Observing HNO3 release dependent upon metal complexes in malonic acid/nitrate droplets.

PubMed

Shao, Xu; Wu, Feng-Min; Yang, Hui; Pang, Shu-Feng; Zhang, Yun-Hong

2018-05-09

Although the dicarboxylic acid has been reported to react with nitrate for aged internally mixed aerosols in atmosphere, the quantitative nitrate depletion dependent upon composition in particles is still not well constrained. The chemical composition evolutions for malonic acid/sodium nitrate (MA/SN), malonic acid/magnesium nitrate (MA/MN) and malonic acid/calcium nitrate (MA/CN) particles with the organic to inorganic molar ratio (OIR) of 1:1 are investigated by vacuum Fourier transform infrared spectroscopy (FTIR). Upon dehydration, the intensity of the asymmetric stretching mode of COO - group (ν as -COO - ) increases, accompanying the decrease in OH feather band and COOH band and NO 3 - band. These band changes suggest malonate salts formation and HNO 3 release. The quantitative NO 3 - depletion data shows that the reactivity of MA-MN is most and that of MA-SN is least. Analysis of the stretching mode of COO - indicates the different bond type between metal cation and carboxylate anion. In addition, water content in particles decreases at the constant RH, implying water loss with the chemical reaction. When the RH changes very quickly, water uptake delay during the humidification process reveals that water mass transport is limited below 37% RH. Copyright © 2018 Elsevier B.V. All rights reserved.

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.

Uptake of methanol on mixed HNO3/H2O clusters: An absolute pickup cross section

NASA Astrophysics Data System (ADS)

Pysanenko, A.; Lengyel, J.; Fárník, M.

2018-04-01

The uptake of atmospheric oxidized organics on acid clusters is relevant for atmospheric new particle formation. We investigate the pickup of methanol (CH3OH) on mixed nitric acid-water clusters (HNO3)M(H2O)N by a combination of mass spectrometry and cluster velocity measurements in a molecular beam. The mass spectra of the mixed clusters exhibit (HNO3)m(H2O)nH+ series with m = 0-3 and n = 0-12. In addition, CH3OH.(HNO3)m(H2O)nH+ series with very similar patterns appear in the spectra after the methanol pickup. The velocity measurements prove that the undoped (HNO3)m(H2O)nH+ mass peaks in the pickup spectra originate from the neutral (HNO3)M(H2O)N clusters which have not picked up any CH3OH molecule, i.e., methanol has not evaporated upon the ionization. Thus the fraction of the doped clusters can be determined and the mean pickup cross section can be estimated, yielding σs ¯ ≈ 20 Å2. This is compared to the lower estimate of the mean geometrical cross section σg ¯ ≈ 60 Å2 obtained from the theoretical cluster geometries. Thus the "size" of the cluster corresponding to the methanol pickup is at least 3-times smaller than its geometrical size. We have introduced a method which can yield the absolute pickup cross sections relevant to the generation and growth of atmospheric aerosols, as illustrated in the example of methanol and nitric acid clusters.

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.

Method and apparatus for synthesizing anhydrous HNO/sub 3/. [Patent application

DOEpatents

Coon, C.L.; Harrar, J.E.; Pearson, R.K.; McGuire, R.R.

1982-07-20

A method and apparatus for electrochemically synthesizing anhydrous HNO/sub 3/ from an aqueous solution of HNO/sub 3/- includes oxidizing a solution of N/sub 2/O/sub 4//aqueous HNO/sub 3/ at an anode, while maintaining a controlled potential between the N/sub 2/O/sub 4//aqueous HNO/sub 3/ solution and the anode. A potential of about 1.80V vs. SCE is preferred. Anhydrous or aqueous HNO/sub 3/ may be disposed at the cathode within the electrochemical cell. Aqueous HNO/sub 3/ having a water content of up to about 12% by weight is utilized to synthesize anhydrous HNO/sub 3/.

Aqua complexes of 18—crown-6 with H 3PO 4, H 2TiF 6, and HNO 3: synthesis and vibrational spectra

NASA Astrophysics Data System (ADS)

Chénevert, R.; Rodrigue, A.; Chamberland, D.; Ouellet, J.; Savoie, R.

1985-11-01

Neutral-component complexes of 2:3:1 (acid:water:18-crown-6) stoichiometry have been obtained with H 3PO 4 and H 2TiF 6. These adducts have been studied by infrared and Raman spectroscopy, along with the corresponding (HNO 3-H 1O) 2-18-crown-6 complex, whose synthesis has already been reported. The spectra indicate that the crown ether has a highly regular conformation in these complexes. In those with H 3PO 4 and HNO 3, the binding of the acid molecule to the ether takes place through a H 2O linker, the strength of the XOH⋯OH 2 hydrogen bond being directly related to the p K a of the acid. With HNO 3, the acidic proton appears to be delocalized between the two oxygen atoms, giving a pseudo H 2O + ion whereas in the corresponding deuterocompound the D atom remains associated with the acid.

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

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

Ozone, nitric acid, and ammonia air pollution is unhealthy for people and ecosystems in southern Sierra Nevada, California.

PubMed

Cisneros, Ricardo; Bytnerowicz, Andrzej; Schweizer, Donald; Zhong, Sharon; Traina, Samuel; Bennett, Deborah H

2010-10-01

Two-week average concentrations of ozone (O3), nitric acid vapor (HNO3) and ammonia (NH3) were measured with passive samplers during the 2002 summer season across the central Sierra Nevada Mountains, California, along the San Joaquin River drainage. Elevated concentrations of the pollutants were determined with seasonal means for individual sites ranging between 62 and 88 ppb for O3, 1.0-3.8 microg m(-3) for HNO3, and 2.6-5.2 microg m(-3) for NH3. Calculated O3 exposure indices were very high, reaching SUM00-191 ppm h, SUM60-151 ppm h, and W126-124 ppm h. Calculated nitrogen (N) dry deposition ranged from 1.4 to 15 kg N ha(-1) for maximum values, and 0.4-8 kg N ha(-1) for minimum values; potentially exceeding Critical Loads (CL) for nutritional N. The U.S., California, and European 8 h O3 human health standards were exceeded during 104, 108, and 114 days respectively, indicating high risk to humans from ambient O3.

The uptake of HNO3 on meteoric smoke analogues

NASA Astrophysics Data System (ADS)

Frankland, Victoria L.; James, Alexander D.; Feng, Wuhu; Plane, John M. C.

2015-05-01

The uptake of HNO3, H2O, NO2 and NO was studied on meteoric smoke particle analogues using a low-pressure Knudsen cell operating at 295 K. The analogues used were olivine (MgFeSiO4) and a haematite/goethite (Fe2O3/FeO(OH)) mixture synthesised by the sol-gel process. For uptake on MgFeSiO4, the following uptake coefficients were obtained: γ(HNO3)=(1.8±0.3)×10-3, γ(H2O)=(4.0±1.3)×10-3, γ(NO2)=(5.7±0.2)×10-4 and γ(NO)<3×10-4. γ(HNO3) did not show a dependence on the mass of MgFeSiO4 in the Knudsen cell (when varied by a factor of 6) implying that, because of relatively efficient uptake, HNO3 is removed only by near-surface particles. This was corroborated by application of a surface uptake model. Saturating the MgFeSiO4 particles with water vapour before exposing them to NO2 increased γ(NO2) to (2.1±0.7)×10-3, but had a very small effect on γ(HNO3). For uptake on Fe2O3/FeO(OH), γ(HNO3)=(1.5±0.2)×10-3. These results were then included in a whole atmosphere chemistry-climate model, which shows that the heterogeneous removal on meteoric smoke particles in the winter polar vortex between 30 and 60 km appears to provide an important sink for HNO3.

Factors dominating 3-dimensional ozone distribution during high tropospheric ozone period.

PubMed

Chen, Xiaoyang; Liu, Yiming; Lai, Anqi; Han, Shuangshuang; Fan, Qi; Wang, Xuemei; Ling, Zhenhao; Huang, Fuxiang; Fan, Shaojia

2018-01-01

Data from an in situ monitoring network and five ozone sondes are analysed during August of 2012, and a high tropospheric ozone episode is observed around the 8th of AUG. The Community Multi-scale Air Quality (CMAQ) model and its process analysis tool were used to study factors and mechanisms for high ozone mixing ratio at different levels of ozone vertical profiles. A sensitive scenario without chemical initial and boundary conditions (ICBCs) from MOZART4-GEOS5 was applied to study the impact of stratosphere-troposphere exchange (STE) on vertical ozone. The simulation results indicated that the first high ozone peak near the tropopause was dominated by STE. Results from process analysis showed that: in the urban area, the second peak at approximately 2 km above ground height was mainly caused by local photochemical production. The third peak (near surface) was mainly caused by the upwind transportation from the suburban/rural areas; in the suburban/rural areas, local photochemical production of ozone dominated the high ozone mixing ratio from the surface to approximately 3 km height. Furthermore, the capability of indicators to distinguish O 3 -precursor sensitivity along the vertical O 3 profiles was investigated. Two sensitive scenarios, which had cut 30% anthropogenic NO X or VOC emissions, showed that O 3 -precursor indicators, specifically the ratios of O 3 /NOy, H 2 O 2 /HNO 3 or H 2 O 2 /NO Z , could partly distinguish the O 3 -precursor sensitivity between VOCs-sensitive and NOx-sensitive along the vertical profiles. In urban area, the O 3 -precursor relationship transferred from VOCs-sensitive within the boundary layer to NOx-sensitive at approximately 1-3 km above ground height, further confirming the dominant roles of transportation and photochemical production in high O 3 peaks at the near-ground layer and 2 km above ground height, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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.

HO2NO2 and HNO3 in the coastal Antarctic winter night: A "lab-in-the-field" experiment

NASA Astrophysics Data System (ADS)

Jones, Anna; Brough, Neil; Anderson, Philip; Wolff, Eric

2015-04-01

Observations of peroxynitric acid (HO2NO2) and nitric acid (HNO3) were made during a 4 month period of Antarctic winter darkness at the coastal Antarctic research station, Halley. Mixing ratios of HNO3 ranged from instrumental detection limits to 8 parts per trillion by volume (pptv), and of HO2NO2 from detection limits to 5 pptv; the average ratio of HNO3:HO2NO2 was 2.0(±0.6):1, with HNO3 always present at greater mixing ratios than HO2NO2 during the winter darkness. An extremely strong association existed for the entire measurement period between mixing ratios of the respective trace gases and temperature: for HO2NO2, R2 = 0.72, and for HNO3, R2 = 0.70. We focus on three cases with considerable variation in temperature, where wind speeds were low and constant, such that, with the lack of photochemistry, changes in mixing ratio were likely to be driven by physical mechanisms alone. We derived enthalpies of adsorption (ΔHads) for these three cases. The average ΔHads for HNO3 was -42±2 kJ.mol-1 and for HO2NO2 was -56±1kJ.mol-1; these values are extremely close to those derived in laboratory studies. This exercise demonstrates i) that adsorption to/desorption from the snow pack should be taken into account when addressing budgets of boundary layer HO2NO2 and HNO3 at any snow-covered site, and ii) that Antarctic winter can be used as a natural 'laboratory in the field' for testing data on physical exchange mechanisms.

Alloy 33: A new material for the handling of HNO{sub 3}/HF media in reprocessing of nuclear fuel

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

Koehler, M.; Heubner, U.; Eichenhofer, K.W.

Alloy 33, an austenitic 33Cr-32Fe-31Ni-1.6Mo-0.6Cu-0.4N material shows excellent resistance to corrosion when exposed to highly oxidizing media as e.g. HNO{sub 3} and HNO{sub 3}/HF mixtures which are encountered in reprocessing of nuclear fuel. According to the test results available so far, resistance to corrosion in boiling azeotropic (67%) HNO{sub 3} is about 6 and 2 times superior to AISI 304 L and 310 L. In higher concentrated nitric acid it can be considered corrosion resistant up to 95% HNO{sub 3} at 25 C, up to 90% HNO{sub 3} at 50 C and up to somewhat less than 85% HNO{sub 3}more » at 75 C. In 20% HNO{sub 3}/7% HF at 50 C its resistance to corrosion is superior to AISI 316 Ti and Alloy 28 by factors of about 200 and 2.4. Other media tested with different results include 12% HNO{sub 3} with up to 3.5% HF and 0.4% HF with 32 to 67.5% HNO{sub 3} at 90 C. Alloy 33 is easily fabricated into all product forms required for chemical plants (e.g. plate, sheet, strip, wire, tube and flanges). Components such as dished ends and tube to tube sheet weldments have been successfully fabricated facilitating the use of Alloy 33 for reprocessing of nuclear fuel.« less

A comparative study of ozonation, iron coated zeolite catalyzed ozonation and granular activated carbon catalyzed ozonation of humic acid.

PubMed

Gümüş, Dilek; Akbal, Feryal

2017-05-01

This study compares ozonation (O 3 ), iron coated zeolite catalyzed ozonation (ICZ-O 3 ) and granular activated carbon catalyzed ozonation (GAC-O 3 ) for removal of humic acid from an aqueous solution. The results were evaluated by the removal of DOC that specifies organic matter, UV 254 absorbance, SUVA (Specific Ultraviolet Absorbance at 254 nm) and absorbance at 436 nm. When ozonation was used alone, DOC removal was 21.4% at an ozone concentration of 10 mg/L, pH 6.50 and oxidation time of 60 min. The results showed that the use of ICZ or GAC as a catalyst increased the decomposition of humic acid compared to ozonation alone. DOC removal efficiencies were 62% and 48.1% at pH 6.5, at a catalyst loading of 0.75 g/L, and oxidation time of 60 min for ICZ and GAC, respectively. The oxidation experiments were also carried out using <100 kDa and <50 kDa molecular size fractions of humic acid in the presence of ICZ or GAC. Catalytic ozonation also yielded better DOC and UV 254 reduction in both <50 kDa and <100 kDa fractions of HA compared to ozonation. Copyright © 2017 Elsevier Ltd. All rights reserved.

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%.

Temperature dependence of the HNO3 UV absorption cross sections

NASA Technical Reports Server (NTRS)

Burkholder, James B.; Talukdar, Ranajit K.; Ravishankara, A. R.; Solomon, Susan

1993-01-01

The temperature dependence of the HNO3 absorption cross sections between 240 and 360 K over the wavelength range 195 to 350 nm has been measured using a diode array spectrometer. Absorption cross sections were determined using both (1) absolute pressure measurements at 298 K and (2) a dual absorption cell arrangement in which the absorption spectrum at various temperatures is measured relative to the room temperature absorption spectrum. The HNO3 absorption spectrum showed a temperature dependence which is weak at short wavelengths but stronger at longer wavelengths which are important for photolysis in the lower stratosphere. The 298 K absorption cross sections were found to be larger than the values currently recommended for atmospheric modeling (DeMore et al., 1992). Our absorption cross section data are critically compared with the previous measurements of both room temperature and temperature-dependent absorption cross sections. Temperature-dependent absorption cross sections of HNO3 are recommended for use in atmospheric modeling. These temperature dependent HNO3 absorption cross sections were used in a two-dimensional dynamical-photochemical model to demonstrate the effects of the revised absorption cross sections on loss rate of HNO3 and the abundance of NO2 in the stratosphere.

The H2SO4-HNO3-NH3 system at high humidities and in fogs: 1. Spatial and temporal patterns in the San Joaquin Valley of California

NASA Astrophysics Data System (ADS)

Jacob, Daniel J.; Munger, J. William; Waldman, Jed M.; Hoffmann, Michael R.

1986-01-01

A systematic characterization of the atmospheric H2SO4-HNO3-NH3 system was conducted in the fog water, the aerosol, and the gas phase at a network of sites in the San Joaquin Valley of California. Spatial patterns of concentrations were established that reflect the distribution of SO2, NOx, and NH3 emissions within the valley. The concept of atmospheric alkalinity was introduced to interpret these concentrations in terms of the buffering capacity of the atmosphere with respect to inputs of strong acids. Regions of predominantly acidic and alkaline fog water were identified. Fog water was found to be alkaline in most of the valley, but small changes in emission budgets could lead to widespread acid fog. An extended stagnation episode was studied in detail: progressive accumulation of H2SO4-HNO3-NH3 species was documented over the course of the episode and interpreted in terms of production and removal mechanisms. Secondary production of strong acids H2SO4 and HNO3 under stagnant conditions resulted in a complete titration of available alkalinity at the sites farthest from NH3 sources. A steady SO2 conversion rate of 0.4-1.1% h-1 was estimated in the stagnant mixed layer under overcast conditions and was attributed to nonphotochemical heterogeneous processes. Removal of SO2 was enhanced in fog, compared to nonfoggy conditions. Conversion of NOx to HNO3 slowed down during the stagnation episode because of reduced photochemical activity; fog did not appear to enhance conversion of NOx. Decreases in total HNO3 concentrations were observed upon acidification of the atmosphere and were attributed to displacement of NO3- by H2SO4 in the aerosol, followed by rapid deposition of HNO3(g). The occurrence of fog was associated with general decreases of aerosol concentrations due to enhanced removal by deposition.

Ozone production, nitrogen oxides, and radical budgets in Mexico City: observations from Pico de Tres Padres

NASA Astrophysics Data System (ADS)

Wood, E. C.; Herndon, S. C.; Onasch, T. B.; Kroll, J. H.; Canagaratna, M. R.; Kolb, C. E.; Worsnop, D. R.; Neuman, J. A.; Seila, R.; Zavala, M.; Knighton, W. B.

2008-08-01

Observations at a mountain-top site within the Mexico City basin are used to characterize ozone production and destruction, the nitrogen oxide budget, and the radical budget during the MILAGRO campaign. An ozone production rate of ~50 ppbv/h was observed in a stagnant air mass during the afternoon of 12 March 2006, which is among the highest observed anywhere in the world. Approximately half of the ozone destruction was due to the oxidation of NO2. During this time period ozone production was VOC-limited, deduced by a comparison of the radical production rates and the formation rate of NOx oxidation products (NOz) For [NOx]/[NOy] values between 0.2 and 0.8, gas-phase HNO3 typically accounted for less than 10% of NOz and accumulation-mode particulate nitrate (NO3-(PM)) accounted for 20% 70% of NOz, consistent with high ambient NH3 concentrations. The fraction of NOz accounted for by the sum of HNO3(g) and NO3-(PM) decreased with photochemical processing. This decrease is apparent even when dry deposition of HNO3 is accounted for, and indicates that HNO3 formation decreased relative to other NOx "sink" processes during the first 12 h of photochemistry and/or a significant fraction of the nitrate was associated with the coarse aerosol size mode. The ozone production efficiency of NOx on 11 and 12 March 2006 was approximately 7 on a time scale of one day. A new metric for ozone production efficiency that relates the dilution-adjusted ozone mixing ratio to cumulative OH exposure is proposed.

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.

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.

Revisiting Antarctic Ozone Depletion

NASA Astrophysics Data System (ADS)

Grooß, Jens-Uwe; Tritscher, Ines; Müller, Rolf

2015-04-01

Antarctic ozone depletion is known for almost three decades and it has been well settled that it is caused by chlorine catalysed ozone depletion inside the polar vortex. However, there are still some details, which need to be clarified. In particular, there is a current debate on the relative importance of liquid aerosol and crystalline NAT and ice particles for chlorine activation. Particles have a threefold impact on polar chlorine chemistry, temporary removal of HNO3 from the gas-phase (uptake), permanent removal of HNO3 from the atmosphere (denitrification), and chlorine activation through heterogeneous reactions. We have performed simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) employing a recently developed algorithm for saturation-dependent NAT nucleation for the Antarctic winters 2011 and 2012. The simulation results are compared with different satellite observations. With the help of these simulations, we investigate the role of the different processes responsible for chlorine activation and ozone depletion. Especially the sensitivity with respect to the particle type has been investigated. If temperatures are artificially forced to only allow cold binary liquid aerosol, the simulation still shows significant chlorine activation and ozone depletion. The results of the 3-D Chemical Transport Model CLaMS simulations differ from purely Lagrangian longtime trajectory box model simulations which indicates the importance of mixing processes.

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.

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.

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.

Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

NASA Astrophysics Data System (ADS)

Li, Jingyi; Mao, Jingqiu; Fiore, Arlene M.; Cohen, Ronald C.; Crounse, John D.; Teng, Alex P.; Wennberg, Paul O.; Lee, Ben H.; Lopez-Hilfiker, Felipe D.; Thornton, Joel A.; Peischl, Jeff; Pollack, Ilana B.; Ryerson, Thomas B.; Veres, Patrick; Roberts, James M.; Neuman, J. Andrew; Nowak, John B.; Wolfe, Glenn M.; Hanisco, Thomas F.; Fried, Alan; Singh, Hanwant B.; Dibb, Jack; Paulot, Fabien; Horowitz, Larry W.

2018-02-01

Widespread efforts to abate ozone (O3) smog have significantly reduced emissions of nitrogen oxides (NOx) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July-August 2004), SENEX (June-July 2013), and SEAC4RS (August-September 2013) and long-term ground measurement networks alongside a global chemistry-climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy) in both 2004 and 2013. Among the major RON species, nitric acid (HNO3) is dominant (˜ 42-45 %), followed by NOx (31 %), total peroxy nitrates (ΣPNs; 14 %), and total alkyl nitrates (ΣANs; 9-12 %) on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

Hydrogen-bonding behavior of various conformations of the HNO3…(CH3OH)2 ternary system.

PubMed

Özsoy, Hasan; Uras-Aytemiz, Nevin; Balcı, F Mine

2017-12-21

Nine minima were found on the intermolecular potential energy surface for the ternary system HNO 3 (CH 3 OH) 2 at the MP2/aug-cc-pVDZ level of theory. The cooperative effect, which is a measure of the hydrogen-bonding strength, was probed in these nine conformations of HNO 3 …(CH 3 OH) 2 . The results are discussed here in terms of structures, energetics, infrared vibrational frequencies, and topological parameters. The cooperative effect was observed to be an important contributor to the total interaction energies of the cyclic conformers of HNO 3 …(CH 3 OH) 2 , meaning that it cannot be neglected in simulations in which the pair-additive potential is applied. Graphical abstract The H-bonding behavior of various conformations of the HNO 3 (CH 3 OH) 2 trimer was investigated.

Gas-particle interactions above a Dutch heathland: I. Surface exchange fluxes of NH3, SO2, HNO3 and HCl

NASA Astrophysics Data System (ADS)

Nemitz, E.; Sutton, M. A.; Wyers, G. P.; Jongejan, P. A. C.

2004-07-01

A field measurement campaign was carried out over a Dutch heathland to investigate the effect of gas-to-particle conversion and ammonium aerosol evaporation on surface/atmosphere fluxes of ammonia and related species. Continuous micrometeorological measurements of the surface exchange of NH3, SO2, HNO3 and HCl were made and are analyzed here with regard to average fluxes, deposition velocities (Vd), canopy resistances (Rc) and canopy compensation point for NH3. Gradients of SO2, HNO3 and HCl were measured with a novel wet-denuder system with online anion chromatography. Measurements of HNO3 and HCl indicate an Rc of 100 to 200 s m-1 during warm daytime periods, probably at least partly due to non-zero acid partial pressures above NH4NO3 and NH4Cl on the leaf surfaces. Although it is likely that this observation is exacerbated by the effect of the evaporation of airborne NH4+ on the gradient measurements, the findings nevertheless add to the growing evidence that HNO3 and HCl are not always deposited at the maximum rate. Ammonia (NH3) fluxes show mainly deposition, with some periods of significant daytime emission. The net exchange could be reproduced both with an Rc model (deposition fluxes only) using resistance parameterizations from former measurements, as well as with the canopy compensation point model, using parameterizations derived from the measurements. The apoplastic ratio of ammonium and hydrogen concentration (Γs=[NH4+]/[H+]) of 1200 estimated from the measurements is large for semi-natural vegetation, but smaller than indicated by previous measurements at this site.

Gas-particle interactions above a Dutch heathland: I. Surface exchange fluxes of NH3, SO2, HNO3 and HCl

NASA Astrophysics Data System (ADS)

Nemitz, E.; Sutton, M. A.; Wyers, G. P.; Jongejan, P. A. C.

2004-03-01

A field measurement campaign was carried out over a Dutch heathland to investigate the effect of gas-to-particle conversion and ammonium aerosol evaporation on surface/atmosphere fluxes of ammonia and related species. Continuous micrometeorological measurements of the surface exchange of NH3, SO2, HNO3 and HCl were made and are analyzed here with regard to average fluxes, deposition velocities (Vd), canopy resistances (Rc) and canopy compensation point for NH3. Gradients of SO2, HNO3 and HCl were measured with a novel wet-denuder system with online anion chromatography. Measurements of HNO3 and HCl indicate an Rc of 100 to 200 s m-1 during warm daytime periods, probably at least partly due to non-zero acid partial pressures above NH4NO3 and NH4Cl on the leaf surfaces. Although it is likely that this observation is exacerbated by the effect of the evaporation of airborne NH4+ on the gradient measurements, the findings nevertheless add to the growing evidence that HNO3 and HCl are not always deposited at the maximum rate. Ammonia (NH3) fluxes show mainly deposition, with some periods of significant daytime emission. The net exchange could be reproduced both with an Rc model (deposition fluxes only) using resistance parameterizations from former measurements, as well as with the canopy compensation point model, using parameterizations derived from the measurements. The apoplastic ratio of ammonium and hydrogen concentration (Γs=[NH4+]/[H+]) of 1200 estimated from the measurements is large for semi- natural vegetation, but smaller than indicated by previous measurements at this site.

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.

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.

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

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.

Simultaneous assimilation of satellite NO2, O3, CO, and HNO3 data for the analysis of the tropospheric chemical composition

NASA Astrophysics Data System (ADS)

Miyazaki, K.; Eskes, H.; Sudo, K.

2012-04-01

Carbon monoxide (CO) and nitrogen oxides (NOx) play an important role in tropospheric chemistry through their influences on the ozone and hydroxyl radical (OH). The simultaneous optimization of various chemical components is expected to improve the emission inversion through the better description of the chemical feedbacks in the NOx- and CO-chemistry. This study aims to reproduce chemical composition distributions in the troposphere by combining information obtained from multiple satellite data sets. The emissions of CO and NOx, together with the 3D concentration fields of all forecasted chemical species in the global CTM CHASER have been simultaneously optimized using the ensemble Kalman filter (EnKF) data assimilation technique, and NO2, O3, CO, and HNO3 data obtained from OMI, TES, MOPITT, and MLS satellite measurements. The performance is evaluated against independent data from ozone sondes, aircraft measurements, GOME-2, and SCIAMACHY satellite data. Observing System Experiments (OSEs) have been carried out. These OSEs quantify the relative importance of each data set on constraining the emissions and concentrations. We confirmed that the simultaneous data assimilation improved the agreement with these independent data sets. The combined analysis of multiple data sets by means of advanced data assimilation system can provide a useful framework for the air quality research.

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%.

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%.

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.

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.;

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.

Removal and toxicity reduction of naphthenic acids by ozonation and combined ozonation-aerobic biodegradation.

PubMed

Vaiopoulou, Eleni; Misiti, Teresa M; Pavlostathis, Spyros G

2015-03-01

A commercial naphthenic acids (NAs) mixture (TCI Chemicals) and five model NA compounds were ozonated in a semibatch mode. Ozonation of 25 and 35 mg/L NA mixture followed pseudo first-order kinetics (k(obs)=0.11±0.008 min(-1); r(2)=0.989) with a residual NAs concentration of about 5 mg/L. Ozone reacted preferentially with NAs of higher cyclicity and molecular weight and decreased both cyclicity and the acute Microtox® toxicity by 3.3-fold. The ozone reactivity with acyclic and monocyclic model NAs varied and depended on other structural features, such as branching and the presence of tertiary or quaternary carbons. Batch aerobic degradation of unozonated NA mixture using a NA-enriched culture resulted in 83% NA removal and a 6.7-fold decrease in toxicity, whereas a combination of ozonation-biodegradation resulted in 89% NA removal and a 15-fold decrease in toxicity. Thus, ozonation of NA-bearing waste streams coupled with biodegradation are effective treatment processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

Ozonization of polyfunctional and humic acids of sapropelites

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

Verkhodanova, N.N.; Myakina, I.A.; Egor'kov, A.N.

Data are presented which show that in the ozonization of polyfunctional acids (PFAs) and humic acids (HAs) in glacial acetic acid, all the organic carbon can be converted into the soluble form. Mono- and dicarboxylic acids of normal structure have been detected in the ozonization products. 5 refs.

Ozonation of clofibric acid catalyzed by titanium dioxide.

PubMed

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

2009-09-30

The removal of clofibric acid from aqueous solution has been investigated in catalytic and non-catalytic semicontinuous ozonation runs. Kinetic data were analyzed using second order expressions for the reaction between organics and ozone or hydroxyl radicals. Catalytic runs used a commercial titanium dioxide catalyst consisting of fumed colloidal particles. The kinetic constant of the non-catalytic ozonation of clofibric acid at pH 3 was 8.16 x 10(-3)+/-3.4 x 10(-4)L mmol(-1)s(-1). The extent of mineralization during non-catalytic runs ranged from 50% at pH 7 to 20% at pH 3 in a reaction that essentially took place during the first 10-20 min. The catalyst increased the total extent of mineralization, its effect being more important during the first part of the reaction. The pseudo-homogeneous catalytic rate constant was 2.17 x 10(-2) L mmol(-1)s(-1) at pH 3 and 6.80 x 10(-1)L mmol(-1)s(-1) at pH 5, with up to a threefold increase with respect to non-catalytic constants using catalyst load of 1g/L. A set of stopped-flow experiments were designed to elucidate the role of catalyst, whose effect was probably due to the adsorption of organics on catalytic sites rather than to the promotion of ozone decomposition.

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.

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.

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

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.

Experimental study of the competitive adsorption of HNO3 and H2O on surfaces by using Brewster angle cavity ring-down spectroscopy in the 295-345 nm region.

PubMed

Du, Juan; Keesee, Robert G; Zhu, Lei

2014-09-18

The competitive adsorption of HNO3 and H2O from the gas phase onto fused silica surfaces is investigated. Brewster angle cavity ring-down spectroscopy is used to measure absorption of a laser probe beam by the HNO3/H2O coadsorbed on fused silica surfaces as a function of the mixture pressure. The laser absorption measurements were made in the 295-345 nm region. Langmuir adsorption constants for nitric acid and water were found to be 107 ± 17 and 562 ± 21 Torr(-1), respectively. A method has been developed for calculating absorption by HNO3 and H2O codeposited on the surface as a function of the HNO3/H2O mixture pressure using multicomponent Langmuir adsorption isotherms and absorption cross-sections at a given wavelength for surface-adsorbed HNO3 and H2O. The validity of this treatment has been evaluated both as a function of wavelength and as a function of mixing ratio.

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.

Mechanism for enhanced degradation of clofibric acid in aqueous by catalytic ozonation over MnOx/SBA-15.

PubMed

Sun, Qiangqiang; Wang, Yu; Li, Laisheng; Bing, Jishuai; Wang, Yingxin; Yan, Huihua

2015-04-09

Comparative experiments were conducted to investigate the catalytic ability of MnO(x)/SBA-15 for the ozonation of clofibric acid (CA) and its reaction mechanism. Compared with ozonation alone, the degradation of CA was barely enhanced, while the removal of TOC was significantly improved by catalytic ozonation (O3/MnO(x)/SBA-15). Adsorption of CA and its intermediates by MnO(x)/SBA-15 was proved unimportant in O3/MnO(x)/SBA-15 due to the insignificant adsorption of CA and little TOC variation after ceasing ozone in stopped-flow experiment. The more remarkably inhibition effect of sodium bisulfite (NaHSO3) on the removal of TOC in catalytic ozonation than in ozonation alone elucidated that MnO(x)/SBA-15 facilitated the generation of hydroxyl radicals (OH), which was further verified by electron spin-resonance spectroscopy (ESR). Highly dispersed MnO(x) on SBA-15 were believed to be the main active component in MnO(x)/SBA-15. Some intermediates were indentified and different degradation routes of CA were proposed in both ozonation alone and catalytic ozonation. The amounts of small molecular carboxylic acids (i.e., formic acid (FA), acetic acid (AA) and oxalic acid (OA)) generated in catalytic ozonation were lower than in ozonation alone, resulting from the generation of more OH. Copyright © 2014 Elsevier B.V. All rights reserved.

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.

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.

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.

Effect of 2 ppm ozone exposure on rat lung lipid fatty acids

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

Rabinowitz, J.L.; Bassett, D.J.

Based on in vitro studies, the initial damage to lung cells by ozone exposure is believed to result in part from the breakdown of lipid polyunsaturated fatty acids to aldehydes, ozonides, and peroxides. The present study measured lipid breakdown products in lungs isolated from rats pretreated with (1-/sup 14/C)acetate 12 h before exposure for 4 h to either air or 2 ppm ozone. Lipid fatty acid breakdown was indicated by a 112% increase in thiobarbituric acid-reactive substances on ozone exposure and by changes in chemical and radioactive measurements of mono- and dicarboxylic acids formed by treatment of lipid fractions withmore » hydrogen peroxide. Ozone exposure resulted in a 63% increase in recovery of short-chain fatty acids accounted for by increased recoveries of malonic acid by 37%, hexanoic acid by 47%, nonanoic acid by 118%, and azelaic acid by 107%. Recovery of glutaric acid was enhanced 15-fold by ozone exposure. Although decreases in tissue arachidonic acid could not be detected, oleic acid was significantly decreased by 36%. Recovery of radiolabel as short-chain fatty acids was increased by 65% on ozone exposure and was mainly accounted for by enhanced labeling of nonanoic and glutaric acid fractions. The failure to observe significant increases in /sup 14/C recovery in the other fractions suggested ozone-induced breakdown of unlabeled fatty acids. These results demonstrate the cleavage of unsaturated fatty acid double bonds following in vivo exposure of lungs to ozone. Breakdown of arachidonic and oleic acids was specifically identified by increased recoveries of glutaric and nonanoic acids, respectively.« less

Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO3 solution

NASA Astrophysics Data System (ADS)

Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura; Ani, F. Che; Samsudin, Z.

2015-09-01

Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO3 solution. The concentration of HNO3 solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth is faster in higher concentration compared with low concentration of HNO3. The concentration of HNO3 solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO3 increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO3 solution is most susceptible to ECM. SnO2 forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO3 solution.

Removal of Procion Red dye from colored effluents using H2SO4-/HNO3-treated avocado shells (Persea americana) as adsorbent.

