment with MnDFB reduced lipid peroxidation upon ozone exposure and increased SOD activity in leaves; it did not alter the metal content in any part of the plant. Conversely, following acid rain exposure, neither the metal content in leaves nor SOD enzyme activity were directly affected by MnDFB, unlike pH. Our findings demonstrated that exogenous MnDFB application before ozone exposure may modulate the MnSOD, Cu/ZnSOD, and FeSOD activities to combat the ROS excess in the cell. Here, we demonstrated that the applied dose of MnDFB enhances antioxidative defenses in soybean following exposure to acid rain and especially to ozone.

  8. On the acidity of dew

    NASA Astrophysics Data System (ADS)

    Pierson, William R.; Brachaczek, Wanda W.; Gorse, Robert A.; Japar, Steven M.; Norbeck, Joseph M.

    1986-03-01

    Nightly dew samples were collected on Allegheny Mountain in southwest Pennsylvania in August 1983. The dew was found to be acidic, with mean pH˜4.0. Free H+ comprised >80% of the total acidity, and the composition approximated an H2SO4/HNO3 mixture with average SO42-/NO3- mol ratio ˜1.3. The chemistry of the dew resembled that of rain at Allegheny, though the dew was generally more dilute. Atmospheric HNO3(g) was chiefly responsible for the dew NO3-. SO2 was the source of ˜80% of the dew SO42-. The allocation of dew H+ among atmospheric precursors was HNO3˜30%, SO2 ≥ 60%, aerosol H+ ≤ 10%. The most acidic dews were associated with wind from the west. Average deposition velocities (stated in centimeters per second) to dew were HNO3, 0.24; NO2, <0.02 SO2, ˜0.04; aerosol SO42-, ˜0.02; aerosol NH4+, 0.024; and aerosol species, 0.02-1. Comparison of the HNO3 deposition velocity with ten-fold higher summer daytime values reveals a pronounced diurnal variation. The 0.24 cm/s value for HNO3 may represent a maximum for any gas or submicron aerosol species whenever the atmosphere is strongly stable. Not all of the S(IV) in dew had been converted to SO42- by morning; thus the rate of oxidation must have been on a time scale of hours at nighttime ambient temperatures. In contrast, S(IV) in rain and fog samples was not evident. Deposition fluxes and cumulative deposition totals involving dew, rain, and settled fog water were compared. Rain proved by far the most important for deposition of all solute species, including acid.

  9. Assessment of the ozone-nitrogen oxide-volatile organic compound sensitivity of Mexico City through an indicator-based approach: measurements and numerical simulations comparison.

    PubMed

    Torres-Jardón, Ricardo; García-Reynoso, J Agustín; Jazcilevich, Arón; Ruiz-Suárez, L Gerardo; Keener, Tim C

    2009-10-01

    The ozone (O3) sensitivity to nitrogen oxides (NOx, or nitric oxide [NO] + nitrogen dioxide [NO2]) versus volatile organic compounds (VOCs) in the Mexico City metropolitan area (MCMA) is a current issue of scientific controversy. To shed light on this issue, we compared measurements of the indicator species O3/NOy (where NOy represents the sum of NO + NO2 + nitric acid [HNO3] + peroxyacetyl nitrate [PAN] + others), NOy, and the semiempirically derived O3/NOz(surrogate) (where NOz(surrogate) is the derived surrogate NOz, and NOz represents NOx reaction products, or NOy - NOx) with results of numerical predictions reproducing the transition regimes between NOx and VOC sensitivities. Ambient air concentrations of O3, NOx, and NOy were measured from April 14 to 25, 2004 in one downwind receptor site of photochemically aged air masses within Mexico City. MCMA-derived transition values for an episode day occurring during the same monitoring period were obtained through a series of photochemical simulations using the Multiscale Climate and Chemistry Model (MCCM). The comparison between the measured indicator species and the simulated spatial distribution of the indicators O3/ NOy, O3/NOz(surrogate), and NOy in MCMA suggest that O3 in this megacity is likely VOC-sensitive. This is in opposition to past studies that, on the basis of the observed morning VOC/NOx ratios, have concluded that O3 in Mexico City is NOx-sensitive. Simulated MCMA-derived sensitive transition values for O3/NOy, hydrogen peroxide (H2O2)/HNO3, and NOy were found to be in agreement with threshold criteria proposed for other regions in North America and Europe, although the transition crossover for O3/NOz and O3/HNO3 was not consistent with values reported elsewhere. An additional empirical evaluation of weekend/weekday differences in average maximum O3 concentrations and 6:00- to 9:00-a.m. NOx and NO levels registered at the same site in April 2004 indirectly confirmed the above results. A preliminary

  10. Effects of prolonged, sequential exposure to acid fog and ozone on pulmonary function in exercising, normal subjects. Final report, 28 Feb 89-28 Dec 90

    SciTech Connect

    Balmes, J.

    1990-05-01

    Thirty-nine apparently healthy and asymptomatic subjects were selected for a study that screened for sensitivity to ozone. After three hours of ozone exposure (at 0.20 ppm), eighteen of the subjects (46 percent) experienced a 10 percent reduction in forced expiratory volume, an indicator of exhaling ability. After four hours of exposure, 62 percent of the subjects experienced a similar reduction in expiratory volume. Further, narrowing of airways among the sensitive subjects was suggested by results of the methacholine challenge test, a standard test for measuring airway resistance. The lung capacity of all subjects decreased progressively during ozone exposures. Capacity was unchanged during acidic fog and pollutant-free air exposures. No statistically significant differences in airway resistance, airway responsiveness and symptoms that could be attributed to acid fog exposure were observed. The study indicates that exposue to fog containing nitric acid followed by exposure to ozone does not have additive or synergistic acute effects. However, the study confirms earlier indications that many apparently healthy and asymptomatic individuals are susceptible to and adversely affected by ozone at relatively low concentrations.

  11. Optimum condition to fabricate 5-10 nm SiO2/Si structure using advanced nitric acid oxidation of Si method with Si source

    NASA Astrophysics Data System (ADS)

    Imamura, Kentaro; Matsumoto, Taketoshi; Kobayashi, Hikaru

    2012-12-01

    A low temperature (≦120 °C) fabrication method to form relatively thick SiO2/Si structure with a Si source has been developed using the advanced nitric acid oxidation of Si (NAOS) method, and the formation mechanism has been investigated. The reaction mechanism consists of direct oxidation of Si, dissolution of Si sources, and surface reaction of the dissolved Si species. The dissolved Si species is present in HNO3 solutions as mono-silicic acid and reacts with oxidizing species formed by decomposition of HNO3 on an ultrathin SiO2 layer (i.e., 1.4 nm) produced by the direct oxidation of Si substrates with HNO3 solutions. To achieve a uniform thickness of SiO2 layer with a smooth surface, HNO3 solutions with concentrations higher than 60 wt. % are needed because the dissolved Si species polymerizes in HNO3 solutions when the concentration is below 60 wt. %, resulting in the formation of SiO2 particles in HNO3, which are deposited afterwards on the SiO2 layer. In spite of the low temperature formation at 120 °C, the electrical characteristics of the advanced NAOS SiO2 layer formed with 68 wt. % HNO3 and subsequent post-metallization anneal at 250 °C are nearly identical to those of thermal oxide formed at 900 °C.

  12. Comparison of the effects of ozone on the modification of amino acid residues in glutamine synthetase and bovine serum albumin.

    PubMed

    Berlett, B S; Levine, R L; Stadtman, E R

    1996-02-23

    During exposure to ozone, the methionine and aromatic amino acid residues of Escherichia coli glutamine synthetase (GS) and bovine serum albumin (BSA) are oxidized rapidly in the order Met > Trp > Tyr approximately His > Phe. The loss of His is matched by a nearly equivalent formation of aspartate or of a derivative that is converted to aspartic acid upon acid hydrolysis. Conversion of His to aspartate was confirmed by showing that the oxidation of E. coli protein in which all His residues were uniformly labeled with 14C gave rise to 14C-labeled aspartic acid in 80% yield and also by the demonstration that His residues in the tripeptides Ala-His-Ala or Ala-Ala-His gave rise to nearly stoichiometric amounts of aspartic acid whereas oxidation of His-Ala-Ala yielded only 36% aspartate. The oxidation of BSA and GS led to formation, respectively, of 11 and 3.3 eq of carbonyl groups and 0.5 and 0.3 eq of quinoprotein per subunit. Although BSA and GS contain nearly identical amounts of each kind of aromatic amino acid residues, oxidation of these residues in BSA was about 1.5-2.0 times faster than in GS indicating that the susceptibility to oxidation is dependent on the primary, secondary, tertiary, and quaternary structure of the protein.

  13. The role of isoprene oxidation in the tropospheric ozone budget in the tropics

    NASA Technical Reports Server (NTRS)

    Brewer, D. A.; Levine, J. S.

    1985-01-01

    A comprehensive chemical mechanism for the oxidation of isoprene (a hydrocarbon, C5H8 emitted primarily by vegetation) by OH and O3 in the troposphere was developed and incorporated into a one-dimensional steady-state photochemical model of the troposphere. Flux boundary conditions for NOx (NO + NO2), HNO3, O3, and CO were used to investigate the changes produced in the tropospheric concentrations and integrated column of ozone from including isoprene chemistry in the model. Two calculations were performed at 15 deg N latitude for annual conditions using identical flux boundary conditions for NOx, HNO3, O3, and CO; in one calculation, the chemistry describing isoprene oxidation was included while in the other it was not. Both sets of calculations included reactions describing the chemistry of anthropogenic nonmethane hydrocarbons. The calculations showed decreases in concentrations of ozone throughout the troposphere when isoprene chemistry was included. Concentrations of NOx and HNO3 increased in the lower troposphere and decreased in the upper troposphere while concentrations of CO and PAN increased throughout the troposphere when isoprene chemistry was included. Implications of this study to the budgets of these species in the tropics is discussed.

  14. Plutonium and Americium Alpha Radiolysis of Nitric Acid Solutions.

    PubMed

    Horne, Gregory P; Gregson, Colin R; Sims, Howard E; Orr, Robin M; Taylor, Robin J; Pimblott, Simon M

    2017-02-02

    The yield of HNO2, as a function of absorbed dose and HNO3 concentration, from the α-radiolysis of aerated HNO3 solutions containing plutonium or americium has been investigated. There are significant differences in the yields measured from solutions of the two different radionuclides. For 0.1 mol dm(-3) HNO3 solutions, the radiolytic yield of HNO2 produced by americium α-decay is below the detection limit, whereas for plutonium α-decay the yield is considerably greater than that found previously for γ-radiolysis. The differences between the solutions of the two radionuclides are a consequence of redox reactions involving plutonium and the products of aqueous HNO3 radiolysis, in particular H2O2 and HNO2 and its precursors. This radiation chemical behavior is HNO3 concentration dependent with the differences between plutonium and americium α-radiolysis decreasing with increasing HNO3 concentration. This change may be interpreted as a combination of α-radiolysis direct effects and acidity influencing the plutonium oxidation state distribution, which in turn affects the radiation chemistry of the system.

  15. The role of EPA`s Acid Rain Division in the Ozone Transport Commission`s NOx budget program

    SciTech Connect

    Schary, C.; Culligan, K.

    1997-12-31

    The Ozone Transport Commission`s (OTC) Nitrogen Oxides (NO{sub x}) Budget Program will implement the emissions reduction goal of the 1994 Memorandum of Understanding between its twelve member states and the District of Columbia. The program will achieve its significant NO{sub x} reductions from electric utilities and industrial boilers using a {open_quotes}cap-and-trade{close_quotes} approach modeled after the US Environmental Protection Agency`s sulfur dioxide emissions trading under the Acid Rain Program. The similarity of the two programs has led to the development of an important partnership between the OTC states and EPA`s Acid Rain Division, Over the past two years, Acid Rain Program staff have shared their technical expertise and assisted extensively in the development of the program`s rules. Leveraging the investment EPA made in the systems used to run the Acid Rain Program, the OTC states have asked the Acid Rain Division to administer the data systems for them, and together are working to expand its existing Emissions Tracking System and to modify a clone of the sulfur dioxide Allowance Tracking System, to fulfill the unique requirements of the NO{sub x} Budget Program. This partnership is an important example of the new type of cooperation and sharing of expertise and resources that should develop between EPA and states as they launch multi-state programs to address regional pollution problems that defy a single-state solution.

  16. Reduction of nitric acid on Ag in ultrahigh vacuum: A Raman spectroscopic investigation

    NASA Astrophysics Data System (ADS)

    Zangmeister, Christopher D.; Davis, Robert J.; Mrozek, Pawel; Pemberton, Jeanne E.

    2008-07-01

    The reduction of HNO 3 on Ag as a function of temperature in ultrahigh vacuum (UHV) is studied using Raman spectroscopy and thermal desorption-mass spectrometry (TDMS). Thin layers of molecular HNO 3 are stable on the surface below 150 K, but are spontaneously reduced above 150 K with concomitant time-dependent partial desorption of products. The asymmetric nitric oxide dimer, NONO, is observed as the sole reduction product that remains on the surface based on its distinctive Raman spectral signature. The mechanism of NONO formation from HNO 3 is proposed to occur through a multistep reduction of HNO 3 on the Ag surface starting from NO3- and proceeding stepwise through NO 2 and NO2- to NO, followed by combination to form NONO in a process catalyzed by a Lewis acid, oxidized Ag species. Desorption of the majority of surface species is largely complete by 210 K.

  17. Re-evaluating the role of phenolic glycosides and ascorbic acid in ozone scavenging in the leaf apoplast of Arabidopsis thaliana L

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To determine if membrane-bound G-proteins are involved in the regulation of defense responses against ozone in the leaf apoplast, the apoplastic concentrations of ascorbic acid and phenolic glycosides in Arabidopsis thaliana L. lines with null mutations in the alpha- and beta-subunits were compared ...

  18. A Three-Tier Diagnostic Test to Assess Pre-Service Teachers' Misconceptions about Global Warming, Greenhouse Effect, Ozone Layer Depletion, and Acid Rain

    ERIC Educational Resources Information Center

    Arslan, Harika Ozge; Cigdemoglu, Ceyhan; Moseley, Christine

    2012-01-01

    This study describes the development and validation of a three-tier multiple-choice diagnostic test, the atmosphere-related environmental problems diagnostic test (AREPDiT), to reveal common misconceptions of global warming (GW), greenhouse effect (GE), ozone layer depletion (OLD), and acid rain (AR). The development of a two-tier diagnostic test…

  19. Strong wintertime ozone events in the Upper Green River basin, Wyoming

    NASA Astrophysics Data System (ADS)

    Rappenglück, B.; Ackermann, L.; Alvarez, S.; Golovko, J.; Buhr, M.; Field, R. A.; Soltis, J.; Montague, D. C.; Hauze, B.; Adamson, S.; Risch, D.; Wilkerson, G.; Bush, D.; Stoeckenius, T.; Keslar, C.

    2014-05-01

    During recent years, elevated ozone (O3) values have been observed repeatedly in the Upper Green River basin (UGRB), Wyoming, during wintertime. This paper presents an analysis of high ozone days in late winter 2011 (1 h average up to 166 ppbv - parts per billion by volume). Intensive operational periods (IOPs) of ambient monitoring were performed, which included comprehensive surface and boundary layer measurements. On IOP days, maximum O3 values are restricted to a very shallow surface layer. Low wind speeds in combination with low mixing layer heights (~ 50 m above ground level around noontime) are essential for accumulation of pollutants within the UGRB. Air masses contain substantial amounts of reactive nitrogen (NOx) and non-methane hydrocarbons (NMHC) emitted from fossil fuel exploration activities in the Pinedale Anticline. On IOP days particularly in the morning hours, reactive nitrogen (up to 69%), aromatics and alkanes (~ 10-15%; mostly ethane and propane) are major contributors to the hydroxyl (OH) reactivity. Measurements at the Boulder monitoring site during these time periods under SW wind flow conditions show the lowest NMHC / NOx ratios (~ 50), reflecting a relatively low reactive NMHC mixture, and a change from a NOx-limited regime towards a NMHC-limited regime as indicated by photochemical indicators, e.g., O3 /NOy, O3 /NOz, and O3 / HNO3 and the EOR (extent of reaction). OH production on IOP days is mainly due to nitrous acid (HONO). On a 24 h basis and as determined for a measurement height of 1.80 m above the surface HONO photolysis on IOP days can contribute ~ 83% to OH production on average, followed by alkene ozonolysis (~ 9%). Photolysis by ozone and HCHO photolysis contribute about 4% each to hydroxyl formation. High HONO levels (maximum hourly median on IOP days: 1096 pptv - parts per trillion by volume) are favored by a combination of shallow boundary layer conditions and enhanced photolysis rates due to the high albedo of the snow

  20. An outbreak of illness after occupational exposure to ozone and acid chlorides.

    PubMed Central

    Ng, T P; Tsin, T W; O'Kelly, F J

    1985-01-01

    New labelling processes installed without adequate ventilation control in an electric motor factory exposed production line workers to toxic gases. Symptoms of eye and respiratory tract irritation together with complaints of headache, fever, chills, dizziness, malaise, general weakness, nausea, and vomiting were widespread. Chest signs, radiographic abnormalities, reduction in ventilatory function, and blood gas abnormalities were found in some cases. Epidemiological analysis of the spatial and temporal distribution of cases supported an exposure effect relationship. Investigations suggested ozone and possibly phosgene and associated trichloroacetyl chlorides as the toxic agents that were generated by an ultraviolet print curing arrangement and perchloroethylene used as a cleaning solvent. PMID:4041387

  1. Nitric acid partitioning in cirrus clouds: a synopsis based on field, laboratory and model studies

    NASA Astrophysics Data System (ADS)

    Krämer, M.; Beuermann, J.; Schiller, C.; Grimm, F.; Arnold, F.; Peter, Th.; Meilinger, S.; Meier, A.; Hendricks, J.; Petzold, A.; Schlager, H.

    2003-02-01

    From a synopsis of field, laboratory and model studies at T>205 K as well as from the field experiments POLSTAR at T<205 K we derive a general picture of the partitioning of nitric acid (HNO3) in cirrus clouds and a new hypothesis on the uptake of HNO3 on ice particles: A substantial part of nitric acid remains in the gas phase under cirrus cloud conditions. The HNO3 removed from the gas phase is distributed between interstitial aerosol and ice particles in dependence on the temperature and ice surface, respectively. In cold cirrus clouds with small ice surface areas (T <205 K) the partitioning is strongly in favour of interstitial ternary solution particles while in warmer cirrus clouds with large ice surface areas the uptake on ice dominates. Consequently, denitrification via sedimenting ice particles may occur only in the -more frequently occurring- warm cirrus clouds The HNO3 coverage on ice is found to be different for ice particles and ice films. On ice films the coverage can increase with decreasing temperature from about 0.1 to 0.8 monolayer, while that on ice particles is found to decrease with temperature and PHNO3 from 0.1 to 0.001 monolayer. An HNO3 uptake behaviour following dissociative Langmuir isotherms where the coverage decreases for descending temperatures may explain the observations for ice particles From a comparison of the HNO3 measurements with model calculations it is found that (i) the global model of Lawrence and Crutzen (1998) overestimates the HNO3 partitioning in favour of the ice particles (ii) the Langmuir surface chemistry model of Tabazadeh et al. (1999) overestimates HNO3 coverages for temperatures ≤210 K More appropriate coverages are calculated when implementing in that model a temperature dependent function for the adsorption free energy (ΔGads (T)), which is empirically derived from the coverage measurements.

  2. Straightforward preparation of labeled potassium cyanate by ozonation and application to the synthesis of [13C] or [14C]ureidocarboxylic acids.

    PubMed

    Loreau, Olivier; Marlière, Philippe

    2013-06-15

    The development of new efficient syntheses of labeled reagents is a great challenge. Avoidance of overcomplicated procedures, availability and cost of starting materials are important considerations in choosing the synthetic route. In this report, we describe a facile and rapid preparation of labeled cyanate by ozonation of cyanide, a basic precursor. The crude cyanate was used without purification for the synthesis of various [(13)C] or [(14)C]ureidocarboxylic acids (20-68% yield from potassium cyanide). According to these results, cyanide ozonation may prove to be a promising alternative to traditional preparations of labeled cyanate.

  3. ACE-FTS ozone, water vapour, nitrous oxide, nitric acid, and carbon monoxide profile comparisons with MIPAS and MLS

    NASA Astrophysics Data System (ADS)

    Sheese, Patrick E.; Walker, Kaley A.; Boone, Chris D.; Bernath, Peter F.; Froidevaux, Lucien; Funke, Bernd; Raspollini, Piera; von Clarmann, Thomas

    2017-01-01

    The atmospheric limb sounders, ACE-FTS on the SCISAT satellite, MIPAS on ESA's Envisat satellite, and MLS on NASA's Aura satellite, take measurements used to retrieve atmospheric profiles of O3, N2O, H2O, HNO3, and CO. Each was taking measurements between February 2004 and April 2012 (ACE-FTS and MLS are currently operational), providing hundreds of profile coincidences in the Northern and Southern hemispheres, and during local morning and evening. Focusing on determining diurnal and hemispheric biases in the ACE-FTS data, this study compares ACE-FTS version 3.5 profiles that are collocated with MIPAS and MLS, and analyzes the differences between instrument retrievals for Northern and Southern hemispheres and for local morning and evening data. For O3, ACE-FTS is typically within ±5% of mid-stratospheric MIPAS and MLS data and exhibits a positive bias of 10 to 20% in the upper stratosphere - lower mesosphere. For H2O, ACE-FTS exhibits an average bias of -5% between 20 and 60 km. For N2O, ACE-FTS agrees with MIPAS and MLS within -20 to +10% up to 45 km and 35 km, respectively. For HNO3, ACE-FTS typically agrees within ±10% below 30 km, and exhibits a positive bias of 10 to 20% above 30 km. With respect to MIPAS CO, ACE-FTS exhibits an average -11% bias between 28 and 50 km, and at higher altitudes a positive bias on the order of 10% (>100%) in the winter (summer). With respect to winter MLS CO, ACE-FTS is typically within ±10% between 25 and 40 km, and has an average bias of -11% above 40 km.

  4. Formation of water-soluble dicarboxylic acids, oxoacids and a-dicarbonyls by ozone oxidation of isoprene

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Sakamoto, Y.; Hirokawa, J.

    2014-12-01

    Water-soluble dicarboxylic acids such as oxalic acid (C2) are the dominant organic compound class in atmospheric aerosols. They can act as cloud condensation nuclei and affect on the Earth climate. Diacids can be primary emitted from fossil fuel combustion and biomass burning and secondarily produced by photochemical oxidations of biogenic and anthropogenic hydrocarbons. However, their sources and formation processes are still not well understood. Recently model and observation studies suggested the importance of isoprene as a precursor of oxalic acid. Isoprene is the most abundant BVOC emitted from terrestrial plants and can serve as important precursors of diacids. We conducted a laboratory oxidation of isoprene (2.0 ppm) with ozone (4.3 ppm) in a Teflon bag for 10 to 480 min. The formed particles were collected with quartz fiber filters and analyzed for diacids, oxoacids and a-dicarbonyls employing water extraction and butyl ester derivatization and using GC and GC/MS techniques. Here, we report the analytical results to better understand the formation process of diacids and related compounds from isoprene. We detected homologous series of saturated diacids (C2-C6), unsaturated diacids (maleic and methylmaleic acids), w-oxocarboxylic acids (C2-C9), pyruvic acid, glyoxal and methylglyoxal. We found that oxalic acid (3000-9700 ngm-3) is the most abundant diacid followed by succinic (C4) or malonic (C3) acid. Their concentrations increased with reaction time showing a maximum in 4 hours. Interestingly, C3/C4 ratios increased with time. The second most abundant species after oxalic acid was generally methylglyoxal (3600-9600 ngm-3), except for the 30 min. sample where methylglyoxal was more abundant than oxalic acid. Glyoxylic acid (wC2) was found as the most abundant oxoacid (1600-3800 ngm-3) followed by wC3 and wC4. Although the concentrations of diacids and related compounds are 1-2 orders magnitude higher than those reported in ambient aerosols, this study

  5. A comparative study on the effectiveness of ozonated water and peracetic acid in the storability of packaged fresh-cut melon.

    PubMed

    Botondi, Rinaldo; Moscetti, Roberto; Massantini, Riccardo

    2016-05-01

    Ozonated water and peracetic acid were tested as sanitizers to enhance the storability of fresh-cut melon cubes. Sanitizers were also combined with suitable packaging materials (polypropylene and polylactic acid based plastic films). Fresh-cut melon cubes were stored at 4 °C for up to 7 days. Ozonated water and peracetic acid treatments were given by dipping cubes into 0.8 ppm O3 and 100 ppm Tsunami 100™ solutions, respectively, for 3 min. Both sanitizers exhibited efficiency in reducing the total microbial counts on melon cubes (< 2 log CFU g(-1)). Respiratory activity and ethylene production were both affected by the interaction between the sanitizer and the packaging used. Carbon dioxide and oxygen reached 9.89 kPa and 12.20 kPa partial pressures, respectively, using peracetic acid treatment in combination with polypropylene film packaging, consequently developing off-odors starting from day 3. Strong color changes were noted in cubes stored in polylactic acid packaging after 7 days of storage, affecting the sensory quality of the melon cubes. Sensory evaluation (overall visual quality) indicated loss in flavor in the polypropylene packaging. The overall visual quality started to decline on 3rd day because of the development of translucency.Overall, the use of ozone in combination with polypropylene packaging provided the best solution to maintain the quality of melon cubes for up to 5 days of storage at 4 °C.

  6. Calorimetry Studies of Ammonia, Nitric Acid, and Ammonium Nitrate

    DTIC Science & Technology

    1979-10-01

    block nmmber) Calorimetry Heat of reaction Ammonium nitrate Heat capacity Nitric acid Heat of solution • Amonia 20. ABSTRACT r(Cmrtfe m,.re a N "no•a.•r sd...identical to the literature spectrum of W NO3. Anhydrous nitric acid was prepared by distillation of 90% HNO 3 from fuming sulfuric acid (oxides of nitrogen

  7. Energetic particle-induced enhancements of stratospheric nitric acid

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1994-01-01

    Inclusion of complete ion chemistry in the calculation of minor species production during energetic particle deposition events leads to significant enhancement in the calculated nitric acid concentration during precipitation. An ionization rate of 1.2 x 10(exp 3)/cu cm/s imposed for 1 day increases HNO3 from 3 x 10(exp 5) to 6 x 10(exp 7)/cu cm at 50 km. With an ionization rate of 600 cu cm/s, the maximum HNO3 is 3 x 10(exp 7)/cu cm. Calculations which neglect negative ions predict the nitric acid will fall during precipitation events. The decay time for converting HNO3 into odd nitrogen and hydrogen is more than 1 day for equinoctial periods at 70 deg latitude. Examination of nitric acid data should yield important information on the magnitude and frequency of charged particle events.

  8. Thermodynamic Phase And Chemical Equilibrium At 0-110°C For The H+-K+-Na+-Cl--H2O System Up To 16 Molal And The HNO3-H2O System Up To 20 Molal Using An Association-Based Pitzer Model Compatible With ASPEN Plus

    SciTech Connect

    Todd T. Nichols; Dean D. Taylor

    2003-09-01

    A status is presented of the parameterization during FY2003 of an association-based Pitzer model to simulate chemical and phase equilibria of acid-chloride-nitrate-mercury aqueous electrolyte systems at 0-100° C within the industry-standard process simulator, ASPEN Plus. Compatibility with ASPEN Plus requires that the Pitzer model used be limited to the third virial coefficient and have the values of b and a1 as originally proposed by Pitzer. Two aqueous models for 0-110° C at atmospheric pressure were parameterized in FY03. The model for the aqueous H+-K+-Na+-Cl- system is applicable for 0-16 molal, and the HNO3-H2O for 0-20 molal. An association-based Pitzer activity coefficient model is combined with Henry.s law to predict activity/osmotic coefficient and VLE. The chloride model also predicts KCl and NaCl solubility, while the nitric acid model has the unique capability of predicting extent of dissociation with an average absolute deviation of 1.43%. The association-based approach presented here extends the utility of the molality-based Pitzer model past 6 molal to predict activity/osmotic coefficients up to 16-20 molal. The association-based approach offers the additional benefits of predicting extent of dissociation and of allowing the Pitzer model to be fully utilized in commercial simulators, such as ASPEN Plus, that require accounting for association to implement Henry’s law. The Pitzer models presented here provide the chemical process simulation engineer with a superior alternative to the Electrolyte NRTL model that can easily be used in ASPEN Plus.

  9. Thermodynamic Phase And Chemical Equilibrium At 0-110 C For The H+-K+-Na+-Cl--H2O System Up To 16 Molal And The HNO3-H2O System Up To 20 Molal Using An Association-Based Pitzer Model Compatible With ASPEN Plus

    SciTech Connect

    Nichols,T.T.; Taylor,D.D.