PubMed

Georgin, Jordana; da Silva Marques, Bianca; da Silveira Salla, Julia; Foletto, Edson Luiz; Allasia, Daniel; Dotto, Guilherme Luiz

2018-03-01

The treatment of colored effluents containing Procion Red dye (PR) was investigated using H 2 SO 4 and HNO 3 modified avocado shells (Persea americana) as adsorbents. The adsorbent materials (AS-H 2 SO 4 and AS-HNO 3 ) were properly characterized. The adsorption study was carried out considering the effects of adsorbent dosage and pH. Kinetic, equilibrium, and thermodynamic aspects were also evaluated. Finally, the adsorbents were tested to treat simulated dye house effluents. For both materials, the adsorption was favored using 0.300 g L -1 of adsorbent at pH 6.5, where, more than 90% of PR was removed from the solution. General order model was able to explain the adsorption kinetics for both adsorbents. The Sips model was adequate to represent the isotherm data, being the maximum adsorption capacities of 167.0 and 212.6 mg g -1 for AS-H 2 SO 4 and AS-HNO 3 , respectively. The adsorption processes were thermodynamically spontaneous, favorable (- 17.0 < ΔG 0  < - 13.2 kJ mol -1 ), and exothermic (ΔH 0 values of - 29 and - 55 kJ mol -1 ). AS-H 2 SO 4 and AS-HNO 3 were adequate to treat dye house effluents, attaining color removal percentages of 82 and 75%. Avocado shells, after a simple acid treatment, can be a low-cost option to treat colored effluents.

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.

Burial of gas-phase HNO(3) by growing ice surfaces under tropospheric conditions.

PubMed

Ullerstam, Maria; Abbatt, Jonathan P D

2005-10-21

The uptake of gas-phase nitric acid by ice surfaces undergoing growth by vapor deposition has been performed for the first time under conditions of the free troposphere. The investigation was performed using a coated-wall flow tube coupled to a chemical ionization mass spectrometer, at nitric acid partial pressures between 10(-7) and 10(-6) hPa, at 214, 229 and 239 K. Ice surfaces were prepared as smooth ice films from ultra-pure water. During the experiments an excess flow of water vapor was added to the carrier gas flow and the existing ice surfaces grew by depositing water vapor. The average growth rates ranged from 0.7-5 microm min(-1), values similar to those which prevail in some portions of the atmosphere. With growing ice the long term uptake of nitric acid is significantly enhanced compared to an experiment performed at equilibrium, i.e. at 100% relative humidity (RH) with respect to ice. The fraction of HNO(3) that is deposited onto the growing ice surface is independent of the growth rate and may be driven by the solubility of the nitric acid in the growing ice film rather than by condensation kinetics alone.

Polar Vortex Conditions During the 1995-96 Arctic Winter: MLS CL0 and HNO(sub 3)

NASA Technical Reports Server (NTRS)

Santee, M. L.; Manney, G. L.; Read, W. G.; Froidevaux, L.; Waters, J. W.

1996-01-01

Microwave Limb Sounder (MLS) measurements of lower stratospheric CLO and HNO(sub 3) during the 1995-96 Arctic winter are presented. The 1995-96 Arctic winter was both colder and more persistently cold than usual, leading to an enhancement in lower stratospheric CLO of greater magnitude, vertical extent, and duration than has been previously observed in the Arctic. Vortex concentrations of HNO(sub 3) in mid-December were large due to diabetic decent. Trajectory calculations indicate that localized severe depletions of gas-phase HNO(sub 3) in mid-February and early March did not arise from intrainment of midlatitude air into the vortex and were therefore probably related to polar stratospheric cloud (PSC) formation.

Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO{sub 3} solution

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

Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura

2015-09-25

Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO{sub 3} solution. The concentration of HNO{sub 3} solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth ismore » faster in higher concentration compared with low concentration of HNO{sub 3}. The concentration of HNO{sub 3} solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO{sub 3} increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO{sub 3} solution is most susceptible to ECM. SnO{sub 2} forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO{sub 3} solution.« less

CO-OCCURRENCE OF OZONE AND ACIDIC CLOUD WATER IN HIGH-ELEVATION FORESTS

EPA Science Inventory

A chemical climatology for high-elevation forests was estimated from ozone and cloudwater acidity data collected in the eastern United States. esides frequent ozone-only and pH-only single-pollutant episodes, both simultaneous and sequential co-occurrence of ozone and acidic clou...

Scavenging of acidic gases (HCOOH, CH3COOH, HNO3, HCl, and SO2) and ammonia in mixed liquid-solid water clouds at the Puy de Do‸me mountain (France)

NASA Astrophysics Data System (ADS)

Voisin, Didier; Legrand, Michel; Chaumerliac, Nadine

2000-03-01

In order to study scavenging processes of chemical species in mixed phase clouds, in-cloud field measurements were conducted in December 1997 at the Puy de Dôme mountain (center of France, 1465 m above sea level). Soluble species including NH+4, Cl-;, NO3-3, SO-4, HCOO-, CH3COO-, and C2O-4 present in the different phases (supercooled water droplets, rimed snowflakes, interstitial gases, and aerosols) of cold clouds have been investigated. Conducted in parallel to microphysical studies of clouds (liquid water and ice contents, and size distribution of hydrometeors), these chemical investigations allow us to examine the partitioning of strong (HNO3 and HCl) and weak (SO2, HCOOH, and CH3COOH) acids as well as ammonia between interstitial air and the condensed phases (liquid and solid water particles) in mixed clouds present during winter at midlatitude regions. From that, we discuss the processes by which these key atmospheric species are taken up from the gas phase by the condensed phases (liquid and ice) in these cold clouds. We examine several factors which are of importance in driving the final composition of cloud ice. They include the partitioning of species between gaseous and supercooled liquid phases, the amount of rimed ice collected by snowflakes, and the retention of gas during shock freezing of supercooled droplets onto ice particles. Strong acids (HCl and HNO3) as well as NH3, being sufficiently soluble in water, are mainly partitioned into supercooled water droplets. Furthermore, being subsaturated in liquid droplets, these species are well retained in rimed ice. For these species, riming is found to be the main process driving the final composition of snowflakes, direct incorporation from the gas phase during growth of snowflakes remaining insignificant because of low concentrations in the gas phase. For light carboxylic acids the riming process mainly determines the composition of the snowflakes, but an additional significant contribution by gas

Effects of simulated acid rain and ozone on foliar chemistry of field-grown Pinus ponderosa seedlings and mature trees.

PubMed

Momen, B; Helms, J A

1996-01-01

We investigated the additive and interactive effects of simulated acid rain and elevated ozone on C and N contents, and the C:N ratio of one-year-old and current-year foliage of field-grown mature trees and their half-sib seedlings of a stress tolerant genotype of ponderosa pine. Acid rain levels (pH 5.1 and 3.0) were applied weekly to foliage only (no soil acidification or N addition), from January to April, 1992. Plants were exposed to two ozone levels (ambient and twice-ambient) during the day from September 1991 to November 1992. The sequential application of acid rain and elevated ozone mimicked the natural conditions. Twice-ambient ozone significantly decreased foliar N content (by 12-14%) and increased the C:N ratio of both one-year-old and current-year foliage of seedlings. Although similar ozone effects were also observed on one-year-old foliage of mature trees, the only statistically significant effect was an increased C:N ratio when twice-ambient ozone combined with pH 3.0 rain (acid rain by ozone interaction). Enhancing the effect of twice-ambient ozone in increasing the C:N ratio of one-year-old foliage of mature trees in June was the only significant effect of acid rain.

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

Interactions of aerosols (ammonium sulfate, ammonium nitrate and ammonium chloride) and of gases (HCl, HNO 3) with fogwater

NASA Astrophysics Data System (ADS)

Ruprecht, Heidi; Sigg, Laura

The concentrations of aerosols (NH 4NO 3, (NH 4) 2SO 4 and NH 4Cl) and of gases (HCl (g), HNO 3(g), NH 3(g) were determined by denuder methods under different conditions (in the absence of fog, before, during and after fog events). At this site situated in an urban region, high concentrations of the gaseous strong acids HCl (g) and HNO 3(g) are observed. NH 4Cl and NH 4NO 3 aerosols represent a major fraction of the Cl - and NO 3- aerosols (<2.4 μm)collected by denuders. During a fog event, very high concentrations of SO 42- were found in small aerosols, which are attributed to the aqueous phase oxidation of SO 2 under the influence of high pH due to the presence of NH 3. Differences in SO 42- concentrations measured in aerosols (<2.4 μm) and in fog droplets were probably due to mass-transport limitations of the SO 2 oxidation. Ammonium sulfate aerosols represent in some cases a significant fraction of the total S present (SO 2(g) + SO 42-. Soluble aerosols and gases contribute to the composition of fogwater and are released again after fog dissipation.

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.

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.

Variability of Stratospheric Reactive Nitrogen and Ozone Related to the QBO

NASA Astrophysics Data System (ADS)

Park, M.; Randel, W. J.; Kinnison, D. E.; Bourassa, A. E.; Degenstein, D. A.; Roth, C. Z.; McLinden, C. A.; Sioris, C. E.; Livesey, N. J.; Santee, M. L.

2017-09-01

The stratospheric quasi-biennial oscillation (QBO) dominates interannual variability of dynamical variables and trace constituents in the tropical stratosphere and provides a natural experiment to test circulation-chemistry interactions. This work quantifies the relationships among ozone (O3), reactive nitrogen (NOy), and source gas N2O, and their links to the QBO, based on satellite constituent measurements and meteorological data spanning 2005-2014 (over four QBO cycles). Data include O3, HNO3, and N2O from the Aura Microwave Limb Sounder and an NOx proxy derived from Optical Spectrograph and Infrared Imager System NO2 measurements combined with a photochemical box model (= NOx*). Results are compared to simulations from the Whole Atmosphere Community Climate Model, version 4 incorporating a QBO circulation nudged to assimilated winds. Cross correlations and composites with respect to the QBO phase show coherent 180° out-of-phase relationships between NOy and N2O throughout the stratosphere, with the NOx/HNO3 ratio increasing with altitude. The anomalies in NOy species propagate coherently downward with the QBO. Ozone is anticorrelated with reactive nitrogen in the middle stratosphere above 28 km due to NOx control of ozone catalytic loss cycles. Quantitative comparisons of nitrogen partitioning and O3 sensitivity to NOx show good overall agreement between satellite observations and model results (suggesting closure of the NOy budget), although the model results show larger (up to 20%) N2O, NOx, and O3 variations near 35 km compared to observations. These analyses serve to assess the consistency of diverse satellite-based data sets and also to evaluate nitrogen partitioning and NOx-dependent ozone chemistry in the global model.

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.

Balloon-Borne Measurements of Total Reactive Nitrogen, Nitric Acid, and Aerosol in the Cold Arctic Stratosphere

NASA Technical Reports Server (NTRS)

Kondo, Y.; Aimedieu, P.; Matthews, W. A.; Fahey, D. W.; Murcray, D. G.; Hofmann, D. J.; Johnston, P. V.; Iwasaka, Y.; Iwata, A.; Sheldon, W. R.

1990-01-01

Total reactive nitrogen (NO(Y)) between 15 and 29 km was measured for the first time on board a balloon within the Arctic cold vortex. Observations of HNO3, aerosol, and ozone were made by instruments on the same balloon gondola which was launched from Esrange, Sweden (68 deg N, 20 deg E) on January 23, 1989. The NO(y) mixing ratio was observed to increase very rapidly from 6 ppbv at 18 km altitude to a maximum of 21 ppbv at 21 km, forming a sharp layer with a thickness of about 2 km. A minimum in the NO(y) mixing ratio of 5 ppbv was found at 27 km. The measured HNO3 profile shows broad similarities to that of NO(y). This observation, together with the observed very low column amount of NO2, shows that NO(x) had been almost totally converted to HNO3, and that NO(y) was composed mainly of HNO3. The enhanced aerosol concentration between 19 and 22 km suggests that the maximum abundance of HNO3 trapped in the form of nitric acid trihydrate (NAT) was about 6 ppbv at 21 km. The sampled air parcels were highly supersaturated with respect to NAT. Although extensive denitrification throughout the stratosphere did not prevail, an indication of denitrification was found at altitudes of 27 and 22 km, and between 18 and 15 km.

Assessing the Parameterization of Nitric Oxide Emissions By Lightning in a Chemical Transport Model with Nitric Acid Columns from the IASI Satellite Instrument

NASA Astrophysics Data System (ADS)

Cooper, M.; Martin, R.; Wespes, C.; Coheur, P. F.; Clerbaux, C.; Murray, L. T.

2014-12-01

Nitrogen oxides (NOx ≡ NO + NO2) in the free troposphere largely control the production of ozone (O3), an important greenhouse gas and atmospheric oxidant. As HNO3 is the dominant sink of tropospheric NOx, improved understanding of its production and loss mechanisms can help to better constrain NOx emissions, and in turn improve understanding of ozone production and its effect on climate. However, this understanding is inhibited by the scarcity of direct measurements of free tropospheric HNO3, particularly in the tropics. We interpret tropical tropospheric nitric acid columns from the IASI satellite instrument with a global chemical transport model (GEOS-Chem). Overall GEOS-Chem generally agrees with IASI, however we find that the simulation underestimates IASI nitric acid over Southeast Asia by a factor of two. The bias is confirmed by comparing the GEOS-Chem simulation with additional satellite (HIRDLS, ACE-FTS) and aircraft (PEM-Tropics A and PEM-West B) observations of the middle and upper troposphere. We show that this bias can be explained by the parameterization of lightning NOx emissions, primarily from the misrepresentation of concentrated subgrid lightning NOx plumes. We tested a subgrid lightning plume parameterization and found that an additional 0.5 Tg N with an ozone production efficiency of 15 mol/mol would reduce the regional nitric acid bias from 92% to 6% without perturbing the rest of the tropics. Other sensitivity studies such as modified NOx yield per flash, increased altitude of lightning NOx emissions, or changes to convective mass flux or wet deposition of nitric acid required unrealistic changes to reduce the bias. This work demonstrates the importance of a comprehensive lightning parameterization to constraining NOx emissions.

[Effects of elevated ozone concentrations on enzyme activities and organic acids content in wheat rhizospheric soil.

PubMed

Yin, Wei Qin; Jing, Hao Qi; Wang, Ya Bo; Wei, Si Yu; Sun, Yue; Wang, Sheng Sen; Wang, Xuai Zhi

2018-02-01

The elevated concentration of tropospheric ozone (O 3 ) is an important global climate change driver, with adverse impacts on soil ecological environment and crop growth. In this study, a pot experiment was carried out in an open top chamber (OTC), to investigate the effects of elevated ozone concentration on soil enzyme activities (catalase, polyphenol oxidase, dehydrogenase and invertase), organic acids contents (oxalic acid, citric acid and malic acid) at different growth stages (tillering, jointing, heading and ripening stages) of wheat, and combined with the rhizospheric soil physicochemical properties and plant root characteristics to analyze the underlying reasons. The results showed that, elevated ozone concentration increased soil catalase, polyphenol oxidase, dehydrogenase and invertase activities at wheat ripening period to different degrees, with the effects on the activities of catalase and polyphenol oxidase being statistically significant. At the heading stage, activities of dehydrogenase and invertase were significantly increased by up to 76.7%. At the ripening stage, elevated ozone concentration significantly increased the content of citric acid and malic acid and redox potential (Eh) in rhizospheric soil, but reduced soil pH, electrical conductivity, total carbon and nitrogen. For root characteristics, elevated ozone concentrations significantly reduced the wheat root biomass, total root length and root surface area but increased the average root diameter.

Optimization of HNO3 leaching of copper from old AMD Athlon processors using response surface methodology.

PubMed

Javed, Umair; Farooq, Robina; Shehzad, Farrukh; Khan, Zakir

2018-04-01

The present study investigates the optimization of HNO 3 leaching of Cu from old AMD Athlon processors under the effect of nitric acid concentration (%), temperature (°C) and ultrasonic power (W). The optimization study is carried out using response surface methodology with central composite rotatable design (CCRD). The ANOVA study concludes that the second degree polynomial model is fitted well to the fifteen experimental runs based on p-value (0.003), R 2 (0.97) and Adj-R 2 (0.914). The study shows that the temperature is the most significant process variable to the leaching concentration of Cu followed by nitric acid concentration. However, ultrasound power shows no significant impact on the leaching concentration. The optimum conditions were found to be 20% nitric acid concentration, 48.89 °C temperature and 5.52 W ultrasound power for attaining maximum concentration of 97.916 mg/l for Cu leaching in solution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nitrogen oxides in the arctic stratosphere: Implications for ozone abundances. Ph.D. Thesis

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

Slusser, J.R.

1994-01-01

In the high latitude winter stratosphere, NO2 sequesters chlorine compounds which are extremely efficient at destroying ozone. During the nighttime, NO2 reacts with ozone to form N2O5 which acts as a reservoir of NO2. Under heavy aerosol loading, N2O5 may react with water on aerosol surfaces to form HNO3, a reservoir more resistant to photolysis. This heterogeneous reaction results in reduced NO2 concentration when the sun returns at the end of the winter. A spectrograph system has been developed to measure scattered zenith skylight and thereby determine stratospheric NO2 slant column abundance. Conversion of the measured slant column abundance tomore » vertical column abundance requires dividing by the air mass. The air mass is the enhancement in the optical path for the scattered twilight as compared to a vertical path. Air mass values determined using a multiple scattering radiative transfer code have been compared to those derived using a Monte Carlo code and were found to agree to within 6% at a 90 deg solar zenith angle for a stratospheric absorber. Six months of NO2 vertical column abundance measured over Fairbanks during the winter 1992-93 exhibited the daylight diminished and increased as the sunlight hours lengthened. The overall seasonal behavior was similar to high-latitude measurements made in the Southern Hemisphere. The ratios of morning to evening column abundance were consistent with predictions based on gas-phase chemistry. The possible heterogeneous reaction of N2O5 on sulfate aerosols was investigated using FTIR Spectrometer measurements of HNO3 column abundance and lidar determinations of the aerosol profile. Using an estimated N2O5 column abundance and aerosol profile as input to a simple model, significant HNO3 production was expected. No increase in HNO3 column abundance was measured. From this set of data, it was not possible to determine whether significant amounts of N2O5 were converted to HNO3 by this heterogeneous reaction.« less

Breaks induced in the deoxyribonucleic acid of aerosolized Escherichia coli by ozonized cyclohexene.

PubMed Central

De Mik, G; De Groot, I

1978-01-01

The inactivation of aerosolized Escherichia coli by ozone, cyclohexene, and ozonized cyclohexene was studied. The parameters for damage were loss of reproduction and introduction of breaks in the deoxyribonucleic acid (DNA). Aerosolization of E. coli in clean air at 80 percent relative humidity or in air containing either ozone or cyclohexene hardly affected survival; however, some breaks per DNA molecule were induced, as shown by sucrose gradient sedimentation of the DNA. Aerosolization of E. coli in air containing ozonized cyclohexene at 80 percent relative humidity decreased the survival by a factor of 10(3) or more after 1 h of exposure and induced many breaks in the DNA. PMID:341811

Subchronic toxicity study of ozonated and ozonated/chlorinated humic acids in Sprague-Dawley rats: A model system for drinking water disinfection

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

Daniel, F.B.; Robinson, M.; Ringhand, H.P.

Male and female Sprague-Dawley rats were administered drinking water containing humic acids either non-disinfected for following ozonation (O{sub 3}) or ozonation/chlorination (O{sub 3}/Cl{sub 2}) for 90 consecutive days. Test animals drank either of two concentrations of humic acids, 0.25 and 1.0 g/L total organic carbon (TOC), while controls received phosphate-buffered, distilled water. No consistent significant treatment-related effects were observed in body weight gain, organ weights, food or water consumption, or hematological and clinical chemistry parameters. No target organs were identified from the histopathological examination of the tissues. The most significant observation, an increase in liver to body weight ratio formore » the male animals in the 1.0 g/L O{sub 3}/Cl{sub 2} humic acid group, was not observed in any other group, nor was it corroborated via any biochemical measurements or histopathological analysis. Kidney lesions, primarily chronic progressive nephropathy, were a common observation in both controls and treated groups with no apparent relationship to either humic acid concentration or the disinfection process.« less

Balloon-borne radiometer measurements of Northern Hemisphere mid-latitude stratospheric HNO3 profiles spanning 12 years

NASA Astrophysics Data System (ADS)

Toohey, M.; Quine, B. M.; Strong, K.; Bernath, P. F.; Boone, C. D.; Jonsson, A. I.; McElroy, C. T.; Walker, K. A.; Wunch, D.

2007-12-01

Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990-2002 are used to retrieve vertical profiles of HNO3, CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and optimization steps. The retrieved HNO3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. We therefore find no evidence of long-term changes in the HNO3 summer mid-latitude profile, although the uncertainty of our measurements precludes a conclusive trend analysis.

Balloon-borne radiometer measurement of Northern Hemisphere mid-latitude stratospheric HNO3 profiles spanning 12 years

NASA Astrophysics Data System (ADS)

Toohey, M.; Quine, B. M.; Strong, K.; Bernath, P. F.; Boone, C. D.; Jonsson, A. I.; McElroy, C. T.; Walker, K. A.; Wunch, D.

2007-08-01

Low-resolution atmospheric thermal emission spectra collected by balloon-borne radiometers over the time span of 1990-2002 are used to retrieve vertical profiles of HNO3, CFC-11 and CFC-12 volume mixing ratios between approximately 10 and 35 km altitude. All of the data analyzed have been collected from launches from a Northern Hemisphere mid-latitude site, during late summer, when stratospheric dynamic variability is at a minimum. The retrieval technique incorporates detailed forward modeling of the instrument and the radiative properties of the atmosphere, and obtains a best fit between modeled and measured spectra through a combination of onion-peeling and global optimization steps. The retrieved HNO3 profiles are consistent over the 12-year period, and are consistent with recent measurements by the Atmospheric Chemistry Experiment-Fourier transform spectrometer satellite instrument. This suggests that, to within the errors of the 1990 measurements, there has been no significant change in the HNO3 summer mid-latitude profile.

Study of the laser-induced decomposition of HNO3/ 2-Nitropropane mixture at static high pressures

NASA Astrophysics Data System (ADS)

Bouyer, Viviane; Hébert, Philippe; Doucet, Michel

2007-06-01

HNO3 / 2-Nitropropane is a well known energetic material on which Raman spectroscopy measurements at static high pressure in a diamond anvil cell (DAC) have already been conducted at CEA/LE RIPAULT in order to examine the evolution of the mixture as a function of composition and pressure [1]. The purpose of the work presented here was to study the laser-induced decomposition of these energetic materials at static high pressures by measuring the combustion front propagation rate in the DAC. First of all, the feasibility of the experimental device was checked with a well known homogeneous explosive, nitromethane. Our results were consistent with those of Rice and Foltz [2]. Then, we investigated the initiation of NA / 2NP mixture as a function of nitric acid proportion, for a given pressure. We chose the mixture for which both the combustion propagation rate and detonation velocity are maximum and we examined the evolution of the front propagation velocity as a function of pressure and energy deposit. [1] Hebert, P., Regache, I., and Lalanne, P., ``High-Pressure Raman Spectroscopy study of HNO3 / 2-Nitropropane Mixtures. Influence of the Composition.'' Proceedings of the 42nd European High-Pressure Research Group Meeting, Lausanne, Suisse, 2004 [2] Rice, S.F., et al., Combustion and Flame 87 (1991) 109-122.

Solar activated ozonation of phenol and malic acid.

PubMed

Sánchez, Laura; Domènech, Xavier; Casado, Juan; Peral, José

2003-03-01

The effect that sunlight has on the degradation rate of two model organic compounds, phenol and malic acid, by ozone is studied. The effect seems to be due to both direct light absorption (300-320 nm photons) by ozone, which produces the pollutant degradation, and light absorption by reaction intermediates. The presence of such a light notably improves the reactivity of ozone toward the organic species, leading to a faster and complete mineralization even at large initial total organic carbon values. The use of artificial sunlight (Xe lamp) is also explored. Finally, the simultaneous presence of sunlight and other ozone degradation catalyst like transition metal ions is studied, showing the beneficial effect of such a combination. Copyright 2002 Elsevier Science Ltd.

Stratospheric H2O and HNO3 profiles derived from solar occultation measurements

NASA Technical Reports Server (NTRS)

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

1985-01-01

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.

Photocatalytic ozonation of terephthalic acid: a by-product-oriented decomposition study.

PubMed

Fuentes, Iliana; Rodríguez, Julia L; Poznyak, Tatyana; Chairez, Isaac

2014-11-01

Terephthalic acid (TA) is considered as a refractory model compound. For this reason, the TA degradation usually requires a prolonged reaction time to achieve mineralization. In this study, vanadium oxide (VxOy) supported on titanium oxide (TiO2) served as a photocatalyst in the ozonation of the TA with light-emitting diodes (LEDs), having a bandwidth centered at 452 nm. The modified catalyst (VxOy/TiO2) in combination with ozone and LEDs improved the TA degradation and its by-products. The results obtained by this system were compared with photolysis, single ozonation, catalytic ozonation, and photocatalytic ozonation of VxOy/TiO2 with UV lamp. The LED-based photocatalytic ozonation showed almost the same decomposition efficiency of the TA, but it was better in comparison with the use of UV lamp. The oxalic acid accumulation, as the final product of the TA decomposition, was directly influenced by either the presence of VxOy or/and the LED irradiation. Several by-products formed during the TA degradation, such as muconic, fumaric, and oxalic acids, were identified. Besides, two unidentified by-products were completely removed during the observed time (60 min). It was proposed that the TA elimination in the presence of VxOy/TiO2 as catalyst was carried out by the combination of different mechanisms: molecular ozone reaction, indirect mechanism conducted by ·OH, and the surface complex formation.

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.

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.

Atmospheric acidity measurements on allegheny mountain and the origins of ambient acidity in the Northeastern United States

NASA Astrophysics Data System (ADS)

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

Atmospheric acidity as HNO 3(g), SO 2(g), and aerosol H + was measured on Allegheny Mountain and Laurel Hill in southwest Pennsylvania in August 1983. The aerosol H + appeared to represent the net after H 2SO 4 reaction with NH 3(g). The resulting H +/SO 42- ratio depended on SO 42- concentration, approaching that of H 2SO 4 at the highest SO 42- concentrations. The atmosphere was acidic; the average concentrations of HNO 3 (78 nmole m -3) and aerosol H + (205 nmole m -3), NH 4+ (172 nmole m -3) and SO 42- (201 nmole m -3), and the dearth of NH 3(< 15 nmolem -3), show that the proton acidity (HNO 3, H 2SO 4) of the air exceeded the acid-neutralizing capacity of the air by a factor of > 2, with one 10-h period averaging 263 and 844 nmolem -3 for HNO 3 and aerosol H +, respectively. SO 2 added another 900 nmole m -3 (average) of potential H + acidity. HNO 3 and aerosol H + episodes were concurrent, on 7-8 day cycles, unrelated to SO 2 which existed more in short-lived bursts of apparently more local origin. NOx was sporadic like SO 2. Laurel and Allegheny, separated by 35.5 km, were essentially identical in aerosol SO 42-, and in aerosol H +, less so in HNO 3 and especially less so in SO 2; apparently, chemistry involving HNO 3 and aerosol H + or SO 42- was slow compared to inter-site transport times (1-2 h). From growth of bscat and decline of SO 2 during one instance of inter-site transport, daytime rate coefficients for SO 2 oxidation and SO 2 dry deposition were inferred to have been, respectively, ~ 0.05 and ⩽ 0.1 h -1. HNO 3 declined at night. Aerosol H + and SO 42- showed no significant diurnal variation, and O 3 showed very little; these observations, together with high PAN/NO x ratios, indicate that regional transport rather than local chemistry is governing. The O 3 concentration (average 56 ppb or 2178 nmolem -3) connotes an oxidizing atmosphere conducive to acid formation. Highest atmospheric acidity was associated with (1) slow westerly winds

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.

Structure and reactivity studies of CoHNO{sup +} in the gas phase

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

Chen, H.; Jacobson, D.B.; Freiser, B.S.

1999-12-16

The structure and energetics of three CoHNO{sup +} isomers [HCo(NO){sup +} (1), Co(HNO){sup +} (2), Co(NOH){sup +} (3)] were probed by using density functional theory (DFT). Theory predicts that 2 is the most stable structure with 1 and 3 14.1 and 15.4 kcal/mol less stable. The transition states for 2 {yields} 1 and 2 {yields} 3 conversions were not located. DFT calculations predict D{degree}(CoH{sup +}-NO) = 34.6 kcal/mol and D{degree}(Co{sup +}-HNO) = 45.5 kcal/mol. The gas-phase ion chemistry of CoHNO{sup +} was also studied by using Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. CID and SORI-CID of CoHNO{sup +}more » yield competitive formation of Co{sup +}, CoH{sup +}, and CoNO{sup +}. These results suggest that the barrier for 2 {yields} 1 conversion is less than 45.5 kcal/mol. Reactions with simple molecules were dominated by NO and HNO displacements. Potential energy surface diagrams are presented to explain these displacement reactions. Surprisingly, CoHNO{sup +} reacts with methane by dehydrogenation to yield CoCH{sub 3}NO{sup +}. Studies suggest CH{sub 3}CoNO{sup +} rather than Co(CH{sub 3}NO){sup +}as the structure for this ion.« less

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.

Global implications of ozone loss in a space shuttle wake

NASA Astrophysics Data System (ADS)

Danilin, Michael Y.; Ko, Malcolm K. W.; Weisenstein, Debra K.

2001-02-01

Existing global model calculations of ozone depletion due to solid-fueled rocket motor (SRM) launches [Prather et al., 1990; Jackman et al., 1998] take into account the effect of globally dispersed chlorine emissions and ignore the ozone loss in the rocket wake. This ozone depletion in the wake could be substantial (up to 100% in the lower stratosphere during the first hour after exhaust [Ross et al., 1997a, 2000]). In this paper, we provide an estimate of whether wake ozone loss could accumulate after each SRM launch, leading to a larger ozone depletion on the global scale. To address this issue, we estimate an upper bound of the ozone loss in a space shuttle wake and use the Atmospheric and Environmental Research, Inc. two-dimensional model to simulate the global effect. For the scenarios considered, the global impact of the localized ozone loss in the wakes is at least an order of magnitude less than the effects from global dispersion of the SRM chlorine emissions alone (on the order of 10-3-10-4% versus 10-2% in the ozone column near 30°N). Additional sensitivity studies performed for different wake dilution rates, seasons, locations, and local times of the shuttle launches and accounting for chlorine activation via ClONO2 + HCl → Cl2 + HNO3 on alumina particles did not change this conclusion.

Nitroxyl (HNO) Reacts with Molecular Oxygen and Forms Peroxynitrite at Physiological pH

PubMed Central

Smulik, Renata; Dębski, Dawid; Zielonka, Jacek; Michałowski, Bartosz; Adamus, Jan; Marcinek, Andrzej; Kalyanaraman, Balaraman; Sikora, Adam

2014-01-01

Nitroxyl (HNO), the protonated one-electron reduction product of NO, remains an enigmatic reactive nitrogen species. Its chemical reactivity and biological activity are still not completely understood. HNO donors show biological effects different from NO donors. Although HNO reactivity with molecular oxygen is described in the literature, the product of this reaction has not yet been unambiguously identified. Here we report that the decomposition of HNO donors under aerobic conditions in aqueous solutions at physiological pH leads to the formation of peroxynitrite (ONOO−) as a major intermediate. We have specifically detected and quantified ONOO− with the aid of boronate probes, e.g. coumarin-7-boronic acid or 4-boronobenzyl derivative of fluorescein methyl ester. In addition to the major phenolic products, peroxynitrite-specific minor products of oxidation of boronate probes were detected under these conditions. Using the competition kinetics method and a set of HNO scavengers, the value of the second order rate constant of the HNO reaction with oxygen (k = 1.8 × 104 m−1 s−1) was determined. The rate constant (k = 2 × 104 m−1 s−1) was also determined using kinetic simulations. The kinetic parameters of the reactions of HNO with selected thiols, including cysteine, dithiothreitol, N-acetylcysteine, captopril, bovine and human serum albumins, and hydrogen sulfide, are reported. Biological and cardiovascular implications of nitroxyl reactions are discussed. PMID:25378389

Inhaled ozone (O{sub 3})-induces changes in serum metabolomic and liver transcriptomic profiles in rats

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

Miller, Desinia B.; Karoly, Edward D.; Jones, Jan C.

Air pollution has been linked to increased incidence of diabetes. Recently, we showed that ozone (O{sub 3}) induces glucose intolerance, and increases serum leptin and epinephrine in Brown Norway rats. In this study, we hypothesized that O{sub 3} exposure will cause systemic changes in metabolic homeostasis and that serum metabolomic and liver transcriptomic profiling will provide mechanistic insights. In the first experiment, male Wistar Kyoto (WKY) rats were exposed to filtered air (FA) or O{sub 3} at 0.25, 0.50, or 1.0 ppm, 6 h/day for two days to establish concentration-related effects on glucose tolerance and lung injury. In a secondmore » experiment, rats were exposed to FA or 1.0 ppm O{sub 3}, 6 h/day for either one or two consecutive days, and systemic metabolic responses were determined immediately after or 18 h post-exposure. O{sub 3} increased serum glucose and leptin on day 1. Glucose intolerance persisted through two days of exposure but reversed 18 h-post second exposure. O{sub 3} increased circulating metabolites of glycolysis, long-chain free fatty acids, branched-chain amino acids and cholesterol, while 1,5-anhydroglucitol, bile acids and metabolites of TCA cycle were decreased, indicating impaired glycemic control, proteolysis and lipolysis. Liver gene expression increased for markers of glycolysis, TCA cycle and gluconeogenesis, and decreased for markers of steroid and fat biosynthesis. Genes involved in apoptosis and mitochondrial function were also impacted by O{sub 3}. In conclusion, short-term O{sub 3} exposure induces global metabolic derangement involving glucose, lipid, and amino acid metabolism, typical of a stress–response. It remains to be examined if these alterations contribute to insulin resistance upon chronic exposure. - Highlights: • Ozone, an ubiquitous air pollutant induces acute systemic metabolic derangement. • Serum metabolomic approach provides novel insights in ozone-induced changes. • Ozone exposure induces

Kinetic study of heterogeneous reaction of deliquesced NaCl particles with gaseous HNO3 using particle-on-substrate stagnation flow reactor approach.

PubMed

Liu, Y; Cain, J P; Wang, H; Laskin, A

2007-10-11

Heterogeneous reaction kinetics of gaseous nitric acid with deliquesced sodium chloride particles NaCl(aq) + HNO3(g) --> NaNO3(aq) + HCl(g) were investigated with a novel particle-on-substrate stagnation flow reactor (PS-SFR) approach under conditions, including particle size, relative humidity, and reaction time, directly relevant to the atmospheric chemistry of sea salt particles. Particles deposited onto an electron microscopy grid substrate were exposed to the reacting gas at atmospheric pressure and room temperature by impingement via a stagnation flow inside the reactor. The reactor design and choice of flow parameters were guided by computational fluid dynamics to ensure uniformity of the diffusion flux to all particles undergoing reaction. The reaction kinetics was followed by observing chloride depletion in the particles by computer-controlled scanning electron microscopy with energy-dispersive X-ray analysis (CCSEM/EDX). The validity of the current approach was examined first by conducting experiments with median dry particle diameter D(p) = 0.82 microm, 80% relative humidity, particle loading densities 4 x 10(4) HNO3 concentrations 2, 7, and 22 ppb. Upon deliquescence the droplet diameter D(d) approximately doubles. The apparent, pseudo-first-order rate constant determined in these experiments varied with particle loading and HNO3 concentration in a manner consistent with a diffusion-kinetic analysis reported earlier (Laskin, A.; Wang, H.; Robertson, W. H.; Cowin, J. P.; Ezell, M. J.; Finlayson-Pitts, B. J. J. Phys. Chem. A 2006, 110, 10619). The intrinsic, second-order rate constant was obtained as kII = 5.7 x 10(-15) cm3 molecule(-1) s(-1) in the limit of zero particle loading and by assuming that the substrate is inert to HNO3. Under this loading condition the experimental, net reaction uptake coefficient was found to be gamma(net) = 0.11 with an uncertainty factor of 3. Additional experiments examined

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.

Line Intensities in the ν 8Band of HNO 3

NASA Astrophysics Data System (ADS)

Wang, W. F.; Looi, E. C.; Tan, T. L.; Ong, P. P.

1996-07-01

Line intensity measurements have been made on the ν 8band of HNO 3using a high-resolution Fourier transform infrared spectrum in the region 739-800 cm -1. A least-squares fit of a total of 710 line intensities in the Pand Rbranches was performed, leading to accurate determination of five dipole moment operator constants. By utilizing these constants, the observed line intensities are well reproduced with an average random error of 6% and the integrated band intensity is found to be 15.7 ± 0.9 cm -2atm -1at 296 K.

Nitric Acid and Water Extraction by T2EHDGA in n -Dodecane

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

Campbell, Emily L.; Holfeltz, Vanessa E.; Hall, Gabriel B.

Liquid-liquid distribution behavior of nitric acid (HNO3) and water by a diglycolamide ligand, N,N,N',N'-tetra-2-ethylhexyldiglycolamide (T2EHDGA) into n-dodecane diluent was investigated. Spectroscopic FTIR and NMR characterization of the organic extraction solutions indicate T2EHDGA carbonyl coordinates HNO3 and progressively aggregates at high acid conditions. Water extraction increases in the presence of HNO3. The experimentally observed distribution of HNO3 was modeled using the computer program, SXLSQI. The results indicated that the formation of two organic phase species—HNO3·T2EHDGA and (HNO3)2·T2EHDGA—satisfactory describes the acid transport behavior. Temperature dependent solvent extraction studies allowed for determination of thermodynamic extraction constants and ΔH and ΔS parameters for themore » corresponding extractive processes.« less

Photo-Fenton-assisted ozonation of p-Coumaric acid in aqueous solution.

PubMed

Monteagudo, J M; Carmona, M; Durán, A

2005-08-01

The degradation of p-Coumaric acid present in olive oil mill wastewater was investigated as a pretreatment stage to obtain more easily biodegradable molecules, with lower toxicity that facilitates subsequent anaerobic digestion. Thus, photo-Fenton-assisted ozonation has been studied and compared with ozonation at alkaline pH and conventional single ultraviolet (UV) and acid ozonation treatments. In the combined process, the overall kinetic rate constant was split into various components: direct oxidation by UV light, direct oxidation by ozone and oxidation by hydroxyl radicals. Molecular and/or radical ozone reaction was studied by conducting the reaction in the presence and absence of tert-butylalcohol at pHs 2, 7 and 9. Ozone oxidation rate increases with pH or by the addition of Fenton reagent and/or UV radiation due to generation of hydroxyl radicals, *OH. Hydrogen peroxide and ferrous ion play a double role during oxidation since at low concentrations they act as initiators of hydroxyl radicals but at high concentrations they act as radical scavengers. Finally, the additional levels of degradation by formation of hydroxyl radicals have been quantified in comparison to the conventional single processes and an equation is proposed for the reaction rate as a function of studied operating variables.

The Chemical Biology of HNO Signaling

PubMed Central

Bianco, Christopher L.; Toscano, John P.; Bartberger, Michael D.; Fukuto, Jon M.

2016-01-01

Nitroxyl (HNO) is a simple molecule with significant potential as a pharmacological agent. For example, its use in the possible treatment of heart failure has received recent attention due to its unique therapeutic properties. Recent progress has been made on the elucidation of the mechanisms associated with its biological signaling. Importantly, the biochemical mechanisms described for HNO bioactivity are consistent with its unique and novel chemical properties/reactivity. To date, much of the biology of HNO can be associated with interactions and modification of important regulatory thiol proteins. Herein will be provided a description of HNO chemistry and how this chemistry translates to some of its reported biological effects. PMID:27555493

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. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

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

PubMed

Ekren, Orhun; Ozkomur, Ahmet

2016-08-01

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. 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. 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. 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.

The Heat of Formation of HNO

NASA Technical Reports Server (NTRS)

Lee, Timothy J.; Dateo, Christopher E.

1995-01-01

The HNO molecule is of interest in both combustion and atmospheric chemistry. For example, Guadagnini et al. have recently presented ab initio potential energy surfaces for the three lowest lying electronic states of HNO and then used these in examining several chemical reactions that take place in the combustion of nitrogen containing fuels and in the oxidation of atmospheric nitrogen. We have previously studied the ground state potential energy surface (i.e., stationary points along the HNO reversible reaction HON path), vibrational spectrum (using an accurate quartic force field), zero-point energy, and bonding of HNO using coupled-cluster ab initio methods. HNO is also very interesting because of the unique nature of its bonding characteristics. That is, the potential energy surface is very flat along the H-N bonding coordinate thereby giving unusual harmonic and fundamental vibrational frequencies, and the H-N bond energy is rather weak in comparison to other H-N bond energies. In fact, using experimental heats of formation for HNO, H, and NO, the H- bond energy is computed to be only 49.9 kcal/ mol (298 K). However, ab initio calculations of isodesmic reaction energies involving HNO, FNO, ClNO, and several other molecules have shown that there is an inconsistency in the experimental heats of formation of the XNO (X double bond H, F, and Cl) species. Hence the motivation for this study was to determine a very accurate (Delta)H(sub f, sup o) value for HNO using state-of-the-art ab initio methods. Based on many recent studies it is evident that the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T), in conjunction with large one-particle basis sets should be reliable to better than +/- 0.8 kcal/mol for this quantity. The computational methodology is described in the next section followed by our results and discussion. Conclusions are presented in the final section.

Quantification of Mesophyll Resistance and Apoplastic Ascorbic Acid as an Antioxidant for Tropospheric Ozone in Durum Wheat (Triticum durum Desf. cv. Camacho)

PubMed Central

de la Torre, Daniel

2008-01-01

The daily variations in cellular and apoplastic ascorbic acid and dehydroascorbic acid levels in a Mediterranean durum wheat cultivar (Triticum durum Desf. cv. Camacho) were analyzed in order to relate them to ambient ozone exposure and to subsequent stomatally absorbed ozone fluxes. The aim of this study is to prove the effectiveness and accuracy of a computer model (SODA) to calculate the mesophyll resistance (rm) to ozone uptake, the percentage of ozone detoxification by apoplastic ascorbic acid, and the ozone flux to the plasmalemma (Fm) in a Mediterranean durum wheat cultivar. These calculated factors were related to apoplastic ascorbic acid levels and to ambient ozone concentrations. These relationships were obtained with a view to explaining the detoxification of ozone by apoplastic ascorbic acid. Ozone detoxifications of up to 52% were found at midday, when maximum ozone concentrations and maximum apoplastic ascorbic acid are seen. Mesophyll resistance was minimum at this time, and ozone flux to the plasmalemma was reduced because of the reaction of ozone with apoplastic ascorbic acid. PMID:19082416

Quantification of mesophyll resistance and apoplastic ascorbic acid as an antioxidant for tropospheric ozone in durum wheat (Triticum durum Desf. cv. Camacho).

PubMed

de la Torre, Daniel

2008-12-14

The daily variations in cellular and apoplastic ascorbic acid and dehydroascorbic acid levels in a Mediterranean durum wheat cultivar (Triticum durum Desf. cv. Camacho) were analyzed in order to relate them to ambient ozone exposure and to subsequent stomatally absorbed ozone fluxes. The aim of this study is to prove the effectiveness and accuracy of a computer model (SODA) to calculate the mesophyll resistance (rm) to ozone uptake, the percentage of ozone detoxification by apoplastic ascorbic acid, and the ozone flux to the plasmalemma (Fm) in a Mediterranean durum wheat cultivar. These calculated factors were related to apoplastic ascorbic acid levels and to ambient ozone concentrations. These relationships were obtained with a view to explaining the detoxification of ozone by apoplastic ascorbic acid. Ozone detoxifications of up to 52% were found at midday, when maximum ozone concentrations and maximum apoplastic ascorbic acid are seen. Mesophyll resistance was minimum at this time, and ozone flux to the plasmalemma was reduced because of the reaction of ozone with apoplastic ascorbic acid.

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.

Measurement and Modeling of Volatile Particle Emissions from Military Aircraft

DTIC Science & Technology

2011-10-01

cruise load (expt #4). (a,d) CO2, ozone , and chamber temperature, (b,e) Concentrations of toluene and acetaldehyde (note scale is not to zero for left...background air containing ozone . NO oxidizes to HNO2 while NO2 oxidizes to HNO3. HNO3 and HNO2 may contribute to 6 volatile PM, but their...contribution is currently not well understood. Under the relatively warm conditions of the lower troposphere relevant to the PM2.5 NAAQS, HNO3 condenses into

Kinetics of p-hydroxybenzoic acid photodecomposition and ozonation in a batch reactor.

PubMed

Benitez, F J; Beltran-Heredia, J; Peres, J A; Dominguez, J R

2000-04-03

The decomposition of p-hydroxybenzoic acid, an important pollutant present in the wastewaters of the olive oil industry, has been carried out by a direct photolysis provided by a polychromatic UV radiation source, and by ozone. In both processes, the conversions obtained as a function of the operating variables (temperature, pH and ozone partial pressure in the ozonation process) are reported. In order to evaluate the radiation flow rate absorbed by the solutions in the photochemical process, the Line Source Spherical Emission Model is used. The application of this model to the experimental results provides the determination of the reaction quantum yields which values ranged between 8.62 and 81.43 l/einstein. In the ozonation process, the film theory allows to establish that the absorption process takes place in the fast and pseudo-first-order regime and the reaction is overall second-order, first-order with respect to both reactants, ozone and p-hydroxybenzoic acid. The rate constants are evaluated and vary between 0.18x10(5) and 29.9x10(5) l/mol s depending on the temperature and pH.

The chemistry-climate model ECHAM6.3-HAM2.3-MOZ1.0

NASA Astrophysics Data System (ADS)

Schultz, Martin G.; Stadtler, Scarlet; Schröder, Sabine; Taraborrelli, Domenico; Franco, Bruno; Krefting, Jonathan; Henrot, Alexandra; Ferrachat, Sylvaine; Lohmann, Ulrike; Neubauer, David; Siegenthaler-Le Drian, Colombe; Wahl, Sebastian; Kokkola, Harri; Kühn, Thomas; Rast, Sebastian; Schmidt, Hauke; Stier, Philip; Kinnison, Doug; Tyndall, Geoffrey S.; Orlando, John J.; Wespes, Catherine

2018-05-01

The chemistry-climate model ECHAM-HAMMOZ contains a detailed representation of tropospheric and stratospheric reactive chemistry and state-of-the-art parameterizations of aerosols using either a modal scheme (M7) or a bin scheme (SALSA). This article describes and evaluates the model version ECHAM6.3-HAM2.3-MOZ1.0 with a focus on the tropospheric gas-phase chemistry. A 10-year model simulation was performed to test the stability of the model and provide data for its evaluation. The comparison to observations concentrates on the year 2008 and includes total column observations of ozone and CO from IASI and OMI, Aura MLS observations of temperature, HNO3, ClO, and O3 for the evaluation of polar stratospheric processes, an ozonesonde climatology, surface ozone observations from the TOAR database, and surface CO data from the Global Atmosphere Watch network. Global budgets of ozone, OH, NOx, aerosols, clouds, and radiation are analyzed and compared to the literature. ECHAM-HAMMOZ performs well in many aspects. However, in the base simulation, lightning NOx emissions are very low, and the impact of the heterogeneous reaction of HNO3 on dust and sea salt aerosol is too strong. Sensitivity simulations with increased lightning NOx or modified heterogeneous chemistry deteriorate the comparison with observations and yield excessively large ozone budget terms and too much OH. We hypothesize that this is an impact of potential issues with tropical convection in the ECHAM model.

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.

Elevated tropospheric ozone increased grain protein and amino acid content of a hybrid rice without manipulation by planting density.

PubMed

Zhou, Xiaodong; Zhou, Juan; Wang, Yunxia; Peng, Bin; Zhu, Jianguo; Yang, Lianxin; Wang, Yulong

2015-01-01

Rising tropospheric ozone affects crop yield and quality. Rice protein concentration, which is closely associated with eating/cooking quality, is of critical importance to nutritional quality. The ozone effect on amino acids of rice grains was little known, especially grown under different cultivation conditions. A hybrid rice cultivar Shanyou 63 was grown in 2010 and 2011 to investigate the interactive effect of ozone exposure and planting density on rice protein quality in a free-air ozone enrichment system. The content of protein, total amino acids (TAA), total essential (TEAA) and non-essential amino acids (TNEAA) in rice grain was increased by 12-14% with elevated ozone. A similar significant response to ozone was observed for concentrations of the seven essential and eight non-essential amino acids. In contrast, elevated ozone caused a small but significant decrease in percentage of TEAA to TAA. The year effect was significant for all measured traits; however, interactions of ozone with year or planting density were not detected. The study suggested that season-long elevation of ozone concentration to projected 2050 levels will increase protein and amino acids of Shanyou 63, and crop management such as changing planting density might not alter the impact. © 2014 Society of Chemical Industry.

Active nitrogen partitioning and the nighttime formation of N sub 2 O sub 5 in the stratosphere: Simultaneous in situ measurements of NO, NO sub 2 , HNO sub 3 , O sub 3 , and N sub 2 O using the BLISS diode laser spectrometer

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

Webster, C.R.; May, R.D.; Toumi, R.

1990-08-20

Simultaneous in situ measurements of NO, NO{sub 2}, HNO{sub 3}, O{sub 3}, N{sub 2}O, pressure, and temperature at 30 km have been made from Palestine. Texas (32{degree}N) on September 13, 1988, using the Jet Propulsion Laboratory Balloon-Borne Laser In-Situ Sensor (BLISS) instrument, with the NOAA dual-channel balloon UV ozone spectrometer on the same gondola. Using tunable diode laser absorption spectroscopy over a long path length, measurements were made during a 24-hour flight of the daytime concentrations of NO, NO{sub 2}, and O{sub 3} and of the diurnal variation in the concentration of NO{sub 2}. Postsunset measurements of NO{sub 2}, mademore » every half minutes throughout much of the night, show the NO{sub 2} mixing ratio falling from a sunset value of 10.5 ppbv to 5.2 ppbv at nights end. From the sunset/sunrise difference din the volume mixing ratio of NO{sub 2} is derived a value of 2.7 {plus minus} 0.4 ppbv for the sunrise N{sub 2}O{sub 5} mixing ratio, in excellent agreement with the model predictions of 2.9 ppbv at this latitude. The measured daytime NO{sub 2}/NO ratio was found to be in good agreement with model predictions at 30 km. The measured presunset sum NO + NO{sub 2} of 10.1 {plus minus} 0.8 ppbv agreed well with the measured postsunset NO{sub 2} amount of 10.5 {plus minus} 0.8 ppbv. Simultaneous measurements of the mixing ratios of HNO{sub 3} and postsunset NO{sub 2} allow an estimate of total reactive nitrogen, approximated at this time by NO{sub 2} + HNO{sub 3} + 2(N{sub 2}O{sub 5}) + ClONO{sub 2}, of 16.4 {plus minus} 1.2 ppbv at 30 km, and (from an earlier flight) of 13.7 {plus minus} 1.7 ppbv at 37 km. Using model predictions incorporating corrections for non-steady state and for diurnal chemistry, an OH mixing ratio of 8 {plus minus} 4 pptv is derived from the measured HNO{sub 3}/NO{sub 2} ratio of 0.72 {plus minus} 0.17 at 30 km.« less

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 - , ...

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.

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. © 2012 Blackwell Publishing Ltd.

The Heat of Formation of HNO

NASA Technical Reports Server (NTRS)

Lee, Timothy J.; Dateo, Christopher E.

1995-01-01

The HNO molecule is of interest in both combustion and atmospheric chemistry. For example, Guadagnini et al. have recently presented ab initio potential energy surfaces for the three lowest lying electronic states of HNO and then used these in examining several chemical reactions that take place in the combustion of nitrogen containing fuels and in the oxidation of atmospheric nitrogen. We have previously studied the ground state potential energy surface (i.e., stationary points along the HNO rev. reaction HON path), vibrational spectrum (using an accurate quartic force field), zero-point energy, and bonding of HNO using coupled-cluster ab initio methods. HNO is also very interesting because of the unique nature of its bonding characteristics. That is, the potential energy surface is very flat along the H-N bonding coordinate thereby giving unusual harmonic and fundamental vibrational frequencies, and the H-N bond energy is rather weak in comparison to other H-N bond energies. In fact, using experimental heats of formation for HO, H, and NO, the H- bond energy is computed to be only 49.9 kcal/ mol (298 K). However, ab initio calculations of isodesmic reaction energies involving HNO, FNO, ClNO, and several other molecules have shown that there is an inconsistency in the experimental heats of formation of the XNO (X=H, F, and Cl) species. Hence the motivation for this study was to determine a very accurate(DELTA)H(sup o)(sub f) value for HNO using state of-the-art ab initio methods. Based on many recent studies it is evident that the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T), in conjunction with large one-particle basis sets should be reliable to better than +0.8 kcal/mol for this quantity. The computational methodology is described in the next section followed by our results and discussion. Conclusions are presented in the final section.

Summer-time distribution of air pollutants in Sequoia National Park, California.

PubMed

Bytnerowicz, Andrzej; Tausz, Michael; Alonso, Rocio; Jones, David; Johnson, Ronald; Grulke, Nancy

2002-01-01

Concentrations of air pollutants were monitored during the May November 1999 period on a network of forested sites in Sequoia National Park, California. Measurements were conducted with: (1) active monitors for nitric oxide (NO), nitrogen dioxide (NO2) and ozone (O3); (2) honeycomb denuder/filter pack systems for nitric acid vapor (HNO3), nitrous acid vapor (HNO2), ammonia (NH3), sulfur dioxide (SO2), particulate nitrate (NO3-), ammonium (NH4+), and sulfate (SO4(2-)); and (3) passive samplers for O3, HNO3 and NO2. Elevated concentrations of O3 (seasonal means 41-71 ppb), HNO3 (seasonal means 0.4-2.9 microg/m3), NH3 (seasonal means 1.6-4.5 microg/m3), NO3 (1.1-2.0 microg/m3) and NH4+ (1.0-1.9 microg/m3) were determined. Concentrations of other pollutants were low. With increasing elevation and distance from the pollution source area of O3, NH3 and HNO3 concentrations decreased. Ammonia and NH4+ were dominant N pollutants indicating strong influence of agricultural emissions on forests and other ecosystems of the Sequoia National Park.

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.

Computational Chemical Kinetics for the Reaction of Criegee Intermediate CH2OO with HNO3 and Its Catalytic Conversion to OH and HCO.

PubMed

Raghunath, P; Lee, Yuan-Pern; Lin, M C

2017-05-25

The kinetics and mechanisms for the reaction of the Criegee intermediate CH 2 OO with HNO 3 and the unimolecular decomposition of its reaction product CH 2 (O)NO 3 are important in atmospheric chemistry. The potential-energy profile of the reactions predicted with the CCSD(T)/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ method shows that the initial association yields a prereaction complex that isomerizes by H migration to yield excited intermediate nitrooxymethyl hydroperoxide NO 3 CH 2 OOH* with internal energy ∼44 kcal mol -1 . A fragmentation of this excited intermediate produces CH 2 (O)NO 3 + OH with its transition state located 5.0 kcal mol -1 below that of the reactants. Further decomposition of CH 2 (O)NO 3 produces HCO + HNO 3 , forming a catalytic cycle for destruction of CH 2 OO by HNO 3 . The rate coefficients and product-branching ratios were calculated in the temperature range 250-700 K at pressure 20-760 Torr (N 2 ) using the variational-transition-state and Rice-Ramsperger-Kassel-Marcus (RRKM) theories. The predicted total rate coefficient for reaction CH 2 OO + HNO 3 at 295 K, 5.1 × 10 -10 cm 3 molecule -1 s -1 , agrees satisfactorily with the experimental value, (5.4 ± 1.0) × 10 -10 cm 3 molecule -1 s -1 . The predicted branching ratios at 295 K are 0.21 for the formation of NO 3 CH 2 OOH and 0.79 for CH 2 (O)NO 3 + OH at a pressure of 40 Torr (N 2 ), and 0.79 for the formation of NO 3 CH 2 OOH and 0.21 for CH 2 (O)NO 3 + OH at 760 Torr (N 2 ). This new catalytic conversion of CH 2 OO to HCO + OH by HNO 3 might have significant impact on atmospheric chemistry.

Simultaneous Observations fo Polar Stratospheric Clouds and HNO3 over Scandinavia in January, 1992

NASA Technical Reports Server (NTRS)

Massie, S. T.; Santee, M. L.; Read, W. G.; Grainger, R. G.; Lambert, A.; Mergenthaler, J. L.; Dye, J. E.; Baumbardner, D.; Randel, W. J.; Tabazadeh, A.;

Balloon profiles of stratospheric NO[sub 2] and HNO[sub 3] for testing the heterogeneous hydrolysis of N[sub 2]O[sub 5] on sulfate aerosols

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

Webster, C.R.; May, R.D.; Allen, M.

1994-01-01

Simultaneous in situ measurements of stratospheric NO[sub 2], HNO[sub 3], HCl, and CH[sub 4] 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 NO[sub 2], HNO[sub 3], and NO[sub 2]/HNO[sub 3] agree well with gas-phase model calculations near 34 km where SAGE II data show little sulfate aerosol, this is not true at the lower altitudes where SAGE II shows high aerosol loadings. At 24 km the BLISS NO[sub 2] and HNO[sub 3] measurements are 70% lower, and 50% higher, respectively,more » than the gas phase model predictions, with a measured NO[sub 2]/HNO[sub 3] ratio 5 times smaller. When the heterogeneous hydrolysis of N[sub 2]O[sub 5] and ClONO[sub 2] on sulfate aerosol of surface area densities matching the SAGE II measurements is added to the model, good agreement with the BLISS measurements is found over the whole altitude range. 24 refs., 4 figs., 1 tab.« less

Effects of acidic rain and ozone on nitrogen fixation and photosynthesis in the lichen lobaria pulmonaria (L. ) Hoffm

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

Sigal, L.L.; Johnston, J.W.

1986-01-01

The lichen Lobaria pulmonaria was subjected to ozone fumigations at 118, 235 and 353 mcg/cu m and simulated acidic rain at pH levels of 2.6, 4.2 and 5.6 for 5 days (M,W,F,M,W) during a 10-day period. Acidic rain at pH 2.6 caused significant reduction in nitrogen fixation and gross photosynthesis of 100 and 90%, respectively, and thallus bleaching was apparent. There were no significant differences between the pH 5.6 and 4.2 treatments in either gross photosynthesis or nitrogen fixation, and the color of the lichen thalli was unchanged. The effect of ozone on nitrogen fixation and photosynthesis over the rangemore » of concentrations used was not significant, but there was a trend toward reduced nitrogen fixation with increasing O/sub 3/ concentration. There were no significant ozone-acidic rain interactions. The threshold for response to rain acidity for L. pulmonaria lies between pH 2.6 and 4.2, and the acidity of wet deposition in parts of the United States may fall in the range.« less

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.

Jasmonic Acid Signaling Modulates Ozone-Induced Hypersensitive Cell Death

PubMed Central

Rao, Mulpuri V.; Lee, Hyung-il; Creelman, Robert A.; Mullet, John E.; Davis, Keith R.

2000-01-01

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 (O3) 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 O3-induced cell death. Expression of salicylate hydroxylase (NahG) in Cvi-0 reduced O3-induced cell death. Methyl jasmonate (Me-JA) pretreatment of Cvi-0 decreased O3-induced H2O2 content and SA concentrations and completely abolished O3-induced cell death. Cvi-0 synthesized as much JA as did Col-0 in response to O3 exposure but exhibited much less sensitivity to exogenous Me-JA. Analyses of the responses to O3 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 O3-induced HR-like cell death. PMID:11006337

Pretreatment of cyanided tailings by catalytic ozonation with Mn2+/O3.

PubMed

Li, Yulong; Li, Dengxin; Li, Jiebing; wang, Jin; Hussain, Asif; Ji, Hao; Zhai, Yijie

2015-02-01

The increasing amount of cyanided tailings produced as a by-product has gained significant attention in recent years because of the rapid development of the gold industry and extensive exploitation of gold mineral resources. The effective use of these secondary resources is becoming an important and urgent problem for all environmental protection staff. Manganese-catalyzed ozonation for the pre-oxidation of cyanided tailings was studied and the effects of Mn2+ dosage, initial sulfuric acid concentration, ozone volume flow, temperature and agitation speed on pretreatment were examined. The optimum reaction conditions were observed to be: ore pulp density 2.5%, agitation speed 700 r/min, temperature 60°C, Mn2+ dosage 40 g/L, ozone volume flow 80 L/hr, initial sulfuric acid concentration 1 mol/L, and reaction time 6 hr. Under these conditions, the leaching rate of Fe and weight loss could reach 94.85% and 48.89% respectively. The leaching process of cyanided tailings by Mn2+/O3 was analyzed, and it was found that the leaching of pyrite depends on synergetic oxidation by high-valent manganese and O3, in which the former played an important part. Copyright © 2014. Published by Elsevier B.V.

Heterogeneous reactions in a stratospheric box model: A sensitivity study

NASA Astrophysics Data System (ADS)

Danilin, Michael Y.; McConnell, John C.

1994-12-01

Recent laboratory data concerning the reactions of HCl and HOx on/in sulfuric acid aerosol (Hanson et al., 1994), N2O5 and ClONO2 hydrolysis on the frozen aerosol (Hanson and Ravishankara, 1993a) and the temperature dependence of the HNO3 absorption cross section (Burkholder et al., 1993) indicate that a reevaluation of the role of heterogeneous reactions in the chemical balance of the stratosphere is required. A chemical module prepared for a three-dimensional (3-D) global chemistry transport model (CTM) and a general circulation model (GCM) has been used to carry out a sensitivity study of the effects of heterogeneous reactions on/in the sulfate aerosol and on the polar stratospheric cloud (PSC) particles. We present here results for the latitudes 60°S, 70°S and 75°S at the 50-mbar level. Our findings indicate that (1) the new values of the HNO3 cross sections result in lower mixing ratios for NOx and make ozone more vulnerable to catalytic destruction by ClOx; (2) the effect of the heterogeneous reactions OH + HNO3(a) → H2O + NO3 and HO2 +HO2(a) → H2O2 + O2 are small in comparison with the same gas phase reactions and play a negligible role for the ozone balance; (3) the HCl reactions in the sulfuric acid aerosol at 60°S and 70°S increase the chlorine activation up to 0.53 parts per billion by volume (ppbv) and 0.72 ppbv, respectively, for liquid aerosol and up to 0.87 ppbv for frozen aerosol at 70°S for volcanic conditions and this results in considerable ozone depletion at these latitudes; (4) studying the ozone "hole" phenomenon, we have considered the different initial ratios of ClONO2/HCl, of N2O5, galactic cosmic rays (GCRs), and longer lifetimes for the PSC. We have speculated an existence of the reaction N2O5 + HCl(a) → ClNO2 + HNO3.

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.

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.

Temperature and acidity effects on WO{sub 3} nanostructures and gas-sensing properties of WO{sub 3} nanoplates

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

Zhang, Huili; Liu, Zhifang; Yang, Jiaqin

2014-09-15

Graphical abstract: Generally, large acid quantity and high temperature are beneficial to the formation of anhydrous WO3, but the acidity effect on the crystal phase is weaker than that of temperature. Large acid quantity is found helpful to the oriented growth of tungsten oxides, forming a nanoplate-like product. - Highlights: • Large acid quantity is propitious to the oriented growth of a WO{sub 3} nanoplate. • Effect of acid quantity on crystal phases of products is weaker than that of temperature. • One step hydrothermal synthesis of WO{sub 3} is facile and can be easily scaled up. • A WO{submore » 3} nanoplate shows a fast response and distinct sensing selectivity to acetone gas. - Abstract: WO{sub 3} nanostructures were successfully synthesized by a facile hydrothermal method using Na{sub 2}WO{sub 4}·2H{sub 2}O and HNO{sub 3} as raw materials. They are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The specific surface area was obtained from N{sub 2} adsorption–desorption isotherm. The effects of the amount of HNO{sub 3}, hydrothermal temperature and reaction time on the crystal phases and morphologies of the WO{sub 3} nanostructures were investigated in detail, and the reaction mechanism was discussed. Large amount of acid is found for the first time to be helpful to the oriented growth of tungsten oxides, forming nanoplate-like products, while hydrothermal temperature has more influence on the crystal phase of the product. Gas-sensing properties of the series of as-prepared WO{sub 3} nanoplates were tested by means of acetone, ethanol, formaldehyde and ammonia. One of the WO{sub 3} nanoplates with high specific surface area and high crystallinity displays high sensitivity, fast response and distinct sensing selectivity to acetone gas.« less

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.

Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

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

Wang, Bingbing; Laskin, Alexander

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.more » 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.« less

The reaction between GSNO and H2S: On the generation of NO, HNO and N2O.

PubMed

Kumar, Murugaeson R; Clover, Tara; Olaitan, Abayomi D; Becker, Christopher; Solouki, Touradj; Farmer, Patrick J

2018-04-26

Several recent reports suggest that HNO may be produced endogenously by reaction of H 2 S and S-nitrosoglutathione (GSNO). This hypothesis was tested using deoxymyoglobin (MbFe II ) to trap the expected HNO released from the target reaction, which should generate the stable HNO adduct, HNO-Mb, under anaerobic conditions. Under numerous experimental conditions, the sole globin product was NO-Mb, as characterized by absorbance, EPR, and NMR spectroscopies. Analogous reactions of GSNO with other biological reductants such as ascorbic acid, dithiothreitol, glutathione, and dithionite also yielded NO-Mb as the sole globin product; however, whereas analogous reduction of GSNO using NaBH 4 generates HNO-Mb in high yield. Quantitative GC/MS analyses of reactions of GS 15 NO with H 2 S showed that the main reaction product was 15 NO, with 15 N 2 produced at a comparable level to 15 N 2 O. Overall yield of N 2 O is unchanged by the presence of MbFe II , discounting the intermediacy of either NO or HNO in its formation. Taken together, these results argue against the generation of free HNO as a major pathway in the reactions of GSNO with H 2 S, and instead imply some as yet uncharacterized intermediates generate the nitrogenic gases. Copyright © 2018 Elsevier Inc. All rights reserved.

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.

HNO and NO release from a primary amine-based diazeniumdiolate as a function of pH

PubMed Central

Salmon, Debra J.; Torres de Holding, Claudia L.; Thomas, Lynta; Peterson, Kyle V.; Goodman, Gens P.; Saavedra, Joseph E.; Srinivasan, Aloka; Davies, Keith M.; Keefer, Larry K.; Miranda, Katrina M.

2011-01-01

The growing evidence that nitroxyl (HNO) has a rich pharmacological potential that differs from that of nitric oxide (NO) has intensified interest in HNO donors. Recently, the diazeniumdiolate (NONOate) based on isopropylamine (IPA/NO; Na[(CH3)2CHNH(N(O)NO)]) was demonstrated to function under physiological conditions as an organic analogue to the commonly used HNO donor Angeli’s salt (Na2N2O3). The decomposition mechanism of Angeli’s salt is dependent on pH, with transition from an HNO to an NO donor occurring abruptly near pH 3. Here, pH is shown to also affect product formation from IPA/NO. Chemical analysis of HNO and NO production led to refinement of an earlier, quantum mechanically based prediction of the pH-dependent decomposition mechanisms of primary amine NONOates such as IPA/NO. Under basic conditions, the amine proton of IPA/NO is able to initiate decomposition to HNO by tautomerization to the nitroso nitrogen (N2). At lower pH, protonation activates a competing pathway to NO production. At pH 8, the donor properties of IPA/NO and Angeli’s salt are demonstrated to be comparable, suggesting that at or above this pH, IPA/NO is primarily an HNO donor. Below pH 5, NO is the major product, while IPA/NO functions as a dual donor of HNO and NO at intermediate pH. This pH-dependent variability in product formation may prove useful in examination of the chemistry of NO and HNO. Furthermore, primary amine NONOates may serve as a tunable class of nitrogen oxide donor. PMID:21405089

Denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter

NASA Astrophysics Data System (ADS)

Khosrawi, Farahnaz; Kirner, Oliver; Sinnhuber, Björn-Martin; Johansson, Sören; Höpfner, Michael; Santee, Michelle L.; Froidevaux, Lucien; Ungermann, Jörn; Ruhnke, Roland; Woiwode, Wolfgang; Oelhaf, Hermann; Braesicke, Peter

2017-11-01

The 2015/2016 Arctic winter was one of the coldest stratospheric winters in recent years. A stable vortex formed by early December and the early winter was exceptionally cold. Cold pool temperatures dropped below the nitric acid trihydrate (NAT) existence temperature of about 195 K, thus allowing polar stratospheric clouds (PSCs) to form. The low temperatures in the polar stratosphere persisted until early March, allowing chlorine activation and catalytic ozone destruction. Satellite observations indicate that sedimentation of PSC particles led to denitrification as well as dehydration of stratospheric layers. Model simulations of the 2015/2016 Arctic winter nudged toward European Centre for Medium-Range Weather Forecasts (ECMWF) analysis data were performed with the atmospheric chemistry-climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the Polar Stratosphere in a Changing Climate (POLSTRACC) campaign. POLSTRACC is a High Altitude and Long Range Research Aircraft (HALO) mission aimed at the investigation of the structure, composition and evolution of the Arctic upper troposphere and lower stratosphere (UTLS). The chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, PSCs and cirrus clouds are investigated. In this study, an overview of the chemistry and dynamics of the 2015/2016 Arctic winter as simulated with EMAC is given. Further, chemical-dynamical processes such as denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter are investigated. Comparisons to satellite observations by the Aura Microwave Limb Sounder (Aura/MLS) as well as to airborne measurements with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) performed aboard HALO during the POLSTRACC campaign show that the EMAC simulations nudged toward ECMWF analysis generally agree well with observations. We derive a maximum polar stratospheric O3 loss of �

Photochemical oxidation of chloride ion by ozone in acid aqueous solution.