    2003-09-26

    A status is presented of the parameterization during FY2003 of an association-based Pitzer model to simulate chemical and phase equilibria of acid-chloride-nitrate-mercury aqueous electrolyte systems at 0-100 C within the industry-standard process simulator, ASPEN Plus. Compatibility with ASPEN Plus requires that the Pitzer model used be limited to the third virial coefficient and have the values of b and a1 as originally proposed by Pitzer. Two aqueous models for 0-110 C at atmospheric pressure were parameterized in FY03. The model for the aqueous H+-K+-Na+-Cl- system is applicable for 0-16 molal, and the HNO3-H2O for 0-20 molal. An association-based Pitzer activity coefficient model is combined with Henry's law to predict activity/osmotic coefficient and VLE. The chloride model also predicts KCl and NaCl solubility, while the nitric acid model has the unique capability of predicting extent of dissociation with an average absolute deviation of 1.43%. The association-based approach presented here extends the utility of the molality-based Pitzer model past 6 molal to predict activity/osmotic coefficients up to 16-20 molal. The association-based approach offers the additional benefits of predicting extent of dissociation and of allowing the Pitzer model to be fully utilized in commercial simulators, such as ASPEN Plus, that require accounting for association to implement Henry's law. The Pitzer models presented here provide the chemical process simulation engineer with a superior alternative to the Electrolyte NRTL model that can easily be used in ASPEN Plus.

  10. Thermometric titration of acids in pyridine.

    PubMed

    Vidal, R; Mukherjee, L M

    1974-04-01

    Thermometric titration of HClO(4), HI, HNO(3), HBr, picric acid o-nitrobenzoic acid, 2,4- and 2,5-dinitrophenol, acetic acid and benzoic acid have been attempted in pyridine as solvent, using 1,3-diphenylguanidine as the base. Except in the case of 2,5-dinitrophenol, acetic acid and benzoic acid, the results are, in general, reasonably satisfactory. The approximate molar heats of neutralization have been calculated.

  11. Combined effects of ozone and nitrogen on secondary compounds, amino acids, and aphid performance in Scots pine

    SciTech Connect

    Kainulainen, P.; Holopainen, J.K.; Holopainen, T.

    2000-02-01

    Combined effects of O{sub 3} and N supply on Scots pine (Pinus sylvestris L.) were studied in two separate growth chamber experiments exposing seedlings to 0, 0.075, 0.15, and 0.3 {micro}L/L of O{sub 3} during 8 h/d, 5 d/wk for a period of 5 wk. Seedlings were fertilized with low, medium, and high levels of N. Ozone and N availability affected concentrations of several primary and secondary metabolites. More changes on metabolites were detected in Exp. 1 (with seedlings ceasing their annual growth) than in Exp. 2 (with seedlings actively growing). Overall, high O{sub 3} exposure levels significantly decreased concentrations of monoterpenes and increased concentrations of resin acids. Concentrations of total phenolics were not affected by O{sub 3} exposure. Mostly lower concentrations of monoterpenes and resin acids were found at a medium N-fertilization level than at low and high N-fertilization levels, while total phenolic concentration decreased by enhanced N availability. In Exp. 1, significantly elevated concentrations of free amino acids were found at O{sub 3} concentration of 0.3 {micro}L/L. Nitrogen availability did not have remarkable effects on amino acid concentrations. In Exp. 1, both {sub 3} and N had a significant effect on the MRGR of the aphid Schizolachnus pineti. In Exp. 2, the weight of the females and nymphs and the total number of reproduced nymphs were significantly affected by O{sub 3} and N. Only a few interaction effects were found, suggesting that the N supply does not significantly modify O{sub 3}-induced effects on studied primary and secondary compounds and aphid performance in Scots pine seedlings.

  12. Experimental Study on How Human Lung Surfactant Protein SP-B1-25 is Oxidized by Ozone in the Presence of Fe(II) and Ascorbic Acid

    NASA Astrophysics Data System (ADS)

    Colussi, A. J.; Enami, S.; Hoffmann, M. R.

    2014-12-01

    We will report the results of experiments on the chemical fate of the human lung surfactant protein SP-B1-25 upon exposure to gaseous ozone in realistic aqueous media simulating the conditions prevalent in epithelial lining fluids in polluted ambient air. Our experiments consist of exposing aqueous microjets containing SP-B1-25, the natural antioxidant ascorbic acid, and the Fe2+ carried by most atmospheric fine particulates, under mild acidic conditions, such as those created by the innate lung host defense response. Reactants and the products of such interactions are detected via online electrospray ionization mass spectrometry. We will show that ascorbic acid largely inhibits the ozonation of SP-B1-25 in the absence of Fe2+, leading to the formation of an ascorbic acid ozonide (Enami et al., PNAS 2008). In the presence of Fe2+, however, the ozonide decomposes into reactive intermediates that result in the partial oxidation of SP-B1-25, presumable affecting its function as surfactant. We infer that these experimental results establish a plausible causal link for the observed synergic adverse health effects of ambient ozone and fine particulates

  13. A global simulation of tropospheric ozone and related tracers: Description and evaluation of MOZART, version 2

    NASA Astrophysics Data System (ADS)

    Horowitz, Larry W.; Walters, Stacy; Mauzerall, Denise L.; Emmons, Louisa K.; Rasch, Philip J.; Granier, Claire; Tie, Xuexi; Lamarque, Jean-FrançOis; Schultz, Martin G.; Tyndall, Geoffrey S.; Orlando, John J.; Brasseur, Guy P.

    2003-12-01

    We have developed a global three-dimensional chemical transport model called Model of Ozone and Related Chemical Tracers (MOZART), version 2. This model, which will be made available to the community, is built on the framework of the National Center for Atmospheric Research (NCAR) Model of Atmospheric Transport and Chemistry (MATCH) and can easily be driven with various meteorological inputs and model resolutions. In this work, we describe the standard configuration of the model, in which the model is driven by meteorological inputs every 3 hours from the middle atmosphere version of the NCAR Community Climate Model (MACCM3) and uses a 20-min time step and a horizontal resolution of 2.8° latitude × 2.8° longitude with 34 vertical levels extending up to approximately 40 km. The model includes a detailed chemistry scheme for tropospheric ozone, nitrogen oxides, and hydrocarbon chemistry, with 63 chemical species. Tracer advection is performed using a flux-form semi-Lagrangian scheme with a pressure fixer. Subgrid-scale convective and boundary layer parameterizations are included in the model. Surface emissions include sources from fossil fuel combustion, biofuel and biomass burning, biogenic and soil emissions, and oceanic emissions. Parameterizations of dry and wet deposition are included. Stratospheric concentrations of several long-lived species (including ozone) are constrained by relaxation toward climatological values. The distribution of tropospheric ozone is well simulated in the model, including seasonality and horizontal and vertical gradients. However, the model tends to overestimate ozone near the tropopause at high northern latitudes. Concentrations of nitrogen oxides (NOx) and nitric acid (HNO3) agree well with observed values, but peroxyacetylnitrate (PAN) is overestimated by the model in the upper troposphere at several locations. Carbon monoxide (CO) is simulated well at most locations, but the seasonal cycle is underestimated at some sites in the

  14. Growth of nitric acid hydrates on thin sulfuric acid films

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

    1994-01-01

    Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

  15. Heterogeneous interactions of chlorine nitrate, hydrogen chloride, and nitric acid with sulfuric acid surfaces at stratospheric temperatures

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Rossi, Michel J.; Golden, David M.

    1988-01-01

    The heterogeneous interactions of ClONO2, HCl, and HNO3 with sulfuric acid surfaces were studied using a Knudsen cell flow reactor. The surfaces studied, chosen to simulate global stratospheric particulate, were composed of 65-75 percent H2SO4 solutions at temperatures in the range -63 to -43 C. Heterogeneous loss, but not reaction, of HNO3 and HCl occurred on these surfaces; the measured sticking coefficients are reported. Chlorine nitrate reacted on the cold sulfuric acid surfaces, producing gas-phase HOCl and condensed HNO3. CLONO2 also reacted with HCl dissolved in the 65-percent H2SO4 solution at -63 C, forming gaseous Cl2. In all cases studied, the sticking and/or reaction coefficients were much larger for the 65-percent H2SO4 solution at -63 C than for the 75-percent solution at -43 C.

  16. Comparison between intrarticular injection of hyaluronic acid, oxygen ozone, and the combination of both in the treatment of knee osteoarthrosis.

    PubMed

    Giombini, A; Menotti, F; Di Cesare, A; Giovannangeli, F; Rizzo, M; Moffa, S; Martinelli, F

    2016-01-01

    This study aimed to compare short-term clinical outcomes between intra-articular injection of hyaluronic acid (HA), oxygen ozone (O2O3), and the combination of both, in patients affected by osteoarthrosis (OA) of the knee. Seventy patients (age 45-75 years) with knee OA were randomized to intra-articular injections of HA (n=23), or O2O3 (n=23) or combined (n=24) one per week for 5 consecutive weeks. KOOS questionnaire and visual analog scale (VAS), before treatment (pre) at the end (post), and at 2 months after treatment ended (follow-up) were used as outcome measures. Analysis showed a significant effect (P < 0.05) of the conditions (pre, post and follow-up) in all parameters of the KOOS score and a significant effect (P < 0.05) of groups (HA, O2O3 and combined) for pain, symptoms, activities of daily living and quality of life. The combined group scores were higher compared to the HA and O2O3 groups, especially at follow-up. The combination of O2O3 and HA treatment led to a significantly better outcome especially at 2-month follow-up compared to HA and O2O3 given separately to patients affected by OA of the knee.

  17. Ozone Basics

    EPA Pesticide Factsheets

    Learn the difference between good (stratospheric) and bad (tropospheric) ozone, how bad ozone affects our air quality, health, and environment, and what EPA is doing about it through regulations and standards.

  18. Polar processing and development of the 2004 Antarctic ozone hole : first results from MLS on Aura

    NASA Technical Reports Server (NTRS)

    Santee, M. L.; Manney, G. L.; Livesey, N. J.; Froidevaux, L.; MacKenzie, I. A.; Pumphrey, H. C.; Read, W. G.; Schwartz, M. J.; Waters, J. W.; Harwood, R. S.

    2005-01-01

    The Microwave Limb Sounder (MLS) on Aura is providing an extensive data set on stratospheric winter polar processing, including the first daily global observations of HCl, together with simultaneous measurements of ClO, HNO3, H2O, O3, N2O, and temperature (among others). We present first results charting the evolution of these quantities during the 2004 Antarctic late winter. MLS observations of chlorine deactivation and ozone loss during this period are shown to be consistent with results from the SLIMCAT chemical transport model.

  19. The use of atmospheric measurements to constrain model predictions of ozone change from chlorine perturbations

    NASA Technical Reports Server (NTRS)

    Douglass, Anne R.; Stolarski, Richard S.

    1987-01-01

    Atmospheric photochemistry models have been used to predict the sensitivity of the ozone layer to various perturbations. These same models also predict concentrations of chemical species in the present day atmosphere which can be compared to observations. Model results for both present day values and sensitivity to perturbation depend upon input data for reaction rates, photodissociation rates, and boundary conditions. A method of combining the results of a Monte Carlo uncertainty analysis with the existing set of present atmospheric species measurements is developed. The method is used to examine the range of values for the sensitivity of ozone to chlorine perturbations that is possible within the currently accepted ranges for input data. It is found that model runs which predict ozone column losses much greater than 10 percent as a result of present fluorocarbon fluxes produce concentrations and column amounts in the present atmosphere which are inconsistent with the measurements for ClO, HCl, NO, NO2, and HNO3.

  20. Ozone oxidation of oleic acid surface films decreases aerosol cloud condensation nuclei activity

    NASA Astrophysics Data System (ADS)

    Schwier, A. N.; Sareen, N.; Lathem, T. L.; Nenes, A.; McNeill, V. F.

    2011-08-01

    Heterogeneous oxidation of aerosols composed of pure oleic acid (C18H34O2, an unsaturated fatty acid commonly found in continental and marine aerosol) by gas-phase O3 is known to increase aerosol hygroscopicity and activity as cloud condensation nuclei (CCN). Whether this trend is preserved when the oleic acid is internally mixed with other electrolytes is unknown and addressed in this study. We quantify the CCN activity of sodium salt aerosols (NaCl and Na2SO4) internally mixed with sodium oleate (SO) and oleic acid (OA). We find that particles containing roughly one monolayer of SO/OA show similar CCN activity to pure salt particles, whereas a tenfold increase in organic concentration slightly depresses CCN activity. O3 oxidation of these multicomponent aerosols has little effect on the critical diameter for CCN activation for unacidified particles at all conditions studied, and the activation kinetics of the CCN are similar in each case to those of pure salts. SO-containing particles which are acidified to atmospherically relevant pH before analysis in order to form oleic acid, however, show depressed CCN activity upon oxidation. This effect is more pronounced at higher organic concentrations. The behavior after oxidation is consistent with the disappearance of the organic surface film, supported by Köhler Theory Analysis (KTA). The κ-Köhler calculations show a small decrease in hygroscopicity after oxidation. The important implication of this finding is that oxidative aging may not always enhance the hygroscopicity of internally mixed inorganic-organic aerosols.

  1. Kinetics of membrane damage to high (HNA) and low (LNA) nucleic acid bacterial clusters in drinking water by ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate.

    PubMed

    Ramseier, Maaike K; von Gunten, Urs; Freihofer, Pietro; Hammes, Frederik

    2011-01-01

    Drinking water was treated with ozone, chlorine, chlorine dioxide, monochloramine, ferrate(VI), and permanganate to investigate the kinetics of membrane damage of native drinking water bacterial cells. Membrane damage was measured by flow cytometry using a combination of SYBR Green I and propidium iodide (SGI+PI) staining as indicator for cells with permeabilized membranes and SGI alone to measure total cell concentration. SGI+PI staining revealed that the cells were permeabilized upon relatively low oxidant exposures of all tested oxidants without a detectable lag phase. However, only ozonation resulted in a decrease of the total cell concentrations for the investigated reaction times. Rate constants for the membrane damage reaction varied over seven orders of magnitude in the following order: ozone > chlorine > chlorine dioxide ≈ ferrate > permanganate > chloramine. The rate constants were compared to literature data and were in general smaller than previously measured rate constants. This confirmed that membrane integrity is a conservative and therefore safe parameter for disinfection control. Interestingly, the cell membranes of high nucleic acid (HNA) content bacteria were damaged much faster than those of low nucleic acid (LNA) content bacteria during treatment with chlorine dioxide and permanganate. However, only small differences were observed during treatment with chlorine and chloramine, and no difference was observed for ferrate treatment. Based on the different reactivity of these oxidants it was suggested that HNA and LNA bacterial cell membranes have a different chemical constitution.

  2. Reuse of sewage sludge as a catalyst in ozonation--efficiency for the removal of oxalic acid and the control of bromate formation.

    PubMed

    Wen, Gang; Pan, Zhi-Hui; Ma, Jun; Liu, Zheng-Qian; Zhao, Lei; Li, Jun-Jing

    2012-11-15

    Sewage derived sludge is produced with an annual amount increase of 2% all over the world and it is an urgent issue to be addressed by human being. In the present study, sludge was converted into sludge-based catalyst (SBC) with ZnCl2 as activation agent and characterized by several methods (e.g., scanning electron microscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope). Then it was used as a catalyst to enhance the removal of refractory organic matter, oxalic acid, and to control the formation of bromate (BrO3-) in bench semi-continuous ozonation experiments. The effects of various operating parameters on the control of BrO3- formation were investigated. Furthermore, the mechanism for the enhancement of organic matter removal and the control of BrO3- formation was discussed as well. Results indicate that the combination of SBC with ozone shows a strong synergistic effect, resulting in a notable improvement on oxalic acid removal. A crucial surface reaction mechanism for the enhancement of organic matter removal is proposed on the basis of negative effect of higher pH and no inhibition effect of tert-butanol. The control for BrO3- formation was demonstrated and the reason for its control in the process of O3/SBC is the combined effect of SBC reductive properties, ozone exposure decrease and hydrogen peroxide concentration increase.

  3. Uptake of formaldehyde by sulfuric acid solutions - Impact on stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Pfaff, Jeanne; Jayaweera, Indira; Prather, Michael J.

    1993-01-01

    The study investigates the uptake of CH2O by low temperature sulfuric acid solutions representative of global stratospheric particulate. It is argued that if similar uptake occurs under stratospheric pressures of CH2O, i.e., 1000 times lower than used in the present study, then the removal of CH2O from the gas phase can take away a significant source of odd hydrogen in the mid- and high-latitude lower stratosphere. It is shown that with the inclusion of this reaction, concentrations of OH and H2O are reduced by as much as 4 percent under background levels of aerosols and more than 15 percent under elevated (volcanic) conditions. The accumulation of CH2O in stratospheric aerosols over a season, reaching about 1 M solutions, will alter the composition and may even change the reactivity of these sulfuric acid-water mixtures.

  4. Dimers in α-pinene secondary organic aerosol: effect of hydroxyl radical, ozone, relative humidity and aerosol acidity

    NASA Astrophysics Data System (ADS)

    Kristensen, K.; Cui, T.; Zhang, H.; Gold, A.; Glasius, M.; Surratt, J. D.

    2014-04-01

    The formation of secondary organic aerosol (SOA) from both ozonolysis and hydroxyl radical (OH)-initiated oxidation of α-pinene under conditions of high nitric oxide (NO) concentrations with varying relative humidity (RH) and aerosol acidity was investigated in the University of North Carolina dual outdoor smog chamber facility. SOA formation from ozonolysis of α-pinene was enhanced relative to that from OH-initiated oxidation in the presence of initially high-NO conditions. However, no effect of RH on SOA mass was evident. Ozone (O3)-initiated oxidation of α-pinene in the presence of ammonium sulfate (AS) seed coated with organic aerosol from OH-initiated oxidation of α-pinene showed reduced nucleation compared to ozonolysis in the presence of pure AS seed aerosol. The chemical composition of α-pinene SOA was investigated by ultra-performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-Q-TOFMS), with a focus on the formation of carboxylic acids and high-molecular weight dimers. A total of eight carboxylic acids and four dimers were identified, constituting between 8 and 12% of the total α-pinene SOA mass. OH-initiated oxidation of α-pinene in the presence of nitrogen oxides (NOx) resulted in the formation of highly oxidized carboxylic acids, such as 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA) and diaterpenylic acid acetate (DTAA). The formation of dimers was observed only in SOA produced from the ozonolysis of α-pinene in the absence of NOx, with increased concentrations by a factor of two at higher RH (50-90%) relative to lower RH (30-50%). The increased formation of dimers correlates with an observed increase in new particle formation at higher RH due to nucleation. Increased aerosol acidity was found to have a negligible effect on the formation of the dimers. SOA mass yield did not influence the chemical composition of SOA formed from α-pinene ozonolysis with respect to

  5. The effect of acids on fluorescence of coumarin-6 in organic solvents

    NASA Astrophysics Data System (ADS)

    Mina, M. V.; Puzyk, I. P.; Puzyk, M. V.

    2013-02-01

    The effect of acids (HCl, HClO4, HNO3, and CH3COOH) on the fluorescence of coumarin-6 in organic solvents (acetonitrile, acetone, butanol-1, and ethanol) is studied. The regions of acid (HCl, HClO4, HNO3) concentrations that lead to a change in the fluorescence spectra are determined for each of the solvents. It is shown that, for all the solvents studied, acetic acid with a concentration within the region 10-1-10-6 M causes no significant changes in the fluorescence spectrum of coumarin-6. A mechanism of the coumarin-6 protonation is proposed.

  6. Effects of ozone and acidic deposition on carbon allocation and mycorrhizal colonization of Pinus taeda L. seedlings

    SciTech Connect

    Adams, M.B.; O'Neal, E.G.

    1991-03-01

    Patterns of carbon allocation and mycorrhizal colonization were examined in loblolly pine seedlings from two half-sib families exposed to three ozone treatments (charcoal-filtered air, ambient air + 80 ppb O{sub 3}, and ambient air + 160 ppb O{sub 3}) and three rain pH levels (5.2, 4.5, and 3.3) for 12 weeks in open-topped chambers in a field setting. No statistically significant effects of ozone or rain pH were detected on biomass, root:shoot ratios, or carbon allocation; some consistent patterns were observed, however. Coarse root starch concentrations and mycorrhizal infection varied significantly with ozone levels. No significant interactions of ozone, rain pH, or genotype were detected.

  7. Improvement in electrochemical capacitance of activated carbon from scrap tires by nitric acid treatment

    NASA Astrophysics Data System (ADS)

    Han, Yan; Zhao, Ping-Ping; Dong, Xiao-Ting; Zhang, Cui; Liu, Shuang-Xi

    2014-12-01

    Activated carbon (AC) obtained from the industrial pyrolytic tire char is treated by concentrated nitric acid (AC-HNO3) and then used as the electrode material for supercapacitors. Surface properties and electrochemical capacitances of AC and ACHNO3 are studied. It is found that the morphology and the porous texture for AC and AC-HNO3 have little difference, while the oxygen content increases and functional groups change after the acid treatment. Electrochemical results demonstrate that the AC-HNO3 electrode displays higher specific capacitance, better stability and cycling performance, and lower equivalent series resistance, indicating that AC obtained from the industrial pyrolytic tire char treated by concentrated nitric acid is applicable for supercapacitors.

  8. The influence of ultraviolet-B radiation on growth, hydroxycinnamic acids and flavonoids of Deschampsia antarctica during Springtime ozone depletion in Antarctica.

    PubMed

    Ruhland, Christopher T; Xiong, Fusheng S; Clark, W Dennis; Day, Thomas A

    2005-01-01

    We examined the influence of solar ultraviolet-B radiation (UV-B; 280-320 nm) on the growth, biomass production and phenylpropanoid concentrations of Deschampsia antarctica during the springtime ozone depletion season at Palmer Station, along the Antarctic Peninsula. Treatments involved placing filters on frames over potted plants that reduced levels of biologically effective UV-B either by 83% (reduced UV-B) or by 12% (near-ambient UV-B) over the 63 day experiment (7 November 1998-8 January 1999) when ozone depletion averaged 17%. Plants growing under near-ambient UV-B had 41% and 40% lower relative growth rates and net assimilation rates, respectively, than those under reduced UV-B. The former plants produced 50% less total biomass as a result of having 47% less aboveground biomass. The reduction in aboveground biomass was a result of a 29% lower leaf elongation rate resulting in shorter leaves and 59% less total leaf area in plants grown under reduced UV-B. p-Coumaric, caffeic and ferulic acids were the major hydroxycinnamic acids, and luteolin derivatives were the major flavonoids in both insoluble and soluble leaf extracts. Concentrations of insoluble p-coumaric and caffeic acid and soluble ferulic acids were 38%, 48% and 60% higher, respectively, under near-ambient UV-B than under reduced UV-B. There were no UV-B effects on concentrations of insoluble or soluble flavonoids.

  9. Kinetic measurements on the reactivity of hydrogen peroxide and ozone towards small atmospherically relevant aldehydes, ketones and organic acids in aqueous solution

    NASA Astrophysics Data System (ADS)

    Schöne, L.; Herrmann, H.

    2013-10-01

    Within the aqueous atmospheric environment free radical reactions are an important degradation process for organic compounds. Nevertheless, non-radical oxidants like hydrogen peroxide and ozone also contribute to the degradation and conversion of this substance group (Tilgner und Herrmann, 2010). In this work kinetic investigations of non-radical reactions were conducted using UV/Vis spectroscopy (dual-beam spectrophotometer and Stopped Flow technique) and a capillary electrophoresis system applying pseudo-first order kinetics of glyoxal, methylglyoxal, glycolaldehyde, glyoxylic, pyruvic and glycolic acids as well as methacrolein (MACR) and methyl vinyl ketone (MVK) towards H2O2 and ozone. The measurements indicate rather small rate constants at room temperature of k2nd < 3 M-1 s-1 (except for the unsaturated compounds exposed to ozone). Compared to radical reaction rate constants the values are about 10 orders of magnitude smaller (kOH· ~ 109 M-1 s-1). However, when considering the much larger non-radical oxidant concentrations compared to radical concentrations in urban cloud droplets, calculated turnovers change the picture to more important H2O2 reactions especially when compared to the nitrate radical. For some reactions also mechanistic suggestions are given.

  10. Kinetic measurements of the reactivity of hydrogen peroxide and ozone towards small atmospherically relevant aldehydes, ketones and organic acids in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Schöne, L.; Herrmann, H.

    2014-05-01

    Free radical reactions are an important degradation process for organic compounds within the aqueous atmospheric environment. Nevertheless, non-radical oxidants such as hydrogen peroxide and ozone also contribute to the degradation and conversion of these substances (Tilgner and Herrmann, 2010). In this work, kinetic investigations of non-radical reactions were conducted using UV / Vis spectroscopy (dual-beam spectrophotometer and stopped flow technique) and a capillary electrophoresis system applying pseudo-first order kinetics to reactions of glyoxal, methylglyoxal, glycolaldehyde, glyoxylic, pyruvic and glycolic acid as well as methacrolein (MACR) and methyl vinyl ketone (MVK) with H2O2 and ozone at 298 K. The measurements indicate rather small rate constants at room temperature of k2nd < 3 M-1 s-1 (except for the unsaturated compounds exposed to ozone). Compared to radical reaction rate constants the values are about 10 orders of magnitude smaller (kOH • ~109 M-1 s-1). However, when considering the much larger non-radical oxidant concentrations compared to radical concentrations in urban cloud droplets, calculated first-order conversion rate constants change the picture towards H2O2 reactions becoming more important, especially when compared to the nitrate radical. For some reactions mechanistic suggestions are also given.

  11. Nitric acid and ammonia emissions from a mid-latitude prescribed wetlands fire

    NASA Astrophysics Data System (ADS)

    LeBel, P. J.; Cofer, W. R., III; Levine, J. S.; Vay, S. A.; Roberts, P. D.

    1988-08-01

    We have obtained the first simultaneous measurements of gaseous nitric acid (HNO3) and ammonia (NH3) in the smoke plume of a wetlands biomass burn. These measurements were made using tungsten oxide-coated diffusion denuder tubes from a helicopter during a prescribed burn at the Merritt Island National Wildlife Refuge, located at the NASA John F. Kennedy Space Center, Florida, on November 9, 1987. The mean NH3 and HNO3 mixing ratios measured in the smoke plume were 19 ppbv and 14 ppbv, respectively, both significantly higher than background mixing ratios. Nitric acid correlated well with carbon dioxide (CO2) produced by the combustion. The mean CO2-normalized emission ratio for HNO3 was found to be 1.2 × 10-4. Ammonia, however, did not correlate well with CO2 suggesting a more complex relationship between combustion and production/release of NH3.

  12. Polar stratospheric clouds and ozone depletion

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Turco, Richard P.

    1991-01-01

    A review is presented of investigations into the correlation between the depletion of ozone and the formation of polar stratospheric clouds (PSCs). Satellite measurements from Nimbus 7 showed that over the years the depletion from austral spring to austral spring has generally worsened. Approximately 70 percent of the ozone above Antarctica, which equals about 3 percent of the earth's ozone, is lost during September and October. Various hypotheses for ozone depletion are discussed including the theory suggesting that chlorine compounds might be responsible for the ozone hole, whereby chlorine enters the atmosphere as a component of chlorofluorocarbons produced by humans. The three types of PSCs, nitric acid trihydrate, slowly cooling water-ice, and rapidly cooling water-ice clouds act as important components of the Antarctic ozone depletion. It is indicated that destruction of the ozone will be more severe each year for the next few decades, leading to a doubling in area of the Antarctic ozone hole.

  13. Effects of hydrocarbon contamination on ozone generation with dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Lopez, Jose L.; Vezzu, Guido; Freilich, Alfred; Paolini, Bernhard

    2013-08-01

    The increasing usage of the feed gases of lower grade liquid oxygen (LOX) containing higher levels of trace hydrocarbon impurities in dielectric barrier discharge (DBD) for ozone generation requires a better understanding of the kinetics of the by-product formation resulting from reactions involving these hydrocarbon impurities. As a case study of hydrocarbon impurities, the kinetics of CH4 conversion in DBDs and the subsequent HNO3 formation were investigated by means of gas-phase plasma diagnostics, supported by detailed process modeling, and extensive in-situ and ex-situ by-product analysis. The by-products formation in the plasma with the presence of CH4, were found to differ significantly in oxygen-fed generators as compared to generators fed with oxygen/nitrogen mixtures. The amount of HNO3 formed depends on the concentration of NOx formed in the plasma and the amount of CH4 that is converted, but not on the O3 concentration. In the present work we have investigated CH4 concentrations of up to 1.95 wt% of the feed gas. The rate of deterioration of the overall ozone generator performance was found to be affected by the concentration of nitrogen in the oxygen/nitrogen mixture.

  14. IR absorption spectra of cellulose obtained from ozonated wood

    NASA Astrophysics Data System (ADS)

    Mamleeva, N. A.; Autlov, S. A.; Kharlanov, A. N.; Bazarnova, N. G.; Lunin, V. V.

    2015-08-01

    The kinetic curves of ozone absorption by aspen wood were obtained. Processing of wood with peracetic acid gave cellulose samples. The yields of ozonated wood, water-soluble compounds, and cellulose were determined for the samples corresponding to different consumptions of ozone. The IR absorption spectra of wood and cellulose isolated from ozonated wood were analyzed. The supramolecular structure of cellulose can be changed by varying the conditions of wood ozonation.

  15. Calibration and evaluation of nitric acid and ammonia permeation tubes by UV optical absorption.

    PubMed

    Neuman, J Andrew; Ryerson, Thomas B; Huey, L Gregory; Jakoubek, Roger; Nowak, John B; Simons, Craig; Fehsenfeld, Frederick C

    2003-07-01

    An ultraviolet (UV) optical absorption system has been developed for absolute calibrations of nitric acid (HNO3) and ammonia (NH3) permeation tube emission rates. Using this technique, dilute mixtures containing NH3 or HNO3, both of which interact strongly with many surfaces, are accurately measured at levels below a part per million by volume. This compact and portable instrument operates continuously and autonomously to rapidly (<1 h) quantify the emission of trace gases from permeation devices that are commonly used to calibrate air-monitoring instruments. The output from several HNO3 and NH3 permeation tubes, with emission rates that ranged between 13 and 150 ng/min, was examined as a function of temperature, pressure, and carrier gas flow. Absorptions of 0.015% can be detected which allows a precision (3sigma) of +/-1 ng/min for the HNO3 and NH3 permeation tubes studied here. The accuracy of the measurements, which relies on published UV absorption cross sections, is estimated to be +/-10%. Measurements of permeation tube emission rates using ion chromatography analysis are made to further assess measurement accuracy. The output from the HNO3 and NH3 permeation tubes examined here was stable over the study period, which ranged between 3 months and 1 year for each permeation tube.

  16. A comparative study of alumina-supported Ni catalysts prepared by photodeposition and impregnation methods on the catalytic ozonation of 2,4-dichlorophenoxyacetic acid

    NASA Astrophysics Data System (ADS)

    Rodríguez, Julia L.; Valenzuela, Miguel A.; Tiznado, Hugo; Poznyak, Tatiana; Chairez, Isaac; Magallanes, Diana

    2017-02-01

    The heterogeneous catalytic ozonation on unsupported and supported oxides has been successfully tested for the removal of several refractory compounds in aqueous solution. In this work, alumina-supported nickel catalysts prepared by photodeposition and impregnation methods were compared in the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D). The catalysts were characterized by high-resolution electron microscopy and X-ray photoelectron spectroscopy. The photochemical decomposition of Ni acetylacetonate to produce Ni(OH)2, NiO, and traces of Ni° deposited on alumina was achieved in the presence of benzophenone as a sensitizer. A similar surface composition was found with the impregnated catalyst after its reduction with hydrogen at 500 °C and exposed to ambient air. Results indicated a higher initial activity and maleic acid (byproduct) concentration with the photodeposited catalyst (1 wt% Ni) compared to the impregnated catalyst (3 wt% Ni). These findings suggest the use of the photodeposition method as a simple and reliable procedure for the preparation of supported metal oxide/metal catalysts under mild operating conditions.

  17. Growth response of four species of Eastern hardwood tree seedlings exposed to ozone, acidic precipitation, and sulfur dioxide. [Prunus serotina, Acer rubrum, Quercus rubra, Liriodendron tulipifera

    SciTech Connect

    Davis, D.D. Skelly, J.M. )

    1992-03-01

    In 1987 a study was conducted in controlled environment chambers to determine the foliar sensitivity of tree seedlings of eight species to ozone and acidic precipitation, and to determine the influence of leaf position on symptom severity. Jensen and Dochinger conducted concurrent similar studies in Continuously Stirred Tank Reactor (CSTR) chambers with ten species of forest trees. Based on the results of these initial studies, four species representing a range in foliar sensitivity to ozone were chosen: black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.), northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.). These species were also chosen because of their ecological and/or commercial importance in Pennsylvania. Seedlings were exposed in growth chambers simulated acid rain. In addition acute exposures to sulfur dioxide were conducted in a regime based on unpublished monitoring data collected near coal-fired power plants. The objective of this study was to determine if the pollutant treatments influenced the growth and productivity of seedlings of these four species. This information will help researchers and foresters understand the role of air pollution in productivity of eastern forests.

  18. Effects of ozone, ultraviolet and peracetic acid disinfection of a primary-treated municipal effluent on the immune system of rainbow trout (Oncorhynchus mykiss).

    PubMed

    Hébert, N; Gagné, F; Cejka, P; Bouchard, B; Hausler, R; Cyr, D G; Blaise, C; Fournier, M

    2008-08-01

    Municipal sewage effluents are complex mixtures that are known to compromise the health condition of aquatic organisms. The aim of this study was to evaluate the impacts of various wastewater disinfection processes on the immune system of juvenile rainbow trout (Oncorhynchus mykiss). The trout were exposed to a primary-treated effluent for 28 days before and after one of each of the following treatments: ultraviolet (UV) radiation, ozonation and peracetic acid. Immune function was characterized in leucocytes from the anterior head kidney by the following three parameters: phagocytosis activity, natural cytotoxic cells (NCC) function and lymphocyte (B and T) proliferation assays. The results show that the fish mass to length ratio was significantly decreased for the primary-treated and all three disinfection processes. Exposure to the primary-treated effluent led to a significant increase in macrophage-related phagocytosis; the addition of a disinfection step was effective in removing this effect. Both unstimulated and mitogen-stimulated T lymphocyte proliferation in fish decreased dramatically in fish exposed to the ozonated effluent compared to fish exposed to either the primary-treated effluent or to aquarium water. Stimulation of T lymphocytes proliferation was observed with the peracetic acid treatment group. In conclusion, the disinfection strategy used can modify the immune system in fish at the level of T lymphocyte proliferation but was effective to remove the effects on phagocytosis activity.

  19. Ozone Layer Protection

    MedlinePlus

    ... EPA United States Environmental Protection Agency Search Search Ozone Layer Protection Share Facebook Twitter Google+ Pinterest Contact Us Ozone Layer Protection Welcome to EPA's ozone layer protection web ...

  20. Ozone decomposition.

    PubMed

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho; Zaikov, Gennadi E

    2014-06-01

    Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates.

  1. Ozone decomposition

    PubMed Central

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho

    2014-01-01

    Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates. PMID:26109880

  2. Polar ozone

    NASA Technical Reports Server (NTRS)

    Solomon, S.; Grose, W. L.; Jones, R. L.; Mccormick, M. P.; Molina, Mario J.; Oneill, A.; Poole, L. R.; Shine, K. P.; Plumb, R. A.; Pope, V.

    1990-01-01

    The observation and interpretation of a large, unexpected ozone depletion over Antarctica has changed the international scientific view of stratospheric chemistry. The observations which show the veracity, seasonal nature, and vertical structure of the Antarctic ozone hole are presented. Evidence for Arctic and midlatitude ozone loss is also discussed. The chemical theory for Antarctic ozone depletion centers around the occurrence of polar stratospheric clouds (PSCs) in Antarctic winter and spring; the climatology and radiative properties of these clouds are presented. Lab studies of the physical properties of PSCs and the chemical processes that subsequently influence ozone depletion are discussed. Observations and interpretation of the chemical composition of the Antarctic stratosphere are described. It is shown that the observed, greatly enhanced abundances of chlorine monoxide in the lower stratosphere are sufficient to explain much if not all of the ozone decrease. The dynamic meteorology of both polar regions is given, interannual and interhemispheric variations in dynamical processes are outlined, and their likely roles in ozone loss are discussed.

  3. Combination of ozonation and photocatalysis for purification of aqueous effluents containing formic acid as probe pollutant and bromide ion.

    PubMed

    Parrino, F; Camera-Roda, G; Loddo, V; Palmisano, G; Augugliaro, V

    2014-03-01

    The treatment by advanced oxidation processes (AOPs) of waters contaminated by organic pollutants and containing also innocuous bromide ions may generate bromate ions as a co-product. In the present work heterogeneous photocatalysis and ozonation have individually been applied and in combination (integrated process) to degrade the organic compounds in water containing also bromide anions. The results show that: i) the sole photocatalysis does not produce bromate ions and in the case of its presence, it is able to reduce bromate to innocuous bromide ions; ii) the integration of photocatalysis and ozonation synergistically enhances the oxidation capabilities; and iii) in the integrated process bromate ions are not produced as long as some oxidizable organics are present.

  4. Evidence that nitric acid increases relative humidity in low-temperature cirrus clouds.

    PubMed

    Gao, R S; Popp, P J; Fahey, D W; Marcy, T P; Herman, R L; Weinstock, E M; Baumgardner, D G; Garrett, T J; Rosenlof, K H; Thompson, T L; Bui, P T; Ridley, B A; Wofsy, S C; Toon, O B; Tolbert, M A; Kärcher, B; Peter, Th; Hudson, P K; Weinheimer, A J; Heymsfield, A J

    2004-01-23

    In situ measurements of the relative humidity with respect to ice (RHi) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RHi values show a sharp increase to average values of over 130% in both cloud types. These enhanced RHi values are attributed to the presence of a new class of HNO3-containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor.

  5. Ozone Pollution

    EPA Pesticide Factsheets

    Known as tropospheric or ground-level ozone, this gas is harmful to human heath and the environment. Since it forms from emissions of volatile organic compounds (VOCs) and nitrogen oxides (NOx), these pollutants are regulated under air quality standards.

  6. Toward a more physical representation of precipitation scavenging in global chemistry models: cloud overlap and ice physics and their impact on tropospheric ozone

    NASA Astrophysics Data System (ADS)

    Neu, J. L.; Prather, M. J.

    2012-04-01

    Uptake and removal of soluble trace gases and aerosols by precipitation represents a major uncertainty in the processes that control the vertical distribution of atmospheric trace species. Model representations of precipitation scavenging vary greatly in their complexity, and most are divorced from the physics of precipitation formation and transformation. Here, we describe a new large-scale precipitation scavenging algorithm, developed for the UCI chemistry-transport model (UCI-CTM), that represents a step toward a more physical treatment of scavenging through improvements in the formulation of the removal in sub-gridscale cloudy and ambient environments and their overlap within the column as well as ice phase uptake of soluble species. The UCI algorithm doubles the lifetime of HNO3 in the upper troposphere relative to a scheme with commonly used fractional cloud cover assumptions and ice uptake determined by Henry's Law and provides better agreement with HNO3 observations. We find that the process of ice phase scavenging of HNO3 is a critical component of the tropospheric O3 budget, but that NOx and O3 mixing ratios are relatively insensitive to large differences in the removal rate. Ozone abundances are much more sensitive to the lifetime of HNO4, highlighting the need for better understanding of its interactions with ice and for additional observational constraints.

  7. Ozone, Tropospheric

    NASA Technical Reports Server (NTRS)

    Fishman, Jack

    1995-01-01

    In the early part of the 20th century, ground-based and balloon-borne measurements discovered that most of atmosphere's ozone is located in the stratosphere with highest concentrations located between 15 and 30 km (9,3 and 18.6 miles). For a long time, it was believed that tropospheric ozone originated from the stratosphere and that most of it was destroyed by contact with the earth's surface. Ozone, O3, was known to be produced by the photo-dissociation of molecular oxygen, O2, a process that can only occur at wavelengths shorter than 242 nm. Because such short-wave-length radiation is present only in the stratosphere, no tropospheric ozone production is possible by this mechanism. In the 1940s, however, it became obvious that production of ozone was also taking place in the troposphere. The overall reaction mechanism was eventually identified by Arie Haagen-Smit of the California Institute of Technology, in highly polluted southern California. The copious emissions from the numerous cars driven there as a result of the mass migration to Los Angeles after World War 2 created the new unpleasant phenomenon of photochemical smog, the primary component of which is ozone. These high levels of ozone were injuring vegetable crops, causing women's nylons to run, and generating increasing respiratory and eye-irritation problems for the populace. Our knowledge of tropospheric ozone increased dramatically in the early 1950s as monitoring stations and search centers were established throughout southern California to see what could be done to combat this threat to human health and the environment.

  8. Influence of hydrofluoric acid on extraction of thorium using a commercially available extraction chromatographic resin.

    PubMed

    Shimada-Fujiwara, Asako; Hoshi, Akiko; Kameo, Yutaka; Nakashima, Mikio

    2009-05-01

    The dependence of Th recovery on hydrofluoric acid (HF) concentration in nitric acid (HNO(3)) solutions (1-5 mol/dm(3)) containing 1x10(-6) mol/dm(3) of Th and various concentrations of HF and the elution behavior were studied using a commercially available UTEVA (for uranium and tetravalent actinide) resin column. Thorium recovery decreased with an increase in HF concentration in the sample solutions. The concentration of HF at which Th recovery started to decrease was approximately 1x10(-4) mol/dm(3) in 1 mol/dm(3) HNO(3) solution, approximately 1x10(-3) mol/dm(3) in 3 mol/dm(3) HNO(3) solution, and approximately 1x10(-2) mol/dm(3) in 5 mol/dm(3) HNO(3) solution. When Al(NO(3))(3) (0.2 mol/dm(3)) or Fe(NO(3))(3) (0.6 mol/dm(3)) was added as a masking agent for F(-) to the Th solution containing 1x10(-1) mol/dm(3) HF and 1 mol/dm(3) HNO(3), Th recovery improved from 1.4+/-0.3% to 95+/-5% or 93+/-3%. Effective extraction of Th using UTEVA resin was achieved by selecting the concentration of HNO(3) and/or adding masking agents such as Al(NO(3))(3) according to the concentration of HF in the sample solution.

  9. Extraction of rare earth oxides using supercritical carbon dioxide modified with Tri-n-butyl phosphate–nitric acid adducts

    DOE PAGES

    Baek, Donna L.; Fox, Robert V.; Case, Mary E.; ...

    2016-06-14

    A new tri-n-butylphosphate–nitric acid (TBP–HNO3) adduct was prepared by combining TBP and fuming (90%) HNO3. The adduct was characterized, and its phase-equilibrium behavior in supercritical carbon dioxide is reported. Supercritical carbon dioxide (sc-CO2) was modified with this new adduct [TBP(HNO3)5.2(H2O)1.7], and the extraction efficacies of selected rare earth oxides (Y, Ce, Eu, Tb, and Dy) at 338 K and 34.5 MPa were compared with those obtained using an adduct formed from concentrated (70%) HNO3 and TBP [TBP(HNO3)1.7(H2O)0.6]. All rare earth oxides tested with both adduct species could be extracted with the exception of cerium oxide. Furthermore, the water and acidmore » concentrations in the different adducts were found to play a significant role in rare earth oxide extraction efficiency.« less

  10. Characteristics and error estimation of stratospheric ozone and ozone-related species over Poker Flat (65° N, 147° W), Alaska observed by a ground-based FTIR spectrometer from 2001 to 2003

    NASA Astrophysics Data System (ADS)

    Kagawa, A.; Kasai, Y.; Jones, N. B.; Yamamori, M.; Seki, K.; Murcray, F.; Murayama, Y.; Mizutani, K.; Itabe, T.

    2007-07-01

    It is important to obtain the year-to-year trend of stratospheric minor species in the context of global changes. An important example is the trend in global ozone depletion. The purpose of this paper is to report the accuracy and precision of measurements of stratospheric chemical species that are made at our Poker Flat site in Alaska (65° N, 147° W). Since 1999, minor atmospheric molecules have been observed using a Fourier-Transform solar-absorption infrared Spectrometer (FTS) at Poker Flat. Vertical profiles of the abundances of ozone, HNO3, HCl, and HF for the period from 2001 to 2003 were retrieved from FTS spectra using Rodgers' formulation of the Optimal Estimation Method (OEM). The accuracy and precision of the retrievals were estimated by formal error analysis. Errors for the total column were estimated to be 5.3%, 3.4%, 5.9%, and 5.3% for ozone, HNO3, HCl, and HF, respectively. The ozone vertical profiles were in good agreement with profiles derived from collocated ozonesonde measurements that were smoothed with averaging kernel functions that had been obtained with the retrieval procedure used in the analysis of spectra from the ground-based FTS (gb-FTS). The O3, HCl, and HF columns that were retrieved from the FTS measurements were consistent with Earth Probe/Total Ozone Mapping Spectrometer (TOMS) and HALogen Occultation Experiment (HALOE) data over Alaska within the error limits of all the respective datasets. This is the first report from the Poker Flat FTS observation site on a number of stratospheric gas profiles including a comprehensive error analysis.

  11. CANOZE measurements of the Arctic ozone hole

    NASA Technical Reports Server (NTRS)

    Evans, W. F. J.; Kerr, J. B.; Fast, H.

    1988-01-01

    In CANOZE 1 (Canadian Ozone Experiment), a series of 20 ozone profile measurements were made in April, 1986 from Alert at 82.5 N. CANOZE is the Canadian program for study of the Arctic winter ozone layer. In CANOZE 2, ozone profile measurements were made at Saskatoon, Edmonton, Churchill and Resolute during February and March, 1987 with ECC ozonesondes. Ground based measurements of column ozone, nitrogen dioxide and hydrochloric acid were conducted at Saskatoon. Two STRATOPROBE balloon flights were conducted on February 26 and March 19, 1987. Two aerosol flights were conducted by the University of Wyoming. The overall results of this study will be reported and compared with the NOZE findings. The results from CANOZE 3 in 1988, are also discussed. In 1988, as part of CANOZE 3, STRATOPROBE balloon flights were conducted from Saskatchewan on January 27 and February 13. A new lightweight infrared instrument was developed and test flown. A science flight was successfully conducted from Alert (82.5 N) on March 9, 1988 when the vortex was close to Alert; a good measurement of the profile of nitric acid was obtained. Overall, the Arctic spring ozone layer exhibits many of the features of the Antarctic ozone phenomenon, although there is obviously not a hole present every year. The Arctic ozone field in March, 1986 demonstrated many similarities to the Antarctic ozone hole. The TOMS imagery showed a crater structure in the ozone field similar to the Antarctic crater in October. Depleted layers of ozone were found in the profiles around 15 km, very similar to those reported from McMurdo. Enhanced levels of nitric acid were measured in air which had earlier been in the vortex. The TOMS imagery for March 1987 did not show an ozone crater, but will be examined for an ozone crater in February and March, 1988, the target date for the CANOZE 3 project.

  12. Impact of biomass burning emissions on the composition of the South Atlantic troposphere: Reactive nitrogen and ozone

    NASA Astrophysics Data System (ADS)

    Singh, H. B.; Herlth, D.; Kolyer, R.; Chatfield, R.; Viezee, W.; Salas, L. J.; Chen, Y.; Bradshaw, J. D.; Sandholm, S. T.; Talbot, R.; Gregory, G. L.; Anderson, B.; Sachse, G. W.; Browell, E.; Bachmeier, A. S.; Blake, D. R.; Heikes, B.; Jacob, D.; Fuelberg, H. E.

    1996-10-01

    In September/October 1992 an instrumented DC-8 aircraft was employed to study the composition and chemistry of the atmosphere over the southern tropical Atlantic Ocean. Analysis of measurements, which included tracers of biomass combustion and industrial emissions, showed that this atmosphere was highly influenced by biomass burning emissions from the South American and African continents. Marine boundary layer was generally capped off by a subsidence inversion and its composition to a large degree was determined by slow entrainment from aloft. Insoluble species (such as PAN, NO, hydrocarbons, CO) were enhanced throughout the troposphere. Soluble species (such as HNO3, HCOOH, H2O2) were minimally elevated in the upper troposphere in part due to scavenging during cloud (wet) convection. Ozone mixing ratios throughout the South Atlantic basin were enhanced by ≈20 ppb. These enhancements were larger in the eastern South Atlantic (African emissions) compared to the western South Atlantic (South American emissions). In much of the troposphere, total reactive nitrogen (NOy) correlated well with tracers of biomass combustion (e.g., CH3Cl, CO). Although NOx (NO + NO2) correlated reasonably with these tracers in the lower (0-3 km) and middle troposphere (3-7 km), these relationships deteriorated in the upper troposphere (7-12 km). Stratospheric intrusions were found to be a minor source of upper tropospheric NOx or HNO3. Sizable nonsurface sources of NOx (e.g., lightning) as well as secondary formation from the NOy reservoir species (such as HNO3, PAN, and organic nitrates) must be invoked to explain the NOx abundance present in the upper troposphere. It is found that HNO3, PAN, and NOx were able to account for most of the NOy, in the middle troposphere (3-7 km); but a significant shortfall was present in the upper troposphere (7-12). This shortfall was also most pronounced in air masses with low HNO3. The reasons for the upper tropospheric reactive nitrogen shortfall is

  13. Ir spectra of preparations of ozonized pyrocatechin

    NASA Astrophysics Data System (ADS)

    Khovratovich, N. N.; Novikova, T. M.; Khmel'Nitskii, A. I.; Cherenkevich, S. N.; Loban, V. A.

    1998-03-01

    We investigate IR spectra of the solid phase of products obtained at different stages in the process of ozonizing aqueous solutions of pyrocatechin. We found that melanin structures are formed in the process of pyrocatechin ozonization. The existence of intra- and intermolecular interactions in the melanin preparations formed, leading to the formation of molecular associates, is shown. Thorough treatment of preparations with ozone leads to destruction of polymer systems and formation of water-soluble products of acid type.

  14. Hydrophilization of Polyvinyl Chloride Surface by Ozonation

    NASA Astrophysics Data System (ADS)

    Kurose, Keisuke; Okuda, Tetsuji; Nakai, Satoshi; Tsai, Tsung-Yueh; Nishijima, Wataru; Okada, Mitsumasa

    The surface modification mechanism of polyvinyl chloride (PVC) by ozonation was investigated to study the selective hydrophilization of PVC surface among other plastics. Infrared analysis confirmed the increase of hydrophilic groups. XPS analysis revealed that the increase was due to the structural change in chlorine group in PVC to hydroxylic acid, ketone, and carboxylic groups by ozonation. This chemical reaction by ozone could occur only for polymers with chlorides in its structure and resulted in the selective hydrophilization of PVC among various polymers.

  15. The influence of tributyl phosphate on molybdenum extraction with solutions of dibutyl phosphoric acid

    NASA Astrophysics Data System (ADS)

    Goletskiy, N. D.; Zilberman, B. Ya.; Fedorov, Yu. S.; Khonina, I. V.; Kukharev, D. N.

    2006-01-01

    Comparative investigations were carried out to study the influence of TBP on Mo extraction by HDBP solutions in xylene and TBP in xylene. The dependences of DMo on HNO3 concentration for both HDBP and D2EHPA have minima at about 3 mol/L HNO3. This shows similar extraction properties of HDBP and D2EHPA. The presence of TBP in the solvent results in the reduction of Mo extraction and in an increase in the formal slopes of the falling and rising parts of the logDMo — log[HNO3] curve from -0.5 and +2 up to -2 and +4. Solvent loading curves with Mo show that in the absence of TBP a molybdenum solvate with two molecules of HDBP is formed at low acidity. Anomalous increase in the maximum solvent loading in the presence of TBP is caused by the ability of TBP to extract Mo from oversaturated low acidity solutions following the acidic mechanism. A molybdenum solvate with two HDBP molecules and one HNO3 molecule is possibly formed at high acidity. A flowsheet for Mo recovery from HLW with HDBP-TBP solvent was tested in centrifugal contactors.

  16. Polymorph-dependent titanium dioxide nanoparticle dissolution in acidic and alkali digestions

    EPA Science Inventory

    Multiple polymorphs (anatase, brookite and rutile) of titanium dioxide nanoparticles (TiO2-NPs) with variable structures were quantified in environmental matrices via microwave-based hydrofluoric (HF) and nitric (HNO3) mixed acid digestion and muffle furnace (MF)-based potassium ...

  17. Oxidative degradation of bis (2,4,4-trimethylpentyl) dithiophosphinic acid in nitric acid studied by electrospray ionization mass spectrometry

    SciTech Connect

    G. S. Groenewold; D. R. Peterman

    2012-10-01

    Samples of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex-301) were analyzed using direct infusion electrospray ionization mass spectrometry. Positive ion spectra of standard and stereo-pure acids displayed ions typical of the unmodified compound, cationized monomeric and dimeric cluster ion species. In addition, a significant ions 2 u less than the dimeric clusters were seen, that correspond to an oxidatively coupled species designated Cyx2 that is observed as H- or Na-cationized species in the electrospray analyses. Based on uncorrected ion intensities, Cyx2 is estimated to account for about 20% of the total in the standard materials. When samples that were contacted with 3 M HNO3 were analyzed, the positive ion spectrum consisted nearly entirely of ions derived from the oxidatively coupled product, indicating that the acid promotes coupling. The negative ion spectra of the standard acids consisted nearly entirely of the conjugate base that is formed by deprotonation of the acids, and cluster ions containing multiple acid molecules. The negative spectra of the HNO3-contacted samples also contained the conjugate base of the unmodified acid, but also two other species that correspond to the dioxo- and perthio- derivatives. It is concluded that HNO3 contact causes significant oxidation, forming at least three major products, Cyx2, the perthio-acid, and the dioxo-acid.

  18. Climate Suite Study for the National Polar-Orbiting Operational Environmental Satellite System Internal Concepts Study. Part A; Ozone Sensors

    NASA Technical Reports Server (NTRS)

    Lucke, R. L.; Planet, Walter G.; Hudson, R. D.

    1995-01-01

    Our recommendations to NPOESS for the sensors it should adopt to meet threshold requirements for global monitoring of ozone and, to some extent, of aerosols and of atmospheric temperature, pressure, and water vapor content are summarized in this report. The degree to which these sensors fulfill other NPOESS requirements than ozone is also summarized. The number of sensors that should be in the constellation is discussed in terms of desired reliability, continuity of coverage, and the ability to cross-calibrate successive sensors. Our recommendations for specific ozone measurement requirements, IORD item 4.1.6.2.28, are given. We make the case that the monitoring of three minor constituents in the upper atmosphere (N20, ClO or ClONO2, and HNO3) should be added to the list of NPOESS requirements because of their importance to long-term ozone studies and the small additional cost required (ozone sensors are already designed to measure them). Specific measurement requirements, which should be regarded as supplementary to the ozone requirement, are given here. The necessity of using two types of sensors, nadir-viewers and limb-scanners, for atmospheric studies is discussed.

  19. Mechanism of enteroviral inactivation by ozone

    SciTech Connect

    Roy, D.; Wong, P.K.; Engelbrecht, R.S.; Chian, E.S.

    1981-03-01

    The mechanism of enteroviral inactivation by ozone was investigated with poliovirus 1 (Mahoney) as the model virus. Ozone was observed to alter two of the four polypeptide chains present in the viral protein coat of poliovirus 1. However, the alteration of the protein coat did not significantly impair virus adsorption or alter the integrity of the virus particle. Damage to the viral RNA after exposure to ozone was demonstrated by velocity sedimentation analysis. It was concluded that the damage to the viral nucleic acid is the major cause of poliovirus 1 inactivation by ozone.

  20. Mechanism of enteroviral inactivation by ozone.

    PubMed Central

    Roy, D; Wong, P K; Engelbrecht, R S; Chian, E S

    1981-01-01

    The mechanism of enteroviral inactivation by ozone was investigated with poliovirus 1 (Mahoney) as the model virus. Ozone was observed to alter two of the four polypeptide chains present in the viral protein coat of poliovirus 1. However, the alteration of the protein coat did not significantly impair virus adsorption or alter the integrity of the virus particle. Damage to the viral RNA after exposure to ozone was demonstrated by velocity sedimentation analysis. It was concluded that the damage to the viral nucleic acid is the major cause of poliovirus 1 inactivation by ozone. PMID:6261692

  1. Tropopause Ozone

    NASA Astrophysics Data System (ADS)

    Prather, M.; Zhu, X.; Hsu, J.; Neu, J.; Tang, Q.