PubMed

Levanov, Alexander V; Isaykina, Oksana Ya; Amirova, Nazrin K; Antipenko, Ewald E; Lunin, Valerii V

2015-11-01

The experimental investigation of chloride ion oxidation under the action of ozone and ultraviolet radiation with wavelength 254 nm in the bulk of acid aqueous solution at pH 0-2 has been performed. Processes of chloride oxidation in these conditions are the same as the chemical reactions in the system O3 - OH - Cl(-)(aq). Despite its importance in the environment and for ozone-based water treatment, this reaction system has not been previously investigated in the bulk solution. The end products are chlorate ion ClO3(-) and molecular chlorine Cl2. The ions of trivalent iron have been shown to be catalysts of Cl(-) oxidation. The dependencies of the products formation rates on the concentrations of O3 and H(+) have been studied. The chemical mechanism of Cl(-) oxidation and Cl2 emission and ClO3(-) formation has been proposed. According to the mechanism, the dominant primary process of chloride oxidation represents the complex interaction with hydroxyl radical OH with the formation of Cl2(-) anion-radical intermediate. OH radical is generated on ozone photolysis in aqueous solution. The key subsequent processes are the reactions Cl2(-) + O3 → ClO + O2 + Cl(-) and ClO + H2O2 → HOCl + HO2. Until the present time, they have not been taken into consideration on mechanistic description and modelling of Cl(-) oxidation. The final products are formed via the reactions 2ClO → Cl2O2, Cl2O2 + H2O → 2H(+) + Cl(-) + ClO3(-) and HOCl + H(+) + Cl(-) ⇄ H2O + Cl2. Some portion of chloride is oxidized directly by O3 molecule with the formation of molecular chlorine in the end.

Precipitation of salts in freezing seawater and ozone depletion events: a status report

NASA Astrophysics Data System (ADS)

Morin, S.; Marion, G. M.; von Glasow, R.; Voisin, D.; Bouchez, J.; Savarino, J.

2008-12-01

In springtime, the polar marine boundary layer exhibits drastic ozone depletion events (ODEs), associated with elevated bromine oxide (BrO) mixing ratios. The current interpretation of this peculiar chemistry requires the existence of acid and bromide-enriched surfaces to heterogeneously promote and sustain ODEs. Sander et al. (2006) have proposed that calcium carbonate (CaCO3) precipitation in any seawater-derived medium could potentially decrease its alkalinity, making it easier for atmospheric acids such as HNO3 and H2SO4 to acidify it. We performed simulations using the state-of-the-art FREZCHEM model, capable of handling the thermodynamics of concentrated electrolyte solutions, to try to reproduce their results, and found that when ikaite (CaCO3·6H2O) rather than calcite (CaCO3) precipitates, there is no such effect on alkalinity. Given that ikaite has recently been identified in Antarctic brines (Dieckmann et al., 2008), our results show that great caution should be exercised when using the results of Sander et al. (2006), and reveal the urgent need of laboratory investigations on the actual link(s) between bromine activation and the pH of the surfaces on which it is supposed to take place at subzero temperature. In addition, the evolution of the Cl/Br ratio in the brine during freezing was computed using FREZCHEM, taking into account Br substitutions in Cl-containing salts.

Kelly et al. (2016): Simulating the phase partitioning of NH3, HNO3, and HCl with size-resolved particles over northern Colorado in winter

EPA Pesticide Factsheets

In this study, modeled gas- and aerosol phase ammonia, nitric acid, and hydrogen chloride are compared to measurements taken during a field campaign conducted in northern Colorado in February and March 2011. We compare the modeled and observed gas-particle partitioning, and assess potential reasons for discrepancies between the model and measurements. This data set contains scripts and data used for each figure in the associated manuscript. Figures are generated using the R project statistical programming language. Data files are in either comma-separated value (CSV) format or netCDF, a standard self-describing binary data format commonly used in the earth and atmospheric sciences. This dataset is associated with the following publication:Kelly , J., K. Baker , C. Nolte, S. Napelenok , W.C. Keene, and A.A.P. Pszenny. Simulating the phase partitioning of NH3, HNO3, and HCl with size-resolved particles over northern Colorado in winter. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, USA, 131: 67-77, (2016).

Recent Advances in the Chemical Biology of Nitroxyl (HNO) Detection and Generation

PubMed Central

Miao, Zhengrui; King, S. Bruce

2016-01-01

Nitroxyl or azanone (HNO) represents the redox-related (one electron reduced and protonated) relative of the well-known biological signaling molecule nitric oxide (NO). Despite the close structural similarity to NO, defined biological roles and endogenous formation of HNO remain unclear due to the high reactivity of HNO with itself, soft nucleophiles and transition metals. While significant work has been accomplished in terms of the physiology, biology and chemistry of HNO, important and clarifying work regarding HNO detection and formation has occurred within the last 10 years. This review summarizes advances in the areas of HNO detection and donation and their application to normal and pathological biology. Such chemical biological tools allow a deeper understanding of biological HNO formation and the role that HNO plays in a variety of physiological systems. PMID:27108951

Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)

NASA Astrophysics Data System (ADS)

Wohltmann, Ingo; Lehmann, Ralph; Rex, Markus

2017-07-01

The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, chemically active chlorine (ClOx), HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortex-averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect caused by the

Heterogeneous ozonation reactions of PAHs and fatty acid methyl esters in biodiesel particulate matter

NASA Astrophysics Data System (ADS)

Kasumba, John; Holmén, Britt A.

2018-02-01

Numerous studies have examined the oxidation of PAHs found in diesel particulate matter (PM) by ozone, but no studies have investigated the ozone oxidation of biodiesel exhaust PM. Fatty acid methyl esters (FAMEs), found in high abundance in biodiesel PM, can potentially alter the kinetics of the reactions between atmospheric oxidants such as ozone and particle-phase PAHs. In this study, the heterogeneous reactivity of 16 EPA PAHs upon 24 h exposure to 0.4 ppm ozone in the presence (PAH + FAMES) and absence (PAH-only) of FAMEs was investigated at room temperature and 50% relative humidity. The ozone-reactivity of the PAHs detected in 20% biodiesel (B20) exhaust PM was also investigated. In the absence of FAMEs, the pseudo-first order ozone reaction rate constant, kO 3 , of PAHs varied from 0.086 ± 0.030 hr-1 (chrysene) to 0.184 ± 0.078 hr-1 (anthracene). In the presence of FAMEs, kO 3 of the PAHs varied between 0.013 ± 0.012 hr-1 (benzo[b]fluoranthene) and 0.168 ± 0.028 hr-1 (benzo[a]pyrene), and with the exception of benzo[a]pyrene, the kO 3 of PAHs were 1.2-8 times lower compared to those obtained during the PAH-only ozone exposure. Only one PAH, benzo[a]pyrene (BaP), did not show a significant change in kO3 with addition of FAMEs. Phenanthrene, fluoranthene, and pyrene, the only PAHs detected in the B20 PM, had kO 3 values about 4 times lower in B20 PM than those obtained when spiked PAHs-only were exposed to ozone. The kO 3 values of phenanthrene and fluoranthene in the B20 PM were 2 times higher than rates obtained when the PAH mix was exposed to ozone in the presence of the FAMEs. In contrast, pyrene's kO 3 in the B20 PM was about 2 times lower than that obtained for the PAH + FAMEs exposure. Observed differences in PAH behavior demonstrate individual PAH heterogeneous reactivity with gas-phase ozone is sensitive to PAH (vapor pressure, solubility/sorption to matrix components, chemical reactivity) as well as substrate properties (PAH and O3 diffusivity

Ozone impacts of gas-aerosol uptake in global chemistry transport models

NASA Astrophysics Data System (ADS)

Stadtler, Scarlet; Simpson, David; Schröder, Sabine; Taraborrelli, Domenico; Bott, Andreas; Schultz, Martin

2018-03-01

The impact of six heterogeneous gas-aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, the Meteorological Synthesizing Centre-West of the European Monitoring and Evaluation Programme (EMEP MSC-W) and the European Centre Hamburg general circulation model combined with versions of the Hamburg Aerosol Model and Model for Ozone and Related chemical Tracers (ECHAM-HAMMOZ). Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3, and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modelled surface area density (Sa) of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in east Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3, and HO2 heterogeneous reactions gain relevance particularly in east Asia due to the presence of high NOx concentrations and high Sa in the same region. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with the biggest impacts on O3 in springtime when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are

Vertical Distribution of NO, NO(2), and HNO(3) as Derived from Stratospheric Absorption Infrared Spectra.

PubMed

Fontanella, J C; Girard, A; Gramont, L; Louisnard, N

1975-04-01

This paper is devoted to the results concerning NO, NO(2), and HNO(3) obtained during airborne experiments performed in June-July 1973 on Concorde 001. The altitude of flight was about 16 km. Results concerning NO are, within the accuracy of measurement, in agreement with results of a previousspectrometric balloonborne experiment conducted jointly by IASB and ONERA (14 May 1973). Nitric oxide is concentrated in stratospheric layers clearly above the flight altitude. Integrated amount of NO along the optical path is (4 +/- 1.5) x 10(16) mol cm(-2) for a solar elevation varying from +2 degrees above the horizontal plane to -1 degrees . A value of 6 x 10(8) mol cm(-3) may be given as an upper limit for the local concentration at the flight altitude. Thereis no significant difference in the integrated amount observed at sunset and sunrise. Measured value of NO(2) local concentration at 15.5 km is (1.1 +/- 0.2) x 10(9) mol cm(-3), in sunset conditions. This value is not greatly modified between 15 km and 30 km. Measured value of HNO(3). This value increases with altitude between 15 km and 20 km. The local concentration is maximum at 20 km. The measured value is (2 +/- 1) x 10(10) mol cm(-3) at 20 km. It seems that local concentration decreases rapidly above 20 km.

Profiling secondary metabolites of needles of ozone-fumigated white pine (Pinus strobus) clones by thermally assisted hydrolysis/methylation GC/MS.

PubMed

Shadkami, F; Helleur, R J; Cox, R M

2007-07-01

Plant secondary metabolites have an important role in defense responses against herbivores and pathogens, and as a chemical barrier to elevated levels of harmful air pollutants. This study involves the rapid chemical profiling of phenolic and diterpene resin acids in needles of two (ozone-tolerant and ozone-sensitive) white pine (Pinus strobus) clones, fumigated with different ozone levels (control, and daily events peaking at 80 and 200 ppb) for 40 days. The phenolic and resin acids were measured using thermally assisted hydrolysis and methylation (THM) gas chromatography/mass spectrometry. Short-term fumigation affected the levels of two phenolic acids, i.e., 3-hydroxybenzoic and 3,4-dihydroxybenzoic acids, in that both showed a substantial decrease in concentration with increased ozone dose. The decrease in concentration of these THM products may be caused by inhibition of the plant's shikimate biochemical pathway caused by ozone exposure. The combined occurrence of these two ozone-sensitive indicators has a role in biomonitoring of ozone levels and its impact on forest productivity. In addition, chromatographic profile differences in the major diterpene resin acid components were observed between ozone-tolerant and ozone-sensitive clones. The resin acids anticopalic, 3-oxoanticopalic, 3beta-hydroxyanticopalic, and 3,4-cycloanticopalic acids were present in the ozone-sensitive pine; however, only anticopalic acid was present in the ozone-tolerant clone. This phenotypic variation in resin acid composition may be useful in distinguishing populations that are differentially adapted to air pollutants.

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.

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.

Pseudo-equilibrium geometry of HNO determined by an E-Band CP-FTmmW spectrometer

DOE PAGES

Zaleski, Daniel P.; Prozument, Kirill

2017-05-16

An E-Band (60–90 GHz) chirped-pulse Fourier transform millimeter-wave spectrometer has been constructed for eventual kinetics and dynamics studies. The performance of the spectrometer is demonstrated with the molecule nitroxyl (HNO). Using the new spectrometer and by passing isotopically labelled methyl nitrite (CH 3ONO) through a pyrolysis nozzle, the spectra of minor isotopologues of HNO have been obtained. The observations on the isotopologues identified here, H 15NO, HN 18O, and D 15NO, have been combined with the earlier isotopic observations, HNO and DNO, to create a global r m (1) HNO geometry that approximates an equilibrium structure. Furthermore, the results aremore » compared to high-level ab initio calculations.« less

Pseudo-equilibrium geometry of HNO determined by an E-Band CP-FTmmW spectrometer

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

Zaleski, Daniel P.; Prozument, Kirill

An E-Band (60–90 GHz) chirped-pulse Fourier transform millimeter-wave spectrometer has been constructed for eventual kinetics and dynamics studies. The performance of the spectrometer is demonstrated with the molecule nitroxyl (HNO). Using the new spectrometer and by passing isotopically labelled methyl nitrite (CH 3ONO) through a pyrolysis nozzle, the spectra of minor isotopologues of HNO have been obtained. The observations on the isotopologues identified here, H 15NO, HN 18O, and D 15NO, have been combined with the earlier isotopic observations, HNO and DNO, to create a global r m (1) HNO geometry that approximates an equilibrium structure. Furthermore, the results aremore » compared to high-level ab initio calculations.« less

Application of the Baxter model for hard-spheres with surface adhesion to SANS data for the U(VI) - HNO{sub 3}, TBP-n-dodecane system.

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

Chiarizia, R.; Nash, K. L.; Jensen, M. P.

2003-11-11

Small-angle neutron scattering (SANS) data for the tri-n-butyl phosphate (TBP)-n-dodecane, HNO{sub 3}-UO{sub 2}(NO{sub 3}){sub 2} solvent extraction system have been interpreted using the Baxter model for hard spheres with surface adhesion. The increase in the scattering intensity in the low Q range observed when increasing amounts of HNO{sub 3} or UO{sub 2}(NO{sub 3}){sub 2} are transferred into the organic phase has been interpreted as arising from interactions between solute particles. The SANS data have been reproduced using a 12--16 {angstrom} diameter of the hard sphere, d{sub hs}, and a 5.6k{sub B}T-7.1k{sub B}T stickiness parameter, {tau}{sup -1}. When in contact withmore » an aqueous phase, TBP in n-dodecane forms small reverse micelles containing three TBP molecules. Upon extraction of water, HNO{sub 3}, and UO{sub 2}(NO{sub 3}){sub 2}, the swollen micelles interact through attractive forces between their polar cores with a potential energy of about 2k{sub B}T and an effective Hamaker constant of about 4k{sub B}T. The intermicellar attraction, under suitable conditions, leads to third-phase formation. Upon phase splitting, most of the solutes in the original organic phase (water, TBP, HNO{sub 3}, and UO{sub 2}(NO{sub 3}){sub 2}) separate in a continuous phase containing interspersed layers of n-dodecane.« less

Temperature-(208-318 K) and pressure-(18-696 Torr) dependent rate coefficients for the reaction between OH and HNO3

NASA Astrophysics Data System (ADS)

Dulitz, Katrin; Amedro, Damien; Dillon, Terry J.; Pozzer, Andrea; Crowley, John N.

2018-02-01

Rate coefficients (k5) for the title reaction were obtained using pulsed laser photolytic generation of OH coupled to its detection by laser-induced fluorescence (PLP-LIF). More than 80 determinations of k5 were carried out in nitrogen or air bath gas at various temperatures and pressures. The accuracy of the rate coefficients obtained was enhanced by in situ measurement of the concentrations of both HNO3 reactant and NO2 impurity. The rate coefficients show both temperature and pressure dependence with a rapid increase in k5 at low temperatures. The pressure dependence was weak at room temperature but increased significantly at low temperatures. The entire data set was combined with selected literature values of k5 and parameterised using a combination of pressure-dependent and -independent terms to give an expression that covers the relevant pressure and temperature range for the atmosphere. A global model, using the new parameterisation for k5 rather than those presently accepted, indicated small but significant latitude- and altitude-dependent changes in the HNO3 / NOx ratio of between -6 and +6 %. Effective HNO3 absorption cross sections (184.95 and 213.86 nm, units of cm2 molecule-1) were obtained as part of this work: σ213.86 = 4.52-0.12+0.23 × 10-19 and σ184.95 = 1.61-0.04+0.08 × 10-17.

Decomposition of 2,4-dichlorophenoxyacetic acid by ozonation, ionizing radiation as well as ozonation combined with ionizing radiation

NASA Astrophysics Data System (ADS)

Drzewicz, Przemyslaw; Trojanowicz, Marek; Zona, Robert; Solar, Sonja; Gehringer, Peter

2004-03-01

Electron beam (EB), ozone (O 3) and the combination EB/O 3 were used to study the oxidative decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) in local tap water. Using an EB treatment, a dose of 10 kGy was required for complete 2,4-D degradation, and a 90% conversion of organic chlorine into chloride ions. Using additionally 1.33 mmol dm -3 O 3 during irradiation, the same result was achieved with a dose of 2.7 kGy. The yields of products acetate and formate were almost doubled by the combined EB/O 3 treatment, compared to those obtained with the same dose by EB irradiation. Gamma radiolysis showed that the degradation dose was proportional to the initial concentration of 2,4-D in the range of 50-2260 μmol dm -3.

[Ru/AC catalyzed ozonation of recalcitrant organic compounds].

PubMed

Wang, Jian-Bing; Hou, Shao-Pei; Zhou, Yun-Rui; Zhu, Wan-Peng; He, Xu-Wen

2009-09-15

Ozonation and Ru/AC catalyzed ozonation of dimethyl phthalate (DMP), phenols and disinfection by-products precursors were studied. It shows that Ru/AC catalyst can obviously enhance the mineralization of organic compounds. In the degradation of DMP, TOC removal was 28.84% by ozonation alone while it was 66.13% by catalytic ozonation. In the oxidation of 23 kinds of phenols, TOC removals were 9.57%-56.08% by ozonation alone while they were 41.81%-82.32% by catalytic ozonation. Compared to ozonation alone, Ru/AC catalyzed ozonation was more effective for the reduction of disinfection by-products formation potentials in source water. The reduction of haloacetic acids formation potentials was more obvious than thichlomethane formation potentials. After the treatment by catalytic ozonation, the haloacetic acids formation potentials decreased from 144.02 microg/L to 58.50 microg/L, which was below the standard value of EPA. However ozonation alone could not make it reach the standard. The treatments of source water by BAC, O3 + BAC, O3/AC + BAC and Ru/AC + O3 + BAC were also studied. In the four processes, TOC removal was 3.80%, 20.14%, 27.45% and 48.30% respectively, COD removal was 4.37%, 27.22%, 39.91% and 50.00% respectively, UV254 removal was 8.16%, 62.24%, 67.03% and 84.95% respectively. Ru/AC + O3 + BAC process is more effective than the other processes for the removal of TOC, COD and UV254 and no ruthenium leaching observed in the solution. It is a promising process for the treatment of micro polluted source water.

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

GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

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

Pierce, R. A.

2012-03-12

HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into themore » H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of

Acid extraction by supported liquid membranes containing basic carriers

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

Danesi, P.R.; Cianetti, C.; Horwitz, E.P.

1983-01-01

The extraction of HNO/sub 3/ (nitric acid) from aqueous solutions by permeation through a number of supported liquid membranes containing basic carriers dissolved in diethylbenzene has been studied. The results have shown that the best permeations are obtained with long chain aliphatic amines (TLA, Primene JM-T) followed by TOPO (trioctylphosphine oxide) and then by other monofunctional and bifunctional organophosphorous basic carriers. The influence of an aliphatic diluent on the permeability of HNO/sub 3/ through a supported liquid membrane containing TLA as carrier was also investigated. In this case the permeability to HNO/sub 3/ decreases as a result of the lowermore » diffusion coefficient of the acid-carrier complex in the more vicous aliphatic solvent. 4 figures.« less

Analysis of Antarctic Denitrification in 2003 Winter Observed by ILAS-II Onboard the ADEOS-II Satellite

NASA Astrophysics Data System (ADS)

Nakajima, H.; Saeki, K.; Sugita, T.

2005-12-01

Polar Stratospheric Clouds (PSC) play an important role in ozone destruction in both Arctic and Antarctic stratosphere in winter. They take up gas-phase nitric acid (HNO3) and grow up when temperature is below nitric acid saturation temperature (TNAT). When PSC becomes large, it starts to descend and nitric acid is removed from the air mass, resulting in denitrification. The Improved Limb Atmospheric Spectrometer-II (ILAS-II) onboard the Advanced Earth Observing Satellite-II (ADEOS-II) successfully made measurements for the whole Antarctic winter in 2003. ILAS-II measured vertical profiles of O3, HNO3, NO2, H2O, N2O, CH4, ClONO2, N2O5, etc. in addition to the aerosol extinction coefficients at 780 nm. In this study, we analyzed denitrification from ILAS-II HNO3 and N2O data in regard to temperature history on the trajectory. The quantity of denitrification was estimated from the difference between measured HNO3 and HNO3* assumed from HNO3-- N2O correlation. In this analysis, it was found that denitrification was observed only for those airmass that experienced temperature below TICE (ice saturation temperature) in late June, 2003. In late July, it was found that most airmass inside the polar vortex was denitrified regardless of temperature history. This suggests that permanent denitrification has occurred in June-July period. The transition of relationship between denitrification and airmass temperature history was discovered from the ILAS-II data. Also, major types of PSC have found to be changed from nitric acid trihydrate (NAT) in June to ice in July, from the ILAS-II data. This is considered to be due to the lack of nitric acid in the airmass due to the denitrification in July.

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.

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

Thermal degradation kinetics of polylactic acid/acid fabricated cellulose nanocrystal based bionanocomposites.

PubMed

Monika; Dhar, Prodyut; Katiyar, Vimal

2017-11-01

Cellulose nanocrystals (CNC) are fabricated from filter paper (as cellulosic source) by acid hydrolysis using different acids such as sulphuric (H 2 SO 4 ), phosphoric (H 3 PO 4 ), hydrochloric (HCl) and nitric (HNO 3 ) acid. The resulting acid derived CNC are melt mixed with Polylactic acid (PLA) using extruder at 180°C. Thermogravimetric (TGA) result shows that increase in 10% and 50% weight loss (T 10 , T 50 ) temperature for PLA-CNC film fabricated with HNO 3 , H 3 PO 4 and HCl derived CNC have improved thermal stability in comparison to H 2 SO 4 -CNC. Nonisothermal kinetic studies are carried out with modified-Coats-Redfern (C-R), Ozawa-Flynn-Wall (OFW) and Kissinger method to predict the kinetic and thermodynamic parameters. Subsequently prediction of these parameter leads to the proposal of thermal induced degradation mechanism of nanocomposites using Criado method. The distribution of E a calculated from OFW model are (PLA-H 3 PO 4 -CNC: 125-139 kJmol -1 ), (PLA-HNO 3 -CNC: 126-145 kJmol -1 ), (PLA-H 2 SO 4 -CNC: 102-123 kJmol -1 ) and (PLA-HCl-CNC: 140-182 kJmol -1 ). This difference among E a for the decomposition of PLA-CNC bionanocomposite is probably due to various acids used in this study. The E a calculated by these two methods are found in consonance with that observed from Kissinger method. Further, hyphenated TG-Fourier transform infrared spectroscopy (FTIR) result shows that gaseous products such as CO 2 , CO, lactide, aldehydes and other compounds are given off during the thermal degradation of PLA-CNC nanocomposite. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Quality of tomato slices disinfected with ozonated water.

PubMed

Aguayo, Encarna; Escalona, Víctor; Silveira, Ana Cecilia; Artés, Francisco

2014-04-01

Fresh-cut industry needs novel disinfectant to replace the use of chlorine. Ozone is one of the most powerful oxidizing agents and is applied in gaseous or aqueous form for sanitation purposes. However, the strong oxidative effect could affect the nutritional and sensorial quality, in particular, when time of washing is extended. For that reason, the overall impact of ozonated water (0.4 mg/L) dipping applied during 1, 3 and 5 min compared to control washed in water during 5 min was studied in tomato slices stored during 14 days at 5 . According to the results, ozonated water treatment of 3 min achieved the best firmness retention, microbial quality (mesophilic, psychrotrophic and yeas load) and reduced the consumption of fructose and glucose. The use of ozonated water did not affect the total acidity, pH, total solid soluble, organic acid as ascorbic, fumaric or succinic acid and the sensorial parameters, which were only affected by storage time. However, the poor appearance, aroma and overall quality obtained in all treatments prevented shelf life of 14 days and the quality at acceptable levels was established in 10 days at 5 . It is recommended to wash tomato slices with 0.4 mg/L ozonated water for 3 min only. Extending treatment duration did not improve the microbiological quality, possibly due to the extra time permitting the ozone to react with other components of the fruit tissue, undermining the antimicrobial benefits.

In situ DRIFTS study of O3 adsorption on CaO, γ-Al2O3, CuO, α-Fe2O3 and ZnO at room temperature for the catalytic ozonation of cinnamaldehyde

NASA Astrophysics Data System (ADS)

Wu, Jianfeng; Su, Tongming; Jiang, Yuexiu; Xie, Xinling; Qin, Zuzeng; Ji, Hongbing

2017-08-01

In situ DRIFTS were conducted to identify adsorbed ozone and/or adsorbed oxygen species on CaO, ZnO, γ-Al2O3, CuO and α-Fe2O3 surfaces at room temperature. Samples were characterized by means of TG, XRD, N2 adsorption-desorption, pyridine-IR, nitrobenzene-IR, chloroform-IR, and CO2-TPD. Pyridine-DRIFTS measurements evidence two kinds of acid sites in all the samples. Nitrobenzene, chloroform-DRIFTS, and CO2-TPD reveal that there are large amounts of medium-strength base sites on all the metal oxides, and only CaO, ZnO, and γ-Al2O3 have strong base sites. And the benzaldehyde selectivity was increased in the same order of the alkalinity of the metal oxides. With weaker sites, ozone molecules form coordinative complexes bound via the terminal oxygen atom, observed by vibrational frequencies at 2095-2122 and 1026-1054 cm-1. The formation of ozonide O3- at 790 cm-1, atomic oxygen at 1317 cm-1, and superoxide O2- at 1124 cm-1 was detected; these species are believed to be intermediates of O3 decomposition on strong acid/base sites. The adsorption of ozone on metal oxides is a weak adsorption, and other gases, such as CO2, will compete with O3 adsorption. The mechanism of cinnamaldehyde ozonation at room temperature over CaO shows that cinnamaldehyde can not only be oxidized into cinnamic acid, but also be further oxidized into benzaldehyde, benzoic acid, maleic anhydride, and ultimately mineralized to CO2 in the presence of O3.

Identification of intermediates and assessment of ecotoxicity in the oxidation products generated during the ozonation of clofibric acid.

PubMed

Rosal, Roberto; Gonzalo, María S; Boltes, Karina; Letón, Pedro; Vaquero, Juan J; García-Calvo, E

2009-12-30

The degradation of an aqueous solution of clofibric acid was investigated during catalytic and non-catalytic ozonation. The catalyst, TiO(2), enhanced the production of hydroxyl radicals from ozone and raised the fraction or clofibric acid degraded by hydroxyl radicals. The rate constant for the reaction of clofibric acid and hydroxyl radicals was not affected by the presence of the catalyst. The toxicity of the oxidation products obtained during the reaction was assessed by means of Vibrio fischeri and Daphnia magna tests in order to evaluate the potential formation of toxic by-products. The results showed that the ozonation was enhanced by the presence of TiO(2,) the clofibric acid being removed completely after 15 min at pH 5. The evolution of dissolved organic carbon, specific ultraviolet absorption at 254 nm and the concentration of carboxylic acids monitored the degradation process. The formation of 4-chlorophenol, hydroquinone, 4-chlorocatechol, 2-hydroxyisobutyric acid and three non-aromatic compounds identified as a product of the ring-opening reaction was assessed by exact mass measurements performed by liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF-MS). The bioassays showed a significant increase in toxicity during the initial stages of ozonation following a toxicity pattern closely related to the formation of ring-opening by-products.

Heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(s)

NASA Technical Reports Server (NTRS)

Leu, Ming-Taun; Timonen, Raimo S.; Keyser, Leon F.; Yung, Yuk L.

1995-01-01

The heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) (eq 1) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(S) (eq 2) were investigated over the temperature range 223-296 K in a flow-tube reactor coupled to a quadrupole mass spectrometer. Either a chemical ionization mass spectrometer (CIMS) or an electron-impact ionization mass spectrometer (EIMS) was used to provide suitable detection sensitivity and selectivity. In order to mimic atmospheric conditions, partial pressures of HNO3 and N2O5 in the range 6 x 10(exp -8) - 2 x 10(exp -6) Torr were used. Granule sizes and surface roughness of the solid NaCl substrates were determined by using a scanning electron microscope. For dry NaCl substrates, decay rates of HNO3 were used to obtain gamma(1) = 0.013 +/- 0.004 (1sigma) at 296 K and > 0.008 at 223 K, respectively. The error quoted is the statistical error. After all corrections were made, the overall error, including systematic error, was estimated to be about a factor of 2. HCl was found to be the sole gas-phase product of reaction 1. The mechanism changed from heterogeneous reaction to predominantly physical adsorption when the reactor was cooled from 296 to 223 K. For reaction 2 using dry salts, gamma(2) was found to be less than 1.0 x 10(exp -4) at both 223 and 296 K. The gas-phase reaction product was identified as ClNO2 in previous studies using an infrared spectrometer. An enhancement in reaction probability was observed if water was not completely removed from salt surfaces, probably due to the reaction of N2O5(g) + H2O(s) yields 2HNO3(g). Our results are compared with previous literature values obtained using different experimental techniques and conditions. The implications of the present results for the enhancement of the hydrogen chloride column density in the lower stratosphere after the El Chichon volcanic eruption and for the chemistry of HCl and HNO3 in the marine troposphere are discussed.

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.

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.

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.

Influence of polyunsaturated fatty acid supplementation and membrane fluidity on ozone and nitrogen dioxide sensitivity of rat alveolar macrophages

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

Rietjens, I.M.; van Tilburg, C.A.; Coenen, T.M.

1987-01-01

The phospholipid polyunsaturated fatty acid (PUFA) content and the membrane fluidity of rat alveolar macrophages were modified dose-dependently and in different ways. This was done to study the importance of both membrane characteristics for the cellular sensitivity toward ozone and nitrogen dioxide. Cells preincubated with arachidonic acid (20:4) complexed to bovine serum albumin (BSA) demonstrated an increased in vitro sensitivity versus ozone and nitrogen dioxide. The phenomenon was only observed at the highest 20:4 concentrations tested, whereas the membrane fluidity of the 20:4-treated cells already showed a maximum increase at lower preincubation concentrations. Hence it could be concluded that themore » increased ozone and nitrogen dioxide sensitivity of PUFA-enriched cells is not caused by their increased membrane fluidity, resulting in an increased accessibility of sensitive cellular fatty acid moieties or amino acid residues. This conclusion receives further support from other observations. These results strongly support the involvement of lipid oxidation in the mechanism(s) of toxic action of both ozone and nitrogen dioxide in an intact cell system.« less

Acidity and hydrogen exchange dynamics of iron(II)-bound nitroxyl in aqueous solution.

PubMed

Gao, Yin; Toubaei, Abouzar; Kong, Xianqi; Wu, Gang

2014-10-20

Nitroxyl-iron(II) (HNO-Fe(II)) complexes are often unstable in aqueous solution, thus making them very difficult to study. Consequently, many fundamental chemical properties of Fe(II)-bound HNO have remained unknown. Using a comprehensive multinuclear ((1)H, (15)N, (17)O) NMR approach, the acidity of the Fe(II)-bound HNO in [Fe(CN)5(HNO)](3-) was investigated and its pK(a) value was determined to be greater than 11. Additionally, HNO undergoes rapid hydrogen exchange with water in aqueous solution and this exchange process is catalyzed by both acid and base. The hydrogen exchange dynamics for the Fe(II)-bound HNO have been characterized and the obtained benchmark values, when combined with the literature data on proteins, reveal that the rate of hydrogen exchange for the Fe(II)-bound HNO in the interior of globin proteins is reduced by a factor of 10(6). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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

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

Investigating isotopic signatures of atmospheric nitrous acid (HONO)

NASA Astrophysics Data System (ADS)

Chai, J.; Miller, D. J.; Hastings, M. G.

2016-12-01

Nitrous acid (HONO) is an important reactive nitrogen species that can be easily photolyzed to nitrogen oxide and hydroxyl radical in the troposphere. HONO greatly influences atmospheric oxidation capacity, affecting the formation of tropospheric ozone (O3) and secondary aerosol. Recent studies have indicated that in addition to heterogeneous NOx reactions, biomass burning, soil emission and photolysis of nitric acid (HNO3) on surfaces (e.g. aerosol particles and soot) are also important sources of HONO. However, these sources have not yet been well constrained. The stable isotope ratios in nitrate have been successfully used to trace NOx sources and oxidation chemistry in the atmosphere. Can the isotopic signatures of HONO be used to trace NOx oxidation and renoxification pathways? For this purpose, we have built an annular denuder HONO collection system for the stable isotope study of HONO. Preliminary tests show successful collection and recovery of HONO synthesized in our lab. Nitrogen and oxygen isotopic analysis of the recovered HONO also shows consistent isotopic signatures. Results from field applications of this method in near road and on road environments, agricultural settings, and laboratory based biomass burns will be presented.