    2009-04-01

    The tropopause, however defined, is meant to describe the boundary between the well mixed troposphere and the stably stratified stratosphere. Ozone abundances in the vicinity of the tropopause exhibit large variations with latitude and season, being controlled by a combination of large-scale transport like the Brewer-Dobson circulation, small-scale turbulent mixing unresolved by global models, and photochemistry. A clear, instantaneous, 3-D definition of the tropopause is needed for diagnostics that separate stratosphere from troposphere, e.g., strat-trop exchange fluxes. In the UCI CTM, we define the stratosphere-troposphere boundary with what is effectively an age-of-air tracer: a tracer emitted uniformly from the surface with a uniform e-fold of 90 days (designated e90). Where the abundance of e90 falls below about 70% of the mass-median value (i.e., 33 days-old), we define as the stratosphere. With this diagnostic of the mixing barrier between stratosphere and troposphere the CTM with EC IFS forecast meteorology is able to match much of the observed seasonal cycle of the tropopause pressure and ozone abundance. With the CTM we examine the importance of chemistry vs. transport in controlling tropopause ozone. For example, we note that photolysis of molecular oxygen in the upper troposphere contributes significantly to tropopause ozone in the tropics and sub-tropics.

  2. Ozonized oils: a qualitative and quantitative analysis.

    PubMed

    Guinesi, Adriana Simionatto; Andolfatto, Carolina; Bonetti Filho, Idomeo; Cardoso, Arnaldo Alves; Passaretti Filho, Juliano; Farac, Roberta Vieira

    2011-01-01

    Most of the problems of endodontic origin have a bacterial etiological agent. Thus, there is a continued interest in seeking more effective chemical substances that can replace the camphorated paramonochiorophenol or antibiotics as intracanal medicaments. Among the possible substances, ozone has some interesting biological characteristics: bactericidal action, debriding effect, angiogenesis stimulation capacity and high oxidizing power. The purpose of this study was to chemically evaluate the presence of ozone in sunflower, castor, olive and almond oil, as well as in propylene glycol and byproducts of ozonation, such as formaldehyde. These compounds were ozonized, inserted into empty and sterile vials, and analyzed by testing the reaction between ozone and indigo, for determining the presence of ozone, and subjected to the chromotropic acid test for determining the presence of formaldehyde. It was observed complete absence of ozone in all samples tested and presence of formaldehyde. The bactericidal and healing action of ozonized oils could be attributed to products formed by the ozonation of mineral oils, such as formaldehyde, not to the ozone itself.

  3. Field test of four methods for gas-phase ambient nitric acid

    NASA Astrophysics Data System (ADS)

    Arnold, J. R.; Hartsell, Benjamin E.; Luke, Winston T.; Rahmat Ullah, S. M.; Dasgupta, Purnendu K.; Greg Huey, L.; Tate, Paul

    Three semi-continuous methods for detecting nitric acid (HNO 3) were tested against the annular denuder + filter pack (ADS) integrated collection technique at the Tampa Bay Regional Atmospheric Chemistry Experiment (BRACE) Sydney research station ˜20km downwind of the Tampa, Florida, urban core. The semi-continuous instruments included: two slightly differing implementations of the NOY-NO (total oxides of nitrogen minus that total denuded of HNO 3) denuder difference technique, one from the NOAA Air Resources Lab (ARL), and one from Atmospheric Research and Analysis, Inc. (ARA); the parallel plate wet diffusion scrubber + online ion chromatography technique from Texas Tech University (TTU); and the chemical ionization mass spectrometer from the Georgia Institute of Technology (GIT). Twelve hour ADS samples were collected by the University of South Florida (USF). Results for 10 min samples computed from the various higher sampling frequencies of each semi-continuous instrument showed good agreement (R2>0.7) for afternoon periods of the highest production and accumulation of HNO 3. Further, agreement was within ±30% for these instruments even at HNO 3 concentrations <0.30ppb. The USF ADS results were biased low, however, by 44%, on average, compared to the corporate 12 h aggregated means from the semi-continuous methods, and by >60% for the nighttime samples; ADS results were below the corporate mean maximum HNO 3 concentration by >30% as well. The four instruments using semi-continuous methods, by contrast, were all within 10% of each other's 12 h mean mixing ratios. While only ARA employed a formal minimum detection limit at 0.050 ppb, error analysis with the other techniques established that at the same level of precision, TTU's effective limit was approximately the same as ARA's and that ARL's limit was 0.030 ppb; analysis for GIT showed no apparent effective limit at the levels of HNO 3 encountered in this field study. The importance of sample inlet height for

  4. The Antarctic Ozone Hole

    ERIC Educational Resources Information Center

    Jones, Anna E.

    2008-01-01

    Since the mid 1970s, the ozone layer over Antarctica has experienced massive destruction during every spring. In this article, we will consider the atmosphere, and what ozone and the ozone layer actually are. We explore the chemistry responsible for the ozone destruction, and learn about why conditions favour ozone destruction over Antarctica. For…

  5. The Effect of Incorporation of HNO(sub 3) Into Liquid Sulfuric Acid on Heterogeneous Reaction Probabilities

    NASA Technical Reports Server (NTRS)

    Zhang, R.; Leu, M-T.; Keyser, L.

    1994-01-01

    Using a fast-flow reactor coupled to a quadrupole mass spectrometer, the heterogeneous reactions of C1ONO2 + HCl and HOCl + HCl as well as hydrolysis of N2O5 and C1ONO2 were investigated on liquid sulfuric acid, with particular emphasis on the effect of incorporation of HNO3 on the reaction probabilities.

  6. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

    SciTech Connect

    Wang, Bingbing; Laskin, Alexander

    2014-03-25

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  7. A laboratory study of the nucleation kinetics of nitric acid hydrates under stratospheric conditions

    NASA Astrophysics Data System (ADS)

    James, Alexander D.; Murray, Benjamin J.; Plane, John M. C.

    2016-04-01

    Measurements of the kinetics of crystallisation of ternary H2O-H2SO4-HNO3 mixtures to produce nitric acid hydrate phases, as occurs in the lower stratosphere, have been a long-standing challenge for investigators in the laboratory. Understanding polar stratospheric chlorine chemistry and thereby ozone depletion is increasingly limited by descriptions of nucleation processes. Meteoric smoke particles have been considered in the past as heterogeneous nuclei, however recent studies suggest that these particles will largely dissolve, leaving mainly silica and alumina as solid inclusions. In this study the nucleation kinetics of nitric acid hydrate phases have been measured in microliter droplets at polar stratospheric cloud (PSC) temperatures, using a droplet freezing assay. A clear heterogeneous effect was observed when silica particles were added. A parameterisation based on the number of droplets activated per nuclei surface area (ns) has been developed and compared to global model data. Nucleation experiments on identical droplets have been performed in an X-Ray Diffractometer (XRD) to determine the nature of the phase which formed. β-Nitric Acid Trihydrate (NAT) was observed alongside a mixture of Nitric Acid Dihydrate (NAD) phases. It is not possible to determine whether NAT nucleates directly or is formed by a phase transition from NAD (likely requiring the presence of a mediating liquid phase). Regardless, these results demonstrate the possibility of forming NAT on laboratory timescales. In the polar stratosphere, sulfuric acid (present at several weight percent of the liquid under equilibrium conditions) could provide such a liquid phase. This study therefor provides insight into previous discrepancies between phases formed in the laboratory and those observed in the atmosphere. It also provides a basis for future studies into atmospheric nucleation of solid PSCs.

  8. Earth's Endangered Ozone

    ERIC Educational Resources Information Center

    Panofsky, Hans A.

    1978-01-01

    Included are (1) a discussion of ozone chemistry; (2) the effects of nitrogen fertilizers, fluorocarbons, and high level aircraft on the ozone layer; and (3) the possible results of a decreasing ozone layer. (MR)

  9. Application of Lactobacillus immobilized by Activated Carbon Fiber in Fermentation of Lactic Acid in Starch Wastewater

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Wang, Peng; Chi, Guoda; Huang, Chenyong

    2010-11-01

    Activated carbon fibers (ACF) as the carrier of Lactobacillus was introduced into fermenting system, and a method of modifying the surface of ACF by HNO3-Fe (III) was established. Factors that affect ACF carrier's effect on immobilization of Lactobacillus were studied. HCl, H2SO4, HNO3 and FeCl3 solutions were respectively used to modify the surface properties of ACF. The amount of Fe (III) carried on ACF surface was 0.1563 mol/kg after ACF surface was modified by HNO3 for 5 h and then by 0.1 mol/L FeCl3 for 4 h, when the thickness of Lactobacillus on a single silk of carrier reached 40 μm. When ACF modified by HNO3-Fe (III) was applied in the fermentation of lactic acid in starch industry wastewater, the fermentation period reduced by 8 h and the output of L-lactic acid was 65.5 g/L, which was 3.3% more than that fermented without the carrier.

  10. Ozonation of Common Textile Auxiliaries

    NASA Astrophysics Data System (ADS)

    Iskender, Gulen; Arslan-Alaton, Idil; Koyunluoglu, Sebnem; Yilmaz, Zeynep; Germirli Babuna, Fatos

    2016-10-01

    The treatability of four different commonly applied textile auxiliary chemicals, namely two tannin formulations (Tannin 1: a condensation product of aryl sulphonate; Tannin 2: natural tannic acid) and two biocidal finishing agents (Biocide 1: 2,4,4’-trichloro-2’- hydroxydiphenyl ether; Biocide 2: a nonionic diphenyl alkane derivative) with ozone was investigated. Increasing the ozone dose yielded higher COD removals for the natural tannin. Optimum ozone doses of 485 and 662 mg/h were obtained at a pH of 3.5 for natural and synthetic tannin carrying textile bath discharges, respectively. When the reaction pH was increased from 3.5 to 7.0, a slight decrease in COD removal was observed for the natural tannin due to ozone selectivity towards its polyaromatic structure. The same increase in ozonation pH enhanced COD removals for the synthetic tannin as a result of enhanced ozone decomposition rendering free radical chain reactions dominant. Optimum ozone doses of 499 and 563 mg/h were established for Biocide 1 and 2, respectively. With the increase of ozonation, pH exhibited a positive influence on COD removals for both textile tannins. A substantial improvement in terms of TOC removals was observed as the reaction pH was increased from 3.5 to 7.0 for the synthetic tannin, and from 7 to 12 for both textile biocides. Higher AOX removals were evident at pH 7 than at pH 12 for Biocide 1 as a result of the higher selectivity of the dehalogenation reaction at neutral pH.

  11. Chemical Degradation Studies on a Series of Dithiophosphinic Acids

    SciTech Connect

    Melissa E. Freiderich; Dean R. Peterman; John R. Klaehn; Philippe Marc; Laetitia H. Delmau

    2014-04-01

    A significant increase in the stability of a series of dithiophosphinic acids (DPAHs) under oxidizing acidic conditions was achieved. The degradation behavior of a series of DPAHs, designed for lanthanide/actinide separation, was examined. The stability of the DPAHs, when contacted with varying nitric acid concentrations, was tested and monitored using 31P {1H} NMR. Changes in the functional groups of the DPAHs resulted in substantial increases in the stability. However, when placed in contact with 2 M HNO3 all the DPAHs eventually showed signs of degradation. The addition of a radical scavenger, hydrazine, inhibited the degradation of the DPAHs. In the presence of a small concentration of hydrazine, five of the DPAHs remained stable for over a month in direct contact with 2 M HNO3.

  12. Chemical Degradation Studies on a Series of Dithiophosphinic Acids

    SciTech Connect

    Freiderich, Melissa E; Delmau, Laetitia Helene; Peterman, D. R.; Marc, Philippe L; Klaehn, John D.

    2014-01-01

    In this study a significant increase in the stability of a series of dithiophosphinic acids (DPAHs) under oxidizing acidic conditions was achieved. The degradation behavior of a series of DPAHs, designed for lanthanide/actinide separation, was examined. The stability of the DPAHs, when contacted with varying nitric acid concentrations, was tested and monitored using 31P {1H} NMR. Changes in the functional groups of the DPAHs resulted in substantial increases in the stability. However, all the DPAHs eventually showed signs of degradation when placed in contact with 2 M HNO3. The addition of a radical scavenger, hydrazine, inhibited the degradation of the DPAHs. With small amounts of hydrazine, five of the DPAHs remained stable for over a month in direct contact with 2 M HNO3.

  13. More rapid polar ozone depletion through the reaction of HOCl with HCl on polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Prather, Michael J.

    1992-01-01

    The direct reaction of HOCl with HCl is shown here to play a critical part in polar ozone loss. Observations of high levels of OClO and ClO in the springtime Antarctic stratosphere confirm that most of the available chlorine is in the form of ClO(x). But current photochemical models have difficulty converting HCl to ClO(x) rapidly enough in early spring to account fully for the observations. Here, a chemical model is used to show that the direct reaction of HOCl with HCl provides the missing mechanism. As alternative sources of nitrogen-containing oxidants have been converted in the late autumn to inactive HNO3 by known reactions on the sulfate layer aerosols, the reaction of HOCl with HCl on polar stratospheric clouds becomes the most important pathway for releasing that stratospheric chlorine which goes into polar night as HCl.

  14. Thermal decomposition of gaseous ammonium nitrate at low pressure: kinetic modeling of product formation and heterogeneous decomposition of nitric acid.

    PubMed

    Park, J; Lin, M C

    2009-12-03

    The thermal decomposition of ammonium nitrate, NH(4)NO(3) (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation of NH(4)NO(3) at 423 K was proposed to produce equal amounts of NH(3) and HNO(3), followed by the decomposition reaction of HNO(3), HNO(3) + M --> OH + NO(2) + M (where M = third-body and reactor surface). The absolute yields of N(2), N(2)O, H(2)O, and NH(3), which can be unambiguously measured and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the detailed [H,N,O]-mechanism established earlier for the simulation of NH(3)-NO(2) (Park, J.; Lin, M. C. Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357). Since the homogeneous decomposition reaction of HNO(3) itself was found to be too slow to account for the consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition of HNO(3) in our kinetic modeling. The heterogeneous decomposition rate of HNO(3), HNO(3) + (B(2)O(3)/SiO(2)) --> OH + NO(2) + (B(2)O(3)/SiO(2)), was determined by varying its rate to match the modeled result to the measured concentrations of NH(3) and H(2)O; the rate could be represented by k(2b) = 7.91 x 10(7) exp(-12 600/T) s(-1), which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO(3) decomposition on glass reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.

  15. Thermal Decomposition of Gaseous Ammonium Nitrate at Low Pressure: Kinetic Modeling of Product Formation and Heterogeneous Decomposition of Nitric Acid

    NASA Astrophysics Data System (ADS)

    Park, J.; Lin, M. C.

    2009-10-01

    The thermal decomposition of ammonium nitrate, NH4NO3 (AN), in the gas phase has been studied at 423-56 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor coated with boric acid. The sublimation of NH4NO3 at 423 K was proposed to produce equal amounts of NH3 and HNO3, followed by the decomposition reaction of HNO3, HNO3 + M → OH + NO2 + M (where M = third-body and reactor surface). The absolute yields of N2, N2O, H2O, and NH3, which can be unambiguously measured and quantitatively calibrated under a constant pressure at 5-6.2 torr He are kinetically modeled using the detailed [H,N,O]-mechanism established earlier for the simulation of NH3-NO2 (Park, J.; Lin, M. C. Technologies and Combustion for a Clean Environment. Proc. 4th Int. Conf. 1997, 34-1, 1-5) and ADN decomposition reactions (Park, J.; Chakraborty, D.; Lin, M. C. Proc. Combust. Inst. 1998, 27, 2351-2357). Since the homogeneous decomposition reaction of HNO3 itself was found to be too slow to account for the consumption of reactants and the formation of products, we also introduced the heterogeneous decomposition of HNO3 in our kinetic modeling. The heterogeneous decomposition rate of HNO3, HNO3 + (B2O3/SiO2) → OH + NO2 + (B2O3/SiO2), was determined by varying its rate to match the modeled result to the measured concentrations of NH3 and H2O; the rate could be represented by k2b = 7.91 × 107 exp(-12 600/T) s-1, which appears to be consistent with those reported by Johnston and co-workers (Johnston, H. S.; Foering, L.; Tao, Y.-S.; Messerly, G. H. J. Am. Chem. Soc. 1951, 73, 2319-2321) for HNO3 decomposition on glass reactors at higher temperatures. Notably, the concentration profiles of all species measured could be satisfactorily predicted by the existing [H,N,O]-mechanism with the heterogeneous initiation process.

  16. The Effects of Acid Passivation, Tricresyl Phosphate Presoak, and UV/Ozone Treatment on the Tribology of Perfluoropolyether-Lubricated 440C Stainless Steel Couples

    NASA Technical Reports Server (NTRS)

    Shogrin, Bradley A.; Jones, William R., Jr.; Herrera-Fierro, Pilar; Jansen, Mark J.

    2001-01-01

    The boundary-lubrication performance of two perfluoropolyether (PFPE) thin films in the presence of passivated 440C stainless steel is presented. The study used a standard ball on disk (BoD) tribometer in dry nitrogen and a vacuum spiral orbit tribometer (SOT). Stainless steel surfaces were passivated with one of four techniques: high and low temperature chromic acid bath, a tricresyl phosphate (TCP) soak, or UV/Ozone treated for 15 min. After passivation, each BoD disk had a 400A film of Krytox 16256 (PFPE) applied to it. The lifetimes of these films were quantified by measuring the number of sliding cycles before an increase in friction occurred. The lubricated lifetime of the 440C couple was not altered as a result of the various passivation techniques. The resulting surface chemistry of each passivation technique was examined using X-ray photoelectron spectroscopy (XPS). The SOT was used to examine the effects of the TCP treatment on the lubricated lifetime of another PFPE, Brayco 815Z, under rolling conditions. None of the passivation techniques were found to dramatically increase the oxide film thickness or lubricated lifetimes.

  17. Incorporation of stratospheric acids into water ice

    NASA Technical Reports Server (NTRS)

    Elliott, Scott; Turco, Richard P.; Toon, Owen B.; Hamill, Patrick

    1990-01-01

    Hydrochloric and hydrofluoric acids are absorbed within the water ice lattice at mole fractions maximizing below 0.00001 and 0.0001 in a variety of solid impurity studies. The absorption mechanism may be substitutional or interstitial, leading in either case to a weak permeation of stratospheric ices by the acids at equilibrium. Impurities could also inhabit grain boundaries, and the acid content of atmospheric ice crystals will then depend on details of their surface and internal microstructures. Limited evidence indicates similar properties for the absorption of HNO3. Water ice lattices saturated with acid cannot be a significant local reservoir for HCl in the polar stratosphere.

  18. Potential sources of nitrous acid (HONO) and their impacts on ozone: A WRF-Chem study in a polluted subtropical region

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Wang, Tao; Zhang, Qiang; Zheng, Junyu; Xu, Zheng; Lv, Mengyao

    2016-04-01

    Current chemical transport models commonly undersimulate the atmospheric concentration of nitrous acid (HONO), which plays an important role in atmospheric chemistry, due to the lack or inappropriate representations of some sources in the models. In the present study, we parameterized up-to-date HONO sources into a state-of-the-art three-dimensional chemical transport model (Weather Research and Forecasting model coupled with Chemistry: WRF-Chem). These sources included (1) heterogeneous reactions on ground surfaces with the photoenhanced effect on HONO production, (2) photoenhanced reactions on aerosol surfaces, (3) direct vehicle and vessel emissions, (4) potential conversion of NO2 at the ocean surface, and (5) emissions from soil bacteria. The revised WRF-Chem was applied to explore the sources of the high HONO concentrations (0.45-2.71 ppb) observed at a suburban site located within complex land types (with artificial land covers, ocean, and forests) in Hong Kong. With the addition of these sources, the revised model substantially reproduced the observed HONO levels. The heterogeneous conversions of NO2 on ground surfaces dominated HONO sources contributing about 42% to the observed HONO mixing ratios, with emissions from soil bacterial contributing around 29%, followed by the oceanic source (~9%), photochemical formation via NO and OH (~6%), conversion on aerosol surfaces (~3%), and traffic emissions (~2%). The results suggest that HONO sources in suburban areas could be more complex and diverse than those in urban or rural areas and that the bacterial and/or ocean processes need to be considered in HONO production in forested and/or coastal areas. Sensitivity tests showed that the simulated HONO was sensitive to the uptake coefficient of NO2 on the surfaces. Incorporation of the aforementioned HONO sources significantly improved the simulations of ozone, resulting in increases of ground-level ozone concentrations by 6-12% over urban areas in Hong Kong and

  19. Differences in leaf characteristics between ozone-sensitive and ozone-tolerant hybrid aspen (Populus tremula x Populus tremuloides) clones.

    PubMed

    Häikiö, Elina; Freiwald, Vera; Julkunen-Tiitto, Riitta; Beuker, Egbert; Holopainen, Toini; Oksanen, Elina

    2009-01-01

    The authors analyzed a suite of leaf characteristics that might help to explain the difference between ozone-sensitive and ozone-tolerant hybrid aspen (Populus tremula L. x Populus tremuloides Michx.) clones. An open-field experiment comprising ambient ozone and 1.5x ambient ozone concentration (about 35 ppb) and two soil nitrogen regimes (60 and 140 kg N ha(-1) year(-1)) was conducted over two growing seasons on potted plants of eight hybrid aspen clones. Four of the clones had previously been determined to be ozone sensitive based on impaired growth in response to elevated ozone concentration. Photosynthetic rate, chlorophyll fluorescence, and concentrations of chlorophyll, protein and carbohydrates were analyzed three times during the second growing season, and foliar phenolic concentrations were measured at the end of the second growing season. Nitrogen amendment counteracted the effects of ozone, but had no effect on growth-related ozone sensitivity of the clones. Ozone-sensitive clones had higher photosynthetic capacity and higher concentrations of Rubisco and phenolics than ozone-tolerant clones, but the effects of ozone were similar in the sensitive and tolerant groups. Nitrogen addition had no effect on phenolic concentration, but elevated ozone concentration increased the concentrations of chlorogenic acid and (+)-catechin. This study suggests that condensed tannins and catechin, but not salicylates or flavonol glycosides, play a role in the ozone tolerance of hybrid aspen.

  20. Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation.

    PubMed

    Morales-Torres, Sergio; Silva, Tânia L S; Pastrana-Martínez, Luisa M; Brandão, Ana T S C; Figueiredo, José L; Silva, Adrián M T

    2014-06-28

    A specific methodology based on nitric acid hydrothermal oxidation was used to control the surface chemistry of multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes (CNTs) with different lengths, and this methodology was adapted to the use of sulphuric acid containing ammonium persulfate as an oxidizing agent. The amount of oxygen-containing surface groups depends on the number and length of the graphene layers of the CNTs, thicker and shorter CNTs having more reactive sites for surface functionalization. In particular, the oxidation of MWCNTs was more pronounced than that of short SWCNTs and less surface groups were introduced into long SWCNTs, regardless of the acid used at any fixed concentration. It was also possible to tailor the surface chemistry of both SWCNTs and MWCNTs by using the adopted methodologies, and the amount of both oxygen- and sulphur-containing functional groups was correlated with the concentration of each oxidizing agent used. Mathematical functions that allow precise control of the amount and type of the surface groups introduced into carbon nanotubes were obtained. Buckypapers were also prepared over a polytetrafluoroethylene commercial membrane. These membranes were tested in direct contact membrane distillation and, under salinity conditions, the membrane prepared using oxidized MWCNTs (instead of SWCNTs) was the most efficient, the permeate flux of the commercial membrane significantly increasing in the presence of these CNTs, while completely rejecting chloride ions. In addition, the permeate flux was precisely correlated with the amount of oxygenated functional surface groups (as well as with the pH of point of zero charge) of the oxidized MWCNTs.

  1. Evaluation of the Single Dilute (0.43 M) Nitric Acid Extraction to Determine Geochemically Reactive Elements in Soil

    PubMed Central

    2017-01-01

    Recently a dilute nitric acid extraction (0.43 M) was adopted by ISO (ISO-17586:2016) as standard for extraction of geochemically reactive elements in soil and soil like materials. Here we evaluate the performance of this extraction for a wide range of elements by mechanistic geochemical modeling. Model predictions indicate that the extraction recovers the reactive concentration quantitatively (>90%). However, at low ratios of element to reactive surfaces the extraction underestimates reactive Cu, Cr, As, and Mo, that is, elements with a particularly high affinity for organic matter or oxides. The 0.43 M HNO3 together with more dilute and concentrated acid extractions were evaluated by comparing model-predicted and measured dissolved concentrations in CaCl2 soil extracts, using the different extractions as alternative model-input. Mean errors of the predictions based on 0.43 M HNO3 are generally within a factor three, while Mo is underestimated and Co, Ni and Zn in soils with pH > 6 are overestimated, for which possible causes are discussed. Model predictions using 0.43 M HNO3 are superior to those using 0.1 M HNO3 or Aqua Regia that under- and overestimate the reactive element contents, respectively. Low concentrations of oxyanions in our data set and structural underestimation of their reactive concentrations warrant further investigation. PMID:28164700

  2. A mitogen-activated protein kinase NtMPK4 activated by SIPKK is required for jasmonic acid signaling and involved in ozone tolerance via stomatal movement in tobacco.

    PubMed

    Gomi, Kenji; Ogawa, Daisuke; Katou, Shinpei; Kamada, Hiroshi; Nakajima, Nobuyoshi; Saji, Hikaru; Soyano, Takashi; Sasabe, Michiko; Machida, Yasunori; Mitsuhara, Ichiro; Ohashi, Yuko; Seo, Shigemi

    2005-12-01

    The mitogen-activated protein kinase (MAPK) cascade is involved in responses to biotic and abiotic stress in plants. In this study, we isolated a new MAPK, NtMPK4, which is a tobacco homolog of Arabidopsis MPK4 (AtMPK4). NtMPK4 was activated by wounding along with two other wound-responsive tobacco MAPKs, WIPK and SIPK. We found that NtMPK4 was activated by salicylic acid-induced protein kinase kinase (SIPKK), which has been isolated as an SIPK-interacting MAPK kinase. In NtMPK4 activity-suppressed tobacco, wound-induced expression of jasmonic acid (JA)-responsive genes was inhibited. NtMPK4-silenced plants showed enhanced sensitivity to ozone. Inversely, transgenic tobacco plants, in which SIPKK or the constitutively active type SIPKK(EE) was overexpressed, exhibited greater responsiveness to wounding with enhanced resistance to ozone. We further found that NtMPK4 was expressed preferentially in epidermis, and the enhanced sensitivity to ozone in NtMPK4-silenced plants was caused by an abnormal regulation of stomatal closure in an ABA-independent manner. These results suggest that NtMPK4 is involved in JA signaling and in stomatal movement.

  3. Degradation of Amino Acids and Structure in Model Proteins and Bacteriophage MS2 by Chlorine, Bromine, and Ozone.

    PubMed

    Choe, Jong Kwon; Richards, David H; Wilson, Corey J; Mitch, William A

    2015-11-17

    Proteins are important targets of chemical disinfectants. To improve the understanding of disinfectant-protein reactions, this study characterized the disinfectant:protein molar ratios at which 50% degradation of oxidizable amino acids (i.e., Met, Tyr, Trp, His, Lys) and structure were observed during HOCl, HOBr, and O3 treatment of three well-characterized model proteins and bacteriophage MS2. A critical question is the extent to which the targeting of amino acids is driven by their disinfectant rate constants rather than their geometrical arrangement. Across the model proteins and bacteriophage MS2 (coat protein), differing widely in structure, methionine was preferentially targeted, forming predominantly methionine sulfoxide. This targeting concurs with its high disinfectant rate constants and supports its hypothesized role as a sacrificial antioxidant. Despite higher HOCl and HOBr rate constants with histidine and lysine than for tyrosine, tyrosine generally was degraded in preference to histidine, and to a lesser extent, lysine. These results concur with the prevalence of geometrical motifs featuring histidines or lysines near tyrosines, facilitating histidine and lysine regeneration upon Cl[+1] transfer from their chloramines to tyrosines. Lysine nitrile formation occurred at or above oxidant doses where 3,5-dihalotyrosine products began to degrade. For O3, which lacks a similar oxidant transfer pathway, histidine, tyrosine, and lysine degradation followed their relative O3 rate constants. Except for its low reactivity with lysine, the O3 doses required to degrade amino acids were as low as or lower than for HOCl or HOBr, indicating its oxidative efficiency. Loss of structure did not correlate with loss of particular amino acids, suggesting the need to characterize the oxidation of specific geometric motifs to understand structural degradation.

  4. Nitric acid dry deposition to conifer forests: Niwot Ridge spruce-fir-pine study

    USGS Publications Warehouse

    Sievering, H.; Kelly, T.; McConville, G.; Seibold, C.; Turnipseed, A.

    2001-01-01

    The dry deposition velocity of nitric acid, Vd(HNO3), over a 12-m (mean height) spruce-fir forest at Niwot Ridge, Colorado was estimated during 13 daytime periods using the flux-gradient approach. Turbulence intensity at this site is high (mean u* of 0.65ms-1 with u of 2.9ms-1) and contributed to the large observed Vd(HNO3). The overriding contributor is identified to be the small aerodynamic needle width of the conifer trees. Two cases had inflated Vd(HNO3) due to height-differentiated nitric acid loss to soil-derived particle surfaces. Not considering these cases, the mean Vd(HNO3) was 7.6cms-1. The mean laminar boundary layer resistance (Rb) was found to be 7.8sm-1 (of similar magnitude to that of the aerodynamic resistance, 8.5sm-1). The data-determined Rb is bracketed by two theoretical estimates of the mean Rb, 5.9 and 8.6sm-1, that include consideration of the small canopy length scale (aerodynamic needle width), 1mm or less, at this conifer forest. However, the poor correlation of data-determined Rb values with both sets of theoretical estimates indicates that measurement error needs to be reduced and/or improved formulations of theoretical Rb values are in order. The large observed Vd(HNO3) at this conifer forest site is attributed to high turbulence intensity, and, especially, to small aerodynamic needle width. Copyright ?? 2001 Elsevier Science Ltd.

  5. Ozone Hole Over Antarctica

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images from the Total Ozone Mapping Spectrometer (TOMS) show the progressive depletion of ozone over Antarctica from 1979 to 1999. This 'ozone hole' has extended to cover an area as large as 10.5 million square miles in September 1998. The previous record of 10.0 million square miles was set in 1996. The Antarctic ozone hole develops each year between late August and early October. Regions with higher levels of ozone are shown in red. NASA and NOAA instruments have been measuring Antarctic ozone levels since the early 1970s. Large regions of depleted ozone began to develop over Antarctica in the early 1980s. Ozone holes of substantial size and depth are likely to continue to form during the next few years, scientists hope to see a reduction in ozone loss as levels of ozone-destroying CFCs (chlorofluorocarbons) are gradually reduced. Credit: Images by Greg Shirah, NASA Goddard Space Flight Center Scientific Visualization Studio

  6. Vapor-deposited water and nitric acid ices

    NASA Astrophysics Data System (ADS)

    Leu, Ming-Taun; Keyser, Leon F.

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

  7. A new numerical model of the middle atmosphere. 2: Ozone and related species

    SciTech Connect

    Garcia, R.R.; Solomon, S. |

    1994-06-01

    A new two-dimensional model with detailed photochemistry is presented. The model includes descriptions of planetary wave and gravity wave propagation and dissipation to characterize the wave forcing and associated mixing in the stratosphere and mesosphere. Such a representation allows for explicit calculation of the regions of strong mixing in the middle atmosphere required for accurate simulation of trace gas transport. The new model also includes a detailed description of photochemical processes in the stratosphere and mesosphere. The downward transport of H2, H2O, and NO(y) from the mesosphere to the stratosphere is examined, and it is shown that mesospheric processes can influence the distributions of these chemical species in polar regions. For HNO3 we also find that small concentrations of liquid aerosols above 30 km could play a major role in determining the abundance in polar winter at high latitudes. The model is also used to examine the chemical budget of ozone in the midlatitude stratosphere and to set constraints on the effectiveness of bromine relative to chlorine for ozone loss and the role of the HO2 + BrO reaction. Recent laboratory data used in this modeling study suggest that this process greatly enhances the effectiveness of bromine for ozone destruction, making bromine-catalyzed chemistry second only to HO(x)-catalyzed ozone destruction in the contemporary stratosphere at midlatitudes below about 18 km. The calculated vertical distribution of ozone in the lower stratosphere agrees well with observations, as does the total column ozone during most seasons and latitudes, with the important exception of southern hemisphere winter and spring.

  8. The Antarctic ozone hole

    NASA Astrophysics Data System (ADS)

    Molina, Mario J.

    Observations of Antarctic ozone levels and the discovery of a hole in the Antarctic region are examined. The effects of chlorofluorocarbons (CFCs) on the level of stratospheric ozone are analyzed. Three cycles explaining the cause of ozone depletion in the poles are proposed. A comparison of field data and proposed depletion cycles reveals that the chemical origin of the ozone hole is due to CFCs. The potential global effects of the Antarctic ozone hole are discussed.

  9. The Consistency of Isotopologues of Ambient Atmospheric Nitric Acid in Passively Collected Samples

    NASA Astrophysics Data System (ADS)

    Bell, M. D.; Sickman, J. O.; Bytnerowicz, A.; Padgett, P.; Allen, E. B.

    2012-12-01

    Anthropogenic sources of nitrogen oxides have previously been shown to have distinctive isotopic signatures of oxygen and nitrogen. Nylon filters are currently used in passive sampling arrays to measure ambient atmospheric nitric acid concentrations and estimate deposition rates. This experiment measured the ability of nylon filters to consistently collect isotopologues of atmospheric nitric acid in the same ratios as they are present in the atmosphere. Samplers were deployed in continuous stirred tank reactors (CSTR) and at field sites across a nitrogen deposition gradient in Southern California. Filters were exposed over a four week period with individual filters being subjected to 1-4 week exposure times. Extracted nitric acid were measured for δ18O and δ15N ratios and compared for consistency based on length of exposure and amount of HNO3 collected. Filters within the CSTRs collected HNO3 at a consistent rate in both high and low concentration chambers. After two weeks of exposure, the mean δ18O values were within 0.5‰ of the δ18O of the source HNO3 solution. The mean of all weekly exposures were within 0.5‰ of the δ15N of the source solution, but after three weeks, the mean δ15N of adsorbed HNO3 was within 0.2‰. As the length of the exposure increased, the variability of measured delta values decreased for both elements. The field samplers collected HNO3 consistent with previously measured values along a deposition gradient. The mean δ18O at high deposition sites was 52.2‰ compared to 35.7‰ at the low deposition sites. Mean δ15N values were similar at all sites across the deposition gradient. Due to precipitation events occurring during the exposure period, the δ15N and δ18O of nitric acid were highly variable at all field sites. At single sites, changes in δ15N and δ18O were negatively correlated, consistent with two-sourcing mixing dynamics, but the slope of the regressions differed between high and low deposition sites. Anthropogenic

  10. Persistent Water-Nitric Acid Condensate with Saturation Water Vapor Pressure Greater than That of Hexagonal Ice.

    PubMed

    Gao, Ru-Shan; Gierczak, Tomasz; Thornberry, Troy D; Rollins, Andrew W; Burkholder, James B; Telg, Hagen; Voigt, Christiane; Peter, Thomas; Fahey, David W

    2016-03-10

    A laboratory chilled mirror hygrometer (CMH), exposed to an airstream containing water vapor (H2O) and nitric acid (HNO3), has been used to demonstrate the existence of a persistent water-nitric acid condensate that has a saturation H2O vapor pressure greater than that of hexagonal ice (Ih). The condensate was routinely formed on the mirror by removing HNO3 from the airstream following the formation of an initial condensate on the mirror that resembled nitric acid trihydrate (NAT). Typical conditions for the formation of the persistent condensate were a H2O mixing ratio greater than 18 ppm, pressure of 128 hPa, and mirror temperature between 202 and 216 K. In steady-state operation, a CMH maintains a condensate of constant optical diffusivity on a mirror through control of only the mirror temperature. Maintaining the persistent condensate on the mirror required that the mirror temperature be below the H2O saturation temperature with respect to Ih by as much as 3 K, corresponding to up to 63% H2O supersaturation with respect to Ih. The condensate was observed to persist in steady state for up to 16 h. Compositional analysis of the condensate confirmed the co-condensation of H2O and HNO3 and thereby strongly supports the conclusion that the Ih supersaturation is due to residual HNO3 in the condensate. Although the exact structure or stoichiometry of the condensate could not be determined, other known stable phases of HNO3 and H2O are excluded as possible condensates. This persistent condensate, if it also forms in the upper tropical troposphere, might explain some of the high Ih supersaturations in cirrus and contrails that have been reported in the tropical tropopause region.

  11. A Three-Tier Diagnostic Test to Assess Pre-Service Teachers' Misconceptions about Global Warming, Greenhouse Effect, Ozone Layer Depletion, and Acid Rain

    NASA Astrophysics Data System (ADS)

    Ozge Arslan, Harika; Cigdemoglu, Ceyhan; Moseley, Christine

    2012-07-01

    This study describes the development and validation of a three-tier multiple-choice diagnostic test, the atmosphere-related environmental problems diagnostic test (AREPDiT), to reveal common misconceptions of global warming (GW), greenhouse effect (GE), ozone layer depletion (OLD), and acid rain (AR). The development of a two-tier diagnostic test procedure as described by Treagust constitutes the framework for this study. To differentiate a lack of knowledge from a misconception, a certainty response index is added as a third tier to each item. Based on propositional knowledge statements, related literature, and the identified misconceptions gathered initially from 157 pre-service teachers, the AREPDiT was constructed and administered to 256 pre-service teachers. The Cronbach alpha reliability coefficient of the pre-service teachers' scores was estimated to be 0.74. Content and face validations were established by senior experts. A moderate positive correlation between the participants' both-tiers scores and their certainty scores indicated evidence for construct validity. Therefore, the AREPDiT is a reliable and valid instrument not only to identify pre-service teachers' misconceptions about GW, GE, OLD, and AR but also to differentiate these misconceptions from lack of knowledge. The results also reveal that a majority of the respondents demonstrated limited understandings about atmosphere-related environmental problems and held six common misconceptions. Future studies could test the AREPDiT as a tool for assessing the misconceptions held by pre-service teachers from different programs as well as in-service teachers and high school students.

  12. Disinfection of Viruses in Water by Ozone.

    DTIC Science & Technology

    1979-12-01

    A0-A092 252 HEBREW UNIV JERUSALEM (ISRAEL) ENVIRONMENTAL HEALTH LAB F/6 6/5 DISINFECTION OF VIRUSES IN WATER BY OZONE.(U) DEC 79 H I SHUVAL, E... resulted in the inactivation of only 50-90% of the viruses. No clear dose response relationship was found. C. Mass Transfer and Reaction Kinetics in...one minute for an ozone dose of less than 0.4 mg/liter. E. Mechanism of Virus Inactivation by Ozone Results have shown that only those amino acids

  13. Antarctic Ozone Hole, 2000

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Each spring the ozone layer over Antarctica nearly disappears, forming a 'hole' over the entire continent. The hole is created by the interaction of some man-made chemicals-freon, for example-with Antarctica's unique weather patterns and extremely cold temperatures. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, thereby protecting living things. Since the ozone hole was discovered many of the chemicals that destroy ozone have been banned, but they will remain in the atmosphere for decades. In 2000, the ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever-11.4 million square miles. The top image shows the average total column ozone values over Antarctica for September 2000. (Total column ozone is the amount of ozone from the ground to the top of the atmosphere. A relatively typical measurement of 300 Dobson Units is equivalent to a layer of ozone 0.12 inches thick on the Earth's surface. Levels below 220 Dobson Units are considered to be significant ozone depletion.) The record-breaking hole is likely the result of lower than average ozone levels during the Antarctic fall and winter, and exceptionally cold temperatures. In October, however (bottom image), the hole shrank dramatically, much more quickly than usual. By the end of October, the hole was only one-third of it's previous size. In a typical year, the ozone hole does not collapse until the end of November. NASA scientists were surprised by this early shrinking and speculate it is related to the region's weather. Global ozone levels are measured by the Total Ozone Mapping Spectrometer (TOMS). For more information about ozone, read the Earth Observatory's ozone fact sheet, view global ozone data and see these ozone images. Images by Greg Shirah, NASA GSFC Scientific Visualization Studio.

  14. Early stage composition of SOA produced by α-pinene/ozone reaction: α-Acyloxyhydroperoxy aldehydes and acidic dimers

    NASA Astrophysics Data System (ADS)

    Witkowski, Bartłomiej; Gierczak, Tomasz

    2014-10-01

    Composition of the freshly formed secondary organic aerosol (SOA) generated by ozonolysis of cyclohexene, cyclohexene-d10 (model precursors) and α-pinene was studied using liquid chromatography coupled to electrospray ionization tandem mass spectrometry (LC-ESI/MS2). SOA was generated in the flow-tube reactor under the following conditions: 22 ± 2 °C, 1 atm and reaction time was approx. 30 s. In an attempt to resolve the current ambiguities, regarding the structure of α-pinene SOA nucleating agents, analytical methods for analysis of α-acyloxyhydroperoxy aldehydes and oligomers containing carboxylic group were developed to study the potential nucleating agents. Negatively charged m/z 351, 341, 337, 357 and 367 ions corresponding to the acidic oligomers were detected in freshly formed α-pinene SOA. For the first time, structures and formation mechanism for compounds detected as m/z 337 and 351 ions were proposed. Based on the model precursor analysis (cyclohexene and cyclohexene-d10) it was concluded that these compounds were most likely formed via aldol reaction of the lower molecular weight aerosol components. α-Acyloxyhydroperoxy aldehydes were studied in the SOA samples using previously developed, novel method, based on the prediction of fragmentation spectrum for the compounds of interest. It was concluded that α-acyloxyhydroperoxy aldehydes were not formed in significant quantities. Based on the obtained results, possible SOA formation and growth mechanism is discussed.

  15. Ozone and hydrogen peroxide as strategies to control biomass in a trickling filter to treat methanol and hydrogen sulfide under acidic conditions.

    PubMed

    García-Pérez, Teresa; Le Borgne, Sylvie; Revah, Sergio

    2016-12-01

    The operation and performance of a biotrickling filter for methanol (MeOH) and hydrogen sulfide (H2S) removal at acid pH was studied. Excess biomass in the filter bed, causing performance loss and high pressure drop, was controlled by intermittent addition, of ozone (O3) and hydrogen peroxide (H2O2). The results showed that after adaptation to acid pH, the maximum elimination capacity (EC) reached for MeOH was 565 g m(-3) h (-1) (97 % RE). High MeOH loads resulted in increased biomass concentration within the support, triggering reductions in the removal efficiency (RE) for both compounds close to 50 %, and high pressure drop. At this stage, an inlet load of 150.2 ± 16.7 g m(-3) h(-1) of O3 was fed by 38 days favoring biomass detachment, and EC recovery and lower pressure dropped with a maximum elimination capacity of 587 g m(-3) h(-1) (81 % RE) and 15.8 g m(-3) h(-1) (97 % RE) for MeOH and H2S, respectively. After O3 addition, a rapid increase in biomass content and higher fluctuations in pressure drop were observed reducing the system performance. A second treatment with oxidants was implemented feeding a O3 load of 4.8 ± 0.1 g m(-3) h(-1) for 7 days, followed by H2O2 addition for 23 days, registering 607.5 gbiomass L(-1)packing before and 367.5 gbiomass L(-1)packing after the oxidant addition. PCR-DGGE analysis of different operating stages showed a clear change in the bacterial populations when O3 was present while the fungal population was less affected.

  16. Plasmadynamic ozone generator

    NASA Astrophysics Data System (ADS)

    Gordeev, Yu. N.; Ogurechnikov, V. A.; Chizhov, Yu. L.

    2009-10-01

    The formation of ozone in a low-temperature supersonic flow of a mixture of air and partly dissociated oxygen supplied from a discharge plasmatron has been experimentally studied. For an oxygen mass fraction of 1.1% in the total gas flow supplied to this ozone generator, an ozone-air mixture containing 4.88 × 10-3 kg/m3 ozone is obtained at a specific energy consumption of 25.8 MJ/(kg ozone). In this regime, the ozone generator could operate for several dozen minutes.

  17. The Antarctic ozone hole

    NASA Astrophysics Data System (ADS)

    Jones, Anna E.

    2008-07-01

    Since the mid 1970s, the ozone layer over Antarctica has experienced massive destruction during every spring. In this article, we will consider the atmosphere, and what ozone and the ozone layer actually are. We explore the chemistry responsible for the ozone destruction, and learn about why conditions favour ozone destruction over Antarctica. For the historical perspective, the events leading up to the discovery of the 'hole' are presented, as well as the response from the international community and the measures taken to protect the ozone layer now and into the future.

  18. Growth response of green and white ash seedlings to ozone, sulfur dioxide, and simulated acid rain. [Fraxinus pennsylvanica Marsh

    SciTech Connect

    Chappelka, A.H.; Chevone, B.I.; Burk, T.E. )

    1988-12-01

    Nine-week-old green (Fraxinus pennsylvanica Marsh.) and white (F. americana L.) ash were exposed to O{sub 3} and/or SO{sub 2} (control, 0.10 ppm O{sub 3}, 0.08 ppm SO{sub 2}, or 0.10 ppm O{sub 3} + 0.08 ppm SO{sub 2}) for 4 h d{sup {minus}1}, 5 d wk{sup {minus}1} in combination with simulated rain (pH 3.0, 4.3 or 5.6, 1 h d{sup {minus}1}, 2 d wk{sup {minus}1} at 0.75 cm h{sup {minus}1}) for 6 weeks, under controlled laboratory conditions, with rain applied either just before or after fumigation. Across all rain treatments, white ash biomass was suppressed by the application of O{sub 3} and cumulative shoot elongation of green ash exposed to O{sub 3} and/or SO{sub 2} was less than controls. The combination of O{sub 3} + SO{sub 2} did not affect the growth of either species more than the pollutants applied alone. Leaf area ratio (LAR) and root to shoot ratio (RSR) exhibited quadratic responses to rain pH in green ash, across all pollutant treatments. Significant pollutant {times} pH interactions occurred in leaf weight ratio (LWR) in green ash and LAR and RSR in white ash. Significant linear increases in LAR and decreases in RSR, with decreasing pH, were observed for O{sub 3} and SO{sub 2}-treated white ash. These findings are discussed relative to implications of the effects of gaseous pollutants in combination with acid rain on green and white ash growth.

  19. Mobilization of Cr(VI) from chromite ore processing residue through acid treatment.

    PubMed

    Tinjum, James M; Benson, Craig H; Edil, Tuncer B

    2008-02-25

    Batch leaching studies on chromite ore processing residue (COPR) were performed using acids to investigate leaching of hexavalent chromium, Cr(VI), with respect to particle size, reaction time, and type of acid (HNO(3) and H(2)SO(4)). Aqueous Cr(VI) is maximized at approximately 0.04 mol Cr(VI) per kg of dry COPR at pH 7.6-8.1. Cr(VI) mobilized more slowly for larger particles, and the pH increased with time and increased more rapidly for smaller particles, suggesting that rate limitations occur in the solid phase. With H(2)SO(4), the pH stabilized at a higher value (8.8 for H(2)SO(4) vs. 8.0 for HNO(3)) and more rapidly (16 h vs. 30 h), and the differences in pH for different particle sizes were smaller. The acid neutralization capacity (ANC) of COPR is very large (8 mol HNO(3) per kg of dry COPR for a stable eluate pH of 7.5). Changes to the elemental and mineralogical composition and distribution in COPR particles after mixing with acid indicate that Cr(VI)-bearing solids dissolved. However, concentrations of Cr(VI) >2800 mg kg(-1) (>50% of the pre-treatment concentration) were still found after mixing with acid, regardless of the particle size, reaction time, or type of acid used. The residual Cr(VI) appears to be partially associated with poorly-ordered Fe and Al oxyhydroxides that precipitated in the interstitial areas of COPR particles. Remediation strategies that use HNO(3) or H(2)SO(4) to neutralize COPR or to maximize Cr(VI) in solution are likely to require extensive amounts of acid, may not mobilize all of the Cr(VI), and may require extended contact time, even under well-mixed conditions.

  20. Efficacy of Slightly Acidic Electrolyzed Water and UV-Ozonated Water Combination for Inactivating Escherichia Coli O157:H7 on Romaine and Iceberg Lettuce during Spray Washing Process.

    PubMed

    Pang, Yu-Hsin; Hung, Yen-Con

    2016-07-01

    Spray washing is a common sanitizing method for the fresh produce industry. The purpose of this research was to investigate the antimicrobial effect of spraying slightly acidic electrolyzed water (SAEW) and a combination of ozonated water with ultraviolet (UV) in reducing Escherichia coli O157:H7 on romaine and iceberg lettuces. Both romaine and iceberg lettuces were spot inoculated with 100 μL of a 3 strain mixture of E. coli O157:H7 to achieve an inoculum of 6 log CFU/g on lettuce. A strong antimicrobial effect was observed for the UV-ozonated water combination, which reduced the population of E. coli by 5 log CFU/g of E. coli O157:H7 on both lettuces. SAEW achieved about 5 log CFU/g reductions in the bacterial counts on romaine lettuce. However, less than 2.5 log CFU/g in the population of E. coli O157:H7 was reduced on iceberg lettuce. The difference may be due to bacteria aggregation near and within stomata for iceberg lettuce but not for romaine lettuce. The UV light treatment may stimulate the opening of the stomata for the UV-ozonated water treatment and hence achieve better bacterial inactivation than the SAEW treatment for iceberg lettuce. Our results demonstrated that the combined treatment of SAEW and UV-ozonated water in the spray washing process could more effectively reduce E. coli O157:H7 on lettuce, which in turn may help reduce incidences of E. coli O157:H7 outbreaks.

  1. XPS and STEM studies of Allende acid insoluble residues

    NASA Technical Reports Server (NTRS)

    Housley, R. M.; Clarke, D. R.

    1980-01-01

    Data on Allende acid residues obtained both before and after etching with hot HNO3 are presented. X-ray photoelectron spectra show predominantly carbonaceous material plus Fe-deficient chromite in both cases. The HNO3 oxidizes the carbonaceous material to some extent. The small chromites in these residues have a wide range of compositions somewhat paralleling those observed in larger Allende chromites and in Murchison chromites, especially in the high Al contents; however, they are deficient in divalent cations, which makes them metastable and indicates that they must have formed at relatively low temperatures. It is suggested that they formed by precipitation of Cr(3+) and Fe(3+) from olivine at low temperature or during rapid cooling.

  2. Photochemical ozone budget during the BIBLE A and B campaigns

    NASA Astrophysics Data System (ADS)

    Ko, Malcolm; Hu, Wenjie; RodríGuez, José M.; Kondo, Yutaka; Koike, Makoto; Kita, Kazuyuki; Kawakami, Shuji; Blake, Donald; Liu, Shaw; Ogawa, Toshihiro

    2002-02-01

    Using the measured concentrations of NO, O3, H2O, CO, CH4, and NMHCs along the flight tracks, a photochemical box model is used to calculate the concentrations of the Ox radicals, the HOx radicals, and the nitrogen species at the sampling points. The calculations make use of the measurements from radiometers to scale clear sky photolysis rates to account for cloud cover and ground albedo at the sampling time/point. The concentrations of the nitrogen species in each of the sampled air parcels are computed assuming they are in instantaneous equilibrium with the measured NO and O3. The diurnally varying species concentrations are next calculated using the box model and used to estimate the diurnally averaged production and removal rates of ozone for the sampled air parcels. Clear sky photolysis rates are used in the diurnal calculations. The campaign also provided measured concentration of NOy. The observed NO/NOy ratio is usually larger than the model calculated equilibrium value. There are several possible explanations. It could be a result of recent injection of NO into the air parcel, recent removal of HNO3 from the parcel, recent rapid transport of an air parcel from another location, or a combination of all processes. Our analyses suggest that the local production rate of O3 can be used as another indicator of recent NO injection. However, more direct studies using air trajectory analyses and other collaborative evidences are needed to ascertain the roles played by individual process.

  3. Photochemical ozone budget during the BIBLE A and B campaigns

    NASA Astrophysics Data System (ADS)

    Ko, Malcolm; Hu, Wenjie; Rodríguez, José M.; Kondo, Yutaka; Koike, Makoto; Kita, Kazuyuki; Kawakami, Shuji; Blake, Donald; Liu, Shaw; Ogawa, Toshihiro

    2003-02-01

    Using the measured concentrations of NO, O3, H2O, CO, CH4, and NMHCs along the flight tracks, a photochemical box model is used to calculate the concentrations of the Ox radicals, the HOx radicals, and the nitrogen species at the sampling points. The calculations make use of the measurements from radiometers to scale clear sky photolysis rates to account for cloud cover and ground albedo at the sampling time/point. The concentrations of the nitrogen species in each of the sampled air parcels are computed assuming they are in instantaneous equilibrium with the measured NO and O3. The diurnally varying species concentrations are next calculated using the box model and used to estimate the diurnally averaged production and removal rates of ozone for the sampled air parcels. Clear sky photolysis rates are used in the diurnal calculations. The campaign also provided measured concentration of NOy. The observed NO/NOy ratio is usually larger than the model calculated equilibrium value. There are several possible explanations. It could be a result of recent injection of NO into the air parcel, recent removal of HNO3 from the parcel, recent rapid transport of an air parcel from another location, or a combination of all processes. Our analyses suggest that the local production rate of O3 can be used as another indicator of recent NO injection. However, more direct studies using air trajectory analyses and other collaborative evidences are needed to ascertain the roles played by individual process.

  4. Reactive nitrogen oxides and ozone above a taiga woodland

    NASA Technical Reports Server (NTRS)

    Bakwin, Peter S.; Jacob, Daniel J.; Wofsy, Steven C.; Munger, J. William; Daube, Bruce C.; Bradshaw, John D.; Sandholm, Scott T.; Talbot, Robert W.; Singh, Hanwant B.; Gregory, Gerald L.

    1994-01-01

    Measurements of reactive nitrogen oxides (NO(x) and NO(y)) and ozone (O3) were made in the planetary boundary layer (PBL) above a taiga woodland in northern Quebec, Canada, during June-August, 1990, as part of NASA Artic Boundary Layer Expedition (ABLE) 3B. Levels of nitrogen oxides and O3 were strongly modulated by the synoptic scale meteorology that brought air from various source regions to the site. Industrial pollution from the Great Lakes region of the U.S. and Canada appears to be a major source for periodic elevation of NO(x), and NO(y) and O3. We find that NO/NO2 ratios at this site at midday were approximately 50% those expected from a simple photochemical steady state between NO(x) and O3, in contrast to our earlier results from the ABLE 3A tundra site. The difference between the taiga and tundra sites is likely due to much larger emissions of biogenic hydrocarbons (particularly isoprene) from the taiga vegetation. Hydrocarbon photooxidation leads to relatively rapid production of peroxy radicals, which convert NO to NO2, at the taiga site. Ratios of NO(x) to NO(y) were typically 2-3 times higher in the PBL during ABLE 3B than during ABLE 3A. This is probably the result of high PAN levels and suppressed formation of HNO3 from NO2 due to high levels of biogenic hydrocarbons at the ABLE 3B site.

  5. Oxidant and acid aerosol exposure in healthy subjects and subjects with asthma. Part 1. Effects of oxidants, combined with sulfuric or nitric acid, on the pulmonary function of adolescents with asthma. Part 2. Effects of sequential sulfuric acid and ozone exposures on the pulmonary function of healthy subjects and subjects with asthma. Research report, February 1989-April 1994

    SciTech Connect

    Koenig, J.Q.; Covert, D.S.; Pierson, W.E.; Hanley, Q.S.; Rebolledo, V.

    1994-11-01

    The study investigated the pulmonary effects of acid summer haze in a controlled laboratory setting. Of 28 adolescent subjects with allergic asthma, exercise-induced bronchospasm, and a positive response to a standardized methacholine challenge enrolled in the study, 22 completed the study. For two consecutive days each subject inhaled each of four test atmospheres by mouthpiece. The order of exposure to the four test atmospheres was assigned via a random protocol; air, oxidants (0.12 parts per million (ppm) ozone plus 0.30 ppm nitrogen dioxide), oxidants plus sulfuric acid at 70 micro/m3 of air, or oxidants plus 0.05 ppm nitric acid. Exposure to each of the different atmospheres was separated by at least one week. A postexposure methacholine challenge was performed on Day 3.

  6. Aircraft observations above London city during a day and a night: ozone and alkyl nitrate formation

    NASA Astrophysics Data System (ADS)

    Aruffo, Eleonora; Di Carlo, Piero; Dari Salisburgo, Cesare; Biancofiore, Fabio; Giammaria, Franco; Busilacchio, Marcella; Lee, James; Moller, Sarah; Bauguitte, Stephane; O'Sullivan, Debbie; Morgan, Will; Ouyang, Bin; Kennedy, Oliver; Jones, Rod; Forster, Grant; Reeves, Claire; Vaughan, Stewart; Heard, Dwayne

    2013-04-01

    Measurements of NO2, ΣPNs, ΣANs and HNO3 have been done using a TD-LIF instrument, installed on board the FAAM BAe-146 research aircraft, during the RONOCO (ROle of Nighttime chemistry in controlling the Oxidising Capacity) campaign. We analyse in detail the chemical mechanisms that have been established during two flights (B536 and B548) characterized by a similar track (flying above the M25 highway around London) and carried out during a day (B548) and a night (B536). In the daytime flight, the chemical species around London present a net spatial distribution defining two distinct areas: the East London region (up-wind) with an older and less polluted (lowest concentrations of NOx) air masses and the West London region (down-wind) with fresh emissions and more polluted (highest concentrations of NOx with peaks of about 30 ppb). In correspondence of these peaks strong ozone tritation phenomena due to the high NOx levels are verified with a corresponding increase of the ΣANs concentrations. In order to verify the impact of the high concentrations of alkyl nitrate (with maximum values of about 3 ppb) on the tropospheric ozone budget, the production and loss of ozone and ΣANs has been studied. The slopes between the production of ozone and alkyl nitrates confirm that around London the ΣANs formation on one side and the relative ozone loss on the other side represent significant processes. Moreover, the loss of the O3 during the nocturnal flight (B536) is less evident that during the B548 flight.