Ozone Sensitivity in Hybrid Poplar Correlates with Insensitivity to Both Salicylic Acid and Jasmonic Acid. The Role of Programmed Cell Death in Lesion Formation1

PubMed Central

Koch, Jennifer Riehl; Creelman, Robert A.; Eshita, Steven M.; Seskar, Mirjana; Mullet, John E.; Davis, Keith R.

2000-01-01

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. PMID:10859179

Extraction of rare earth oxides using supercritical carbon dioxide modified with Tri- n-butyl phosphate–nitric acid adducts

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

Baek, Donna L.; Fox, Robert V.; Case, Mary E.

A new tri- n-butylphosphate–nitric acid (TBP–HNO 3) adduct was prepared by combining TBP and fuming (90%) HNO 3. The adduct was characterized, and its phase-equilibrium behavior in supercritical carbon dioxide is reported. Supercritical carbon dioxide (sc-CO 2) was modified with this new adduct [TBP(HNO 3) 5.2(H 2O) 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%) HNO 3 and TBP [TBP(HNO 3) 1.7(H 2O) 0.6]. All rare earth oxides tested with both adduct species couldmore » be extracted with the exception of cerium oxide. Furthermore, the water and acid concentrations in the different adducts were found to play a significant role in rare earth oxide extraction efficiency.« less

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–HNO 3) adduct was prepared by combining TBP and fuming (90%) HNO 3. The adduct was characterized, and its phase-equilibrium behavior in supercritical carbon dioxide is reported. Supercritical carbon dioxide (sc-CO 2) was modified with this new adduct [TBP(HNO 3) 5.2(H 2O) 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%) HNO 3 and TBP [TBP(HNO 3) 1.7(H 2O) 0.6]. All rare earth oxides tested with both adduct species couldmore » be extracted with the exception of cerium oxide. Furthermore, the water and acid concentrations in the different adducts were found to play a significant role in rare earth oxide extraction efficiency.« less

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.

Seasonal variations of NO and O3 at altitudes of 18.3 and 21.3 km

NASA Technical Reports Server (NTRS)

Loewenstein, M.; Savage, H. F.; Whitten, R. C.

1975-01-01

Nitric oxide and ozone concentrations have been measured in situ from a high-altitude research aircraft. Data which show the variations of NO and O3 with the time of year are presented for altitudes of 18.3 and 21.3 km. The extreme values of the observed NO concentrations at 21.3 km are 1.2 billion per cu cm in summer and 0.2 billion per cu cm in winter. At 18.3 km the extreme values are 1.6 billion per cu cm in summer and 0.1 billion per cu cm in winter. The smoothed NO seasonal data show a variation of about a factor of 2.5 at 21.3 km and a factor of 4 at 18.3 km. The ozone data show the generally expected magnitude and seasonal variation. We have used a photochemical model employing the measured ozone concentrations, the mean solar zenith angle, and seasonal HNO3 data reported by others to predict the seasonal NO variation at 20 km. The result is a summer-to-winter NO ratio of 2.5 which is in fair agreement with the observed ratios.

Products of ozone-initiated chemistry in a simulated aircraft environment.

PubMed

Wisthaler, Armin; Tamás, Gyöngyi; Wyon, David P; Strøm-Tejsen, Peter; Space, David; Beauchamp, Jonathan; Hansel, Armin; Märk, Tilmann D; Weschler, Charles J

2005-07-01

We used proton-transfer-reaction mass spectrometry (PTR-MS) to examine the products formed when ozone reacted with the materials in a simulated aircraft cabin, including a loaded high-efficiency particulate air (HEPA) filter in the return air system. Four conditions were examined: cabin (baseline), cabin plus ozone, cabin plus soiled T-shirts (surrogates for human occupants), and cabin plus soiled T-shirts plus ozone. The addition of ozone to the cabin without T-shirts, at concentrations typically encountered during commercial air travel, increased the mixing ratio (v:v concentration) of detected pollutants from 35 ppb to 80 ppb. Most of this increase was due to the production of saturated and unsaturated aldehydes and tentatively identified low-molecular-weight carboxylic acids. The addition of soiled T-shirts, with no ozone present, increased the mixing ratio of pollutants in the cabin air only slightly, whereas the combination of soiled T-shirts and ozone increased the mixing ratio of detected pollutants to 110 ppb, with more than 20 ppb originating from squalene oxidation products (acetone, 4-oxopentanal, and 6-methyl-5-hepten-2-one). For the two conditions with ozone present, the more-abundant oxidation products included acetone/propanal (8-20 ppb), formaldehyde (8-10 ppb), nonanal (approximately 6 ppb), 4-oxopentanal (3-7 ppb), acetic acid (approximately 7 ppb), formic acid (approximately 3 ppb), and 6-methyl-5-hepten-2-one (0.5-2.5 ppb), as well as compounds tentatively identified as acrolein (0.6-1 ppb) and crotonaldehyde (0.6-0.8 ppb). The odor thresholds of certain products were exceeded. With an outdoor air exchange of 3 h(-1) and a recirculation rate of 20 h(-1), the measured ozone surface removal rate constant was 6.3 h(-1) when T-shirts were not present, compared to 11.4 h(-1) when T-shirts were present.

Blue-shifted and red-shifted hydrogen bonds: Theoretical study of the CH3CHO· · ·HNO complexes

NASA Astrophysics Data System (ADS)

Yang, Yong; Zhang, Weijun; Gao, Xiaoming

The blue-shifted and red-shifted H-bonds have been studied in complexes CH3CHO?HNO. At the MP2/6-31G(d), MP2/6-31+G(d,p) MP2/6-311++G(d,p), B3LYP/6-31G(d), B3LYP/6-31+G(d,p) and B3LYP/6-311++G(d,p) levels, the geometric structures and vibrational frequencies of complexes CH3CHO?HNO are calculated by both standard and CP-corrected methods, respectively. Complex A exhibits simultaneously red-shifted C bond H?O and blue-shifted N bond H?O H-bonds. Complex B possesses simultaneously two blue-shifted H-bonds: C bond H?O and N bond H?O. From NBO analysis, it becomes evident that the red-shifted C bond H?O H-bond can be explained on the basis of the two opposite effects: hyperconjugation and rehybridization. The blue-shifted C bond H?O H-bond is a result of conjunct C bond H bond strengthening effects of the hyperconjugation and the rehybridization due to existence of the significant electron density redistribution effect. For the blue-shifted N bond H?O H-bonds, the hyperconjugation is inhibited due to existence of the electron density redistribution effect. The large blue shift of the N bond H stretching frequency is observed because the rehybridization dominates the hyperconjugation.

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.

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.

Nitrous Acid as an Oxidant in Acidic Media

DTIC Science & Technology

1979-09-25

nitroso oxidations were run in sulfuric acid. The Hammett acidity function is used as the abscissa because it conveniently represents the acidity region...oxidation. 13 Consistent with the general mechanism, equations (1)-(3), and in contrast to nitration, phenol nitrosation displays a primary kinetic...oxidized 1(III) + Alc - 104O + C-O (4) with the only route now removing HNO being NO+ + H - H + + 2N0 (5) Apparently while alcohol remains, equation (5

Reference electrode for strong oxidizing acid solutions

DOEpatents

Rigdon, Lester P.; Harrar, Jackson E.; Bullock, Sr., Jack C.; McGuire, Raymond R.

1990-01-01

A reference electrode for the measurement of the oxidation-reduction potentials of solutions is especially suitable for oxidizing solutions such as highly concentrated and fuming nitric acids, the solutions of nitrogen oxides, N.sub.2 O.sub.4 and N.sub.2 O.sub.5, in nitric acids. The reference electrode is fabricated of entirely inert materials, has a half cell of Pt/Ce(IV)/Ce(III)/70 wt. % HNO.sub.3, and includes a double-junction design with an intermediate solution of 70 wt. % HNO.sub.3. The liquid junctions are made from Corning No. 7930 glass for low resistance and negligible solution leakage.

Three millimeter molecular line observations in Sagittarius B2. 1: Full synthesis mapping study of HNO, CCS, and HC(13)CCN

NASA Technical Reports Server (NTRS)

Kuan, Yi-Jehng; Snyder, Lewis E.

1994-01-01

We present the first full synthesis maps of the small molecules HNO, CCS, and HC(13)CCN in Sgr B2. We have observed the 3.8 mm continuum, the HNO J(sub K(sub -1)K(sub 1)) = 1(sub O1)-0(sub OO), the CCS J(sub N) = 7(sub 6)-6(sub 5), and the HC(13)CCN J = 9-8 transitions in the core of the Sgr B2 molecular cloud, using the Berkeley Illinois Maryland Association (BIMA) millimeter array and the NRAO 12 m telescope. We have found that HNO exists in five major gas clumps in the Sgr B2 region, which we have labeled HNO(N), HNO(NW), HNO(E), HNO(M), and HNO(S). Of particular interest is HNO(M), a major molecular gas concentration approximately 15 sec west of Sgr B2(M) in a region of young star formation. HNO is found to be closely associated with the ionized gas and might be depleted around bright H II complexes. In general, the peak intensity of the HNO emission is found to be offset from the peak of the continuum emission. We found evidence for some chemical differentiation among the three species, HNO, CCS, and HC(13)CCN, but the abundance ratios are in fair agreement with theoretical models. Two unidentified lines, U81420 and U81518, were observed, and a previously unknown compact dust source was detected. Our HNO data indicate the presence of a rotating approximately (2.2-4.4) x 10(exp 3)solar mass gas envelope surrounding Sgr B2(N), a possible bipolar gas outflow in HNO(M), and possibly a large (approximately 4.2 x 10(exp 4)solar mass) extended rotating disk associated with HNO(S). In addition, the CCS and HC(13)CCN data approximately outline the extended component of Sgr B2 and clearly show that the southern continuum source Sgr B2(S) is actually a major molecular source as well. Consequently, the kinematics of the Sgr B2 molecular cloud is quite complex, but in moving from the northwest to south, the LSR velocity generally changes from 79 to 46 km/s.

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.

Playing with Cardiac “Redox Switches”: The “HNO Way” to Modulate Cardiac Function

PubMed Central

Tocchetti, Carlo G.; Stanley, Brian A.; Murray, Christopher I.; Sivakumaran, Vidhya; Donzelli, Sonia; Mancardi, Daniele; Pagliaro, Pasquale; Gao, Wei Dong; van Eyk, Jennifer; Kass, David A.; Wink, David A.

2011-01-01

Abstract The nitric oxide (NO•) sibling, nitroxyl or nitrosyl hydride (HNO), is emerging as a molecule whose pharmacological properties include providing functional support to failing hearts. HNO also preconditions myocardial tissue, protecting it against ischemia-reperfusion injury while exerting vascular antiproliferative actions. In this review, HNO's peculiar cardiovascular assets are discussed in light of its unique chemistry that distinguish HNO from NO• as well as from reactive oxygen and nitrogen species such as the hydroxyl radical and peroxynitrite. Included here is a discussion of the possible routes of HNO formation in the myocardium and its chemical targets in the heart. HNO has been shown to have positive inotropic/lusitropic effects under normal and congestive heart failure conditions in animal models. The mechanistic intricacies of the beneficial cardiac effects of HNO are examined in cellular models. In contrast to β-receptor/cyclic adenosine monophosphate/protein kinase A-dependent enhancers of myocardial performance, HNO uses its “thiophylic” nature as a vehicle to interact with redox switches such as cysteines, which are located in key components of the cardiac electromechanical machinery ruling myocardial function. Here, we will briefly review new features of HNO's cardiovascular effects that when combined with its positive inotropic/lusitropic action may render HNO donors an attractive addition to the current therapeutic armamentarium for treating patients with acutely decompensated congestive heart failure. Antioxid. Redox Signal. 14, 1687–1698. PMID:21235349

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.

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)

A Recent History of HNO (Nitroxyl) Chemistry, Pharmacology and Therapeutic Potential.

PubMed

Fukuto, Jon M

2018-06-02

Due to the excitement surrounding the discovery of nitric oxide (NO) as an endogenously generated signaling molecule, numerous other nitrogen oxides were also investigated as possible physiological mediators. Among these was nitroxyl (HNO). Over the past 25 years or so, a significant amount of work by this lab and many others has discovered that HNO possesses unique chemical properties and important pharmacological utility. Indeed, the pharmacological potential for HNO as a treatment for heart failure, among other uses, has garnered this curious molecule tremendous recent attention. This review thus summarizes the events that led to this recent attention as well as pose remaining questions that are important to answer with regards to understanding the chemistry and biology of HNO. This article is protected by copyright. All rights reserved.

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

Extraction chromatography of the Rf homologs, Zr and Hf, using TEVA and UTEVA resins in HCl, HNO3, and H2SO4 media

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

Alfonso, M. C.; Bennett, M. E.; Folden, C. M.

2015-06-20

The extraction behavior of the Rf homologs, Zr and Hf, has been studied in HCl, HNO3, and H2SO4 media using TEVA (R) (a trioctyl and tridecyl methyl ammonium-based resin) and UTEVA (R) (a diamyl amylphosphonate-based resin). All six systems were considered for the future chemical characterization of Rf. Batch uptake studies were first performed to determine which systems could separate Zr and Hf and these results were used to determine what acid concentration range to focus on for the column studies. The batch uptake studies showed that UTEVA separates Zr and Hf in all media, while the intergroup separation wasmore » only observed in HCl media with TEVA. Both HCl systems showed viability for potential extraction chromatographic studies of Rf.« less

Antarctic stratospheric chemistry of chlorine nitrate, hydrogen chloride, and ice - Release of active chlorine

NASA Technical Reports Server (NTRS)

Molina, Mario J.; Tso, Tai-Ly; Molina, Luisa T.; Wang, Frank C.-Y.

1987-01-01

The reaction rate between atmospheric hydrogen chloride (HCl) and chlorine nitrate (ClONO2) is greatly enhanced in the presence of ice particles; HCl dissolves readily into ice, and the collisional reaction probability for ClONO2 on the surface of ice with HCl in the mole fraction range from about 0.003 to 0.010 is in the range from about 0.05 to 0.1 for temperatures near 200 K. Chlorine is released into the gas phase on a time scale of at most a few milliseconds, whereas nitric acid (HNO3), the other product, remains in the condensed phase. This reaction could play an important role in explaining the observed depletion of ozone over Antarctica; it releases photolytically active chlorine from its most abundant reservoir species, and it promotes the formation of HNO3 and thus removes nitrogen dioxide from the gas phase. Hence it establishes the necessary conditions for the efficient catalytic destruction of ozone by halogenated free radicals.

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

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

Nouchi, Isamu; Toyama, Susumu

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 aftermore » 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.« less

In situ stratospheric measurements of HNO3 and HCl near 30 km using the balloon-borne laser in situ sensor tunable diode laser spectrometer

NASA Technical Reports Server (NTRS)

May, R. D.; Webster, C. R.

1989-01-01

In situ stratospheric measurements of the concentrations of the reservoir species HNO3 and HCl made during two flights of the high-resolution (0.0005/cm) balloon-borne laser in situ sensor instrument from Palestine, Texas, are reported. A measured HNO3 volume mixing ratio of 4.3 parts per billion by volume (ppbv) at 31 km altitude is about 1 ppbv larger than previously reported measurements at 32 deg N. An HCl mixing ratio of 1.6 ppbv at 29 km is in agreement with values obtained from earlier remote sensing techniques within the experimental uncertainties. Upper limits at 31 km of 0.4 ppbv for H2O2 and 0.2 ppbv for HOCl are also derived from analyses of spectra recorded near 1252/cm.

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.

α-Tocopherol/Gallic Acid Cooperation in the Protection of Galactolipids Against Ozone-Induced Oxidation.

PubMed

Rudolphi-Skórska, Elżbieta; Filek, Maria; Zembala, Maria

2016-04-01

The protective ability of α-tocopherol (TOH) and gallic acid (GA) acting simultaneously at the moment of oxidizer application was evaluated by determination of galactolipid layers' oxidation degree. Addition of GA resulted in a significant decrease of ozone-derived radicals shifting the threshold of lipid sensitivity by an amount approximately corresponding to the GA intake in bulk reaction with ozone. TOH presence in lipid layers results in a change of the role of GA which additionally may be involved in the reduction of tocopheroxyl radical formed during oxidation. This leads to a decrease in effectiveness of GA in diminishing the amount of ozone radicals. Such an effect was not observed for mixed layers containing galactolipid and pre-oxidized tocopherol where the ozone threshold level was associated with a stoichiometry of GA + O3 reaction. It was concluded that probably subsequent transformations of tocopheroxyl radical to less reactive forms prevent its reaction with GA the entire quantity of which is used for radicals scavenging. This result shows the role of time parameter in systems where substrates are engaged in various reactions taking place simultaneously. The inactivation of 1,1-diphenyl-2-picrylhydrazyl radical by studied antioxidants in homogeneous system confirmed observations made on the basis of lipid layer properties indicating their antagonistic action (at least at studied conditions). Formation of layers in post-oxidation situation did not depend whether tocopherol was oxidized during oxidation of lipid/tocopherol mixture or was introduced as pre-oxidized. This may be interpreted as indication that products of tocopherol oxidation may stabilize lipid layers.

Choice of intra-articular injection in treatment of knee osteoarthritis: platelet-rich plasma, hyaluronic acid or ozone options.

PubMed

Duymus, Tahir Mutlu; Mutlu, Serhat; Dernek, Bahar; Komur, Baran; Aydogmus, Suavi; Kesiktas, Fatma Nur

2017-02-01

This study was performed to compare the efficacy of treatment in three groups of patients with knee osteoarthritis (OA) given an intra-articular injection of platelet-rich plasma (PRP), hyaluronic acid (HA) or ozone gas. A total of 102 patients with mild-moderate and moderate knee OA who presented at the polyclinic with at least a 1-year history of knee pain and VAS score ≥4 were randomly separated into three groups. Group 1 (PRP group) received intra-articular injection of PRP × 2 doses, Group 2 (HA group) received a single dose of HA, and Group 3 (Ozone group) received ozone × four doses. Weight-bearing anteroposterior-lateral and Merchant's radiographs of both knees were evaluated. WOMAC and VAS scores were applied to all patients on first presentation and at 1, 3, 6 and 12 months. At the end of the 1st month after injection, significant improvements were seen in all groups. In the 3rd month, the improvements in WOMAC and VAS scores were similar in Groups 1 and 2, while those in Group 3 were lower (p < 0.001). At the 6th month, while the clinical efficacies of PRP and HA were similar and continued, the clinical effect of ozone had disappeared (p < 0.001). At the end of the 12th month, PRP was determined to be both statistically and clinically superior to HA (p < 0.001). In the treatment of mild-moderate knee OA, PRP was more successful than HA and ozone injections, as the application alone was sufficient to provide at least 12 months of pain-free daily living activities. Therapeutic study, Level I.

HNO3 modified biochars for uranium (VI) removal from aqueous solution.

PubMed

Jin, Jie; Li, Shiwei; Peng, Xianqiang; Liu, Wei; Zhang, Chenlu; Yang, Yan; Han, Lanfang; Du, Ziwen; Sun, Ke; Wang, Xiangke

2018-05-01

The HNO 3 treatment was used to chemically modify the biochars produced from wheat straw (WH) and cow manure for U(VI) removal from aqueous solution. Macroscopic experiments proved that the enrichment of U(VI) on the biochars was regulated by surface complexation and electrostatic interactions. FTIR and XPS analyses confirmed that the highly efficient adsorption of U(VI) was due to the carboxyl groups on the biochar surfaces. The reducing agents of the R-CH 2 OH groups facilitated U(VI) adsorption on the untreated biochars. Owing to the higher contents of surface COO groups and more negative surface charge, the modified biochars showed enhanced U(VI) adsorption ability than the untreated ones. The maximum adsorption capacity of U(VI) by the oxidized WH was calculated to be 355.6 mg/g at pH 4.5 and 298 K, which was an improvement of 40 times relative to the untreated WH and was higher than that of most carbon-based adsorbents. Copyright © 2018 Elsevier Ltd. All rights reserved.

Harvesting of Scenedesmus obliquus FSP-3 using dispersed ozone flotation.

PubMed

Cheng, Ya-Ling; Juang, Yu-Chuan; Liao, Guan-Yu; Tsai, Pei-Wen; Ho, Shih-Hsin; Yeh, Kuei-Ling; Chen, Chun-Yen; Chang, Jo-Shu; Liu, Jhy-Chern; Chen, Wen-Ming; Lee, Duu-Jong

2011-01-01

The Scenedesmus obliquus FSP-3, a species with excellent potential for CO(2) capture and lipid production, was harvested using dispersed ozone flotation. While air aeration does not, ozone produces effective solid-liquid separation through flotation. Ozone dose applied for sufficient algal flotation is similar to those used in practical drinking waterworks. The algae removal rate, surface charge, and hydrophobicity of algal cells, and fluorescence characteristics and proteins and polysaccharides contents of algogenic organic matter (AOM) were determined during ozonation. Proteins released from tightly bound AOM are essential to modifying the hydrophobicity of bubble surfaces for easy cell attachment and to forming a top froth layer for collecting floating cells. Humic substances in the suspension scavenge dosed ozone that adversely affects ozone flotation efficiency of algal cells. Copyright © 2010 Elsevier Ltd. All rights reserved.

Plant resistance mechanisms to air pollutants: rhythms in ascorbic acid production during growth under ozone stress

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

Lee, E.H.

1991-01-01

Relationships between ozone (O3) tolerance and leaf ascorbic acid concentrations in O3-susceptible (O3-S) 'Hark' and O3-resistant (O3-R) 'Hood' soybean, Glycine max (L.) Merr., cultivars were examined with high-performance liquid chromatography (HPLC). Leaf samples were analyzed at 4 intervals during a 24 h period. Soybean cultivars grown in the greenhouse with charcoal filtered (CF) and nonfiltered (NF) air showed daily oscillations in ascorbic acid production. Highest ascorbic acid levels in leaves during light coincided with highest concentrations of photochemical oxidants in the atmosphere at 2:00 p.m. The resistant genotype produced more ascorbic acid in its trifoliate leaves than did the correspondingmore » susceptible genotype. Under CF air (an O3-reduced environment) O3-S and O3-R cultivars showed rhythms in ascorbic acid production. In NF air (an O3 stress environment) the O3-R cultivar alone showed rhythms in ascorbic acid production. Results indicated that superior O3 tolerance in the Hood soybean cultivar (compared with Hark) was associated with a greater increase in endogenous levels of ascorbic acid. Ascorbic acid may scavenge free radicals and thereby protect cells from injury by O3 or other oxyradical products. Plants defend themselves against photochemical oxidant stress, such as O3, by several mechanisms. Experimental evidence indicates that antioxidant defense systems existing in plant tissues may function to protect cellular components from deleterious effects of photochemical oxidants through endogenous and exogenous controls.« less

Diagnosing ozone recovery using the O3-N2O relationship

NASA Astrophysics Data System (ADS)

Butler, A. H.; Gao, R. S.; Maycock, A.; Portmann, R. W.; Thornberry, T. D.; Rosenlof, K. H.; Fahey, D. W.

2016-12-01

The ubiquitous compact correlation between collocated values of stratospheric ozone (O3) and the tracer nitrous oxide (N2O) results from the stratospheric photochemical processes that produce ozone and destroy N2O combined with common transport and mixing processes. Changes in the correlation slope under certain circumstances reflect changes in the production and loss balance of ozone. This approach has been used extensively to diagnose and quantify ozone loss in polar spring. Using a coupled atmosphere-ocean model with interactive chemistry (CESM/WACCM), we show that this relationship can be used to diagnose ozone recovery in the lower extratropical stratosphere. We then consider in situ measurements of O3 and N2O from ATTREX, GloPac, and HIPPO as well as satellite measurements from ACE and Aura MLS to consider whether ozone recovery can be detected in observations during the period 2004-2016.

A new numerical model of the middle atmosphere. 2: Ozone and related species

NASA Technical Reports Server (NTRS)

Garcia, Rolando R.; Solomon, Susan

1994-01-01

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.

Atmospheric chemistry of a 33-34 hour old volcanic cloud from Hekla Volcano (Iceland): Insights from direct sampling and the application of chemical box modeling

USGS Publications Warehouse

Rose, William I.; Millard, G.A.; Mather, T.A.; Hunton, D.E.; Anderson, B.; Oppenheimer, C.; Thornton, B.F.; Gerlach, T.M.; Viggiano, A.A.; Kondo, Y.; Miller, T.M.; Ballenthin, J.O.

2006-01-01

On 28 February 2000, a volcanic cloud from Hekla volcano, Iceland, was serendipitously sampled by a DC-8 research aircraft during the SAGE III Ozone Loss and Validation Experiment (SOLVE I). It was encountered at night at 10.4 km above sea level (in the lower stratosphere) and 33-34 hours after emission. The cloud is readily identified by abundant SO2 (???1 ppmv), HCl (???70 ppbv), HF (???60 ppbv), and particles (which may have included fine silicate ash). We compare observed and modeled cloud compositions to understand its chemical evolution. Abundances of sulfur and halogen species indicate some oxidation of sulfur gases but limited scavenging and removal of halides. Chemical modeling suggests that cloud concentrations of water vapor and nitric acid promoted polar stratospheric cloud (PSC) formation at 201-203 K, yielding ice, nitric acid trihydrate (NAT), sulfuric acid tetrahydrate (SAT), and liquid ternary solution H2SO4/H2O/HNO3 (STS) particles. We show that these volcanically induced PSCs, especially the ice and NAT particles, activated volcanogenic halogens in the cloud producing >2 ppbv ClOx. This would have destroyed ozone during an earlier period of daylight, consistent with the very low levels of ozone observed. This combination of volcanogenic PSCs and chlorine destroyed ozone at much faster rates than other PSCs that Arctic winter. Elevated levels of HNO3 and NOy in the cloud can be explained by atmospheric nitrogen fixation in the eruption column due to high temperatures and/or volcanic lightning. However, observed elevated levels of HOx remain unexplained given that the cloud was sampled at night. Copyright 2006 by the American Geophysical Union.

Treatment of azo dye Acid Orange 52 using ozonation and completed-mixed activated sludge process

NASA Astrophysics Data System (ADS)

Abidin, C. Z. A.; Fahmi; Ong, S. A.; Ahmad, R.; Sabri, S. N.

2017-06-01

In this study, the characteristic of colour and COD removal of azo dye Acid Orange 52 (AO52) by ozonation, in combination with complete-mixed activated sludge process (CMAS) was evaluated. The experimentation was arranged in two phases: during the first one, only ozonation was performed, while, during the second phase, it was integrated with CMAS. The performance of colour and COD concentration of AO52 with and without CMAS treatment, is compared and evaluated. From the results, it is obvious that high decolourization from the start of CMAS was contributed from the pre-treatments. The colour removal was due to the fact that ozonation able to cleave the azo bonds that represent colour. Thus, CMAS without pre-treatment are unable to decolourize the dyes sufficiently. 59.6% COD was removed from the first-stage, while merely 9.8% COD fraction removed from the subsequence second-stage CMAS. It is suggested that the rapid COD removal without ozonation are due to activated sludge adsorption processes. The decreased of mixed liquor suspended solids (MLSS) affected the CMAS performances, as the biomass decreased due to lack of nutrient for activated sludge microorganisms to multiply. Results from pre-ozonation alone contributed more than 50% of total COD removal, which indicated that at higher ozone dosage, tend to mineralize azo dye. Thus, ozonation not oxidized the dye though complete mineralization that produce carbon dioxide and water. However, it is a potential process for enhancing colour removal and biodegradability of dye-containing wastewater, once the appropriate ozonation time is determined. Therefore, the role of ozonation seems to break down the dye molecules and created ozonation by-product that is easily biodegraded in the subsequent biological treatment.

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.

Formation of aldehydes and carboxylic acids in ozonated surface water and wastewater: a clear relationship with fluorescence changes.

PubMed

Liu, Chen; Tang, Xiangyu; Kim, Jaeshin; Korshin, Gregory V

2015-04-01

This study examined the formation of aldehydes and carboxylic acids in ozonated surface water and municipal wastewater secondary effluent and addressed correlations between the generation of these compounds and concurrent changes of the fluorescence of natural/effluent organic matter (NOM/EfOM) substrates. Ozonation was effective in removing fluorophores in all excitation/emission matrix (EEM) regions, with those operationally assigned to humic- and protein-like species showing relatively higher reactivity than fulvic-like species. Examination of HO exposures and attendant changes of fluorescence-based parameters allows establishing strong linear relationships between formation of the aldehydes and carboxylic acids and the relative changes of integrated fluorescence (ΔIF/IF0). This demonstrates the feasibility of surrogate monitoring of the formation of biodegradable ozonation by-products via online measurements of water/wastewater EEM fluorescence. Copyright © 2014 Elsevier Ltd. All rights reserved.

Theoretical Investigation of the Reactivity of Sodium Dicyanamide with Nitric Acid.

PubMed

Vogelhuber, Kristen M; Booth, Ryan S; Annesley, Christopher J

2018-03-01

There is a need to replace current hydrazine fuels with safer propellants, and dicyanamide (DCA - )-based systems have emerged as promising alternatives because they autoignite when mixed with some oxidizers. Previous studies of the hypergolic reaction mechanism have focused on the reaction between DCA - and the oxidizer HNO 3 ; here, we compare the calculated pathway of DCA - + HNO 3 with the reaction coordinate of the ion pair sodium dicyanamide with nitric acid, Na[DCA] + HNO 3 . Enthalpies and free energies are calculated in the gas phase and in solution using a quantum mechanical continuum solvation model, SMD-GIL. The barriers to the Na[DCA] + HNO 3 reaction are dramatically lowered relative to those of the reaction with the bare anion, and an exothermic exit channel to produce NaNO 3 and the reactive intermediate HDCA appears. These results suggest that Na[DCA] may accelerate the ignition reaction.

Understanding the similarities and differences between ozone and peroxone in the degradation of naphthenic acids: Comparative performance for potential treatment.

PubMed

Meshref, Mohamed N A; Klamerth, Nikolaus; Islam, Md Shahinoor; McPhedran, Kerry N; Gamal El-Din, Mohamed

2017-08-01

Ozonation at high doses is a costly treatment for oil sands process-affected water (OSPW) naphthenic acids (NAs) degradation. To decrease costs and limit doses, different peroxone (hydrogen peroxide/ozone; H 2 O 2 :O 3 ) processes using mild-ozone doses of 30 and 50 mg/L were investigated. The degradation efficiency of O x -NAs (classical (O 2 -NAs) + oxidized NAs) improved from 58% at 30 mg/L ozone to 59%, 63% and 76% at peroxone (1:1), 50 mg/L ozone, and peroxone (1:2), respectively. Suppressing the hydroxyl radical (•OH) pathway by adding tert-butyl alcohol did significantly reduce the degradation in all treatments, while molecular ozone contribution was around 50% and 34% for O 2 -NAs and O x -NAs, respectively. Structure reactivity toward degradation was observed with degradation increase for both O 2 -NAs and O x -NAs with increase of both carbon (n) and hydrogen deficiency/or |-Z| numbers in all treatments. However, the combined effect of n and Z showed specific insights and differences between ozone and peroxone treatments. The degradation pathway for |-Z|≥10 isomers in ozone treatments through molecular ozone was significant compared to •OH. Though peroxone (1:2) highly reduced the fluorophore organics and toxicity to Vibrio fischeri, the best oxidant utilization in the degradation of O 2 -NAs (mg/L) per ozone dose (mg/L) was observed in the peroxone (1:1) (0.91) and 30 mg/L ozone treatments (0.92). At n = 9-11, peroxone (1:1) had similar or enhanced effect on the O 2 -NAs degradation compared to 50 mg/L ozone. Enhancing •OH pathway through peroxone versus ozone may be an effective OSPW treatment that will allow its safe release into receiving environments with marginal cost addition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanisms of ozone toxicity in cultured cells. I. Reduced clonogenic ability of polyunsaturated fatty acid-supplemented fibroblasts. Effect of vitamin E

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

Konings, A.W.

1986-01-01

The direct action of ozone on viability and survival of normal and modified mouse lung fibroblasts has been studied. By cell manipulation of fibroblasts in culture, the content of polyunsaturated fatty acids (PUFA) in the phospholipids was increased from about 6% to about 40%. The cellular content of alpha-tocopherol (alpha-T) (vitamin E) could be drastically enhanced. Vitamin E supplementation to the cell did not influence the PUFA manipulation. Normal, PUFA, and PUFA(alpha-T) fibroblasts were exposed to ozone by bubbling 10 ppm through the cell suspensions for different periods of time (0-6 h). No significant effects of the ozone exposure couldmore » be established when normal fibroblasts were used. The PUFA fibroblasts, however, were very vulnerable to ozone toxicity, both in terms of dye uptake (Trypan blue) and cell death (clonogenic ability). When alpha-tocopherol was present in the cell (200 ng/10(6) cells), a clear protection against ozone toxicity was found. It is concluded that ozone toxicity might be higher under conditions of a relative high amount of polyunsaturated fatty acids in the membrane phospholipids of the cell and a low cellular antioxidant capacity. Cellular membranes are probably an important target for ozone-induced cell death.« less

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.

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.

TES/Aura L2 Ozone (O3) Nadir V6 (TL2O3NS)

Atmospheric Science Data Center

2018-01-22

TES/Aura L2 Ozone (O3) Nadir (TL2O3NS) News:  TES News Join ... Project Title:  TES Discipline:  Tropospheric Composition Version:  V6 Level:  L2 Platform:  TES/Aura L2 Ozone Spatial Coverage:  5.3 x 8.5 km nadir ...

TES/Aura L2 Ozone (O3) Nadir V6 (TL2O3N)

Atmospheric Science Data Center

2018-01-18

TES/Aura L2 Ozone (O3) Nadir (TL2O3N) News:  TES News Join ... Project Title:  TES Discipline:  Tropospheric Composition Version:  V6 Level:  L2 Platform:  TES/Aura L2 Ozone Spatial Coverage:  5.3 x 8.5 km nadir ...

Effect of ozone application on the resin-dentin microtensile bond strength.