  7. Acute Ozone-Induced Pulmonary and Systemic Metabolic ...

    EPA Pesticide Factsheets

    Acute ozone exposure increases circulating stress hormones and induces metabolic alterations in animals and humans. We hypothesized that the increase of adrenal-derived stress hormones is necessary for both ozone-induced metabolic effects and lung injury. Male Wistar-Kyoto rats underwent adrenal demedullation (DEMED), total bilateral adrenalectomy (ADREX), or sham surgery (SHAM). After a 4 day recovery, rats were exposed to air or ozone (1ppm), 4h/day for 1 or 2 days. Circulating adrenaline levels dropped to nearly zero in DEMED and ADREX rats relative to air-exposed SHAM. Corticosterone levels tended to be low in DEMED rats and dropped to nearly zero in ADREX rats. Adrenalectomy in air-exposed rats caused modest changes in metabolites and lung toxicity parameters. Ozone-induced hyperglycemia and glucose intolerance were markedly attenuated in DEMED rats with nearly complete reversal in ADREX rats. Ozone increased circulating epinephrine and corticosterone in SHAM but not in DEMED or ADREX rats. Free fatty acids (p=0.15) and branched-chain amino acids increased after ozone exposure in SHAM but not in DEMED or ADREX rats. Lung minute volume was not affected by surgery or ozone but ozone-induced labored breathing was less pronounced in ADREX rats. Ozone-induced increases in lung protein leakage and neutrophilic inflammation were markedly reduced in DEMED and ADREX rats (ADREX>DMED). Ozone-mediated decreases in circulating white blood cells in SHAM were not obser

  8. Acute Ozone-Induced Pulmonary and Systemic Metabolic ...

    EPA Pesticide Factsheets

    Acute ozone exposure increases circulating stress hormones and induces peripheral metabolic alterations in animals and humans. We hypothesized that the increase of adrenal-derived stress hormones is necessary for ozone-induced systemic metabolic effects and lung injury. Male Wistar-Kyoto rats (12 week-old) underwent total bilateral adrenalectomy (ADREX), adrenal demedullation (DEMED) or sham surgery (SHEM). After 4 day recovery, rats were exposed to air or ozone (1ppm), 4h/day for 1 or 2 days. Circulating adrenaline levels dropped to nearly zero in DEMED and ADREX rats relative to air-exposed SHAM. Corticosterone levels tended to be low in DEMED rats and dropped to nearly zero in ADREX rats. Adrenalectomy in air-exposed rats caused modest changes in metabolites and lung toxicity parameters. Ozone-induced hyperglycemia and glucose intolerance were markedly attenuated in DEMED with nearly complete reversal in ADREX rats. Ozone increased circulating epinephrine and corticosterone in SHAM but not in DEMED or ADREX rats. Free fatty acids and branched-chain amino acids tended to increase after ozone exposure in SHAM but not in DEMED or ADREX rats. Lung minute volume was not affected by surgery or ozone but ozone-induced labored breathing was less pronounced in ADREX rats. Ozone-induced increases in lung protein leakage and neutrophilic inflammation were markedly reduced in DEMED and ADREX rats (ADREX>DMED). Ozone-mediated decrease in circulating WBC in SHAM was not

  9. On the coupled chemistry of ozone and organic nitrates as observed in the Uintah Basin, Utah during winter

    NASA Astrophysics Data System (ADS)

    Lee, L.; Wooldridge, P. J.; Gilman, J. B.; Lerner, B. M.; De Gouw, J. A.; Williams, E. J.; Holloway, J. S.; Warneke, C.; Roberts, J. M.; Graus, M.; Cohen, R. C.

    2012-12-01

    Total alkyl nitrates (∑ANs), peroxynitrates (∑PNs) and NO2 were measured using thermal dissociation laser induced fluorescence (TD-LIF) during the 2012 Uintah Basin Winter Ozone Study (UBWOS). The ∑ANs exhibit diurnal variations with a peak at noon indicating photochemical production is occurring. ∑ANs ranged from 0 to 5 ppb with a median value of 1 ppb. From observed ∑ANs, HNO3 and J values we calculate an effective alkyl nitrate formation branching ratio (α) of ~0.15. A similar value is obtained by directly calculating the α using measured VOC composition. The temperature dependence of this chemistry and its effects on O3 production and HOx chain length will be discussed.

  10. Photolysis of RDX in Aqueous Solution, With and Without Ozone

    DTIC Science & Technology

    1979-02-09

    this complex mixture vas treated with ozone,, there was found carbon dioxide , cyanic acid$ nitrate ion, anid ammonia. It’ the RDX so1Qtion is...simultaneously exposed to UV radiation and ozone, there is found carbon dioxide , carbon monoxide., nitrate ion, und ammonia. _ DO ~ 147 EDIIONOP IOY ill...6 Experiment 1. Photolysis of RDX in the presence of ozone; carbon -14 distribution and carbon dioxide formation .......... 6

  11. Thermal hazard evaluation of lauroyl peroxide mixed with nitric acid.

    PubMed

    Tsai, Lung-Chang; You, Mei-Li; Ding, Mei-Fang; Shu, Chi-Min

    2012-07-04

    Many thermal runaway incidents have been caused by organic peroxides due to the peroxy group, -O-O-, which is essentially unstable and active. Lauroyl peroxide (LPO) is also sensitive to thermal sources and is incompatible with many materials, such as acids, bases, metals, and ions. From the thermal decomposition reaction of various concentrations of nitric acid (HNO3) (from lower to higher concentrations) with LPO, experimental data were obtained as to its exothermic onset temperature (T0), heat of decomposition (ΔHd), isothermal time to maximum rate (TMRiso), and other safety parameters exclusively for loss prevention of runaway reactions and thermal explosions. As a novel finding, LPO mixed with HNO3 can produce the detonation product of 1-nitrododecane. We used differential scanning calorimetry (DSC), thermal activity monitor III (TAM III), and gas chromatography/mass spectrometer (GC/MS) analyses of the reactivity for LPO and itself mixed with HNO3 to corroborate the decomposition reactions and reaction mechanisms in these investigations.

  12. Basic Ozone Layer Science

    EPA Pesticide Factsheets

    Learn about the ozone layer and how human activities deplete it. This page provides information on the chemical processes that lead to ozone layer depletion, and scientists' efforts to understand them.

  13. Ozone Trend Detectability

    NASA Technical Reports Server (NTRS)

    Campbell, J. W. (Editor)

    1981-01-01

    The detection of anthropogenic disturbances in the Earth's ozone layer was studied. Two topics were addressed: (1) the level at which a trend in total ozoning is detected by existing data sources; and (2) empirical evidence in the prediction of the depletion in total ozone. Error sources are identified. The predictability of climatological series, whether empirical models can be trusted, and how errors in the Dobson total ozone data impact trend detectability, are discussed.

  14. Ozone Layer Observations

    NASA Technical Reports Server (NTRS)

    McPeters, Richard; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The US National Aeronautics and Space Administration (NASA) has been monitoring the ozone layer from space using optical remote sensing techniques since 1970. With concern over catalytic destruction of ozone (mid-1970s) and the development of the Antarctic ozone hole (mid-1980s), long term ozone monitoring has become the primary focus of NASA's series of ozone measuring instruments. A series of TOMS (Total Ozone Mapping Spectrometer) and SBUV (Solar Backscatter Ultraviolet) instruments has produced a nearly continuous record of global ozone from 1979 to the present. These instruments infer ozone by measuring sunlight backscattered from the atmosphere in the ultraviolet through differential absorption. These measurements have documented a 15 Dobson Unit drop in global average ozone since 1980, and the declines in ozone in the antarctic each October have been far more dramatic. Instruments that measure the ozone vertical distribution, the SBUV and SAGE (Stratospheric Aerosol and Gas Experiment) instruments for example, show that the largest changes are occurring in the lower stratosphere and upper troposphere. The goal of ozone measurement in the next decades will be to document the predicted recovery of the ozone layer as CFC (chlorofluorocarbon) levels decline. This will require a continuation of global measurements of total column ozone on a global basis, but using data from successor instruments to TOMS. Hyperspectral instruments capable of measuring in the UV will be needed for this purpose. Establishing the relative roles of chemistry and dynamics will require instruments to measure ozone in the troposphere and in the stratosphere with good vertical resolution. Instruments that can measure other chemicals important to ozone formation and destruction will also be needed.

  15. Ozone inhibits prostacyclin synthesis in pulmonary endothelium.

    PubMed

    Friedman, M; Madden, M C; Saunders, D S; Gammon, K; White, G C; Kwock, L

    1985-12-01

    The effects of ozone on lung arachidonate metabolism in-vitro were studied in cultured bovine pulmonary endothelial cells exposed for 2 hours to ozone in concentrations up to 1.0 ppm. A concentration-dependent decrease in prostacyclin synthesis was found (90% decrease at the highest ozone level of 1.0 ppm). The inhibition of prostacyclin synthesis was not due to a decreased release of arachidonic acid from membrane lipids. We also examined the hypoxic pulmonary vasoconstrictive response to 10% oxygen inhalation in anesthetized dogs in-vivo after exposure to 1.0 ppm ozone for 1 hour. Pulmonary vascular resistance was significantly increased after ozone exposure, similar to the findings in dogs given indomethacin (15 mg/kg). The percentage change in the hypoxic pulmonary pressor response was similar between the ozone exposure and indomethacin-treated groups, although due to the variance of the pulmonary vascular resistance values during hypoxia the results did not reach statistical significance. These results suggest that ozone inhalation affects pulmonary endothelial arachidonate metabolism in-vivo as well as in-vitro.

  16. New method of treating dilute mineral acids using magnesium-aluminum oxide.

    PubMed

    Kameda, Tomohito; Yabuuchi, Fumiko; Yoshioka, Toshiaki; Uchida, Miho; Okuwaki, Akitsugu

    2003-04-01

    Mineral acids, such as H(3)PO(4), H(2)SO(4), HCl, and HNO(3,) were treated with magnesium-aluminum oxide (Mg-Al oxide), which behaved as a neutralizer and fixative of anions. Anion removal increased with increasing Mg-Al oxide quantity, time, Mg/Al molar ratio, and initial acid concentration. Up to 95% removal of anions was achieved in 0.5 N acids using a stoichiometric quantity of Mg(0.80)Al(0.20)O(1.10) for H(3)PO(4), 1.75 stoichiometric quantities for H(2)SO(4), or 2.5 stoichiometric quantities for HCl or HNO(3) at 20 degrees C over a period of 6 h. The final solutions were found to have a pH in the range of 8-12. Selectivity of acid removal was found to follow the following order: H(3)PO(4) > H(2)SO(4) > HCl > HNO(3). The equivalent of acid removal per 1 g of Mg-Al oxide decreased as the Mg/Al molar ratio of Mg-Al oxide increased.

  17. Ozone drinking water treatment handbook

    SciTech Connect

    Rice, R.G.

    1990-01-01

    This book explains how ozone can be used to provide primary disinfection, while minimizing halogenated by-products. This is of use to those who design pilot plant studies in full scale ozone plants-and those who employ ozone and regulatory personnel. Detailed section on components of an ozonization system outlines feed gas preparation (air and oxygen), ozone generation, ozone contacting, ozone off gas destruction, monitoring and control of ozonation systems, engineering aspects of ozone, cost factors in ozone technology, case histories (European and U.S.).

  18. Ozone Antimicrobial Efficacy

    EPA Science Inventory

    Ozone is a potent germicide that has been used extensively for water purification. In Europe, 90 percent of the municipal water systems are treated with ozone, and in France, ozone has been used to treat drinking water since 1903. However, there is limited information on the bioc...

  19. Photoenhanced degradation of veratraldehyde upon the heterogeneous ozone reactions.

    PubMed

    Net, Sopheak; Gligorovski, Sasho; Pietri, Sylvia; Wortham, Henri

    2010-07-21

    Light-induced heterogeneous reactions between gas-phase ozone and veratraldehyde adsorbed on silica particles were performed. At an ozone mixing ratio of 250 ppb, the loss of veratraldehyde largely increased from 1.81 x 10(-6) s(-1) in the dark to 2.54 x 10(-5) s(-1) upon exposure to simulated sunlight (lambda > 300 nm). The observed rates of degradation exhibited linear dependence with the ozone in the dark ozonolysis experiments which change in the non-linear Langmuir-Hinshelwood dependence in the experiments with simultaneous ozone and light exposure of the coated particles. When the coated silica particles were exposed only to simulated sunlight in absence of ozone the loss of veratraldehyde was about three times higher i.e. 5.97 x 10(-6) s(-1) in comparison to the ozonolysis experiment under dark conditions at 250 ppb ozone mixing ratio, 1.81 x 10(-6) s(-1).These results clearly show that the most important loss of veratraldehyde occurs under simultaneous ozone and light exposure of the coated silica particles. The main identified product in the heterogeneous reactions between gaseous ozone and adsorbed veratraldehyde under dark conditions and in presence of light was veratric acid.Carbon yields of veratric acid were calculated and the obtained results indicated that at low ozone mixing ratio (250 ppb) the carbon yield obtained under dark conditions is 70% whereas the carbon yield obtained in the experiments with simultaneous ozone and light exposure of the coated particles is 40%. In both cases the carbon yield of veratric acid exponentially decayed leading to the plateau ( approximately 35% of carbon yield) at an ozone mixing ratio of 6 ppm. Two reaction products i.e. 3-hydroxy-4-methoxybenzoic acid and 4-hydroxy-3-methoxybenzoic acid were identified (confirmed with the standards) only in the experiments performed under simultaneous ozonolysis and light irradiation of the particles.

  20. Ozonation of sunflower oils: impact of experimental conditions on the composition and the antibacterial activity of ozonized oils.

    PubMed

    Moureu, Sophie; Violleau, Frédéric; Ali Haimoud-Lekhal, Djamila; Calmon, Anne

    2015-02-01

    Ozone can react with vegetable oils to produce ozonized oils which have antimicrobial properties and can be used in dermatology. The aim of this study was to evaluate the influence of ozonation conditions and of the initial fatty acid composition on iodine index (II), peroxide index (IP), acidity value (AV) of ozonized sunflower oils. The antibacterial activity of these products against the three bacterial strains that are more often involved in mastitis (Staphylococcus aureus, Escherichia coli and Streptococcus uberis) was also evaluated. In that purpose, two different sunflower oils have been studied: a "classical" oil (55% linoleic acid, 35% oleic acid) and a "high oleic" oil (90% oleic acid). Both were ozonized with or without water during different times (from 1 to 7 h). Results show that the addition of water has a direct impact on the increase in IP (up to 2600 meq of active oxygen/kg of oil with water and 430 without) and AV but does not influence the kinetic of the decrease in II. Minimal inhibitory concentrations were ranging from 1.25 to 40 mg/mL and the antibacterial activity of oils ozonized with water was better than the one of oils ozonized alone. These results are an open door to new applications of ozonized oils.

  1. Simultaneous depolymerization and decolorization of chitosan by ozone treatment.

    PubMed

    Seo, S; King, J M; Prinyawiwatkul, W

    2007-11-01

    Currently, depolymerization and decolorization of chitosan are achieved by chemical or enzymatic methods, which are time consuming and expensive. Ozone has been shown to be able to degrade macromolecules and remove pigments due to its high oxidation potential. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated. Crawfish chitosan was ozonated in water and acetic acid solution for 0, 5, 10, 15, and 20 min at room temperature with 12 wt% gas. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated by measuring the molecular weight, viscosity, and color of chitosan. The color of ozone-treated chitosan was analyzed using a Minolta spectrophotometer. The degree of deacetylation was determined by a colloid titration method. Molecular weight of ozone-treated chitosan in acetic acid solution decreased appreciably as the ozone treatment duration increased. Ozonation for 20 min reduced the molecular weight of the chitosan by 92% (104 kDa) compared to the untreated chitosan (1333 kDa) with a decrease in viscosity of the chitosan solution. Ozonation for 5 min markedly increased the whiteness of chitosan with a molecular weight of 432 kDa; however, further ozonation resulted in development of yellowness. In the case of the ozonation in water, there were no significant differences in the molecular weight and color between ozone-treated chitosans. This study showed that ozone can be used to modify molecular weight and remove pigments of chitosan without chemical use in a shorter time and with less cost.

  2. Methane production from ozonated pulp mill effluent

    SciTech Connect

    Bremmon, C.E.; Jurgensen, M.F.; Patton, J.T.

    1980-07-01

    A study was made of the production of methane from desugared spent sulfite liquor (SSL) reacted with ozone. The ozonated SSL was fed continuously to three anaerobic fermenters for three months as the sole source of carbon and energy. The fermenters were inoculated with anaerobic bacteria obtained from sewage sludge and acclimated for 1 month in ozonated SSL prior to continuous fermentation. Chemical and biological parameters such as COD, BOD, total sulfur content, redox potential, pH, fatty acid composition, and methane bacteria populations were monitored to determine changes in the SSL during fermentation. Methane production from ozone-treated SSL averaged 1.7 liters/ liter or 17 ml of CH/sub 4/ produced/gram of volatile solids fed. Fatty acis analysis of fermenter effluent indicated a net production of 58 mM/ liter of acetate during ozonated SSL fermentation. This acetic acid production shows future potential for further fermentation by protein-producing yeast. Although the rate of conversion of volatile solids to CH/sub 4/ in this process was not competitive with domestic or agricultural waste digesters, this study did indicate the potential benefits of ozonating organic wastes for increased methane fermentation yields.

  3. The Ozone-Iodine-Chlorate Clock Reaction

    PubMed Central

    Sant'Anna, Rafaela T. P.; Monteiro, Emily V.; Pereira, Juliano R. T.; Faria, Roberto B.

    2013-01-01

    This work presents a new clock reaction based on ozone, iodine, and chlorate that differs from the known chlorate-iodine clock reaction because it does not require UV light. The induction period for this new clock reaction depends inversely on the initial concentrations of ozone, chlorate, and perchloric acid but is independent of the initial iodine concentration. The proposed mechanism considers the reaction of ozone and iodide to form HOI, which is a key species for producing non-linear autocatalytic behavior. The novelty of this system lies in the presence of ozone, whose participation has never been observed in complex systems such as clock or oscillating reactions. Thus, the autocatalysis demonstrated in this new clock reaction should open the possibility for a new family of oscillating reactions. PMID:24386257

  4. The ozone-iodine-chlorate clock reaction.

    PubMed

    Sant'Anna, Rafaela T P; Monteiro, Emily V; Pereira, Juliano R T; Faria, Roberto B

    2013-01-01

    This work presents a new clock reaction based on ozone, iodine, and chlorate that differs from the known chlorate-iodine clock reaction because it does not require UV light. The induction period for this new clock reaction depends inversely on the initial concentrations of ozone, chlorate, and perchloric acid but is independent of the initial iodine concentration. The proposed mechanism considers the reaction of ozone and iodide to form HOI, which is a key species for producing non-linear autocatalytic behavior. The novelty of this system lies in the presence of ozone, whose participation has never been observed in complex systems such as clock or oscillating reactions. Thus, the autocatalysis demonstrated in this new clock reaction should open the possibility for a new family of oscillating reactions.

  5. Application of photochemical indicators to evaluate ozone nonlinear chemistry and pollution control countermeasure in China

    NASA Astrophysics Data System (ADS)

    Xie, Min; Zhu, Kuanguang; Wang, Tijian; Yang, Haoming; Zhuang, Bingliang; Li, Shu; Li, Minggao; Zhu, Xinsheng; Ouyang, Yan

    2014-12-01

    Ozone sensitivity in China was investigated by using a comprehensive three-dimensional air quality model system WRF-CALGRID. A real case and two cases with 35% emission reduction for either NOx or VOC were conducted for the period of March in 2010. The simulation results of O3 agreed fairly well with the observation data. Based on the meaning of O3 sensitivity, the ratio Ra was defined, with the transition value of 1 to distinguish NOx-sensitive region from VOC-sensitive region. With the aid of Ra, VOC- and NOx-sensitive regions in China were preliminary located. The transition ranges for some photochemical indicators were quantified. Only those of H2O2/NOz and H2O2/HNO3 met the requirement that the 95th percentile VOC-sensitive value should be equal to or lower than the 5th percentile NOx-sensitive value. 0.16-0.40 for H2O2/HNO3 and 0.14-0.28 for H2O2/NOz were adopted to distinguish different O3 sensitivity in China. The results showed that the VOC-sensitive regions are primarily distributed over the urban centers and the developed industrial areas in eastern and southern China, while the NOx-sensitive regions are mainly located in the remote areas of northern and western China. High correlation between Ra and indicators was found, and a new approach to quantify the transition values of indicators was proposed. These indicators can play an important role in the air complex pollution control of urban clusters over East Asia.

  6. Improving regional ozone modeling through systematic evaluation of errors using the aircraft observations during the International Consortium for Atmospheric Research on Transport and Transformation

    NASA Astrophysics Data System (ADS)

    Mena-Carrasco, Marcelo; Tang, Youhua; Carmichael, Gregory R.; Chai, Tianfeng; Thongbongchoo, Narisara; Campbell, J. Elliott; Kulkarni, Sarika; Horowitz, Larry; Vukovich, Jeffrey; Avery, Melody; Brune, William; Dibb, Jack E.; Emmons, Louisa; Flocke, Frank; Sachse, Glen W.; Tan, David; Shetter, Rick; Talbot, Robert W.; Streets, David G.; Frost, Gregory; Blake, Donald

    2007-06-01

    During the operational phase of the ICARTT field experiment in 2004, the regional air quality model STEM showed a strong positive surface bias and a negative upper troposphere bias (compared to observed DC-8 and WP-3 observations) with respect to ozone. After updating emissions from NEI 1999 to NEI 2001 (with a 2004 large point sources inventory update), and modifying boundary conditions, low-level model bias decreases from 11.21 to 1.45 ppbv for the NASA DC-8 observations and from 8.26 to -0.34 for the NOAA WP-3. Improvements in boundary conditions provided by global models decrease the upper troposphere negative ozone bias, while accounting for biomass burning emissions improved model performance for CO. The covariances of ozone bias were highly correlated to NOz, NOy, and HNO3 biases. Interpolation of bias information through kriging showed that decreasing emissions in SE United States would reduce regional ozone model bias and improve model correlation coefficients. The spatial distribution of forecast errors was analyzed using kriging, which identified distinct features, which when compared to errors in postanalysis simulations, helped document improvements. Changes in dry deposition to crops were shown to reduce substantially high bias in the forecasts in the Midwest, while updated emissions were shown to account for decreases in bias in the eastern United States. Observed and modeled ozone production efficiencies for the DC-8 were calculated and shown to be very similar (7.8) suggesting that recurring ozone bias is due to overestimation of NOx emissions. Sensitivity studies showed that ozone formation in the United States is most sensitive to NOx emissions, followed by VOCs and CO. PAN as a reservoir of NOx can contribute to a significant amount of surface ozone through thermal decomposition.

  7. Photochemical modeling of the Antarctic stratosphere: Observational constraints from the airborne Antarctic ozone experiment and implications for ozone behavior

    NASA Technical Reports Server (NTRS)

    Rodriguez, Jose M.; Sze, Nien-Dak; Ko, Malcolm K. W.

    1988-01-01

    The rapid decrease in O3 column densities observed during Antarctic spring has been attributed to several chemical mechanisms involving nitrogen, bromine, or chlorine species, to dynamical mechanisms, or to a combination of the above. Chlorine-related theories, in particular, predict greatly elevated concentrations of ClO and OClO and suppressed abundances of NO2 below 22 km. The heterogeneous reactions and phase transitions proposed by these theories could also impact the concentrations of HCl, ClNO3 and HNO3 in this region. Observations of the above species have been carried out from the ground by the National Ozone Expedition (NOZE-I, 1986, and NOZE-II, 1987), and from aircrafts by the Airborne Antarctic Ozone Experiment (AAOE) during the austral spring of 1987. Observations of aerosol concentrations, size distribution and backscattering ratio from AAOE, and of aerosol extinction coefficients from the SAM-II satellite can also be used to deduce the altitude and temporal behavior of surfaces which catalyze heterogeneous mechanisms. All these observations provide important constraints on the photochemical processes suggested for the spring Antarctic stratosphere. Results are presented for the concentrations and time development of key trace gases in the Antarctic stratosphere, utilizing the AER photochemical model. This model includes complete gas-phase photochemistry, as well as heterogeneous reactions. Heterogeneous chemistry is parameterized in terms of surface concentrations of aerosols, collision frequencies between gas molecules and aerosol surfaces, concentrations of HCl/H2O in the frozen particles, and probability of reaction per collision (gamma). Values of gamma are taken from the latest laboratory measurements. The heterogeneous chemistry and phase transitions are assumed to occur between 12 and 22 km. The behavior of trace species at higher altitudes is calculated by the AER 2-D model without heterogeneous chemistry. Calculations are performed for

  8. Effect of acid additives on sugarcane bagasse pyrolysis: Production of high yields of sugars.

    PubMed

    David, Geraldo Ferreira; Perez, Victor Haber; Rodriguez Justo, Oselys; Garcia-Perez, Manuel

    2017-01-01

    The aim of this work was to improve sugarcane bagasse thermochemical conversion to pyrolytic sugars production, particularly to levoglucosan. The experiments were carried out evaluating the effect of acid washing with HNO3 (0.1wt.%) followed by H2SO4 addition (0.1, 0.2 and 0.3wt.%) at pyrolysis temperatures of 350, 400, 450, 500, 550 and 600°C was studied by Py-GC/MS. The experimental results showed that HNO3 washing, followed by H2SO4 concentration of 0.2wt.% at 350°C resulted in an increase in levoglucosan yield between 5 and 7 times the yield obtained when the raw bagasse was processed. Thus, these results are very attractive to improve pyrolytic sugars production in sugarcane bagasse by previously acid treatment to pyrolysis technology.

  9. Enhancement of acidic gases in biomass burning impacted air masses over Canada

    NASA Technical Reports Server (NTRS)

    Lefer, B. L.; Talbot, R. W.; Harriss, R. C.; Bradshaw, J. D.; Sandholm, S. T.; Olson, J. O.; Sachse, G. W.; Collins, J.; Shipham, M. A.; Blake, D. R.

    1994-01-01

    Biomass-burning impacted air masses sampled over central and eastern Canada during the summer of 1990 as part of ABLE 3B contained enhanced mixing ratios of gaseous HNO3, HCOOH, CH3COOH, and what appears to be (COOH)2. These aircraft-based samples were collected from a variety of fresh burning plumes and more aged haze layers from different source regions. Values of the enhancement factor, delta X/delta CO, where X represents an acidic gas, for combustion-impacted air masses sampled both near and farther away from the fires, were relatively uniform. However, comparison of carboxylic acid emission ratios measured in laboratory fires to field plume enhancement factors indicates significant in-plume production of HCOOH. Biomass-burning appears to be an important source of HNO3, HCOOH, and CH3COOH to the troposphere over subarctic Canada.

  10. Nitric acid and ammonia emissions from a mid-latitude prescribed wetlands fire

    NASA Technical Reports Server (NTRS)

    Lebel, P. J.; Cofer, W. R., III; Levine, J. S.; Vay, S. A.; Roberts, P. D.

    1988-01-01

    The first simultaneous measurements of gaseous nitric acid and ammonia in the smoke plume of a wetlands biomass burn were obtained. The measurements were made using tungsten oxide-coated diffusion denuder tubes from a helicopter during a prescribed burn on November 9, 1987, at the Merritt Island National Wildlife Refuge, located at the NASA John F. Kennedy Space Center, Florida. The mean NH3 and HNO3 mixing ratios measured in the smoke plume were 19 ppbv and 14 ppbv, respectively, both significantly higher than background mixing ratios. Nitric acid correlated well with carbon dioxide produced by the combustion. The mean CO2-normalized emission ratio for HNO3 was found to be 0.00012. Ammonia, however, dit not correlate well with CO2, suggesting a more complex relationship between combustion and production/release of NH3.

  11. Advanced treatment of biotreated textile industry wastewater with ozone, virgin/ozonated granular activated carbon and their combination.