PubMed

Rodrigues, P C F; Souza, J B; Soares, C J; Lopes, L G; Estrela, C

2011-01-01

When ozone is used during caries treatment, bond strength can be compromised by the release of oxygen. The use of antioxidant agents neutralizes the free oxygen. The aim of this study was to evaluate the effects of ozone and sodium ascorbate on resin-dentin microtensile bond strength (μTBS). Forty human third molars were divided into four groups: Group 1, not treated with ozone; Group 2, ozone application followed by acid etching; Group 3, acid etching followed by ozone application; and Group 4, ozone and application of sodium ascorbate. Bonded beams (1.0 mm(2)) were tested under tension (0.5 mm min(-1)). The μTBS values were analyzed using one-way analysis of variance (ANOVA) and the Tukey test (p=0.05). All beams that fractured were analyzed under stereomicroscopy (40×). Group 1 had significantly higher μTBS values than Group 2 or 3. The μTBS values of Groups 1 and 4 were similar and higher than those of Group 2. The use of ozone in Group 2 resulted in lower values of μTBS in all conditions evaluated. The predominant failure mode was adhesive. The application of ozone decreased the μTBS of the dentin-composite resin interface. These values were reversed when compared with Groups 1 and 2 when sodium ascorbate was used.

Activated carbon with excellent chromium(VI) adsorption performance prepared by acid-base surface modification.

PubMed

Liu, S X; Chen, X; Chen, X Y; Liu, Z F; Wang, H L

2007-03-06

In the present work, activated carbon (AC) with excellent Cr(VI) adsorption performance especially at low concentrations was prepared by an acid-base surface modification method. Raw activated carbon (AC(0)) was first oxidized in boiling HNO(3) (AC(1)), then treated with a mixture of NaOH and NaCl (AC(2)). Batch equilibrium and continuous column adsorption were conducted to evaluate the adsorption performance. Boehm titration, elemental analysis, and N(2)/77K adsorption isotherm methods were used to characterize the surface properties and pore structure of modified ACs. The results revealed that the modified AC exhibited excellent Cr(VI) adsorption performance in terms of adsorption capacity and adsorption rate: AC(2)>AC(1)>AC(0). Modification caused S(BET) to decrease and the total number of surface oxygen acidic groups to increase. HNO(3) oxidization produced positive acid groups, and subsequently NaOH treatment replaced H(+) of surface acid groups by Na(+), and the acidity of AC decreased. The main cause of higher Cr(VI) adsorption capacity and rate for AC(2) was the presence of more oxygen surface acidic groups and suitable surface acidity. HNO(3)-NaOH modification shows potential for the preparation of high quality AC for the effective removal of low concentrations of Cr(VI).

A kinetic study of 3-chlorophenol enhanced hydroxyl radical generation during ozonation.

PubMed

Utsumi, Hideo; Han, Youn-Hee; Ichikawa, Kazuhiro

2003-12-01

Hydroxyl (OH) radical is proposed as an important factor in the ozonation of water. In the present study, the enhancing effect of 3-chlorophenol on OH radical generation was mathematically evaluated using electron spin resonance (ESR)/spin-trapping technique. OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO-OH. The initial velocity of DMPO-OH generation in ozonated water containing 3-chlorophenol was quantitatively measured using a combined system of ESR spectroscopy with stopped-flow apparatus which was controlled by home-made software. The initial velocity of DMPO-OH generation increased as a function of the concentration of ozone and the more effectively of 3-chlorophenol concentration. The relation among ozone concentration, amount of 3-chlorophenol and the initial velocity (nu(0)) of DMPO-OH generation was mathematically analyzed and the following equation was obtained, nu(0) (10(-6)M/s)=[9.7 x [3-chlorophenol (10(-9)M)] + 0.0005]exp(57 x [ozone (10(-9)M)]). The equation fitted very well with the experimental results, and the correlation coefficient was larger than 0.99. The equation for the enhancing effect by 3-chlorophenol should provide useful information to optimize the condition in ozone treatment process of water containing phenolic pollutants.

Kinetics of ozonation. 4. Reactions of ozone with. cap alpha. -tocopherol and oleate and linoleate esters in carbon tetrachloride and in aqueous micellar solvents

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

Giamalva, D.H.; Church, D.F.; Pryor, W.A.

1986-10-15

Vitamin E (..cap alpha..-tocopherol; ..cap alpha..-T) is known to protect animals against the deleterious effects of ozone in polluted air; one such effect is the ozone-initiated autooxidation of polyunsaturated fatty acids (PUFA) that occur in membranes. In order to assess the possibility of a direct reaction of ozone with ..cap alpha..-T competing with the very fast ozone-PUFA reaction, we have measured the rates of reaction of ozone with ..cap alpha..-T, oleic acid, and linoleic acid. I CCl/sub 4/ as solvent, ..cap alpha..-T reacts with ozone with a rate constant of about 5500 M/sup -1/ s/sup -1/; methyl oleate and methylmore » linoleate react 2 orders of magnitude faster. In aqueous micellar solutions the rate constants for ..cap alpha..-T and the fatty acids are more similar. The k for the ozone/..cap alpha..-T reaction is about 1 x 10/sup 6/ M/sup -1/ s/sup -1/ at pH 7, but decreases as the solution becomes more acidic; the k's for oleic acid and linoleic acid are ca. 1 x 10/sup 6/ M/sup -1/ s/sup -1/ and exhibit no significant pH dependence. Since the ratio of fatty acids to ..cap alpha..-T in membranes is typically at least 100-1000 to 1, we conclude that the direct reaction of ozone with ..cap alpha..-T is unlikely. Thus, the protection that vitamin E provides to animals breathing ozone-containing air must result from vitamin E acting as a free radical scavenger. We have also detected the ..cap alpha..-tocopheroxyl radical as an intermediate from the reaction of ozone with ..cap alpha..-T both in CCl/sub 4/ and aqueous micelles using electron spin resonance spectroscopy. The authors suggest that the observation of this intermediate is consistent with an initial electron transfer from ..cap alpha..-T to ozone.« less

Iron catalyzed conversion of NO into nitrosonium (NO+) and nitroxyl (HNO/NO-) species.

PubMed

Stojanović, Srdjan; Stanić, Dragana; Nikolić, Milan; Spasić, Mihailo; Niketić, Vesna

2004-11-01

The conversion of NO into its congeners, nitrosonium (NO+) and nitroxyl (HNO/NO-) species, has important consequences in NO metabolism. Dinitrosyl iron complex (DNIC) combined with thiol ligands was shown to catalyze the conversion of NO into NO+, resulting in the synthesis of S-nitrosothiols (RSNO) both in vitro and in vivo. The formation mechanism of DNIC was proposed to involve the intermediate release of nitroxyl. Since the detection of hydroxylamine (as the product of a rapid reaction of HNO/NO- with thiols) is taken as the evidence for nitroxyl generation, we examined the formation of hydroxylamine, RSNO, and nitrite (the product of a rapid reaction of NO+ with water) in neutral solutions containing iron ions and thiols exposed to NO under anaerobic conditions. Hydroxylamine was detected in NO treated solutions of iron ions in the presence of cysteine, but not glutathione (GSH). The addition of urate, a major "free" iron-binding agent in humans, to solutions of GSH and iron ions, and the subsequent treatment of these solutions with NO increased the synthesis of GSNO and resulted in the formation of hydroxylamine. This caused a loss of urate and yielded a novel nitrosative/nitration product. GSH attenuated the urate decomposition to such a degree that it could be reflected as the function of GSH:urate. Results described here contribute to the understanding of the role of iron ions in catalyzing the conversion of NO into HNO/NO- and point to the role of uric acid not previously described.

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

Degradation of recalcitrant naphthenic acids from raw and ozonated oil sands process-affected waters by a semi-passive biofiltration process.

PubMed

Zhang, Lei; Zhang, Yanyan; Gamal El-Din, Mohamed

2018-04-15

In this study, a fixed-bed biofiltration system (biofilter) that utilized indigenous microorganisms was developed for the reclamation of oil sands process-affected water (OSPW). With the assistance of quantitative polymerase chain reaction (qPCR) and confocal laser scanning microscopy (CLSM), indigenous microorganisms from OSPW were able to attach to the surface of sand media and form biofilms. The number of total bacteria on the biofilter media reached a steady state (10 9 /g) after 23 days of operation. Ultra Performance Liquid Chromatography/High Resolution Mass Spectrometry (UPLC/HRMS) analysis showed that 21.8% of the classical naphthenic acids (NAs) removal was achieved through the circulation of raw OSPW on the biofilter for 8 times (equivalent to a hydraulic retention time of 16 h). When ozonation with utilized ozone dose of 30 mg/L was applied as pretreatment, the classical NAs in the ozonated OSPW were removed by 89.3% with an accelerated biodegradation rate of 0.5 mg/L/h. Compared with other biofilm reactors such as moving bed biofilm reactor (MBBR), ozonation pretreatment could benefit the biodegradation of NAs in the biofilter more (classical NA removal: 89.3% vs. 34.4%), especially for those with high carbon number and cyclicity. The combined ozonation-biofiltration process could remove 92.7% of classical NAs from raw OSPW in 16 h. Although both ozonation and biofiltration alone did not show degradation of oxidized NAs from raw OSPW, the combined process led to a 52.9% and 42.6% removal for O 3 -NAs and O 4 -NAs, respectively, which were the dominant oxidized NA species in OSPW. Metagenomic sequencing analysis showed that Rhodococcus was the dominant bacterial genus on the sand media, which may play a crucial role during the NA biodegradation. With the advantage of high NA removal efficiency, the combined ozonation-biofiltration process is a promising approach for NA degradation and shows high potential to be scaled up for in-situ OSPW

Towards reducing DBP formation potential of drinking water by favouring direct ozone over hydroxyl radical reactions during ozonation.

PubMed

De Vera, Glen Andrew; Stalter, Daniel; Gernjak, Wolfgang; Weinberg, Howard S; Keller, Jurg; Farré, Maria José

2015-12-15

When ozonation is employed in advanced water treatment plants to produce drinking water, dissolved organic matter reacts with ozone (O3) and/or hydroxyl radicals (OH) affecting disinfection byproduct (DBP) formation with subsequently used chlorine-based disinfectants. This study presents the effects of varying exposures of O3 and •OH on DBP concentrations and their associated toxicity generated after subsequent chlorination. DBP formation potential tests and in vitro bioassays were conducted after batch ozonation experiments of coagulated surface water with and without addition of tertiary butanol (t-BuOH, 10 mM) and hydrogen peroxide (H2O2, 1 mg/mg O3), and at different pH (6-8) and transferred ozone doses (0-1 mg/mg TOC). Although ozonation led to a 24-37% decrease in formation of total trihalomethanes, haloacetic acids, haloacetonitriles, and trihaloacetamides, an increase in formation of total trihalonitromethanes, chloral hydrate, and haloketones was observed. This effect however was less pronounced for samples ozonated at conditions favoring molecular ozone (e.g., pH 6 and in the presence of t-BuOH) over •OH reactions (e.g., pH 8 and in the presence of H2O2). Compared to ozonation only, addition of H2O2 consistently enhanced formation of all DBP groups (20-61%) except trihalonitromethanes. This proves that •OH-transformed organic matter is more susceptible to halogen incorporation. Analogously, adsorbable organic halogen (AOX) concentrations increased under conditions that favor •OH reactions. The ratio of unknown to known AOX, however, was greater at conditions that promote direct O3 reactions. Although significant correlation was found between AOX and genotoxicity with the p53 bioassay, toxicity tests using 4 in vitro bioassays showed relatively low absolute differences between various ozonation conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process.

PubMed

Qiang, Zhimin; Liu, Chao; Dong, Bingzhi; Zhang, Yalei

2010-01-01

The degradation of alachlor by direct ozonation and advanced oxidation process O(3)/H(2)O(2) was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5+/-0.1M(-1)s(-1) at pH 7.0 and 20 degrees C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O(3)/H(2)O(2), respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2',6'-diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2'-acetyl-6'-ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2',6'-ethyl-acetanilide, 2-chloro-2',6'-acetyl-acetanilide and 2-chloro-2'-ethyl-6'-acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O(3) and O(3)/H(2)O(2) also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O(3)/H(2)O(2)). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O(3) or O(3)/H(2)O(2) treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly reduced. 2009 Elsevier Ltd. All rights reserved.

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.

Variation in isotopologues of atmospheric nitric acid in passively collected samples along an air pollution gradient in southern California

Treesearch

Michael D. Bell; James O. Sickman; Andrzej Bytnerowicz; Pamela E. Padgett; Edith B. Allen

2014-01-01

The sources and oxidation pathways of atmospheric nitric acid (HNO3) can be evaluated using the isotopic signatures of oxygen (O) and nitrogen (N). This study evaluated the ability of Nylasorb nylon filters to passively collect unbiased isotopologues of atmospheric HNO3 under controlled and field conditions. Filters...

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.

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. Copyright © 2013 Elsevier GmbH. All rights reserved.

Catalytic ozonation of p-chlorobenzoic acid by activated carbon and nickel supported activated carbon prepared from petroleum coke.

PubMed

Li, Xukai; Zhang, Qiuyun; Tang, Lili; Lu, Ping; Sun, Fengqiang; Li, Laisheng

2009-04-15

The aim of this research was to investigate catalytic activity of petroleum coke, activated carbon (AC) prepared from this material, Ni supported catalyst on activated carbon (Ni/AC) in the ozonation of aqueous phase p-chlorobenzoic acid (p-CBA). Activated carbon and Ni/AC catalyst were characterized by XRD and SEM. The presence of petroleum coke did not improve the degradation of p-CBA compared to ozonation alone, but it was advantageous for p-CBA mineralization (total organic carbon, TOC, reduction), indicating the generation of highly oxidant species (*OH) in the medium. The presence of either activated carbon or Ni/AC considerably improves TOC removal during p-CBA ozonation. Ni/AC catalyst shows the better catalytic activity and stability based on five repeated tests during p-CBA ozonation. During the ozonation (50 mg/h ozone flow rate) of a 10 mg/L p-CBA (pH 4.31), it can be more mineralized in the presence of Ni/AC catalyst (5.0 g/L), TOC removal rate is over 60% in 60 min, 43% using activated carbon as catalyst, only 30% with ozonation alone.

TES/Aura L2 Ozone (O3) Limb V6 (TL2O3LS)

Atmospheric Science Data Center

2018-03-01

TES/Aura L2 Ozone (O3) Limb (TL2O3LS) News:  TES News Join ... Project Title:  TES Discipline:  Tropospheric Composition Version:  V6 Level:  L2 Platform:  TES/Aura L2 Ozone Spatial Coverage:  27 x 23 km Limb Spatial ...

TES/Aura L2 Ozone (O3) Limb V6 (TL2O3L)

Atmospheric Science Data Center

2018-03-01

TES/Aura L2 Ozone (O3) Limb (TL2O3L) News:  TES News Join TES ... Project Title:  TES Discipline:  Tropospheric Composition Version:  V6 Level:  L2 Platform:  TES/Aura L2 Ozone Spatial Coverage:  27 x 23 km Limb Spatial ...

Simultaneous removal of 2,4,6-tribromophenol from water and bromate ion minimization by ozonation.

PubMed

Gounden, Asogan N; Singh, Sooboo; Jonnalagadda, Sreekantha B

2018-06-02

The study investigates the degradation of 2,4,6-tribromophenol (2,4,6-TBP) and the influence of solution pH, alkalinity, H 2 O 2 and O 3 dosage. Debromination efficiency of 2,4,6-TBP was the highest in basic water (pH = 10.61). The extent of TOC removal compared favourably with the amount of substrate converted, suggesting favourable mineralization of oxygenated by-products (OBPs). Ozonation in basic water favoured the formation of toxicBrO 3 - , while in acidic water (pH = 2.27) BrO 3 - yield was lowest. In acidic water the presence of CO 3 2- showed negligible effect on conversion, TOC and  BrO 3 - yield compared to ozonation alone. In basic water both 2,4,6-TBP conversion and TOC removal decreased with an increase in CO 3 2- , hence minimizing BrO 3 - formation. The O 3 /H 2 O 2 process showed an improvement in the debromination efficiency and TOC data revealed that total mineralization of OBP's was achieved. However, only 10% H 2 O 2 was able to effectively decrease BrO 3 - formation. Increasing the ozone concentration from 20 to 100 ppm enhanced the conversion of 2,4,6-TBP and TOC removal. At low ozone concentrations poor mineralization of OBP's occurred, while complete mineralization was achieved at higher ozone dose. The reaction pathways for ozone degradation of 2,4,6-TBP in acidic and basic waters is proposed. Copyright © 2018 Elsevier B.V. All rights reserved.

THE EFFECT OF ALKYL AMINE TYPE ON THE EXTRACTION OF NITRIC ACID AND NITROSYLRUTHENIUM NITRATO COMPLEXES

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

Timmins, T.H.; Mason, E.A.

1963-04-01

An investigation of the solvent extraction characteristics of nitric acid and the nitrato complexes of nitrosylruthenium was conducted, using alkyl amines as extractants. The alkyl amines used were a primary amine Primene JMT, a tertiary amine trilaurylamine (TLA), and a quaternary amine Aliquat 336. The organic phase concentrations of HNO/sub 3/ resulting during extraction by alkyl amines were found to correlate well on the basis of the undissociated aqueous HNO/ sub 3/ activity for both salted (NaNO/sub 3/) and unsalted aqueous phases. The distribution ratios for Ru extraction showed better correlation on this basis than on the basis of aqueousmore » phase nitrate and nitric acid. The order of decreasing Ru extraction at low HNO/sub 3/ concentration (2N) was found to be Aliquat 336, TLA, and Primene JMT. At high HNO/sub 3/ concentration (9N). Primene JMT had the highest Ru extractability. Hapid dilution experiments were utilized to determine the number and aqueous phase concentrations of the extractable species of Ru, and the amine partition coefficients for the species. It was found that two Ru species are extractable, and the more extractable species is present in the aqueous phase at lower concentration than the less extractable species. The mole fractions of both species were found to increase with increasing HNO/sub 3/ concentration. The TLA partition coefficients for the extractable species were found to decrease with increasing HNO/sub 3/ concentration. The quaternary amine, Aliquat 336, was found to have partition coefficients an order of magnitude greater than the tertiary amine, TLA. Equations for the mole fractions and TLA partition coefficients in the region of HNO/sub 3/ concentration investigated were developed. (auth)« less

Reducing bacterial contamination in fuel ethanol fermentations by ozone treatment of uncooked corn mash.

PubMed

Rasmussen, Mary L; Koziel, Jacek A; Jane, Jay-lin; Pometto, Anthony L

2015-06-03

Ozonation of uncooked corn mash from the POET BPX process was investigated as a potential disinfection method for reducing bacterial contamination prior to ethanol fermentation. Corn mash (200 g) was prepared from POET ground corn and POET corn slurry and was ozonated in 250 mL polypropylene bottles. Lactic and acetic acid levels were monitored daily during the fermentation of ozonated, aerated, and nontreated corn mash samples to evaluate bacterial activity. Glycerol and ethanol contents of fermentation samples were checked daily to assess yeast activity. No yeast supplementation, no addition of other antimicrobial agents (such as antibiotics), and spiking with a common lactic acid bacterium found in corn ethanol plants, Lactobacillus plantarum, amplified the treatment effects. The laboratory-scale ozone dosages ranged from 26-188 mg/L, with very low estimated costs of $0.0008-0.006/gal ($0.21-1.6/m(3)) of ethanol. Ozonation was found to decrease the initial pH of ground corn mash samples, which could reduce the sulfuric acid required to adjust the pH prior to ethanol fermentation. Lactic and acetic acid levels tended to be lower for samples subjected to increasing ozone dosages, indicating less bacterial activity. The lower ozone dosages in the range applied achieved higher ethanol yields. Preliminary experiments on ozonating POET corn slurry at low ozone dosages were not as effective as using POET ground corn, possibly because corn slurry samples contained recycled antimicrobials from the backset. The data suggest additional dissolved and suspended organic materials from the backset consumed the ozone or shielded the bacteria.

Differential Effects of Elevated Ozone on Two Hybrid Aspen Genotypes Predisposed to Chronic Ozone Fumigation. Role of Ethylene and Salicylic Acid1

PubMed Central

Vahala, Jorma; Keinänen, Markku; Schützendübel, Andres; Polle, Andrea; Kangasjärvi, Jaakko

2003-01-01

The role of ethylene (ET) signaling in the responses of two hybrid aspen (Populus tremula L. × P. tremuloides Michx.) clones to chronic ozone (O3; 75 nL L−1) was investigated. The hormonal responses differed between the clones; the O3-sensitive clone 51 had higher ET evolution than the tolerant clone 200 during the exposure, whereas the free salicylic acid concentration in clone 200 was higher than in clone 51. The cellular redox status, measured as glutathione redox balance, did not differ between the clones suggesting that the O3 lesions were not a result of deficient antioxidative capacity. The buildup of salicylic acid during chronic O3 exposure might have prevented the up-regulation of ET biosynthesis in clone 200. Blocking of ET perception with 1-methylcyclopropene protected both clones from the decrease in net photosynthesis during chronic exposure to O3. After a pretreatment with low O3 for 9 d, an acute 1.5-fold O3 elevation caused necrosis in the O3-sensitive clone 51, which increased substantially when ET perception was blocked. The results suggest that in hybrid aspen, ET signaling had a dual role depending on the severity of the stress. ET accelerated leaf senescence under low O3, but under acute O3 elevation, ET signaling seemed to be required for protection from necrotic cell death. PMID:12746525

Ozonation of Canadian Athabasca asphaltene

NASA Astrophysics Data System (ADS)

Cha, Zhixiong

Application of ozonation in the petrochemical industry for heavy hydrocarbon upgrading has not been sufficiently explored. Among heavy hydrocarbons, asphaltenes are the heaviest and the most difficult fractions for analysis and treatment. Therefore, ozonation of asphaltenes presents an interesting application in the petrochemical industry. Commercial application of ozonation in the petrochemical industry has three obstacles: availability of an ozone-resistant and environmentally friendly solvent, the precipitation of ozonation intermediates during reaction, and recovery of the solvent and separation of the ozonation products. Preliminary ozonation of Athabasca oil sands asphaltene in nonparticipating solvents encountered serious precipitation of the ozonation intermediates. The precipitated intermediates could be polymeric ozonides and intermolecular ozonides or polymeric peroxides. Because the inhomogeneous reaction medium caused low ozone efficiency, various participating solvents such as methanol and acetic acid were added to form more soluble hydroperoxides. The mass balance results showed that on average, one asphaltene molecule reacted with 12 ozone molecules through the electrophilic reaction and the subsequent decomposition of ozonation intermediates generated acetone extractable products. GC/MS analysis of these compounds indicated that the free radical reactions could be important for generation of volatile products. The extensively ozonated asphaltene in the presence of participating solvents were refluxed with methanol to generate more volatile products. GC/MS analysis of the methanol-esterified ozonation products indicated that most volatile products were aliphatic carboxylic acid esters generated through cleavage of substituents. Reaction kinetics study showed that asphaltene ozonation was initially a diffusion rate-controlled reaction and later developed to a chemical reaction rate-controlled reaction after depletion of the reactive aromatic sites

Comparison of pharmaceutical abatement in various water matrices by conventional ozonation, peroxone (O3/H2O2), and an electro-peroxone process.

PubMed

Wang, Huijiao; Zhan, Juhong; Yao, Weikun; Wang, Bin; Deng, Shubo; Huang, Jun; Yu, Gang; Wang, Yujue

2018-03-01

Pharmaceutical abatement in a groundwater (GW), surface water (SW), and secondary effluent (SE) by conventional ozonation, the conventional peroxone (O 3 /H 2 O 2 ), and the electro-peroxone (E-peroxone) processes was compared in batch tests. SE had significantly more fast-reacting dissolved organic matter (DOM) moieties than GW and SW. Therefore, O 3 decomposed much faster in SE than in GW and SW. At specific ozone doses of 0.5-1.5 mg O 3 /mg dissolved organic carbon (DOC), the application of O 3 /H 2 O 2 and E-peroxone process (by adding external H 2 O 2 stocks or in-situ generating H 2 O 2 from cathodic O 2 reduction during ozonation) similarly enhanced the OH yield from O 3 decomposition by ∼5-12% and 5-7% in GW and SW, respectively, compared to conventional ozonation. In contrast, due to the slower reaction kinetics of O 3 with H 2 O 2 than O 3 with fast-reacting DOM moieties, the addition or electro-generation of H 2 O 2 hardly increased the OH yield (<4% increases) in SE. Corresponding to the changes in the OH yields, the abatement efficiencies of ozone-resistant pharmaceuticals (ibuprofen and clofibric acid) increased evidently in GW (up to ∼14-18% at a specific ozone dose of 1.5 mg O 3 /mg DOC), moderately in SW (up to 6-10% at 0.5 mg O 3 /mg DOC), and negligibly in SE during the O 3 /H 2 O 2 and E-peroxone treatment compared to conventional ozonation. These results indicate that similar to the conventional O 3 /H 2 O 2 process, the E-peroxone process can more pronouncedly enhance O 3 transformation to OH, and thus increase the abatement efficiency of ozone-resistant pharmaceuticals in water matrices exerting relatively high ozone stability (e.g., groundwater and surface water with low DOM contents). Therefore, by installing electrodes in existing ozone reactors, the E-peroxone process may provide a convenient way to enhance pharmaceutical abatement in drinking water applications, where groundwater and surface water with low DOM contents are used as

REDUCTION OF PLUTONIUM VALUES IN AN ACIDIC AQUEOUS SOLUTION WITH FORMALDEHYDE

DOEpatents

Olson, C.M.

1959-06-01

A method is given for reducing Pu to the tetravalent state and lowering the high acidity of dissolver solutions containing U and Pu. Formaldehyde is added to the HNO/sub 3/ solution of U and Pu to effect a formaldehyde to HNO/sub 3/ molar ratio of 0.375:1 to 1.5:1. The Pu can then be removed from the solution by carrier precipitation using BiPO/sub 4/ or by ion exchange. (T.R.H.)

Mechanism insight of pollutant degradation and bromate inhibition by Fe-Cu-MCM-41 catalyzed ozonation.

PubMed

Chen, Weirui; Li, Xukai; Tang, Yiming; Zhou, Jialu; Wu, Dan; Wu, Yin; Li, Laisheng

2018-03-15

A flexible catalyst, Fe-Cu-MCM-41, was employed to enhance diclofenac (DCF) mineralization and inhibit bromate formation in catalytic ozonation process. Greater TOC removal was achieved in Fe-Cu-MCM-41/O 3 process (78%) than those in Fe-MCM-41/O 3 (65%), Cu-MCM-41/O 3 (73%) and sole ozonation (42%). But it was interesting that both Cu-MCM-41/O 3 and Fe-MCM-41/O 3 achieved 93% bromate inhibition efficiency, only 71% inhibition efficiency was observed in Fe-Cu-MCM-41/O 3 . Influence of pH, TBA/NaHSO 3 and detection of by-products were conducted to explore the mechanism. By Pyridine adsorption-IR and XPS, a relationship was found among activity of catalysts, Lewis acid sites and electron transfer effect between Fe (II/III) and Cu (I/II). Fe-Cu-MCM-41 promoted ozone decomposition to generate OH, which accounted for enhanced DCF mineralization. The consumption of aqueous O 3 also suppressed the oxidative of Br - and HBrO/Br - . More HBrO/BrO - accumulated in catalytic ozonation process and less bromate generated. Bromate formation in Fe-Cu-MCM-41/O 3 process was sensitive with pH value, the acidic condition was not favor for bromate formation. Both DCF mineralization and bromate inhibition were influenced by surface reaction. Moreover, Fe-Cu-MCM-41 showed excellent catalytic performance in suppressing the accumulation of carboxylic acid, especially for oxalic acid. Nearly no oxalic acid was detected during Fe-Cu-MCM-41/O 3 process. Copyright © 2017 Elsevier B.V. All rights reserved.

Observations on particulate organic nitrates and unidentified components of NO y

NASA Astrophysics Data System (ADS)

Nielsen, Torben; Egeløv, Axel H.; Granby, Kit; Skov, Henrik

A method to determine the total content of particulate organic nitrates (PON) has been developed and ambient air measurements of PON, NO, N02, HNO3, peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), gas NOY and particulate inorganic nitrate have been performed in the spring and early summer at an agricultural site in Denmark and compared with measurements of ozone, H 2O 2, SO 2, formic acid, acetic acid and methane sulphonic acid. The gas NO y detector determines the sum NO + NO 2 + HNO 2 + HNO 3 + PAN + PPN + gas phase organic nitrates + 2 × N 2O 5 + NO 3. The content of residual gas NO y ( = gas NO y - NO - NO 2 - HNO 3 - PAN - PPN) was determined and a group of unidentified NO y compounds was found. The phenomenon was observed at a site with relatively high NO x/NO y ratios compared to previous observations in U.S.A. and Canada. The residual gas NO y made up 7 ± 6% of total NOY (total NO y = gas NO y + particulate inorganic nitrate). Residual gas NO y was much higher than the particulate fraction of organic nitrates (PON). PON was only 0.25 ± 0.11% of total NO y. Both residual gas NO y and particulate organic nitrates episodes occurred with elevated concentrations of photochemical oxidants in connection with high-pressure systems suggesting atmospheric processes being the major source. Clean marine air can be discarded as a source for PON and residual gas NO y.

3D analysis of high ozone production rates observed during the ESCOMPTE campaign

NASA Astrophysics Data System (ADS)

Coll, Isabelle; Pinceloup, Stéphanie; Perros, Pascal E.; Laverdet, Gérard; Le Bras, Georges

2005-03-01

The development of environmental policies to reduce the ozone levels around large agglomerations requires a good understanding of the development of ozone episodes. In particular, it is necessary to know the location and photochemical activity of the plume where ozone is formed. Measurement campaigns make it possible not only to characterize the concentration fields of ozone and its precursors but also to identify the zones of strong ozone production, by means of specific measurements and kinetic calculations. The combination of the observation-based data with numerical simulations allows to better characterize photochemical pollution. This paper presents a study carried out within the ESCOMPTE program and based on the determination of ozone production rates by experimental and numerical methods: ground measurements of peroxy radicals, NO x at a rural site, airborne measurements of NO X and O 3, Eulerian modeling. The reported case is of particular interest since it corresponds to an episode with very different photochemical situations. The diurnal variations of the peroxy radical concentration are analyzed in relation to those of ozone and its precursors. Ozone production rates— P(O 3)-are studied over one particular day. The results show particularly high concentrations of RO 2+HO 2 at ground level (up to 200 pptv) under the influence of the urban and industrial plume, but also highlight very high production rates of ozone (60 to 80 ppbv h -1) a few tens of kilometers from the sources. The results show satisfactory agreement between the various approaches. Modeling provides a four-dimensional (4D) description of the plumes, in particular the relation between the ozone precursor concentrations and P(O 3) on the ground.

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.

Oxides of nitrogen at two sites in New Zealand

NASA Astrophysics Data System (ADS)

Stedman, D. H.; McEwan, M. J.

1983-02-01

Oxides of nitrogen, ozone and solar UV radiation were measured at two New Zealand sites, four months at Mt. John near Lake Tekapo, and one month at the New Zealand Department of scientific and Industrial Research, Physics and Engineering Laboratory Atmospheric Station (PELAS) near Lauder. The former site proved ideal for clean-air measurements. Ozone concentrations of ˜20-25 ppb, with little diurnal variation were accompanied by total nitrogen oxide (NOy) levels frequently less than 150 ppt (parts in 1012 by volume). The noon NO and NO2 data were well correlated with a slope comparable to model values. Gaseous HNO3 was observed to be significantly above the noise level (˜15 ppt) for only twenty-seven four-hour averages. For these a median of 43 ppt was obtained with a median ([NOy]-[HNO3])/[HNO3] ratio of 7.5, not comparable with model values of around 1.1. This low HNO3 may arise from the fact that the Mt. John site is downwind of a mountain range which experiences significant upwind precipitation. At the PELAS site, strong diurnal variation of ozone and much larger NOy concentrations were observed. The difference is apparently caused by local sources of nitrogen oxides and the local meteorology at the fertile valley PELAS site.

Organic acids and selected nitrogen species for ABLE-3

NASA Technical Reports Server (NTRS)

Talbot, Robert W.

1991-01-01

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

Unconventional Constraints on Nitrogen Chemistry using DC3 Observations and Trajectory-based Chemical Modeling

NASA Astrophysics Data System (ADS)

Shu, Q.; Henderson, B. H.

2017-12-01

Chemical transport models underestimate nitrogen dioxide observations in the upper troposphere (UT). Previous research in the UT succeeded in combining model predictions with field campaign measurements to demonstrate that the nitric acid formation rate (HO + NO2 → HNO3 (R1)) is overestimated by 22% (Henderson et al., 2012). A subsequent publication (Seltzer et al., 2015) demonstrated that single chemical constraint alters ozone and aerosol formation/composition. This work attempts to replicate previous chemical constraints with newer observations and a different modeling framework. We apply the previously successful constraint framework to Deep Convection Clouds and Chemistry (DC3). DC3 is a more recent field campaign where simulated nitrogen imbalances still exist. Freshly convected air parcels, identified in the DC3 dataset, as initial coordinates to initiate Lagrangian trajectories. Along each trajectory, we simulate the air parcel chemical state. Samples along the trajectories will form ensembles that represent possible realizations of UT air parcels. We then apply Bayesian inference to constrain nitrogen chemistry and compare results to the existing literature. Our anticipated results will confirm overestimation of HNO3 formation rate in previous work and provide further constraints on other nitrogen reaction rate coefficients that affect terminal products from NOx. We will particularly focus on organic nitrate chemistry that laboratory literature has yet to fully address. The results will provide useful insights into nitrogen chemistry that affects climate and human health.

Characterization of N-nitrosodimethylamine formation from the ozonation of ranitidine.

PubMed

Lv, Juan; Wang, Lin; Li, Yongmei

2017-08-01

N-nitrosodimethylamine (NDMA) is an emerging disinfection by-product which is formed during water disinfection in the presence of amine-based precursors. Ranitidine, as one kind of amine-based pharmaceuticals, has been identified as NDMA precursor with high NDMA molar conversion during chloramination. This study focused on the characterization of NDMA formation during ozonation of ranitidine. Influences of operational variables (ozone dose, pH value) and water matrix on NDMA generation as well as ranitidine degradation were evaluated. The results indicate high reactivity of ranitidine with ozone. Dimethylamine (DMA) and NDMA were generated due to ranitidine oxidation. High pH value caused more NDMA accumulation. NDMA formation was inhibited under acid conditions (pH≤5) mainly due to the protonation of amines. Water matrix such as HCO 3 - and humic acid impacted NDMA generation due to OH scavenging. Compared with OH, ozone molecules dominated the productions of DMA and NDMA. However, OH was a critical factor in NDMA degradation. Transformation products of ranitidine during ozonation were identified using gas chromatography-mass spectrometry. Among these products, just DMA and N,N-dimethylformamide could contribute to NDMA formation due to the DMA group in the molecular structures. The NDMA formation pathway from ranitidine ozonation was also proposed. Copyright © 2017. Published by Elsevier B.V.

Growth response and drought susceptibility of red spruce seedlings exposed to simulated acidic rain and ozone

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

Lee, W.S.; Chevone, B.I.; Seiler, J.R.

1988-01-01

Red spruce (Picea rubens Sarg.) is a long-lived, shade-tolerant tree that is commonly present in the cool, moist climates at high elevations of the Appalachian Mountains. Recently, an accelerated decline of red spruce has been reported in the northern Appalachians in the Green Mountains on Camels Hump, Vermont and on Whiteface Mountain in New York as well as in the mid and southern Appalachians. Even though many possible causes of this decline have been suggested, none have been established conclusively at present. High acid inputs and elevated concentrations of heavy metals, in addition to ozone stress, have been strongly suspectedmore » as contributing factors for the decline. The objectives of this research is to investigate the efforts of simulated acidic rain and ozone on growth and drought susceptibility of red spruce seedlings by measuring biomass, foliar nutrient status, root hydraulic conductivity, and gas exchange rates.« less

Conversion of Monogalactosyldiacylglycerols to Triacylglycerols in Ozone-Fumigated Spinach Leaves

PubMed Central

Sakaki, Takeshi; Saito, Kazuki; Kawaguchi, Akihiko; Kondo, Noriaki; Yamada, Mitsuhiro

1990-01-01

Molecular species and fatty acid distribution of triacylglycerol (TG) accumulated in spinach (Spinacia oleracea L.) leaves fumigated with ozone (0.5 microliter per liter) were compared with those of monogalactosyldiacylglycerol (MGDG). Analysis of positional distribution of the fatty acids in MGDG and the accumulated TG by the enzymatic digestion method showed that hexadecatrienoate (16:3) was restricted to sn-2 position of the glycerol backbone in both MGDG and TG, whereas α-linolenate (18:3) was preferentially located at sn-1 position in MGDG, and sn-1 and/or sn-3 positions in TG, suggesting that 1,2-diacylglycerol moieties of MGDG are the direct precursor of TG in ozonefumigated leaves. Further analysis of TG molecular species by argentation chromatography and mass spectrometry showed that TG increased with ozone fumigation consisted of approximately an equal molar ratio of sn-1,3-18:3-2-16:3 and sn-1,2,3-18:3. Because the molecular species of MGDG in spinach leaves is composed of a similar molar ratio of sn-1-18:3-2-16:3 and sn-1,2-18:3, we concluded that MGDG was converted to 1,2-diacylglycerol and acylated with 18:3 to TG in ozone-fumigated spinach leaves. Images Figure 1 PMID:16667777

The effect of hydrochloric acid addition to increase carbon nanotubes dispersibility as drug delivery system by covalent functionalization

NASA Astrophysics Data System (ADS)

Wulan, P. P. D. K.; Ulwani, S. H.; Wulandari, H.; Purwanto, W. W.; Mulia, K.

2018-03-01

This study is to obtain the effect of adding hydrochloric acid (HCl) to the mixture of sulfuric acid (H2SO4) and HNO3 in CNT covalent functionalization. HCl expected to increase the dispersibility of functionalized CNT by improving the dispersion time period done with H2SO4 or HNO3. Functionalization used mixture of H2SO4 and HNO3 with volume ratio of 3:1. Covalent functionalization used 0.5 grams of MWCNT ultra sonicated in 50mL HNO3 with and mixture of H2SO4 and HNO3. Additions of 200 mL HCl used variation of molarity from 1M, 2M, 3M, 4M, 5M to 6M. CNT were oxidized to form carboxylic and hydroxyl bonds on the surface that increase dispersibility of CNT. FTIR spectrums showed the existences of carboxyl and hydroxyl group on spectra of 2600-3700 cm-1 and 900-1400 cm-1. Dispersion tests, which showed functionalized CNT (f-CNT) dispersion capabilities, were done by dissolving f-CNT in water. The study resulted that 6M f-CNT (NSC6) gave the best dispersion with zeta potential value of -37.1mV. NSC6 gave the longest dispersion time which was 20 days until f-CNT settle again. SEM-EDS micrographs showed the surface structure of 6M f-CNT without significant damage and no longer contain impurities of Fe, Ni, and Cl.

RADIATION STABILITY OF ORGANIC LIQUIDS. Semi-Annual Report No. 3 for January 1 to June 30, 1958

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

Wagner, R.M.; Towle, L.H.

1958-06-30

2 1 9 0 5 - completed on the nature and amount of the radiolysis products of tributyl phosphate containing equilibration quantities of 2M aqueous HNO/sub 3/, a 1: 2 volume ratio two-phase TBP-2M aqueous HNO/sub 3/ system, a 5% TBP-95% Amsco-2M HNO/sub 3/ two-phase system, four different (15-30- 45-60%) TBP-Amsco phases containing equilibration quantities of 2M HNO/sub 3/, didecyl decanephosphonate, diethyl carbonate, diethyl carbonate containing equilibration quantities of 1M HNO/sub 3/, di-(2ethylhexyl) phosphoric acid, tri- n-octyl phosphine oxide, and tri-iso-octyl amine. The effect of nitric acid on tributyl phosphate radiolysis was tested in a variety of situations. G(MBP) valuesmore » obtained from the two TBPHNO/sub 3/ studies indicated that 2M HNO/sub 3/ resent either in an acid-saturated single phase, or as a second phase, increased the G(MBP) value by a factor of four. Amsco solutions of TBP in the presence of HrO/sub 3/ did not differ in G(MBP) yield from pure TBP irradiations. Acidsatarated TBP produced G(gas) values twice that of pure TBP. Amsco solutions of TBP, equilibrated with 2M HNO/sub 3/ prior to irradiation, produced G(gas) values roughly one-half of the value for pure TBP. Studies of new alternate solvents for TBP were extended to include a detailed study of diethyl carbonate for process application. Diethyl carbonate, when saturated by equilibration with 2M HNO/sub 3/, yielded G(gas) values 20% higher than pure diethyl carbonate. G(acid) levels were 1% of those found for irradiated TBP. Irradiations of didecyl decanephosphonate and tri-n-octyl phosphine oxide indicated that the two compounds had comparable G(gas) values, but the phosphine oxide produced G(acid) values three to four factors smaller. Irradiation of a commercial tri-iso-octyl amine to 1795 whr/liter dose level produced a gross target destruction by radiolysis of almost 60%. Irradiation of pure tributyl phosphate to the same dose results in about 35% destruction. Irradiation of

Ozone Exposure Increases Circulating Stress Hormones and Lipid Metabolites in Humans

PubMed Central

Miller, Desinia B.; Ghio, Andrew J.; Karoly, Edward D.; Bell, Lauren N.; Snow, Samantha J.; Madden, Michael C.; Soukup, Joleen; Cascio, Wayne E.; Gilmour, M. Ian

2016-01-01

Rationale: Air pollution has been associated with increased prevalence of type 2 diabetes; however, the mechanisms remain unknown. We have shown that acute ozone exposure in rats induces release of stress hormones, hyperglycemia, leptinemia, and glucose intolerance that are associated with global changes in peripheral glucose, lipid, and amino acid metabolism. Objectives: To examine ozone-induced metabolic derangement in humans using serum metabolomic assessment, establish human-to-rodent coherence, and identify novel nonprotein biomarkers. Methods: Serum samples were obtained from a crossover clinical study that included two clinic visits (n = 24 each) where each subject was blindly exposed in the morning to either filtered air or 0.3 parts per million ozone for 2 hours during 15-minute on-off exercise. Serum samples collected within 1 hour after exposure were assessed for changes in metabolites using a metabolomic approach. Measurements and Main Results: Metabolomic analysis revealed that ozone exposure markedly increased serum cortisol and corticosterone together with increases in monoacylglycerol, glycerol, and medium- and long-chain free fatty acids, reflective of lipid mobilization and catabolism. Additionally, ozone exposure increased serum lysolipids, potentially originating from membrane lipid breakdown. Ozone exposure also increased circulating mitochondrial β-oxidation–derived metabolites, such as acylcarnitines, together with increases in the ketone body 3-hydroxybutyrate. These changes suggested saturation of β-oxidation by ozone in exercising humans. Conclusions: As in rodents, acute ozone exposure increased stress hormones and globally altered peripheral lipid metabolism in humans, likely through activation of a neurohormonally mediated stress response pathway. The metabolomic assessment revealed new biomarkers and allowed for establishment of rodent-to-human coherence. Clinical trial registered with www.clinicaltrials.gov (NCT 01492517

The oleic acid-ozone heterogeneous reaction system: products, kinetics, secondary chemistry, and atmospheric implications of a model system - a review

NASA Astrophysics Data System (ADS)

Zahardis, J.; Petrucci, G. A.

2007-02-01

The heterogeneous processing of organic aerosols by trace oxidants has many implications to atmospheric chemistry and climate regulation. This review covers a model heterogeneous reaction system (HRS): the oleic acid-ozone HRS and other reaction systems featuring fatty acids, and their derivatives. The analysis of the commonly observed aldehyde and organic acid products of ozonolysis (azelaic acid, nonanoic acid, 9-oxononanoic acid, nonanal) is described. The relative product yields are noted and explained by the observation of secondary chemical reactions. The secondary reaction products arising from reactive Criegee intermediates are mainly peroxidic, notably secondary ozonides and α-acyloxyalkyl hydroperoxide oligomers and polymers, and their formation is in accord with solution and liquid-phase ozonolysis. These highly oxygenated products are of low volatility and hydrophilic which may enhance the ability of particles to act as cloud condensation nuclei (CCN). The kinetic description of this HRS is critically reviewed. Most kinetic studies suggest this oxidative processing is either a near surface reaction that is limited by the diffusion of ozone or a surface based reaction. Internally mixed particles and coatings represent the next stage in the progression towards more realistic proxies of tropospheric organic aerosols and a description of the products and the kinetics resulting from the ozonolysis of these proxies, which are based on fatty acids or their derivatives, is presented. Finally, the main atmospheric implications of oxidative processing of particulate containing fatty acids are presented. These implications include the extended lifetime of unsaturated species in the troposphere facilitated by the presence of solids, semi-solids or viscous phases, and an enhanced rate of ozone uptake by particulate unsaturates compared to corresponding gas-phase organics. Ozonolysis of oleic acid enhances its CCN activity, which implies that oxidatively processed

Large-scale production of anhydrous nitric acid and nitric acid solutions of dinitrogen pentoxide

DOEpatents

Harrar, Jackson E.; Quong, Roland; Rigdon, Lester P.; McGuire, Raymond R.

2001-01-01

A method and apparatus are disclosed for a large scale, electrochemical production of anhydrous nitric acid and N.sub.2 O.sub.5. The method includes oxidizing a solution of N.sub.2 O.sub.4 /aqueous-HNO.sub.3 at the anode, while reducing aqueous HNO.sub.3 at the cathode, in a flow electrolyzer constructed of special materials. N.sub.2 O.sub.4 is produced at the cathode and may be separated and recycled as a feedstock for use in the anolyte. The process is controlled by regulating the electrolysis current until the desired products are obtained. The chemical compositions of the anolyte and catholyte are monitored by measurement of the solution density and the concentrations of N.sub.2 O.sub.4.

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.

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

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

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

Atmospheric Science Data Center

2018-02-28

... 37 x 23 km Spatial Resolution:  2.3 x 23 km Temporal Coverage:  08/22/2004 - 04/10/2005 ... Guide Documents:  Data User's Guide (PDF):  Level 3 Level 3 Algorithms, Requirements, & Products (PDF) ...

A Total Ozone Dependent Ozone Profile Climatology Based on Ozone-Sondes and Aura MLS Data

NASA Astrophysics Data System (ADS)

Labow, G. J.; McPeters, R. D.; Ziemke, J. R.

2014-12-01

A new total ozone-based ozone profile climatology has been created for use in satellite and/or ground based ozone retrievals. This climatology was formed by combining data from the Microwave Limb Sounder (MLS) with data from balloon sondes and binned by zone and total ozone. Because profile shape varies with total column ozone, this climatology better captures the ozone variations than the previously used seasonal climatologies, especially near the tropopause. This is significantly different than ozone climatologies used in the past as there is no time component. The MLS instrument on Aura has excellent latitude coverage and measures ozone profiles daily from the upper troposphere to the lower mesosphere at ~3.5 km resolution. Almost a million individual MLS ozone measurements are merged with data from over 55,000 ozonesondes which are then binned as a function of total ozone. The climatology consists of average ozone profiles as a function of total ozone for six 30 degree latitude bands covering altitudes from 0-75 km (in Z* pressure altitude coordinates). This new climatology better represents the profile shape as a function of total ozone than previous climatologies and shows some remarkable and somewhat unexpected correlations between total ozone and ozone in the lower altitudes, particularly in the lower and middle troposphere. These data can also be used to infer biases and errors in either the MLS retrievals or ozone sondes.

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.

The oleic acid-ozone heterogeneous reaction system: products, kinetics, secondary chemistry, and atmospheric implications of a model system a review

NASA Astrophysics Data System (ADS)

Zahardis, J.; Petrucci, G. A.

2006-11-01

The heterogeneous processing of organic aerosols by trace oxidants has many implications to atmospheric chemistry and climate regulation. This review covers a model heterogeneous reaction system (HRS): the oleic acid-ozone HRS and other reaction systems featuring fatty acids, and their derivatives. The analysis of the primary products of ozonolysis (azelaic acid, nonanoic acid, 9-oxononanoic acid, nonanal) is described. Anomalies in the relative product yields are noted and explained by the observation of secondary chemical reactions. The secondary reaction products arising from reactive Criegee intermediates are mainly peroxidic, notably secondary ozonides and α-acyloxyalkyl hydroperoxide polymers. These highly oxygenated products are of low volatility and hydrophilic which may enhance the ability of particles to act as cloud condensation nuclei. The kinetic description of this HRS is critically reviewed. Most kinetic studies suggest this oxidative processing is either a near surface reaction that is limited by the diffusion of ozone or a surface based reaction. Internally mixed particles and coatings represent the next stage in the progression towards more realistic proxies of tropospheric organic aerosols and a description of the products and the kinetics resulting from the ozonolysis of these proxies, which are based on fatty acids or their derivatives, is presented. Finally, a series of atmospheric implications of oxidative processing of particulate containing fatty acids is presented. These implications include the extended lifetime of unsaturated species in the troposphere facilitated by the presence of solids, semisolids or viscous phases, and an enhanced rate of ozone uptake by particulate unsaturates compared to corresponding gas phase organics. Ozonolysis of oleic acid enhances its CCN activity, which implies that oxidatively processed particulate may contribute to indirect forcing of radiation. Other effects, including the potential role of aldehydic

Balloon Profiles of Stratospheric NO(sub 2) and HNO(sub 3) for Testing the Heterogeneous Hydrolysis of N(sub 2)O(sub 5) on Sulfate Aerosols

NASA Technical Reports Server (NTRS)

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

1993-01-01

Simultaneous in situ measurements of stratospheric NO(sub 2), HNO(sub 3), HCI, and CH(sub 4) 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.

Regulation of ozone-induced lung inflammation and injury by the β-galactoside-binding lectin galectin-3

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

Sunil, Vasanthi R., E-mail: sunilva@pharmacy.rutgers.edu; Francis, Mary, E-mail: maryfranrutgers@gmail.com; Vayas, Kinal N., E-mail: kinalv5@gmail.com

Macrophages play a dual role in ozone toxicity, contributing to both pro- and anti-inflammatory processes. Galectin-3 (Gal-3) is a lectin known to regulate macrophage activity. Herein, we analyzed the role of Gal-3 in the response of lung macrophages to ozone. Bronchoalveolar lavage (BAL) and lung tissue were collected 24–72 h after exposure (3 h) of WT and Gal-3{sup -/-} mice to air or 0.8 ppm ozone. In WT mice, ozone inhalation resulted in increased numbers of proinflammatory (Gal-3{sup +}, iNOS{sup +}) and anti-inflammatory (MR-1{sup +}) macrophages in the lungs. While accumulation of iNOS{sup +} macrophages was attenuated in Gal-3{sup -/-}more » mice, increased numbers of enlarged MR-1{sup +} macrophages were noted. This correlated with increased numbers of macrophages in BAL. Flow cytometric analysis showed that these cells were CD11b{sup +} and consisted mainly (> 97%) of mature (F4/80{sup +}CD11c{sup +}) proinflammatory (Ly6GLy6C{sup hi}) and anti-inflammatory (Ly6GLy6C{sup lo}) macrophages. Increases in both macrophage subpopulations were observed following ozone inhalation. Loss of Gal-3 resulted in a decrease in Ly6C{sup hi} macrophages, with no effect on Ly6C{sup lo} macrophages. CD11b{sup +}Ly6G{sup +}Ly6C{sup +} granulocytic (G) and monocytic (M) myeloid derived suppressor cells (MDSC) were also identified in the lung after ozone. In Gal-3{sup -/-} mice, the response of G-MDSC to ozone was attenuated, while the response of M-MDSC was heightened. Changes in inflammatory cell populations in the lung of ozone treated Gal-3{sup -/-} mice were correlated with reduced tissue injury as measured by cytochrome b5 expression. These data demonstrate that Gal-3 plays a role in promoting proinflammatory macrophage accumulation and toxicity in the lung following ozone exposure. - Highlights: • Multiple monocytic-macrophage subpopulations accumulate in the lung after ozone inhalation. • Galectin-3 plays a proinflammatory role in ozone-induced lung injury. �

By-passing acidification limitations during the biofiltration of high formaldehyde loads via the application of ozone pulses.

PubMed

García-Pérez, Teresa; Aizpuru, Aitor; Arriaga, Sonia

2013-11-15

A formaldehyde airstream was treated in a biofilter for an extended period of time. During the first 133 days, the reactor was operated without ozone, whereas over the following 82 days ozone was intermittently implemented. The maximum stable elimination capacity obtained without ozone was around 57 g m(-3) h(-1). A greater load could not be treated under these conditions, and no significant formaldehyde removal was maintained for inlet loads greater than 65 g m(-3) h(-1); the activity of microorganisms was then inhibited by the presence of acidic byproducts, and the media acidified (pH<4). The implementation of ozone pulses allowed a stable elimination capacity to be obtained, even at greater loads (74 g m(-3) h(-1)). The effect of ozone on the extra cellular polymeric substances detachment from the biofilm could not be confirmed due to the too low biofilter biomass content. Thus, the results suggest that ozone acted as an in situ pH regulator, preventing acidic byproducts accumulation, and allowing the treatment of high loads of formaldehyde. Copyright © 2013 Elsevier B.V. All rights reserved.

Nitroxyl (HNO) Releasing Therapeutics | NCI Technology Transfer Center | TTC

Cancer.gov

The National Cancer Institute's Cancer and Inflammation Program is seeking statements of capability or interest from parties interested in licensing therapeutic agents that generate Nitroxyl (HNO) in physiological media.

Effects of ozone fumigation treatment on the removal of residual difenoconazole from strawberries and on their quality.

PubMed

Heleno, Fernanda F; de Queiroz, Maria Eliana L R; Neves, Antônio Augusto; Freitas, Romenique S; Faroni, Lêda Rita A; De Oliveira, André Fernando

2014-01-01

The effect of ozone fumigation on the reduction of difenoconazole residue on strawberries was studied. Strawberries were immersed in 1.0 L of aqueous solution containing 400 μL of the commercial product (250 g L(-1) of difenoconazole) for 1 min. Then, they were dried and exposed to ozone gas (O3) at concentrations of 0.3, 0.6 and 0.8 mg L(-1) for 1 h. The ozone fumigation treatments reduced the difenoconazole residue on strawberries to concentrations below 0.5 mg kg(-1), which corresponds to a 95% reduction. The strawberries treated with ozone and the control group, which was not treated with ozone, were stored at 4°C for 10 days. Some characteristics of the fruit were monitored throughout this period. Among these, pH, weight loss and total color difference did not change significantly (P > 0.05). The fumigation with ozone significantly affected the soluble solids, titratable acidity and ascorbic acid content (vitamin C) of the strawberries preventing a sharp reduction of these parameters during storage.

Effects of ozone (O3) therapy on cisplatin-induced ototoxicity in rats.

PubMed

Koçak, Hasan Emre; Taşkın, Ümit; Aydın, Salih; Oktay, Mehmet Faruk; Altınay, Serdar; Çelik, Duygu Sultan; Yücebaş, Kadir; Altaş, Bengül

2016-12-01

The aim of this study is to investigate the effect of rectal ozone and intratympanic ozone therapy on cisplatin-induced ototoxicity in rats. Eighteen female Wistar albino rats were included in our study. External auditory canal and tympanic membrane examinations were normal in all rats. The rats were randomly divided into three groups. Initially, all the rats were tested with distortion product otoacoustic emissions (DPOAE), and emissions were measured normally. All rats were injected with 5-mg/kg/day cisplatin for 3 days intraperitoneally. Ototoxicy had developed in all rats, as confirmed with DPOAE after 1 week. Rectal and intratympanic ozone therapy group was Group 1. No treatment was administered for the rats in Group 2 as the control group. The rats in Group 3 were treated with rectal ozone. All the rats were tested with DPOAE under general anesthesia, and all were sacrificed for pathological examination 1 week after ozone administration. Their cochleas were removed. The outer hair cell damage and stria vascularis damage were examined. In the statistical analysis conducted, a statistically significant difference between Group 1 and Group 2 was observed in all frequencies according to the DPOAE test. In addition, between Group 2 and Group 3, a statistically significant difference was observed in the DPOAE test. However, a statistically significant difference was not observed between Group 1 and Group 3 according to the DPOAE test. According to histopathological scoring, the outer hair cell damage score was statistically significantly high in Group 2 compared with Group 1. In addition, the outer hair cell damage score was also statistically significantly high in Group 2 compared with Group 3. Outer hair cell damage scores were low in Group 1 and Group 3, but there was no statistically significant difference between these groups. There was no statistically significant difference between the groups in terms of stria vascularis damage score examinations

Denitrification and nitrification in the Arctic stratosphere during the winter of 1996-1997

NASA Astrophysics Data System (ADS)

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

2000-02-01

The concentrations of HNO3, N2O, ozone, and aerosol in the lower stratosphere inside the Arctic vortex were observed by the Improved Limb Atmospheric Spectrometer (ILAS) in the winter of 1996-1997. These data demonstrate that irreversible loss of reactive nitrogen by sedimentation of HNO3 containing particles (denitrification) at 18-23 km occurred in mid-late February soon after the Arctic vortex cooled below ice saturation temperature (TICE). Denitrification exceeding 40% was observed only in air masses which experienced temperature below TICE. It occurred within 2 days in some of these air masses. Increases in HNO3 by evaporation of the particles (nitrification) at 13-15 km occurred 0-3 days after denitrification was observed, indicating particle radii of 5-10 µm or larger. It is likely that these particles were composed of nitric acid trihydrate (NAT) or NAT-coated ice particles, given that the temperatures below 16 km were higher than TICE. Continued exposure of air masses below NAT saturation temperature for 1-4 days did not lead to any significant denitrification as long as the temperature did not fall below TICE, indicating that possible nucleation of NAT at these temperatures within 4 days did not play a significant role in causing denitrification. There was little change in the average HNO3 column from February 11 to 28 since HNO3 decreases at 18-23 km were almost completely offset by increases at 12-17 km.

The impact of urban canopy meteorological forcing on summer photochemistry

NASA Astrophysics Data System (ADS)

Huszár, Peter; Karlický, Jan; Belda, Michal; Halenka, Tomáš; Pišoft, Petr

2018-03-01

The regional climate model RegCM4.4, including the surface model CLM4.5, was offline coupled to the chemistry transport model CAMx version 6.30 in order to investigate the impact of the urban canopy induced meteorological changes on the longterm summer photochemistry over central Europe for the 2001-2005 period. First, the urban canopy impact on the meteorological conditions was calculated performing a reference experiment without urban landsurface considered and an experiment with urban surfaces modeled with the urban parameterization within the CLM4.5 model. In accordance with expectations, strong increases of urban surface temperatures (up to 2-3 K), decreases of wind speed (up to -1 ms-1) and increases of vertical turbulent diffusion coefficient (up to 60-70 m2s-1) were found. For the impact on chemistry, these three components were considered. Additionally, we accounted for the effect of temperature enhanced biogenic emission increase. Several experiments were performed by adding these effects one-by-one to the total impact: i.e., first, only the urban temperature impact was considered driving the chemistry model; secondly, the wind impact was added and so on. We found that the impact on biogenic emission account for minor changes in the concentrations of ozone (O3), oxides of nitrogen NOx = NO + NO2 and nitric acid (HNO3). On the other hand, the dominating component acting is the increased vertical mixing, resulting in up to 5 ppbv increase of urban ozone concentrations while causing -2 to -3 ppbv decreases and around 1 ppbv increases of NOx and HNO3 surface concentrations, respectively. The temperature impact alone results in reduction of ozone, increase in NO, decrease in NO2 and increases of HNO3. The wind impact leads, over urban areas, to ozone decreases, increases of NOx and a slight increase in HNO3. The overall impact is similar to the impact of increased vertical mixing alone. The Process Analysis (PA) technique implemented in CAMx was adopted to

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.

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...

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.

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 (CaCO 3 ) 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.

Results from the US/Russian Meteor-3/Total Ozone Mapping Spectrometer

NASA Technical Reports Server (NTRS)

Herman, Jay R. (Editor)

1993-01-01

The development of Meteor-3/TOMS (Total Ozone Mapping Spectrometer) was a joint project of the United States and Russia to fly a U.S. ozone measuring instrument (TOMS) onboard a Russian spacecraft (Meteor-3) and rocket (Cyclone), launched from Plesetsk, Russia. The Meteor-3/TOMS (M3TOMS) was launched into a 1202-km-high, near-polar orbit on 15 Aug. 1991, where it can obtain complete global coverage for most of each year. Both the U.S. and Russian sides have successfully received and processed data into ozone amounts from 25 Aug. 1991 to 1 Jun. 1992, and expect to continue for the life of the instrument and spacecraft. The successful development of the instrument hardware, spacecraft interface, data memory, telemetry systems, and software are described. Descriptions are given of the U.S. and Russian ground stations for receiving M3TOMS data. In addition, the data reduction software was independently developed by the U.S. and by the Russians, and is shown to agree to better than the precision of the measurements.

Impact of ozonation on naphthenic acids speciation and toxicity of oil sands process-affected water to Vibrio fischeri and mammalian immune system.

PubMed

Wang, Nan; Chelme-Ayala, Pamela; Perez-Estrada, Leonidas; Garcia-Garcia, Erick; Pun, Jonathan; Martin, Jonathan W; Belosevic, Miodrag; Gamal El-Din, Mohamed

2013-06-18

Oil sands process-affected water (OSPW) is the water contained in tailings impoundment structures in oil sands operations. There are concerns about the environmental impacts of the release of OSPW because of its toxicity. In this study, ozonation followed by biodegradation was used to remediate OSPW. The impacts of the ozone process evolution on the naphthenic acids (NAs) speciation and acute toxicity were evaluated. Ion-mobility spectrometry (IMS) was used to preliminarily separate isomeric and homologous species. The results showed limited effects of the ozone reactor size on the treatment performance in terms of contaminant removal. In terms of NAs speciation, high reactivity of NAs with higher number of carbons and rings was only observed in a region of high reactivity (i.e., utilized ozone dose lower than 50 mg/L). It was also found that nearly 0.5 mg/L total NAs was oxidized per mg/L of utilized ozone dose, at utilized ozone doses lower than 50 mg/L. IMS showed that ozonation was able to degrade NAs, oxidized NAs, and sulfur/nitrogenated NAs. Complete removal of toxicity toward Vibrio fischeri was achieved after ozonation followed by 28-day biodegradation period. In vitro and in vivo assays indicated that ozonation reduced the OSPW toxicity to mice.

Investigation of the synergistic effects for p-nitrophenol mineralization by a combined process of ozonation and electrolysis using a boron-doped diamond anode.

PubMed

Qiu, Cuicui; Yuan, Shi; Li, Xiang; Wang, Huijiao; Bakheet, Belal; Komarneni, Sridhar; Wang, Yujue

2014-09-15

Electrolysis and ozonation are two commonly used technologies for treating wastewaters contaminated with nitrophenol pollutants. However, they are often handicapped by their slow kinetics and low yields of total organic carbon (TOC) mineralization. To improve TOC mineralization efficiency, we combined electrolysis using a boron-doped diamond (BDD) anode with ozonation (electrolysis-O3) to treat a p-nitrophenol (PNP) aqueous solution. Up to 91% TOC was removed after 60 min of the electrolysis-O3 process. In comparison, only 20 and 44% TOC was respectively removed by individual electrolysis and ozonation treatment conducted under similar reaction conditions. The result indicates that when electrolysis and ozonation are applied simultaneously, they have a significant synergy for PNP mineralization. This synergy can be mainly attributed to (i) the rapid degradation of PNP to carboxylic acids (e.g., oxalic acid and acetic acid) by O3, which would otherwise take a much longer time by electrolysis alone, and (ii) the effective mineralization of the ozone-refractory carboxylic acids to CO2 by OH generated from multiple sources in the electrolysis-O3 system. The result suggests that combining electrolysis with ozonation can provide a simple and effective way to mutually compensate the limitations of the two processes for degradation of phenolic pollutants. Copyright © 2014 Elsevier B.V. All rights reserved.

Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions.

PubMed

Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

2017-07-01

Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO 3 ) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO 3 -nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO 3 ) was produced in the flame. The HNO 3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO 3 showed the strongest affinity to histidine and formed (M histidine -H+HNO 3 ) - complex ions, whereas some amino acids did not react with HNO 3 at all. Reactions between HNO 3 and histidine residues in AI and AII resulted in the formation of dominant [M AI -H+(HNO 3 )] - and [M AII -H+(HNO 3 )] - ions. Results from analyses of AAs and insulin indicated that HNO 3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO 3 ) n ] 3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins. Graphical Abstract ᅟ.

Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions

NASA Astrophysics Data System (ADS)

Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

2017-07-01

Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO3) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO3-nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO3) was produced in the flame. The HNO3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO3 showed the strongest affinity to histidine and formed (Mhistidine-H+HNO3)- complex ions, whereas some amino acids did not react with HNO3 at all. Reactions between HNO3 and histidine residues in AI and AII resulted in the formation of dominant [MAI-H+(HNO3)]- and [MAII-H+(HNO3)]- ions. Results from analyses of AAs and insulin indicated that HNO3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO3)n]3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins.

ESR evidence for radical production from the reaction of ozone with unsaturated lipids

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

Church, D.F.; McAdams, M.L..; Pryor, W.A.

1991-03-15

The authors report electron spin resonance (ESR) spin trapping evidence for radical production by the reaction of ozone with unsaturated compounds. Soy and egg phosphatidylcholine liposomes, fatty acid emulsions, and homogeneous aqueous solutions of 3-hexenoic acid were treated with ozone in the presence of the spin trap {alpha}-phenyl-N-tert-butyl nitrone (PBN). Under these conditions, they observe spin adducts resulting from the trapping of both organic carbon- and oxygen-centered radicals. When the lipid-soluble antioxidant alpha-tocopherol is included in the liposomal systems, the formation of spin adducts is completely inhibited. The authors suggest that radicals giving rise to these spin adducts arise formmore » the rapid decomposition of the 1,2,3-trioxolane intermediate that is initially formed when ozone reacts with the carbon-carbon double bonds of the substrates. These free radicals are not formed by the decomposition of the Criegee ozonide, since little of the ozonide is formed in the presence of water. Although hydrogen peroxide is the predominate peroxidic product of the ozone/alkene reaction, its decomposition is not responsible for the observed radical production since neither catalase nor iron chelators significantly affect the spin adduct yield. The radical yield is approximately 1%. Since a polyunsaturated fatty acid (PUFA) such as linoleic acid produces much higher concentrations of spin trappable radicals than does the monounsaturated fatty oleic acid, the results also suggest that sites in the lung containing higher levels of PUFA may be an important target for radical formation.« less

Effect of ozonation on minocycline degradation and N-Nitrosodimethylamine formation.

PubMed

Lv, Juan; Li, Yong M

2018-06-07

The objective of this study was to assess reactivity of Minocycline (MNC) towards ozone and determine the effects of ozone dose, pH value, and water matrix on MNC degradation as well as to characterize N-Nitrosodimethylamine (NDMA) formation from MNC ozonation. The MNC initial concentration of the solution was set in the range of 2-20 mg/L to investigate NDMA formation during MNC ozonation. Four ozone doses (22.5, 37.2, 58.0, and 74.4 mg/min) were tested to study the effect of ozone dose. For the evaluation of effects of pH value, pH was adjusted from 5 to 9 in the presence of phosphate buffer. MNC ozonation experiments were also conducted in natural water to assess the influence of water matirx. The influence of the typical component of natural water was also investigated with the addition of HA and NaHCO 3 solution. Results indicated that ozone was effective in MNC removal. Consequently, NDMA and dimethylamine (DMA) were generated from MNC oxidation. Increasing pH value enhanced MNC removal but led to greater NDMA generation. Water matrices, such as HCO 3 - and humic acid, affected MNC degradation. Conversely, more NDMA accumulated due to the inhibition of NDMA oxidation by oxidant consumption. Though ⋅OH can enhance MNC degradation, ozone molecules were heavily involved in NDMA production. Seven transformation products were identified. However, only DMA and the unidentified tertiary amine containing DMA group contributed to NDMA formation.

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.

Products and kinetics of the heterogeneous reaction of suspended vinclozolin particles with ozone.

PubMed

Gan, Jie; Yang, Bo; Zhang, Yang; Shu, Xi; Liu, Changgeng; Shu, Jinian

2010-11-25

Vinclozolin is a widely used fungicide that can be released into the atmosphere via application and volatilization. This paper reports an experimental investigation on the heterogeneous ozonation of vinclozolin particles. The ozonation of vinclozolin adsorbed on azelaic acid particles under pseudo-first-order conditions is investigated online with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The ozonation products are analyzed with a combination of VUV-ATOFMS and GC/MS. Two main ozonation products are observed. The formation of the ozonation products results from addition of O(3) on the C-C double bond of the vinyl group. The heterogeneous reactive rate constant of vinclozolin particles under room temperature is (2.4 ± 0.4) × 10(-17) cm(3) molecules(-1) s(-1), with a corresponding lifetime at 100 ppbv O(3) of 4.3 ± 0.7 h, which is almost comparable with the estimated lifetime due to the reaction with atmospheric OH radicals (∼1.7 h). The reactive uptake coefficient for O(3) on vinclozolin particles is (6.1 ± 1.0) × 10(-4).