    PubMed

    Arslan-Alaton, Idil; Seremet, Ozden

    2004-01-01

    Biotreated textile wastewater (CODo = 248 mg L(-1); TOCo = 58 mg L(-1); A620 = 0.007 cm(-1); A525 = 0.181 cm(-1); A436 = 0.198 cm(-1)) was subjected to advanced treatment with ozonation, granular activated carbon (GAC) adsorption in serial and simultaneous applications. Experiments were conducted to investigate the effects of applied ozone dose, ozone absorption rate, specific ozone absorption efficiency, GAC dose, and reaction pH on the treatment performance of the selected tertiary treatment scheme. In separate experiments, the impact of virgin GAC ozonation on its adsorptive capacity for biotreated and biotreated + ozonated textile effluent was also investigated. Ozonation appeared to be more effective for decolorization (kd = 0.15 min(-1) at pH = 3), whereas GAC adsorption yielded higher COD removal rates (54% at pH = 3). It was also found that GAC addition (4 g/L) at pH = 7 and 9 enhanced the COD abatement rate of the ozonation process significantly and that the sequential application of ozonation (at pH = 3-11, 675 mg L(-1) O3) followed by GAC adsorption (at pH = 3-7, 10 g L(-1) GAC) resulted in the highest treatment performances both in terms of color and COD reduction. Simultaneous application of GAC and ozone at acidic and alkaline pH seriously inhibited COD abatement rates as a consequence of competitive adsorption and partial oxidation of textile components and GAC. It could also be established that ozone absorption efficiency decreased after color removal was complete. Ozonation of biotreated textile wastewater with 113 mg L(-1) ozone resulted in an appreciable enhancement of GAC adsorptive capacity in terms of residual color removal. Ozonation of GAC at relatively low doses (= 10.8 mg/g GAC) did not improve its overall adsorption capacity.

  12. INHALATION OF OZONE AND DIESEL EXHAUST PARTICLES (DEP) INDUCES ACUTE AND REVERSIBLE CARDIAC GENE EXPRESSION CHANGES

    EPA Science Inventory

    We have recently shown that episodic but not acute exposure to ozone or DEP induces vascular effects that are associated with the loss of cardiac mitochondrial phospholipid fatty acids (DEP 2.0 mg/m3 > ozone, 0.4 ppm). In this study we determined ozone and DEP-induced cardiac gen...

  13. Ozone-induced changes in natural organic matter (NOM) structure

    USGS Publications Warehouse

    Westerhoff, P.; Debroux, J.; Aiken, G.; Amy, G.

    1999-01-01

    Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sources and two US fiver systems with terrestrial organic carbon sources, were ozonated. Several analyses, including 13C-NMR, UV absorbance, fluorescence, hydrophobic/transphilic classification, and potentiometric titrations, were performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the samples resulted in increased aliphatic, carboxyl, plus acetal and ketal anomeric carbon content and shifted towards less hydrophobic compounds.Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sources and two US river systems with terrestrial organic carbon sources, were ozonated. Several analyses, including 13C-NMR, UV absorbance, fluorescence, hydrophobic/transphilic classification, and potentiometric titrations, were performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the samples resulted in increased aliphatic, carboxyl, plus acetal and ketal anomeric carbon content and shifted towards less hydrophobic compounds.

  14. Overview of ozone bleaching

    SciTech Connect

    Sonnenberg, L.B.

    1995-12-31

    The potential impact of the pulp and paper industry on the environment may be reduced by replacing chlorine-based bleaching reagents with ozone. The reactivity of ozone coupled with the heterogeneity of pulp allows many types of reactions to occur during pulp bleaching. Ozone cleaves the aromatic rings and side chain double bonds in lignin in Criegee-type mechanisms. Activated carbon-hydrogen bonds are fragmented in lignin side chains, as well as Cl carbons of {beta}-glycosides, by way of a 1,3 dipolar insertion forming a hydrotrioxide intermediate. Ozone also attacks carbohydrates at acetal oxygens, depolymerizing at the glycosidic bond. Unsaturated sites are ozonated before aliphatic sites resulting in a predominance of lignin reactions over carbohydrate reactions until lignin is substantially removed from the pulp. Important factors in the successful application of ozone bleaching include minimizing ozone decomposition and other secondary reactions, reducing exposure of cellulose to high concentrations of ozone and radicals, and promoting uniform exposure of ozone to lignin. The quantity of chlorinated organic compounds in effluents can be drastically reduced by replacing chlorine-based bleaching reagents with ozone; less organochlorine is formed and there can be greater recycle of bleach plant wastes back to the recovery cycle. Recycling of bleach plant waste also reduces total organic loading in the effluent. The toxicity of ozone filtrates is variable compared to conventional filtrates and depends on several parameters including bleaching conditions, biological treatment, and target organisms.

  15. Spring polar ozone behavior

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1992-01-01

    Understanding of the springtime behavior of polar stratospheric ozone as of mid 1990 is summarized. Heterogeneous reactions on polar stratospheric clouds as hypothesis for ozone loss are considered and a simplified description of the behavior of Antarctic ozone in winter and spring is given. Evidence that the situation is more complicated than described by the theory is produced. Many unresolved scientific issues remain and some of the most important problems are identified. Ozone changes each spring since 1979 have clearly established for the first time that man made chlorine compounds influence stratospheric ozone. Long before important advances in satellite and in situ investigations, it was Dobson's decision to place a total ozone measuring spectrometer at Halley Bay in Antarctica during the International Geophysical Year and subsequent continuous monitoring which led to the discovery that ozone was being destroyed each spring by chlorine processed by polar stratospheric clouds.

  16. Ozone and the stratosphere

    NASA Technical Reports Server (NTRS)

    Shimazaki, Tatsuo

    1987-01-01

    It is shown that the stratospheric ozone is effective in absorbing almost all radiation below 300 nm at heights below 300 km. The distribution of global ozone in the troposphere and the lower stratosphere, and the latitudinal variations of the total ozone column over four seasons are considered. The theory of the ozone layer production is discussed together with catalytic reactions for ozone loss and the mechanisms of ozone transport. Special attention is given to the anthropogenic perturbations, such as SST exhaust gases and freon gas from aerosol cans and refrigerators, that may cause an extensive destruction of the stratospheric ozone layer and thus have a profound impact on the world climate and on life.

  17. Origin and Variability of Upper Tropospheric Nitrogen Oxides and Ozone at Northern Mid-Latitudes

    NASA Technical Reports Server (NTRS)

    Grewe, V.; Brunner, D.; Dameris, M.; Grenfell, J. L.; Hein, R.; Shindell, D.; Staehelin, J.

    1999-01-01

    Measurements of NO(x) and ozone performed during the NOXAR project are compared with results from the coupled chemistry-climate models ECHAM4.L39(DLR)/CHEM and GISS-model. The measurements are based on flights between Europe and the East coast of America and between Europe and the Far East in the latitude range 40 deg N to 65 deg N. The comparison concentrates on tropopause altitudes and reveals strong longitudinal variations of seasonal mean NO,, of 200 pptv. Either model reproduced strong variations 3 km below but not at the tropopause, indicating a strong missing NO(x) or NO(y) sink over remote areas, e.g. NO(x) to HNO3 conversion by OH from additional OH sources or HNO3 wash-out. Vertical profiles show maximum NO(x) values 2-3 km below the tropopause with a strong seasonal cycle. ECHAM4.L39(DLR)/CHEM reproduces a maximum, although located at the tropopause with a less pronounced seasonal cycle, whereas the GISS model reproduces the seasonal cycle but not the profile's shape due to its coarser vertical resolution. A comparison of NO(x) frequency distributions reveals that both models are capable of reproducing the observed variability, except that ECHAM4.L39(DLR)/CHEM shows no very high NO(x) mixing ratios. Ozone mean values, vertical profiles and frequency distributions are much better reproduced in either model, indicating that the NO(x) frequency distribution, namely the most frequent NO(x) mixing ratio, is more important for the tropospheric photochemical ozone production than its mean value. Both models show that among all sources, NO(x) from lightning contributes most to the seasonal cycle of NO(x) at tropopause altitudes. The impact of lightning in the upper troposphere on NO(x) does not vary strongly with altitude, whereas the impact of surface emissions decreases with altitude. However, the models show significant differences in lightning induced NO(x) concentrations, especially in winter, which may be related to the different treatment of the lower

  18. Densities and apparent molar volumes of atmospherically important electrolyte solutions. 1. The solutes H2SO4, HNO3, HCl, Na2SO4, NaNO3, NaCl, (NH4)2SO4, NH4NO3, and NH4Cl from 0 to 50 °C, including extrapolations to very low temperature and to the pure liquid state, and NaHSO4, NaOH, and NH3 at 25 °C.

    PubMed

    Clegg, S L; Wexler, A S

    2011-04-21

    Calculations of the size and density of atmospheric aerosols are complicated by the fact that they can exist at concentrations highly supersaturated with respect to dissolved salts and supercooled with respect to ice. Densities and apparent molar volumes of solutes in aqueous solutions containing the solutes H(2)SO(4), HNO(3), HCl, Na(2)SO(4), NaNO(3), NaCl, (NH(4))(2)SO(4), NH(4)NO(3), and NH(4)Cl have been critically evaluated and represented using fitted equations from 0 to 50 °C or greater and from infinite dilution to concentrations saturated or supersaturated with respect to the dissolved salts. Using extrapolated densities of high-temperature solutions and melts, the relationship between density and concentration is extended to the hypothetical pure liquid solutes. Above a given reference concentration of a few mol kg(-1), it is observed that density increases almost linearly with decreasing temperature, and comparisons with available data below 0 °C suggest that the fitted equations for density can be extrapolated to very low temperatures. As concentration is decreased below the reference concentration, the variation of density with temperature tends to that of water (which decreases as temperature is reduced below 3.98 °C). In this region below the reference concentration, and below 0 °C, densities are calculated using extrapolated apparent molar volumes which are constrained to agree at the reference concentrations with an equation for the directly fitted density. Calculated volume properties agree well with available data at low temperatures, for both concentrated and dilute solutions. Comparisons are made with literature data for temperatures of maximum density. Apparent molar volumes at infinite dilution are consistent, on a single ion basis, to better than ±0.1 cm(3) mol(-1) from 0 to 50 °C. Volume properties of aqueous NaHSO(4), NaOH, and NH(3) have also been evaluated, at 25 °C only. In part 2 of this work (ref 1 ) an ion interaction (Pitzer

  19. Interaction of Peroxynitric Acid with Solid H2O Ice

    NASA Technical Reports Server (NTRS)

    Li, Zhuangjie; Friedl, Randall R.; Moore, Steven B.; Sander, Stanley P.

    1996-01-01

    The uptake of peroxynitric acid (PNA), HO2NO2 or HNO4, on solid H2O ice at 193 K (-80 C) was studied using a fast flow-mass spectrometric technique. An uptake coefficient of 0.15 +/- 0.10 was measured, where the quoted uncertainty denotes 2 standard deviations. The uptake process did not result in the production of gas phase products. The composition of the condensed phase was investigated using programmed heating (3 K/min) of the substrate coupled with mass spectrometric detection of desorbed species. Significant quantities of HNO, and HNO3 desorbed from the substrates at temperatures above 225 K and 246 K, respectively. The desorbed HNO3, which was less than 9% of the desorbed HNO, and remained unchanged upon incubation of the substrate, was likely due to impurities in the HNO4 samples rather than reaction of HNO, on the substrate. The onset temperatures for HNO4 desorption increased with increasing H2O to HNO4 ratios, indicating that HNO4, like HNO3, tends to be hydrated in the presence of water. These observations suggest possible mechanisms for removal of HNO4 or repartitioning of total odd nitrogen species in the Earth's upper troposphere and stratosphere.

  20. Heterogeneous conversion of calcite aerosol by nitric acid.

    PubMed

    Preszler Prince, A; Grassian, V H; Kleiber, P; Young, M A

    2007-02-07

    The reaction of nitric acid with calcite aerosol at varying relative humidities has been studied under suspended particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reactant concentration in the chamber, as well as the appearance of gas phase products and surface adsorbed species, was spectroscopically monitored before and after mixing with CaCO(3) (calcite) particles. The interaction with HNO(3) was found to lead to gas phase CO(2) evolution and increased water uptake due to heterogeneous conversion of the carbonate to particulate nitrate. The reaction was enhanced as the relative humidity of the system was increased, especially at relative humidities above the reported deliquescence point of particulate Ca(NO(3))(2). The measured reaction extent demonstrates that the total calcite particulate mass is available for reaction with HNO(3) and the conversion process is not limited to the particle surface. The spectroscopy of the surface formed nitrate suggests a highly concentrated solution environment with a significant degree of ion pairing. The implications of the HNO(3) loss and the formation of the particulate nitrate product for atmospheric chemistry are discussed.

  1. Why unprecedented ozone loss in the Arctic in 2011? Is it related to climatic change?

    NASA Astrophysics Data System (ADS)

    Pommereau, J.-P.; Goutail, F.; Lefèvre, F.; Pazmino, A.; Adams, C.; Dorokhov, V.; Eriksen, P.; Kivi, R.; Stebel, K.; Zhao, X.; van Rozendael, M.

    2013-01-01

    An unprecedented ozone loss occurred in the Arctic in spring 2011. The details of the event are re-visited from the twice-daily total ozone and NO2 columns measurements of the eight SAOZ/NDACC (Système d'Analyse par Observation Zénitale/Network for Detection of Atmospheric Composition Changes) stations in the Arctic. It is shown that the total ozone depletion in the polar vortex reached 38% (approx. 170 DU) by the end of March that is larger than the 30% of the previous record in 1996. Asides from the long extension of the cold stratospheric NAT PSC period, the amplitude of the event is shown to be resulting from a record daily total ozone loss rate of 0.7% day-1 after mid-February, never seen before in the Arctic but similar to that observed in the Antarctic over the last 20 yr. This high loss rate is attributed to the absence of NOx in the vortex until the final warming, in contrast to all previous winters where, as shown by the early increase of NO2 diurnal increase, partial renoxification is occurring by import of NOx or HNO3 from the outside after minor warming episodes, leading to partial chlorine deactivation. The cause of the absence of renoxification and thus of high loss rate, is attributed to a vortex strength similar to that of the Antarctic but never seen before in the Arctic. The total ozone reduction on 20 March was identical to that of the 2002 Antarctic winter, which ended around 20 September, and a 15-day extension of the cold period would have been enough to reach the mean yearly amplitude of the Antarctic ozone hole. However there is no sign of trend since 1994, neither in PSC volume, early winter denitrification, late vortex renoxification, and vortex strength nor in total ozone loss. The unprecedented large Arctic ozone loss in 2011 appears to resulting from an extreme meteorological event and there is no indication of possible strengthening related to climate change.

  2. Why unprecedented ozone loss in the Arctic in 2011? Is it related to climate change?

    NASA Astrophysics Data System (ADS)

    Pommereau, J.-P.; Goutail, F.; Lefèvre, F.; Pazmino, A.; Adams, C.; Dorokhov, V.; Eriksen, P.; Kivi, R.; Stebel, K.; Zhao, X.; van Roozendael, M.

    2013-05-01

    An unprecedented ozone loss occurred in the Arctic in spring 2011. The details of the event are revisited from the twice-daily total ozone and NO2 column measurements of the eight SAOZ/NDACC (Système d'Analyse par Observation Zénithale/Network for Detection of Atmospheric Composition Changes) stations in the Arctic. It is shown that the total ozone depletion in the polar vortex reached 38% (approx. 170 DU) by the end of March, which is larger than the 30% of the previous record in 1996. Aside from the long extension of the cold stratospheric NAT PSC period, the amplitude of the event is shown to be resulting from a record daily total ozone loss rate of 0.7% d-1 after mid-February, never seen before in the Arctic but similar to that observed in the Antarctic over the last 20 yr. This high loss rate is attributed to the absence of NOx in the vortex until the final warming, in contrast to all previous winters where, as shown by the early increase of NO2 diurnal increase, partial renoxification occurs by import of NOx or HNO3 from the outside after minor warming episodes, leading to partial chlorine deactivation. The cause of the absence of renoxification and thus of high loss rate, is attributed to a vortex strength similar to that of the Antarctic but never seen before in the Arctic. The total ozone reduction on 20 March was identical to that of the 2002 Antarctic winter, which ended around 20 September, and a 15-day extension of the cold period would have been enough to reach the mean yearly amplitude of the Antarctic ozone hole. However there is no sign of trend since 1994, either in PSC (polar stratospheric cloud) volume (volume of air cold enough to allow formation of PSCs), early winter denitrification, late vortex renoxification, and vortex strength or in total ozone loss. The unprecedented large Arctic ozone loss in 2011 appears to result from an extreme meteorological event and there is no indication of possible strengthening related to climate change.

  3. Heterogeneous Reactions of ClONO2, HCl, and HOCl on Liquid Sulfuric Acid Surfaces

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Leu, Ming-Taun; Keyser, Leon F.

    1994-01-01

    The heterogeneous reactions of ClONO2 + H2O yields HNO3 + HOCl (1), ClONO2 + HCl yields C12 + HNO3 (2), and HOCl + HCl yields Cl2 + H2O (3) on liquid sulfuric acid surfaces have been studied using a fast flow reactor coupled to a quadrupole mass spectrometer. The main objectives of the study are to investigate: (a) the temperature dependence of these reactions at a fixed H2O partial pressure typical of the lower stratosphere (that is, by changing temperature at a constant water partial pressure, the H2SO4 content of the surfaces is also changed), (b) the relative importance or competition between reactions 1 and 2, and (c) the effect of HNO3 on the reaction probabilities due to the formation of a H2SO4/HNO3/H2O ternary system. The measurements show that all the reactions depend markedly on temperature at a fixed H2O partial pressure: they proceed efficiently at temperatures near 200 K and much slower at temperatures near 220 K. The reaction probability (gamma(sub 1)) for ClONO2 hydrolysis approaches 0.01 at temperatures below 200 K, whereas the values for gamma(sub 2) and gamma(sub 3) are on the order of a few tenths at 200 K. Although detailed mechanisms for these reactions are still unknown, the present data indicate that the competition between ClONO2 hydrolysis and ClONO2 reaction with HCl may depend on temperature (or H2SO4 Wt %): in the presence of gaseous HCl at stratospheric concentrations, reaction 2 is dominant at lower temperatures (less than 200 K), but reaction 1 becomes important at temperatures above 210 K. Furthermore, reaction probability measurements performed on the H2SO4/HNO3/ H2O ternary solutions do not exhibit noticeable deviation from those performed on the H2SO4/H2O binary system, suggesting little effect of HNO3 in sulfate aerosols on the ClONO2 and HOCl reactions with HCl. The results reveal that significant reductions in the chlorine-containing reservoir species (such as ClONO2 and HCl) can take place on stratospheric sulfate aerosols at

  4. Role of heterogeneous conversion of N2O5 on sulphate aerosols in global ozone losses

    NASA Technical Reports Server (NTRS)

    Rodriguez, Jose M.; Ko, Malcolm K. W.; Sze, Nien D.

    1991-01-01

    The reaction rate of N2O5 on sulphate aerosols is included in a model to predict global ozone loss and the column abundances of atmospheric gases. Because the reaction of N2O5 and the aerosols can take place in the stratospheric sulphate aerosol layer, it is included in the 2D model so that the results can be compared to abundances derived from satellite data and ground-based measurements. The N2O5/sulphate reaction is the only heterogeneous reaction in the model, in which aerosol loading is assumed to be constant and only diurnal values are examined. The decadal ozone trends resulting from calculations based on the model are found to be closer to the observed values. An important conclusion is that measurements of OH, ClO, HNO3, NO, and NO2 in the region of about 14-25 km are needed to examine significant changes in their abundances resulting from the inclusion of the N2O5/sulphate aerosol reaction.

  5. Ozone therapy in periodontics.

    PubMed

    Gupta, G; Mansi, B

    2012-02-22

    Gingival and Periodontal diseases represent a major concern both in dentistry and medicine. The majority of the contributing factors and causes in the etiology of these diseases are reduced or treated with ozone in all its application forms (gas, water, oil). The beneficial biological effects of ozone, its anti-microbial activity, oxidation of bio-molecules precursors and microbial toxins implicated in periodontal diseases and its healing and tissue regeneration properties, make the use of ozone well indicated in all stages of gingival and periodontal diseases. The primary objective of this article is to provide a general review about the clinical applications of ozone in periodontics. The secondary objective is to summarize the available in vitro and in vivo studies in Periodontics in which ozone has been used. This objective would be of importance to future researchers in terms of what has been tried and what the potentials are for the clinical application of ozone in Periodontics.

  6. Ozone therapy in periodontics

    PubMed Central

    Gupta, G; Mansi, B

    2012-01-01

    Gingival and Periodontal diseases represent a major concern both in dentistry and medicine. The majority of the contributing factors and causes in the etiology of these diseases are reduced or treated with ozone in all its application forms (gas, water, oil). The beneficial biological effects of ozone, its anti-microbial activity, oxidation of bio-molecules precursors and microbial toxins implicated in periodontal diseases and its healing and tissue regeneration properties, make the use of ozone well indicated in all stages of gingival and periodontal diseases. The primary objective of this article is to provide a general review about the clinical applications of ozone in periodontics. The secondary objective is to summarize the available in vitro and in vivo studies in Periodontics in which ozone has been used. This objective would be of importance to future researchers in terms of what has been tried and what the potentials are for the clinical application of ozone in Periodontics. PMID:22574088

  7. Tropospheric Ozone Changes

    NASA Astrophysics Data System (ADS)

    Oltmans, S. J.; Lefohn, A. S.; Scheel, H.; Brunke, E. G.; Claude, H.; Tarasick, D. W.; Galbally, I.; Bodeker, G.; Redondas, A.; Simmonds, P.; Koide, T.; Schmidlin, F. J.; Harris, J. M.; Johnson, B. J.; Davies, J.; Cuevas, E.; Meyer, C.; Shadwick, D.

    2008-12-01

    Growing recognition of the role of "background" tropospheric ozone on climate forcing and as a boundary condition for air quality changes highlights the importance of obtaining a broad picture of tropospheric ozone changes. Key surface and ozonesonde observing sites with tropospheric ozone measurement records longer than ~15 years have been selected to characterize longer term tropospheric ozone changes over broad geographic regions. The sites chosen vary from those with minimal impact by local ozone pollution sources to those that are in relatively close proximity to ozone precursor emissions and are thus affected in part by these sources. Consideration is given to the extent to which various time series represent broad geographic scales. Some series with more limited geographic representativeness can provide valuable information because of the length of the record, particularly in an underrepresented region. The vertical profile information from the ozonesonde stations, which have some of the longest tropospheric ozone records, provides a unique perspective on ozone in the free troposphere that is much less influenced by more local conditions. The general slowing or flattening of ozone increases seen at a number of locations beginning in the early 1990s has generally continued. At Naha, Japan there has been a significant increase in recent years that has not been seen at other Japanese ozonesonde locations. At high latitudes over North America a decade long decline in tropospheric ozone beginning in the 1980s has generally reversed with amounts now similar to those at the beginning of the record. In the S.H. several sites in the mid latitudes have shown significant increases. Although some overall patterns on changes emerge on regional scales and in some cases on continental scales, more general conclusions on hemispheric and global scales do not emerge. This is likely consistent with the varied pattern of ozone lifetimes, precursor emission changes, and

  8. The Antarctic ozone hole

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.

    1988-01-01

    Processes that may be responsible for the thinning in the ozone layer above the South Pole are described. The chlorine catalytic cycle which destroys ozone is described, as are the major types of reactions that are believed to interfere with this cycle by forming chlorine reservoirs. The suspected contributions of polar stratospheric clouds to these processes are examined. Finally, the possibility that the ozone hole may be due more to a shift in atmospheric dynamics than to chemical destruction is addressed.

  9. Fourier transform infrared studies of model polar stratospheric cloud surfaces - Growth and evaporation of ice and nitric acid/ice

    NASA Technical Reports Server (NTRS)

    Tolbert, Margaret A.; Middlebrook, Ann M.

    1990-01-01

    Fourier-transform infrared surface studies are used to probe the microphysical properties of nitric acid trihydrate (NAT) and ice films representative of type I and II polar stratospheric clouds (PSC). Experiments indicate that, on initial exposure to 1.8 microtorr of HNO3, a layer of ice is quantitatively converted to NAT. However, conversion of ice to NAT does not proceed indefinitely, but rather the system reaches saturation. For longer exposures or higher HNO3 pressures, NAM becomes the dominant nitric acid containing species on the surface. Evaporation studies were performed to test the feasibility of a recent denitrification mechanism. The results indicate that ice coated with 0.20 micron of NAT evaporates at a temperature of about 4 C higher than uncoated ice.

  10. SMM mesospheric ozone measurements

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.

    1990-01-01

    The main objective was to understand the secular and seasonal behavior of ozone in the lower mesosphere, 50 to 70 km. This altitude region is important in understanding the factors which determine ozone behavior. A secondary objective is the study of stratospheric ozone in the polar regions. Use is made of results from the SBUV satellite borne instrument. In the Arctic the interaction between chlorine compounds and low molecular weight hydrocarbons is studied. More than 30,000 profiles were obtained using the UVSP instrument on the SMM spacecraft. Several orbits of ozone data per day were obtained allowing study of the current rise in solar activity from the minimum until the present. Analysis of Nimbus 7 SBUV data in Antarctic spring indicates that ozone is depleted within the polar vortex relative to ozone outside the vortex. This depletion confirms the picture of ozone loss at altitudes where polar stratospheric clouds exist. In addition, there is ozone loss above the cloud level indicating that there is another mechanism in addition to ozone loss initiated by heterogeneous chlorine reactions on cloud particles.

  11. Evaluation of sampling methods for measuring exposure to volatile inorganic acids in workplace air. Part 1: sampling hydrochloric acid (HCl) and nitric acid (HNO₃) from a test gas atmosphere.

    PubMed

    Howe, Alan; Musgrove, Darren; Breuer, Dietmar; Gusbeth, Krista; Moritz, Andreas; Demange, Martine; Oury, Véronique; Rousset, Davy; Dorotte, Michel

    2011-08-01

    Historically, workplace exposure to the volatile inorganic acids hydrochloric acid (HCl) and nitric acid (HNO(3)) has been determined mostly by collection on silica gel sorbent tubes and analysis of the corresponding anions by ion chromatography (IC). However, HCl and HNO(3) can be present in workplace air in the form of mist as well as vapor, so it is important to sample the inhalable fraction of airborne particles. As sorbent tubes exhibit a low sampling efficiency for inhalable particles, a more suitable method was required. This is the first of two articles on "Evaluation of Sampling Methods for Measuring Exposure to Volatile Inorganic Acids in Workplace Air" and describes collaborative sampling exercises carried out to evaluate an alternative method for sampling HCl and HNO(3) using sodium carbonate-impregnated filters. The second article describes sampling capacity and breakthrough tests. The method was found to perform well and a quartz fiber filter impregnated with 500 μL of 1 M Na(2)CO(3) (10% (m/v) Na(2)CO(3)) was found to have sufficient sampling capacity for use in workplace air measurement. A pre-filter is required to remove particulate chlorides and nitrates that when present would otherwise result in a positive interference. A GSP sampler fitted with a plastic cone, a closed face cassette, or a plastic IOM sampler were all found to be suitable for mounting the pre-filter and sampling filter(s), but care has to be taken with the IOM sampler to ensure that the sampler is tightly closed to avoid leaks. HCl and HNO(3) can react with co-sampled particulate matter on the pre-filter, e.g., zinc oxide, leading to low results, and stronger acids can react with particulate chlorides and nitrates removed by the pre-filter to liberate HCl and HNO(3), which are subsequently collected on the sampling filter, leading to high results. However, although there is this potential for both positive and negative interferences in the measurement, these are unavoidable

  12. Evidence That Nitric Acid Increases Relative Humidity in Low-Temperature Cirrus Clouds

    NASA Technical Reports Server (NTRS)

    Gao, R. S.; Popp, P. J.; Fahey, D. W.; Marcy, T. P.; Herman, R. L.; Weinstock, E. M.; Baumgardner, D. G.; Garrett, T. J.; Rosenlof, K. H.; Thompson, T. L.

    2004-01-01

    In situ measurements of the relative humidity with respect to ice (RH(sub(i)) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RH(sub i) values show a sharp increase to average values of over 130% in both cloud types. These enhanced RH(sub i) values are attributed to the presence of a new class of NHO3- containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor.

  13. Treatment of ammonia contaminated water by ozone and hydrogen peroxide

    SciTech Connect

    Yuan, F.; Hill, D.O.; Kuo, C.H.

    1995-12-31

    The present research concerns kinetics of oxidation of ammonia by ozone and ozone-hydrogen peroxide mixtures in alkaline solutions. Experiments were carried out at 15 to 35{degrees}C in solutions with pH values varying from 8 to 10 utilizing a stopped-flow spectrophotometer system. Fractions of free ammonia present in acidic and neutral solutions are negligible, and the reaction is very slow. This confirms that only free ammonia can react with ozone in the aqueous phase. The reaction proceeds at moderate rates in the alkaline solutions requiring four moles of ozone to react with each mole of ammonia. The free ammonia is oxidized and converted completely to nitrate in the solutions. The overall reaction between ammonia and ozone is second order with first order in each reactant. The reaction rate constant increases with temperature and pH value of the solution. The average activation energy is 59 Kcal/gmol for all systems investigated at different pH values. The results of the kinetic experiments suggest that the reaction is predominated by the direct oxidation between ammonia and ozone molecules, and that the hydroxyl radical reactions play insignificant roles in the ozonation process. The oxidation rate of ammonia is enhanced considerably in the presence of hydrogen peroxide and ozone mixtures. The formation of hydroxyl radical from interactions between ozone and hydrogen peroxide and the subsequent free radical reactions of ammonia seem important in controlling the destruction rate of free ammonia, as suggested by the results of this study.

  14. Growth, physiological and biochemical response of ponderosa pine pinus ponderosa' to ozone. Final report

    SciTech Connect

    Temple, P.J.; Bytnerowicz, A.

    1993-11-01

    In 1989 and 1990, the effects of multi-year ozone exposures on growth, foliar injury and physiological responses in ponderosa pine were examined. Two-year old seedlings were exposed to four ozone treatments in open-top chambers: clean air (subambient levels of oxidants and particles); ambient ozone; twice-ambient ozone; or ambient air. The study was performed at Shirley Meadow in the southern Sierra Nevada. In both years, ambient ozone levels were representative of other forests in the region. While ozone is the most phytotoxic air pollutant, seedlings also experienced elevated concentrations of nitric acid and ammonia. In 1990, ambient ozone significantly increased injury to previous year needles. Premature senescence and alterations in physiological responses were also noted. Exposure to twice-ambient ozone reduced seedling biomass, increased injury and caused decreases in a variety of physiological responses.

  15. Wintertime nitric acid chemistry - Implications from three-dimensional model calculations

    NASA Technical Reports Server (NTRS)

    Rood, Richard B.; Kaye, Jack A.; Douglass, Anne R.; Allen, Dale J.; Steenford, Stephen

    1990-01-01

    A three-dimensional simulation of the evolution of HNO3 has been run for the winter of 1979. Winds and temperatures are taken from a stratospheric data assimilation analysis, and the chemistry is based on Limb Infrared Monitor of the Stratosphere (LIMS) observations. The model is compared to LIMS observations to investigate the problem of 'missing' nitric acid chemistry in the winter hemisphere. Both the model and observations support the contention that a nitric acid source is needed outside of the polar vortex and north of the subtropics. Observations suggest that HNO3 is not dynamically controlled in middle latitudes. The model shows that given the time scales of conventional chemistry, dynamical control is expected. Therefore, an error exists in the conventional chemistry or additional processes are needed to bring the model and data into agreement. Since the polar vortex is dynamically isolated from the middle latitudes, and since the highest HNO3 values are observed in October and November, a source associated solely with polar stratospheric clouds cannot explain the deficiencies in the chemistry. The role of heterogeneous processes on background aerosols is reviewed in light of these results.

  16. Timescale for hygroscopic conversion of calcite mineral particles through heterogeneous reaction with nitric acid.

    PubMed

    Sullivan, Ryan C; Moore, Meagan J K; Petters, Markus D; Kreidenweis, Sonia M; Roberts, Greg C; Prather, Kimberly A

    2009-09-28

    Atmospheric heterogeneous reactions can potentially change the hygroscopicity of atmospheric aerosols as they undergo chemical aging processes in the atmosphere. A particle's hygroscopicity influences its cloud condensation nuclei (CCN) properties with potential impacts on cloud formation and climate. In this study, size-selected calcite mineral particles were reacted with controlled amounts of nitric acid vapour over a wide range of relative humidities in an aerosol flow tube to study the conversion of insoluble and thus apparently non-hygroscopic calcium carbonate into soluble and hygroscopic calcium nitrate. The rate of hygroscopic change particles undergo during a heterogeneous reaction is derived from experimental measurements for the first time. The chemistry of the reacted particles was determined using an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS) while the particles' hygroscopicity was determined through measuring CCN activation curves fit to a single parameter of hygroscopicity, kappa. The reaction is rapid, corresponding to atmospheric timescales of hours. At low to moderate HNO3 exposures, the increase in the hygroscopicity of the particles is a linear function of the HNO3(g) exposure. The experimentally observed conversion rate was used to constrain a simple but accurate kinetic model. This model predicts that calcite particles will be rapidly converted into hygroscopic particles (kappa>0.1) within 4 h for low HNO3 mixing ratios (10 pptv) and in less than 3 min for 1000 pptv HNO3. This suggests that the hygroscopic conversion of the calcite component of atmospheric mineral dust aerosol will be controlled by the availability of nitric acid and similar reactants, and not by the atmospheric residence time.

  17. Control of the red tide dinoflagellate Cochlodinium polykrikoides by ozone in seawater.

    PubMed

    Shin, Minjung; Lee, Hye-Jin; Kim, Min Sik; Park, Noh-Back; Lee, Changha

    2017-02-01

    The inactivation of C. polykrikoides, a red tide dinoflagellate, by ozonation was investigated in seawater by monitoring numbers of viable and total cells. Parameters affecting the inactivation efficacy of C. polykrikoides such as the ozone dose, initial cell concentration, pH, and temperature were examined. The viable cell number rapidly decreased in the initial stage of the reaction (mostly in 1-2 min), whereas the decrease in total cell number was relatively slow and steady. Increasing ozone dose and decreasing initial cell concentration increased the inactivation efficacy of C. polykrikoides, while increasing pH and temperature decreased the cell inactivation efficacy. The addition of humic acid (a promoter for the ozone decomposition) inhibited the inactivation of C. polykrikoides, whereas bicarbonate ion (an inhibitor for the ozone decomposition) accelerated the C. polykrikoides inactivation. Observations regarding the effects of pH, temperature, humic acid, and bicarbonate ion collectively indicate that the inactivation of C. polykrikoides by ozonation is mainly attributed to oxidative cell damages by molecular ozone, rather than by hydroxyl radical, produced during the ozone decomposition. At high ozone dose (e.g., 5 mg/L), hypobromous acid formed by the reaction of bromide with ozone may partially contribute to cell inactivation. The use of ozone of less than 1 mg/L produced 0.75-2.03 μg/L bromate.

  18. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Fioletov, Vitali; Bishop, Lane; Godin, Sophie; Bojkov, Rumen D.; Kirchhoff, Volker; Chanin, Marie-Lise; Zawodny, Joseph M.; Zerefos, Christos S.; Chu, William

    1991-01-01

    An update of the extensive reviews of the state of knowledge of measured ozone trends published in the Report of the International Ozone Trends Panel is presented. The update contains a review of progress since these reports, including reviewing of the ozone records, in most cases through March 1991. Also included are some new, unpublished reanalyses of these records including a complete reevaluation of 29 stations located in the former Soviet Union. The major new advance in knowledge of the measured ozone trend is the existence of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer (TOMS) and Stratospheric Aerosol and Gas Experiment (SAG) instruments. These confirm many of the findings, originally derived from the Dobson record, concerning northern mid-latitude changes in ozone. We now have results from several instruments, whereas the previously reported changes were dependent on the calibration of a single instrument. This update will compare the ozone records from many different instruments to determine whether or not they provide a consistent picture of the ozone change that has occurred in the atmosphere. The update also briefly considers the problem of stratospheric temperature change. As in previous reports, this problem received significantly less attention, and the report is not nearly as complete. This area needs more attention in the future.

  19. Saving Our Ozone Shield.

    ERIC Educational Resources Information Center

    Lacoste, Beatrice

    1992-01-01

    Discusses the introduction and continued use of chlorofluorocarbons (CFCs) as related to stratospheric ozone depletion. Presents the characteristics of CFCs conducive to the chemical reaction with ozone, the history of CFC use and detection of related environmental problems, health hazards, and alternatives to CFC use. (MCO)

  20. Polar Ozone Workshop. Abstracts

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1988-01-01

    Results of the proceedings of the Polar Ozone Workshop held in Snowmass, CO, on May 9 to 13, 1988 are given. Topics covered include ozone depletion, ozonometry, polar meteorology, polar stratospheric clouds, remote sensing of trace gases, atmospheric chemistry and dynamical simulations.

  1. The Antarctic Ozone Hole.

    ERIC Educational Resources Information Center

    Stolarski, Richard S.

    1988-01-01

    Discusses the Airborne Antarctic Ozone Experiment (1987) and the findings of the British Antarctic Survey (1985). Proposes two theories for the appearance of the hole in the ozone layer over Antarctica which appears each spring; air pollution and natural atmospheric shifts. Illustrates the mechanics of both. Supports worldwide chlorofluorocarbon…

  2. Observing trends in total ozone and extreme ozone events

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2014-05-01

    The ozone layer in the stratosphere has been recovering since the 1989 Montreal Protocol reduced the use of ozone-destroying chlorofluorocarbons. Fitzka et al. observed trends in total ozone levels and the vertical distribution of ozone at Hoher Sonnblick, a mountain in Austria, from 1994 to 2011.

  3. Natural emissions under future climate condition and their effects on surface ozone in the Yangtze River Delta region, China

    NASA Astrophysics Data System (ADS)

    Xie, Min; Shu, Lei; Wang, Ti-jian; Liu, Qian; Gao, Da; Li, Shu; Zhuang, Bing-liang; Han, Yong; Li, Meng-meng; Chen, Pu-long

    2017-02-01

    The natural emissions of ozone precursors (NOx and VOCs) are sensitive to climate. Future climate change can impact O3 concentrations by perturbing these emissions. To better estimate the variation of natural emissions under different climate conditions and understand its effect on surface O3, we model the present and the future air quality over the Yangtze River Delta (YRD) region by running different simulations with the aid of the WRF-CALGRID model system that contains a natural emission module. Firstly, we estimate the natural emissions at present and in IPCC A1B scenario. The results show that biogenic VOC emission and soil NOx emission over YRD in 2008 is 657 Gg C and 19.1 Gg N, respectively. According to climate change, these emissions in 2050 will increase by 25.5% and 11.5%, respectively. Secondly, the effects of future natural emissions and meteorology on surface O3 are investigated and compared. It is found that the variations in meteorological fields can significantly alter the spatial distribution of O3 over YRD, with the increases of 5-15 ppb in the north and the decreases of -5 to -15 ppb in the south. However, only approximately 20% of the surface O3 increases caused by climate change can be attributed to the natural emissions, with the highest increment up to 2.4 ppb. Finally, Ra (the ratio of impacts from NOx and VOCs on O3 formation) and H2O2/HNO3 (the ratio between the concentrations of H2O2 and HNO3) are applied to study the O3 sensitivity in YRD. The results show that the transition value of H2O2/HNO3 will turn from 0.3 to 0.5 in 2008 to 0.4-0.8 in 2050. O3 formation in the YRD region will be insensitive to VOCs under future climate condition, implying more NOx need to be cut down. Our findings can help us understand O3 variation trend and put forward the reasonable and effective pollution control policies in these famous polluted areas.

  4. Resistance properties of a macroporous silica-based N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide-impregnated polymeric adsorption material against nitric acid, temperature and γ-irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Anyun; Wei, Yuezhou; Hoshi, Harutaka; Kumagai, Mikio; Kamiya, Masayoshi; Koyama, Tomozo

    2005-04-01

    The resistance of a novel silica-based N,N,N',N'-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) polymeric adsorption material (TODGA/SiO 2-P) against nitric acid, temperature and γ-irradiation had been investigated. The adsorption property of the treated TODGA/SiO 2-P was evaluated by a 3 M HNO 3 solution containing 0.01 M Nd(III). It was found that both 3 and 0.01 M HNO 3 concentrations did not decrease the stability of TODGA/SiO 2-P at 25°C. The quantity of TODGA leaked from TODGA/SiO 2-P was equivalent to its solubility in the corresponding HNO 3 aqueous solution. The effect of 3 M HNO 3 on the leakage of TODGA at 80°C was significantly higher than that in 0.01 M HNO 3 as well as in all cases at 25°C. The amount of Nd(III) adsorbed towards the treated TODGA/SiO 2-P was determined in the range of 0.143-0.148 mmol/g for the HNO 3 concentration effect and 0.142-0.0506 mmol/g for the temperature effect. γ-Irradiation showed a more noticeable destruction effect on TODGA/SiO 2-P. The content of TODGA leaked increased with an increase in the γ-irradiation dose (ID) from 1.06 to 3.72 MGy in terms of the linear equation [TODGA]=794.5ID+84.0. The amount of Nd(III) adsorbed onto the irradiated TODGA/SiO 2-P decreased rapidly from 0.134 to 0.0438 mmol/g, which was lower than 0.153 mmol/g, the adsorption of fresh TODGA/SiO 2-P for Nd(III), according to the equation QNd(III)=-0.0301ID+0.160, showing that a large quantity of TODGA leaked from TODGA/SiO 2-P. The adsorbed amount of Nd(III) decreased obviously in this order: the HNO 3 concentration effect, temperature effect and γ-irradiation.

  5. The Hole in the Ozone Layer.

    ERIC Educational Resources Information Center

    Hamers, Jeanne S.; Jacob, Anthony T.

    This document contains information on the hole in the ozone layer. Topics discussed include properties of ozone, ozone in the atmosphere, chlorofluorocarbons, stratospheric ozone depletion, effects of ozone depletion on life, regulation of substances that deplete the ozone layer, alternatives to CFCs and Halons, and the future of the ozone layer.…

  6. The Two Faces of Ozone.

    ERIC Educational Resources Information Center

    Monastersky, Richard

    1989-01-01

    Provides answers to questions regarding the ozone problem: (1) nature of ozone in the troposphere and stratosphere; (2) possibility of sending the excess ozone at ground level to the stratosphere; (3) possibility of producing pure ozone and carrying it to the stratosphere; and (4) banning chlorofluorocarbons. (YP)

  7. Fundamentals of ISCO Using Ozone

    EPA Science Inventory

    In situ chemical oxidation (ISCO) using ozone involves the introduction of ozone gas (O3) into the subsurface to degrade organic contaminants of concern. Ozone is tri-molecular oxygen (O2) that is a gas under atmospheric conditions and is a strong oxidant. Ozone may react with ...

  8. Acid Rain

    USGS Publications Warehouse

    Bricker, Owen P.; Rice, Karen C.

    1993-01-01

    Acid deposition, or acid rain as it is more commonly referred to, has become a widely publicized environmental issue in the U.S. over the past decade. The term usually conjures up images of fish kills, dying forests, "dead" lakes, and damage to monuments and other historic artifacts. The primary cause of acid deposition is emission of S02 and NOx to the atmosphere during the combustion of fossil fuels. Oxidation of these compounds in the atmosphere forms strong acids - H2SO4 and HNO3 - which are returned to the Earth in rain, snow, fog, cloud water, and as dry deposition.Although acid deposition has only recently been recognized as an environmental problem in the U.S., it is not a new phenomenon (Cogbill & Likens 1974). As early as the middle of the 17th century in England, the deleterious effects of industrial emissions on plants, animals, and humans, and the atmospheric transport of pollutants between England and France had become issues of concern (Evelyn 1661, Graunt 1662). It is interesting that well over three hundred years ago in England, recommendations were made to move industry outside of towns and build higher chimneys to spread the pollution into "distant parts." Increasing the height of smokestacks has helped alleviate local problems, but has exacerbated others. In the U.S. the height of the tallest smokestack has more than doubled, and the average height of smokestacks has tripled since the 1950s (Patrick et al 1981). This trend occurred in most industrialized nations during the 20th century and has had the effect of transforming acid rain from a local urban problem into a problem of global scale.

  9. Acid Rain

    USGS Publications Warehouse

    Bricker, Owen P.; Rice, Karen C.; Dietrich, W.E.; Sposito, Garrison

    1997-01-01

    Acid deposition, or acid rain as it is more commonly referred to, has become a widely publicized environmental issue in the U.S. over the past decade. The term usually conjures up images of fish kills, dying forests, "dead" lakes, and damage to monuments and other historic artifacts. The primary cause of acid deposition is emission of S02 and NOx to the atmosphere during the combustion of fossil fuels. Oxidation of these compounds in the atmosphere forms strong acids - H2SO4 and HNO3 - which are returned to the Earth in rain, snow, fog, cloud water, and as dry deposition.Although acid deposition has only recently been recognized as an environmental problem in the U.S., it is not a new phenomenon (Cogbill & Likens 1974). As early as the middle of the 17th century in England, the deleterious effects of industrial emissions on plants, animals, and humans, and the atmospheric transport of pollutants between England and France had become issues of concern (Evelyn 1661, Graunt 1662). It is interesting that well over three hundred years ago in England, recommendations were made to move industry outside of towns and build higher chimneys to spread the pollution into "distant parts." Increasing the height of smokestacks has helped alleviate local problems, but has exacerbated others. In the U.S. the height of the tallest smokestack has more than doubled, and the average height of smokestacks has tripled since the 1950s (Patrick et al 1981). This trend occurred in most industrialized nations during the 20th century and has had the effect of transforming acid rain from a local urban problem into a problem of global scale.

  10. Interactions of Gas-Phase Nitric/Nitrous Acids and Primary Organic Aerosol in the Atmosphere of Houston, TX

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Whitlow, S. I.; Lefer, B. L.; Flynn, J.; Rappenglück, B.

    2007-12-01

    Concentrations of aerosol and gas-phase pollutants were measured on the roof of an 18-story building during the Texas Air Quality Study II Radical and Aerosol Measurement Project (TRAMP) from August 15 through September 28, 2006. Aerosol measurements included size-resolved, non-refractory mass concentrations of ammonium, nitrate, sulfate, chloride, and organic aerosol in submicron particles using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Particulate water-soluble organic carbon (PWSOC) was quantified using a mist chamber/total organic carbon analysis system. Concentration data for gas-phase pollutants included those for nitric acid (HNO3), nitrous acid (HONO), and hydrochloric acid (HCl) collected using a mist chamber/ion chromatographic technique, oxides of nitrogen (NOx) collected using a chemiluminescent method, and carbon monoxide (CO) collected using an infrared gas correlation wheel instrument. Coincident increases in nitrate and organic aerosol mass concentrations were observed on many occasions throughout the measurement campaign, most frequently during the morning rush hour. Based on the lack of organic aerosol processing (defined by the ratio of m/z = 44/57 in the Q-AMS spectra), strong correlation with NOx and CO, and a lack of significant increase in PWSOC concentration, the spikes in organic aerosol were likely associated with primary organic aerosol (POA). During these events, gas-phase HNO3 concentration decreases were observed simultaneously with increases in gas-phase HONO concentrations. These data likely indicate uptake of HNO3 and subsequent heterogeneous conversion to HONO involving POA. Preliminary calculations show that HNO3 partitioning could account for the majority of the observed HONO and aerosol nitrate concentrations during these events. Q-AMS chloride and HCl data also indicate uptake of chloride by particles during these events. This phenomenon was also observed during the night, but these nocturnal events were less

  11. Some consequences of ozone exposure on health.

    PubMed

    Paz, C

    1997-01-01

    The reaction of ozone with polyunsaturated fatty acids from the surfactant factor and pulmonary epithelial cells produces different reaction products which can cross the alveolar-capillary barrier and reach distant structures. Although only a few papers claim extrapulmonary changes in animals exposed to this gas, some neurological deficits, such as complaints of fatigue, lethargy, headache in humans, as well as significant disarrangements in the sleep pattern related to biochemical changes in the brain have been referred to in animals exposed to ozone. In the present review, the molecular configuration and the reaction of ozone at different lung levels are related to impairment at the respiratory and blood systems, in order to elucidate the mechanisms by which this gas or its reaction products, such as free radicals, prostaglandins and others can cross the alveolar-capillary and hemato-encephalic barriers, and to explain those neurological effects.

  12. Application of ozone based treatments of secondary effluents.

    PubMed

    Tripathi, Smriti; Pathak, Vinita; Tripathi, Devendra Mani; Tripathi, B D

    2011-02-01

    The present work was aimed at studying the efficiency of ozone in oxidation processes, coliform inactivation and Disinfection Byproducts (DBPs) formation, associated with the potential of ozone to increase the Biodegradable Dissolved Organic Carbon (BDOC) in secondary effluent with applied ozone doses of 5.0, 10.0 and 15.0 mg/L for contact times of 2, 5 and 10 min. The wastewater used in this work was collected from the Bhagwanpur Sewage Treatment Plant, Varanasi, India. Results of this experiment showed that 10 mg O(3)/L O(3) for 5 min exposure was found most suitable dose for highest degradation of COD, TOC, UV(254), color, turbidity and total nitrogen parameters. The inactivation range of microbial biomass range was found in between 95% and 98%. Experiment revealed the fact that aldehydes and carboxylic acid formation were significantly related with the ozone dose and exposure time and ozone might enhance the treatment efficiency of secondary effluent treatment.

  13. Laboratory studies on the retention of nitric acid, hydrochloric acid and ammonia on aerosol filters

    NASA Astrophysics Data System (ADS)

    Keck, Lothar; Wittmaack, Klaus

    Retention efficiencies of nitric acid, hydrochloric acid and ammonia were measured for different filters, with particular emphasis on cellulose (CE) and cellulose acetate-nitrate (CA) materials. Gases were produced either by nebulising aqueous solutions or by a novel technique based on the desorption from ammonium salts deposited on quartz fibre (QF) filters. Efficiencies for pure acidic gases and ammonia on CE and CA ranged from very low (⩽3.6%) to low (˜10% for HNO 3 on CE). In contrast, if acidic gases and ammonia were supplied in equimolar concentrations, they were retained (almost) completely on CE, with high efficiency on CA (60-80% for NH 3+HNO 3; 20-45% for NH 3+HCl), also with high efficiency on glass fibre filter, but with very low efficiency on QF and Teflon (Tf) filters (<1%). For CA, retention efficiencies were found to increase with increasing relative humidity and to decrease with decreasing mean pressure at which the filters were exposed to the gases. Once retained on CA filters, the retained gases may be lost again during subsequent exposure to clean air.

  14. Ozone Depletion Potential of CH3Br. Appendix H

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Sze, Nien Dak; Scott, Courtney; Rodriguez, Jose M.; Weisenstein, Debra K.; Sander, Stanley P.

    1998-01-01

    The ozone depletion potential (ODP) of methyl bromide (CH3Br) can be determined by combining the model-calculated bromine efficiency factor (BEF) for CH3Br and its atmospheric lifetime. This paper examines how changes in several key kinetic data affect BEF. The key reactions highlighted in this study include the reaction of BrO + HO2, the absorption cross section of HOBr, the absorption cross section and the photolysis products of BrONO2, and the heterogeneous conversion of BrONO2 to HOBr and HNO3 on aerosol particles. By combining the calculated BEF with the latest estimate of 0.7 year for the atmospheric lifetime of CH3Br, the likely value of ODP for CH3Br is 0.39. The model-calculated concentration of HBr (approx. 0.3 pptv) in the lower stratosphere is substantially smaller than the reported measured value of about 1 pptv. Recent publications suggested models can reproduce the measured value if one assumes a yield for HBr from the reaction of BrO + OH or from the reaction of BrO + HO2. Although the evaluation concluded any substantial yield of HBr from BrO + HO2 is unlikely, for completeness, we calculate the effects of these assumed yields on BEF for CH3Br. Our calculations show that the effects are minimal: practically no impact for an assumed 1.3% yield of HBr from BrO + OH and 10% smaller for an assumed 0.6% yield from BrO + HO2.

  15. Sludge ozonation: disintegration, supernatant changes and mechanisms.

    PubMed

    Zhang, Guangming; Yang, Jing; Liu, Huanzhi; Zhang, Jie

    2009-02-01

    This paper studied in detail the sludge disintegration and supernatant changes during ozonation and investigated the possible mechanisms. Ozone effectively lysed the sludge. The most important mechanism is proposed to be damages of microorganism cells. The ozone dose of 50 mgO(3)/gDS was found optimal for sludge lysis; 25 mgO(3)/gDS achieved only 10.4% sludge lysis after 90 min and 80 mgO(3)/gSS did not further improve sludge decomposition. When the ozone dose was 50 mgO(3)/gDS, the sludge disintegration degree was 46.7% after 105 min. The sludge solid concentration and volatile solid concentration decreased by 49.1% and 45.7%, respectively. The supernatant soluble chemical oxygen demand, total nitrogen, total phosphorus, protein, polysaccharide, and deoxyribonucleic acid increased by 699%, 169%, 2379%, 602%, 528%, and 556%, respectively. Various components showed quite different patterns. Ozone treatment significantly reduced the sludge bioactivity, decreased the partition coefficients of heavy metals between sludge and supernatant, but did not alter the sludge size distribution.

  16. Stratospheric solar geoengineering without ozone loss.

    PubMed

    Keith, David W; Weisenstein, Debra K; Dykema, John A; Keutsch, Frank N

    2016-12-27

    Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of -1 W⋅m(-2), for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tg⋅y(-1) of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.

  17. Stratospheric solar geoengineering without ozone loss

    PubMed Central

    Weisenstein, Debra K.; Dykema, John A.; Keutsch, Frank N.

    2016-01-01

    Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of −1 W⋅m−2, for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tg⋅y−1 of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods. PMID:27956628

  18. Stratospheric solar geoengineering without ozone loss

    NASA Astrophysics Data System (ADS)

    Keith, David W.; Weisenstein, Debra K.; Dykema, John A.; Keutsch, Frank N.

    2016-12-01

    Injecting sulfate aerosol into the stratosphere, the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously increasing column ozone toward its preanthropogenic baseline. A radiative forcing of ‑1 Wṡm‑2, for example, might be achieved with a simultaneous 3.8% increase in column ozone using 2.1 Tgṡy‑1 of 275-nm radius calcite aerosol. Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.

  19. Secondary acidification: Changes in gas-aerosol partitioning of semivolatile nitric acid and enhancement of its deposition due to increased emission and concentration of SOx

    NASA Astrophysics Data System (ADS)

    Kajino, Mizuo; Ueda, Hiromasa; Nakayama, Shinji

    2008-02-01

    Secondary acidification, or the indirect enhancement of semivolatile air pollutant deposition associated with increased SO42- concentrations, is shown to occur in general air pollution using data collected from six stations of the Acid Deposition Monitoring Network in East Asia (EANET) in Japan. This effect was first detected as a result of volcanic SO2 plumes in our previous studies. Results indicate that as SO42- concentration increases, gas-aerosol partitioning of nitric acid shifts to the gas phase, increasing the HNO3 gas concentration. Since the dry and wet deposition rates of HNO3 gas are very high, deposition can be enhanced even when the emission of NOx remains unchanged. In western Japan, the indirect effect for wet deposition is most apparent from spring to autumn, when the Asian continental outflow carries sulfate-rich contaminated air masses. However, it is not pronounced in air masses containing abundant sea-salt particles and related cation components in aerosols. In areas such as forests or farmlands with low surface resistance, dry deposition of nitric acid is more pronounced than wet deposition as the dry deposition velocity of HNO3 gas is high. Increased dry deposition of t-NO3 due to the indirect effect and consequent vegetation damage is thus of considerable concern in such regions. The deposition of other semivolatile components, such as hydrochloric acid and ammonia, can be altered and can also induce secondary acidification.

  20. Ozone - plant surface reactions an important ozone loss term?

    NASA Astrophysics Data System (ADS)

    Hansel, Armin; Jud, Werner; Fischer, Lukas; Canaval, Eva; Wohlfahrt, Georg; Tissier, Alain

    2015-04-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants responsible for global crop losses with associated economic costs of several billions dollar per year. Plant injuries have been related to the uptake of ozone through stomatal pores and oxidative effects damaging the internal leaf tissue. But a striking question remains: How much ozone enters the plant through open stomata and how much ozone is lost by chemical reactions at the plant surface? Until now surface losses are estimated from measured total ozone deposition fluxes and calculated stomatal conductance values. While stomatal conductance of CO2 and H2O is well understood and extensively used in describing plant atmosphere gas exchange, stomatal conductance of ozone is not well known. Here we use different Nicotiana tabacum varieties and find that surface reactions of ozone with diterpenoids synthesized by glandular trichomes reduce ozone flux through open stomata. Our measurements reveal that fast ozone loss at the plant surface is accompanied with prompt release of oxygenated volatile compounds. In the ozone fumigation experiments of different Nicotiana tabacum varieties the release of specific volatile oxy-VOCs allowed to identify the semi volatile precursor compounds at the plant surface. Ozone fumigation experiments with Norway spruce (Picea abies) and Scots Pine (Pinus sylvestris), two common species in the Northern Hemisphere, show also a significant ozone loss at the plant surface for Picea abies. Fluid dynamic calculations of ozone transport in the diffusive leaf boundary layer reveal a vertical but no horizontal ozone gradient thus reducing ozone fluxes through the pores in case of efficient ozone scavenging plant surfaces. We explain this efficient ozone protection mechanism by the porous surface architecture of plants in combination with unsaturated semi-volatile compounds deposited at the plant surface. These results show that unsaturated semi-volatile compounds at