Heterogeneous nucleation of nitric acid trihydrate on clay minerals: relevance to type ia polar stratospheric clouds.

PubMed

Hatch, Courtney D; Gough, Raina V; Toon, Owen B; Tolbert, Margaret A

2008-01-17

Although critical to atmospheric modeling of stratospheric ozone depletion, selective heterogeneous nuclei that promote the formation of Type Ia polar stratospheric clouds (PSCs) are largely unknown. While mineral particles are known to be good ice nuclei, it is currently not clear whether they are also good nuclei for PSCs. In the present study, a high-vacuum chamber equipped with transmission Fourier transform infrared spectroscopy and a quadrupole mass spectrometer was used to study heterogeneous nucleation of nitric acid trihydrate (NAT) on two clay minerals-Na-montmorillonite and kaolinite-as analogs of atmospheric terrestrial and extraterrestrial minerals. The minerals are first coated with a 3:1 supercooled H2O/HNO3 solution prior to the observed nucleation of crystalline NAT. At 220 K, NAT formation was observed at low SNAT values of 12 and 7 on kaolinite and montmorillonite clays, respectively. These are the lowest SNAT values reported in the literature on any substrate. However, NAT nucleation exhibited significant temperature dependence. At lower temperatures, representative of typical polar stratospheric conditions, much higher supersaturations were required before nucleation was observed. Our results suggest that NAT nucleation on mineral particles, not previously treated with sulfuric acid, may not be an important nucleation platform for Type Ia PSCs under normal polar stratospheric conditions.

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)

Structure of a microbial community in soil after prolonged addition of low levels of simulated acid rain

PubMed

Pennanen; Fritze; Vanhala; Kiikkila; Neuvonen; Baath

1998-06-01

Humus samples were collected 12 growing seasons after the start of a simulated acid rain experiment situated in the subarctic environment. The acid rain was simulated with H2SO4, a combination of H2SO4 and HNO3, and HNO3 at two levels of moderate acidic loads close to the natural anthropogenic pollution levels of southern Scandinavia. The higher levels of acid applications resulted in acidification, as defined by humus chemistry. The concentrations of base cations decreased, while the concentrations of exchangeable H+, Al, and Fe increased. Humus pH decreased from 3.83 to 3.65. Basal respiration decreased with decreasing humus pH, and total microbial biomass, measured by substrate-induced respiration and total amount of phospholipid fatty acids (PLFA), decreased slightly. An altered PLFA pattern indicated a change in the microbial community structure at the higher levels of acid applications. In general, branched fatty acids, typical of gram-positive bacteria, increased in the acid plots. PLFA analysis performed on the bacterial community growing on agar plates also showed that the relative amount of PLFA specific for gram-positive bacteria increased due to the acidification. The changed bacterial community was adapted to the more acidic environment in the acid-treated plots, even though bacterial growth rates, estimated by thymidine and leucine incorporation, decreased with pH. Fungal activity (measured as acetate incorporation into ergosterol) was not affected. This result indicates that bacteria were more affected than fungi by the acidification. The capacity of the bacterial community to utilize 95 different carbon sources was variable and only showed weak correlations to pH. Differences in the toxicities of H2SO4 and HNO3 for the microbial community were not found.

Effects of inhalation of acidic compounds on pulmonary function in allergic adolescent subjects

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

Koenig, J.Q.; Covert, D.S.; Pierson, W.E.

There is concern about the human health effects of inhalation of acid compounds found in urban air pollution. It was the purpose of this study to investigate three of these acid compounds, sulfur dioxide (SO/sub 2/), sulfuric acid (H/sub 2/SO/sub 4/), and nitric acid (HNO/sub 3/) in a group of allergic adolescent subjects. Subjects were exposed during rest and moderate exercise to 0.7 mumole/m/sup 3/ (68 micrograms/m/sup 3/) H/sub 2/SO/sub 4/, 4.0 mumole/m/sup 3/ (0.1 ppm) SO/sub 2/, or 2.0 mumole/m/sup 3/ (0.05 ppm) HNO/sub 3/. Pulmonary functions (FEV1, total respiratory resistance, and maximal flow) were measured before and aftermore » exposure. Preliminary analysis based on nine subjects indicates that exposure to 0.7 mumole/m/sup 3/ H/sub 2/SO/sub 4/ alone and in combination with SO/sub 2/ caused significant changes in pulmonary function, whereas exposure to air or SO/sub 2/ alone did not. FEV1 decreased an average of 6% after exposure to H/sub 2/SO/sub 4/ alone and 4% when the aerosol was combined with SO/sub 2/. The FEV1 decrease was 2% after both air and SO/sub 2/ exposures. Total respiratory resistance (RT) increased 15% after the combined H/sub 2/SO/sub 4/ exposures, 12% after H/sub 2/SO/sub 4/ alone, and 7% after exposure to air. After exposures to HNO3 alone, FEV1 decreased by 4%, and RT increased by 23%. These results are preliminary; final conclusions must wait for completion of the study.« less

Effects of simulated acid rain, ozone and sulfur dioxide on suitability of elms for elm leaf beetle

Treesearch

Richard W. Hall; Jack H. Barger; Alden M. Townsend

1988-01-01

Cuttings from two clonally propagated elm hybrids ('Pioneer' and 'Homestead') were treated with ozone (03), sulfur dioxide (S02), simulated acid rain or left untreated. Fumigants were applied 7 hours per day, 5 days per week for 9 weeks in open-top chambers. Fumigation treatments were: 0.1 ppm 0

Influence of peracetic acid modification on the physicochemical properties of activated carbon and its performance in the ozone-catalytic oxidation of gaseous benzene

NASA Astrophysics Data System (ADS)

Fang, Ruimei; Huang, Haibao; Huang, Wenjun; Ji, Jian; Feng, Qiuyu; Shu, Yajie; Zhan, Yujie; Liu, Gaoyuan; Xie, Ruijie

2017-10-01

Coal based activated carbon (AC) was pretreated by peracetic acid solution and used for supporting Mn catalyst towards oxidation of gaseous benzene by catalytic ozonation. The as-obtained activated carbon was characterized by XPS, BET, SEM, and TG technologies. It indicates that peracetic acid solution modification not only raised the quantity of chemisorbed oxygen or water, and hydroxyl group on activated carbon material surface, but also increased the specific surface area and benzene adsorption capacity of activated carbon. Benzene could be completely removed in 300 min and CO2 selectivity reached to 61.9% over Mn/AC-modified catalyst. A possible catalytic ozonation mechanism of activated carbon which was treated by peracetic acid solution supported Mn catalyst for oxidation of benzene was proposed.

The effect of ultrasonic and HNO3 treatment of activated carbon from fruit stones on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors.

PubMed

Venhryn, B Ya; Stotsko, Z A; Grygorchak, I I; Bakhmatyuk, B P; Mudry, S I

2013-09-01

The effect of ultrasonic treatment and modification with nitric acid of activated carbon obtained from fruit stones, on the parameters of electric double-layer (EDL) as well as on farad-volt characteristics of its boundary with electrolyte 7.6 m KОН, 4 m KI and 2 m ZnI2 aqueous solutions has been studied by means of precision porometry, cyclic voltamperometry, electrochemical impedance spectroscopy and computer simulation methods. It is shown that HNO3 treatment results in an increase of the electrostatic capacitance up to 202 F/g in 7.6 m KОН-solution as well as pseudocapacitance up to 1250 F/g in 4 m KI. This increase is supposed to be related both with hydrophilicity and with an increase of the density of states on Fermi level. The ultrasonic treatment enables one to significantly increase (more than 200 times) the density of states on Fermi level which in turn causes both quantitative and qualitative changes in farad-volt dependences. A hybrid supercapacitor with specific capacitance of 1100 F/g and specific energy of 49 Wh/kg per active mass of two electrodes was developed. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of ozonation pretreatment on natural organic matter and wastewater derived organic matter - Possible implications on the formation of ozonation by-products.

PubMed

Papageorgiou, Alexandros; Stylianou, Stylianos K; Kaffes, Pavlos; Zouboulis, Anastasios I; Voutsa, Dimitra

2017-03-01

The aim of this study was to investigate possible implications of natural and wastewater derived organic matter in river water that is subsequently used following treatment for drinking purposes. River water was subjected to lab-scale ozonation experiments under different ozone doses (0.1, 0.4, 0.8, 1.0 and 2.0 mgO 3 /mgC) and contact times (1, 3, 5, 8 and 10 min). Mixtures of river water with humic acids or wastewaters (sewage wastewater and secondary effluents) at different proportions were also ozonated. Dissolved organic carbon and biodegradable dissolved organic carbon concentrations as well as spectroscopic characteristics (UV absorbance and fluorescence intensities) of different types of dissolved organic matter and possible changes due to the ozonation treatment are presented. River water, humic substances and wastewater exhibited distinct spectroscopic characteristics that could serve for pollution source tracing. Wastewater impacted surface water results in higher formation of carbonyl compounds. However, the formation yield (μg/mgC) of wastewaters was lower than that of surface water possibly due to different composition of wastewater derived organic matter and the presence of scavengers, which may limit the oxidative efficiency of ozone. Copyright © 2016 Elsevier Ltd. All rights reserved.

First Reprocessing of Southern Hemisphere ADditional OZonesondes Profile Records: 3. Uncertainty in Ozone Profile and Total Column

NASA Astrophysics Data System (ADS)

Witte, Jacquelyn C.; Thompson, Anne M.; Smit, Herman G. J.; Vömel, Holger; Posny, Françoise; Stübi, Rene

2018-03-01

Reprocessed ozonesonde data from eight SHADOZ (Southern Hemisphere ADditional OZonesondes) sites have been used to derive the first analysis of uncertainty estimates for both profile and total column ozone (TCO). The ozone uncertainty is a composite of the uncertainties of the individual terms in the ozone partial pressure (PO3) equation, those being the ozone sensor current, background current, internal pump temperature, pump efficiency factors, conversion efficiency, and flow rate. Overall, PO3 uncertainties (ΔPO3) are within 15% and peak around the tropopause (15 ± 3 km) where ozone is a minimum and ΔPO3 approaches the measured signal. The uncertainty in the background and sensor currents dominates the overall ΔPO3 in the troposphere including the tropopause region, while the uncertainties in the conversion efficiency and flow rate dominate in the stratosphere. Seasonally, ΔPO3 is generally a maximum in the March-May, with the exception of SHADOZ sites in Asia, for which the highest ΔPO3 occurs in September-February. As a first approach, we calculate sonde TCO uncertainty (ΔTCO) by integrating the profile ΔPO3 and adding the ozone residual uncertainty, derived from the McPeters and Labow (2012, doi:10.1029/2011JD017006) 1σ ozone mixing ratios. Overall, ΔTCO are within ±15 Dobson units (DU), representing 5-6% of the TCO. Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument (TOMS and OMI) satellite overpasses are generally within the sonde ΔTCO. However, there is a discontinuity between TOMS v8.6 (1998 to September 2004) and OMI (October 2004-2016) TCO on the order of 10 DU that accounts for the significant 16 DU overall difference observed between sonde and TOMS. By comparison, the sonde-OMI absolute difference for the eight stations is only 4 DU.

Concentrations of nitrous acid, nitric acid, nitrite and nitrate in the gas and aerosol phase at a site in the emission zone during ESCOMPTE 2001 experiment

NASA Astrophysics Data System (ADS)

Acker, K.; Möller, D.; Auel, R.; Wieprecht, W.; Kalaß, D.

2005-03-01

Ground-based measurements were performed at the "Expérience sur Site pour COntraindre les Modèles de Pollution atmosphérique et de Transport d`Emissions" (ESCOMPTE) field site E3 (Realtor) about 30 km north of the urban environment of Marseille and east of the industrial centre Berre pond to investigate the formation of nitrous and nitric acid and to detect the distribution of reactive N-species between the gas and particle phase during photochemical pollution events. A wet denuder sampling for gases followed by a steam jet collection for aerosols was both coupled to anion chromatographic analysis. The analytical system provided data continuously with 30-min time resolution between June 13 and July 13, 2001. Indications for heterogeneous formation of nitrous acid during nighttime and daytime on ground and aerosol surfaces were found, the average HNO 2/NO 2 ratio was 6%. Highest concentrations were observed during two episodes of strong pollution accumulation when sea breeze transported industrial, traffic and urban pollution land-inwards. After nocturnal heterogeneous formation (about 0.1 ppb v h -1 were estimated corresponding to increasing HNO 2/NO 2 ratios) and accumulation processes up to 1.2 ppb v HNO 2 were observed. Their photolysis produces up to 5-9×10 6 OH cm -3 s -1 and will contribute significantly to initiation of the daily photochemistry in the lowest part of the troposphere. For the key tropospheric species, HNO 3 daily peaks up to 4 ppb v were detected.

Fabrication of interconnected porous β-tricalcium phosphate (β-TCP) based on a setting reaction of β-TCP granules with HNO3 followed by heat treatment.

PubMed

Ishikawa, Kunio; Putri, Tansza Setiana; Tsuchiya, Akira; Tanaka, Keisuke; Tsuru, Kanji

2018-03-01

β-Tricalcium phosphate [β-TCP] is the typical bone substitute due to its excellent osteoconductivity and bioresorbability. One of the keys to improve its potential as bone substitute is to introduce porous structure and its regulation. In this study, interconnected porous β-TCP blocks were fabricated through a setting reaction of β-TCP granules and subsequent heat treatment. First, β-TCP granules were mixed with HNO 3 . Upon mixing, β-TCP granules were bridged with dicalcium phosphate dihydrate [DCPD: CaHPO 4 ·2H 2 O] containing Ca(NO 3 ) 2 . Then, the DCPD-bridged β-TCP was heated at 1100°C. During the heating process, DCPD containing Ca(NO 3 ) 2 transformed into β-TCP and bonded with β-TCP granules. As a result, an interconnected porous β-TCP block formed. The diametral tensile strength and porosity of the interconnected porous β-TCP block fabricated from 200-300-μm β-TCP granules and 5 N HNO 3 and then heated at 1,100°C were 1.4 ± 0.2 MPa and 57% ± 2%, respectively. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 797-804, 2018. © 2017 Wiley Periodicals, Inc.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantifying foliar responses of white ash to ozone and simulated acid precipitation: an assessment proposal for forest exposure studies

Treesearch

Leon S. Dochinger; Keith F. Jensen; Keith F. Jensen

1990-01-01

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

Catalytic ozonation of dimethyl phthalate and chlorination disinfection by-product precursors over Ru/AC.

PubMed

Wang, Jianbing; Zhou, Yunrui; Zhu, Wanpeng; He, Xuwen

2009-07-15

Catalytic ozonation of dimethyl phthalate (DMP) in aqueous solution (5mg/L) under various reactions was performed to examine the effect of catalyst dosage, catalyst particle size, ozone dosage, and gas flow rate on the mineralization of DMP. The mineralization of DMP can be achieved via ozonation and the presence of Ru/AC could greatly accelerate the mineralization rate of DMP in ozonation process. In the continuous experiment of the Ru/AC catalyzed ozonation of DMP, total organic carbon (TOC) removals were kept stable around 75% during 42 h reaction. No leaching of ruthenium was observed in the treated water samples. The treatment of natural water using Ru/AC+O(3), Ru/AC+O(2) and ozonation alone was studied. In the Ru/AC+O(3) process, TOC removals, the reductions of the haloacetic acid formation potentials (HAAFPs), and the reductions of the trihalomethane formation potentials (THMFPs) of 11 water samples were 22-44%, 39-61% and 50-65%, respectively. Ru/AC+O(3) process was much more effective than ozonation alone for TOC removal and the reduction of disinfection by-product formation potential (DBPFP) in the treatment of natural water. It is a promising water treatment technology.

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.

Heterogeneous catalytic ozonation of clofibric acid using Ce/MCM-48: Preparation, reaction mechanism, comparison with Ce/MCM-41.

PubMed

Li, Shangyi; Tang, Yiming; Chen, Weirui; Hu, Zhe; Li, Xukai; Li, Laisheng

2017-10-15

Three-dimensional mesoporous MCM-48 and Ce loaded MCM-48 (Ce/MCM-48) were synthesized by hydrothermal and impregnating methods, respectively. They were characterized by XRD, SEM, TEM, EDS, XPS, N 2 adsorption-desorption techniques, and the results showed that Ce/MCM-48 still retained a highly ordered cubic structure. A series of experiments were conducted to study the catalytic activity of Ce/MCM-48 and Ce/MCM-41 for ozonation of clofibric acid in aqueous solution. Total Organic Carbon (TOC) removal efficiency in Ce/MCM-48/O 3 can be improved to 64% at 120min reaction time, 54% by Ce/MCM-41/O 3 , only 24% by MCM-48/O 3 , 23% by single ozonation. Ce/MCM-48 did not show any adsorption capacity for CA. Effect of initial pH revealed that active sites were surface protonated hydroxyl groups. The restraint of phosphate and sodium hydrogen sulfite (NaHSO 3 ) on the mineralization of CA illustrated more hydroxyl radicals were generated by Ce/MCM-48 catalysts than Ce/MCM-41. The degradation pathway of CA was investigated by the alterations of pH under different conditions. Recycle tests of catalysts demonstrated that compared with Ce/MCM-41, Ce/MCM-48 exhibited more excellent catalytic efficiency and stability because of its unique pore systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Natural zeolite reactivity towards ozone: the role of compensating cations.

PubMed

Valdés, Héctor; Alejandro, Serguei; Zaror, Claudio A

2012-08-15

Among indoor pollutants, ozone is recognised to pose a threat to human health. Recently, low cost natural zeolites have been applied as alternative materials for ozone abatement. In this work, the effect of compensating cation content of natural zeolite on ozone removal is studied. A Chilean natural zeolite is used here as starting material. The amount of compensating cations in the zeolite framework was modified by ion exchange using an ammonium sulphate solution (0.1 mol L(-1)). Characterisation of natural and modified zeolites were performed by X-ray powder diffraction (XRD), nitrogen adsorption at 77K, elemental analysis, X-ray fluorescence (XRF), thermogravimetric analysis coupled with mass spectroscopy (TGA-MS), and temperature-programmed desorption of ammonia (NH(3)-TPD). Ozone adsorption and/or decomposition on natural and modified zeolites were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Results show that the zeolite compensating cation content affects ozone interaction with zeolite active sites. Ammonium ion-exchange treatments followed by thermal out-gassing at 823 K, reduces ozone diffusion resistance inside the zeolite framework, increasing ozone abatement on zeolite surface active sites. Weak and strong Lewis acid sites of zeolite surface are identified here as the main active sites responsible of ozone removal. Copyright © 2012 Elsevier B.V. All rights reserved.

Ozone response to emission reductions in the southeastern United States

NASA Astrophysics Data System (ADS)

Blanchard, Charles L.; Hidy, George M.

2018-06-01

Ozone (O3) formation in the southeastern US is studied in relation to nitrogen oxide (NOx) emissions using long-term (1990s-2015) surface measurements of the Southeastern Aerosol Research and Characterization (SEARCH) network, U.S. Environmental Protection Agency (EPA) O3 measurements, and EPA Clean Air Status and Trends Network (CASTNET) nitrate deposition data. Annual fourth-highest daily peak 8 h O3 mixing ratios at EPA monitoring sites in Georgia, Alabama, and Mississippi exhibit statistically significant (p < 0.0001) linear correlations with annual NOx emissions in those states between 1996 and 2015. The annual fourth-highest daily peak 8 h O3 mixing ratios declined toward values of ˜ 45-50 ppbv and monthly O3 maxima decreased at rates averaging ˜ 1-1.5 ppbv yr-1. Mean annual total oxidized nitrogen (NOy) mixing ratios at SEARCH sites declined in proportion to NOx emission reductions. CASTNET data show declining wet and dry nitrate deposition since the late 1990s, with total (wet plus dry) nitrate deposition fluxes decreasing linearly in proportion to reductions of NOx emissions by ˜ 60 % in Alabama and Georgia. Annual nitrate deposition rates at Georgia and Alabama CASTNET sites correspond to 30 % of Georgia emission rates and 36 % of Alabama emission rates, respectively. The fraction of NOx emissions lost to deposition has not changed. SEARCH and CASTNET sites exhibit downward trends in mean annual nitric acid (HNO3) concentrations. Observed relationships of O3 to NOz (NOy-NOx) support past model predictions of increases in cycling of NO and increasing responsiveness of O3 to NOx. The study data provide a long-term record that can be used to examine the accuracy of process relationships embedded in modeling efforts. Quantifying observed O3 trends and relating them to reductions in ambient NOy species concentrations offers key insights into processes of general relevance to air quality management and provides important information supporting strategies for

Effect of Ozone Treatment on Deoxynivalenol and Wheat Quality

PubMed Central

Wang, Li; Shao, Huili; Luo, Xiaohu; Wang, Ren; Li, Yongfu; Li, Yanan; Luo, Yingpeng; Chen, Zhengxing

2016-01-01

Deoxynivalenol (DON) is a secondary metabolite produced by Fusarium fungi, which is found in a wide range of agricultural products, especially in wheat, barley, oat and corn. In this study, the distribution of DON in the wheat kernel and the effect of exposure time to ozone on DON detoxification were investigated. A high concentration of toxin was found in the outer part of the kernel, and DON was injected from the outside to the inside. The degradation rates of DON were 26.40%, 39.16%, and 53.48% after the samples were exposed to 75 mg/L ozone for 30, 60, and 90 min, respectively. The effect of ozonation on wheat flour quality and nutrition was also evaluated. No significant differences (P > 0.05) were found in protein content, fatty acid value, amino acid content, starch content, carbonyl and carboxyl content, and swelling power of ozone-treated samples. Moreover, the ozone-treated samples exhibited higher tenacity and whiteness, as well as lower extensibility and yellowness. This finding indicated that ozone treatment can simultaneously reduce DON levels and improve flour quality. PMID:26812055

"OZONE SOURCE APPORTIONMENT IN CMAQ' | Science ...

EPA Pesticide Factsheets

Ozone source attribution has been used to support various policy purposes including interstate transport (Cross State Air Pollution Rule) by U.S. EPA and ozone nonattainment area designations by State agencies. Common scientific applications include tracking intercontinental transport of ozone and ozone precursors and delineating anthropogenic and non-anthropogenic contribution to ozone in North America. As in the public release due in September 2013, CMAQ’s Integrated Source Apportionment Method (ISAM) attributes PM EC/OC, sulfate, nitrate, ammonium, ozone and its precursors NOx and VOC, to sectors/regions of users’ interest. Although the peroxide-to-nitric acid productions ratio has been the most common indicator to distinguish NOx-limited ozone production from VOC-limited one, other indicators are implemented in addition to allowing for an ensemble decision based on a total of 9 available indicator ratios. Moreover, an alternative approach of ozone attribution based on the idea of chemical sensitivity in a linearized system that has formed the basis of chemical treatment in forward DDM/backward adjoint tools has been implemented in CMAQ. This method does not require categorization into either ozone regime. In this study, ISAM will simulate the 2010 North America ozone using all of the above gas-phase attribution methods. The results are to be compared with zero-out difference out of those sectors in the host model runs. In addition, ozone contribution wil

Ozone injury on Bel W-3 tobacco controlled by at least two genes

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

Taylor, G.S.

1968-08-01

Tobacco varieties differ widely in susceptibility to injury by ozone in polluted air. Ordinarily, this injury appears as small flecks on the upper surface of the leaf. The highly susceptible variety Bel W-3, commonly used as an indicator plant for ozone, develops both the flecking plus larger brown or white spots which interfere with the assessment of injury. The highly resistant breeding line 6524 develops no spots but only a few flecks under like conditions. The F/sub 1/ of Bel W-3 x 6524 is intermediate, showing flecks but fewer spots than Bel W-3. The F/sub 2/, however, segregated into 40%more » highly resistant, 10% highly susceptible, and 50% intermediate individuals. When exposed to ozone, resistant plants developed only a few small flecks, and susceptible plants responded as does Bel W-3. Among the plants in the intermediate group were individuals that formed only larger brown or white spots without fleck. Plants with the severe spot reaction showed injury on the calyx remnant surrounding the seed pod. Microbial infection was not involved. This is the first evidence that the severe symptoms of ozone injury on Bel W-3 are a combination of reactions controlled by at least two separate genes.« less

A Novel Gene, OZONE-RESPONSIVE APOPLASTIC PROTEIN1, Enhances Cell Death in Ozone Stress in Rice1

PubMed Central

Ueda, Yoshiaki; Siddique, Shahid; Frei, Michael

2015-01-01

A novel protein, OZONE-RESPONSIVE APOPLASTIC PROTEIN1 (OsORAP1), was characterized, which was previously suggested as a candidate gene underlying OzT9, a quantitative trait locus for ozone stress tolerance in rice (Oryza sativa). The sequence of OsORAP1 was similar to that of ASCORBATE OXIDASE (AO) proteins. It was localized in the apoplast, as shown by transient expression of an OsORAP1/green fluorescent protein fusion construct in Nicotiana benthamiana leaf epidermal and mesophyll cells, but did not possess AO activity, as shown by heterologous expression of OsORAP1 in Arabidopsis (Arabidopsis thaliana) mutants with reduced background AO activity. A knockout rice line of OsORAP1 showed enhanced tolerance to ozone stress (120 nL L−1 average daytime concentration, 20 d), as demonstrated by less formation of leaf visible symptoms (i.e. cell death), less lipid peroxidation, and lower NADPH oxidase activity, indicating reduced active production of reactive oxygen species. In contrast, the effect of ozone on chlorophyll content was not significantly different among the lines. These observations suggested that OsORAP1 specifically induced cell death in ozone stress. Significantly enhanced expression of jasmonic acid-responsive genes in the knockout line implied the involvement of the jasmonic acid pathway in symptom mitigation. Sequence analysis revealed extensive polymorphisms in the promoter region of OsORAP1 between the ozone-susceptible cv Nipponbare and the ozone-tolerant cv Kasalath, the OzT9 donor variety, which could be responsible for the differential regulation of OsORAP1 reported earlier. These pieces of evidence suggested that OsORAP1 enhanced cell death in ozone stress, and its expression levels could explain the effect of a previously reported quantitative trait locus. PMID:26220952

Ozonation by-products issued from the destruction of microorganisms present in wastewaters treated for reuse.

PubMed

Rojas-Valencia, M N; Orta-de-Velásquez, M T; Vaca-Mier, M; Franco, V

2004-01-01

This work demonstrates the reaction of ozone on the amino acids comprising the covering layer of resistant micro-organisms. A secondary aim was to check the byproducts generated when ozone was applied to synthetic samples (such as Vibrio cholerae NO 01 WFCC-449, Salmonella typhi ATTC-6539, faecal coliforms and Ascaris suum). The ozone was applied at a concentration of 18.4 mgO3/min at pH 3, for different lengths of time. In the case of bacteria, results showed that, at 8 minutes, the number was reduced to the level of the Official Mexican Standards set for treated water destined for irrigation purposes (1,000 MPN/100 mL). Excellent correlation coefficients (0.95 to 0.99) were obtained for microbial concentrations versus ozone contact time. Destruction times required for 100% removal of the initial bacteria population varied between 2 and 14 minutes, while Ascaris suum required 1 hour. When Gram-negative bacteria die due to the effects of ozone, cellular lysis and the liberation of endotoxins (biodegradable) were observed. The ozonation of amino acids in the shell of Ascaris suum eggs, leads to the formation of aldehydes, such as formaldehyde and acetaldehyde, in low concentrations (0.0003 and 0.0005 microg/mL respectively). These levels are not hazardous to human health.

The ozonolysis of primary aliphatic amines in single and multicomponent fine particles

NASA Astrophysics Data System (ADS)

Zahardis, J.; Geddes, S.; Petrucci, G. A.

2007-10-01

The oxidative processing by ozone of the particulate amines octadecylamine (ODA) and hexadecylamine (HDA) is reported. Ozonolysis of these amines resulted in strong NO2- and NO3- ion signals that increased with ozone exposure as monitored by photoelectron resonance capture ionization aerosol mass spectrometry. These products suggest a mechanism of progressive oxidation of the particulate amines to nitro alkanes. Additionally, a strong ion signal at 125 m/z is assigned to the ion NO3-(HNO3). For ozonized mixed particles containing ODA or HDA + oleic acid (OL), with pO3≥3×10^{-7 atm, imine, secondary amide, and tertiary amide products were measured. These products most likely arise from reactions of amines with aldehydes (for imines) and stabilized Criegee intermediates (SCI) or secondary ozonides (for amides) from the fatty acid. The routes to amides via SCI and/or secondary ozonides was shown to be more important than comparable amide forming reactions between amines and organic acids, using azelaic acid as a test compound. Finally, direct evidence is provided for the formation of a surface barrier in the ODA + OL reaction system that resulted in the retention of OL at high ozone exposures (up to 10-3 atm for 17 s). This effect was not observed in HDA + OL or single component OL particles, suggesting that it may be a species-specific surfactant effect from an in situ generated amide or imine. Implications to tropospheric chemistry, including particle bound amines as sources of oxidized gas phase nitrogen species (e.g. NO2, NO3), formation of nitrogen enriched HULIS via ozonolysis of amines and source apportionment are discussed.}

The ozonolysis of primary aliphatic amines in fine particles

NASA Astrophysics Data System (ADS)

Zahardis, J.; Geddes, S.; Petrucci, G. A.

2008-02-01

The oxidative processing by ozone of the particulate amines octadecylamine (ODA) and hexadecylamine (HDA) is reported. Ozonolysis of these amines resulted in strong NO2- and NO3- ion signals that increased with ozone exposure as monitored by photoelectron resonance capture ionization aerosol mass spectrometry. These products suggest a mechanism of progressive oxidation of the particulate amines to nitroalkanes. Additionally, a strong ion signal at 125 m/z is assigned to the ion NO3- (HNO3). For ozonized mixed particles containing ODA or HDA + oleic acid (OL), with pO3≥3×10-7 atm, imine, secondary amide, and tertiary amide products were measured. These products most likely arise from reactions of amines with aldehydes (for imines) and stabilized Criegee intermediates (SCI) or secondary ozonides (for amides) from the fatty acid. The routes to amides via SCI and/or secondary ozonides were shown to be more important than comparable amide forming reactions between amines and organic acids, using azelaic acid as a test compound. Finally, direct evidence is provided for the formation of a surface barrier in the ODA + OL reaction system that resulted in the retention of OL at high ozone exposures (up to 10-3 atm for 17 s). This effect was not observed in HDA + OL or single component OL particles, suggesting that it may be a species-specific surfactant effect from an in situ generated amide or imine. Implications to tropospheric chemistry, including particle bound amines as sources of oxidized gas phase nitrogen species (e.g.~NO2, NO3), formation of nitrogen enriched HULIS via ozonolysis of amines and source apportionment are discussed.

Global 3-D Modeling Studies Of Tropospheric Ozone And Related Gases

NASA Technical Reports Server (NTRS)

Jacob, Daniel J.; Logan, Jennifer A.

2003-01-01

Our research was targeted at three issues: (1) the factors controlling ozone in the tropical troposphere, (2) the Asian outflow of ozone and its precursors, and (3) the causes of decadal trends observed in ozone and CO. We have also used support from this ACMAP grant to (1) work with Kelly Chance on the retrieval and interpretation of HCHO and NO2 observations from GOME, and (2) develop GEOS-CHEM into a versatile model supporting the work of a large number of users including outside Harvard. ACMAP has provided the core support for GEOS-CHEM development. Applications of the GEOS-CHEM model with primary support from ACMAP are discussed below. A list of publications resulting from this grant is given at the end of the report.

Ozone Profiles and Tropospheric Ozone from Global Ozone Monitoring Experiment

NASA Technical Reports Server (NTRS)

Liu, X.; Chance, K.; Sioris, C. E.; Sparr, R. J. D.; Kuregm, T. P.; Martin, R. V.; Newchurch, M. J.; Bhartia, P. K.

2003-01-01

Ozone profiles are derived from backscattered radiances in the ultraviolet spectra (290-340 nm) measured by the nadir-viewing Global Ozone Monitoring Experiment using optimal estimation. Tropospheric O3 is directly retrieved with the tropopause as one of the retrieval levels. To optimize the retrieval and improve the fitting precision needed for tropospheric O3, we perform extensive wavelength and radiometric calibrations and improve forward model inputs. Retrieved O3 profiles and tropospheric O3 agree well with coincident ozonesonde measurements, and the integrated total O3 agrees very well with Earth Probe TOMS and Dobson/Brewer total O3. The global distribution of tropospheric O3 clearly shows the influences of biomass burning, convection, and air pollution, and is generally consistent with our current understanding.

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

Removal of atmospheric oxidants with annular denuders

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

Williams, E.L. II; Grosjean, D.

1990-06-01

Annular denuders have been tested for their ability to remove atmospheric photochemical oxidants including ozone (150-170 ppb), nitrogen dioxide (40-200 ppb), nitric acid (35 ppb), and peroxyacetyl nitrate (PAN, 6-25 ppb). Formaldehyde (80-140 ppb) was also tested as a copollutant. Tests were carried out at low rates of 1,2, and 20 L/min, with oxidants tested singly or as part of photochemical mixtures in purified air. Efficient collection was obtained with annular denuders coated with potassium iodide (O{sub 3}), phenoxamine (O{sub 3}), sodium carbonate (HNO{sub 3}), potassium hydroxide (PAN), and 2,4-dinitrophenylhydrazine (HCHO).

Depression of Photosynthesis, Growth, and Yield in Field-Grown Green Pepper (Capsicum annuum L.) Exposed to Acidic Fog and Ambient Ozone 1

PubMed Central

Takemoto, Brent K.; Bytnerowicz, Andrzej; Olszyk, David M.

1988-01-01

The relationship among physiological, injury, growth, and yield responses was examined in field-grown green pepper (Capsicum annuum L. `California Wonder') subjected to two airborne environmental stresses. The primary objectives were to determine if the stresses could cause alterations in the plant responses, and to determine if any stress induced alterations in physiological or injury responses were correlated with effects on growth or yield. Responses were monitored in green pepper exposed to simulated acidic fog alone, or in combination with ambient concentrations of ozone in open-top field chambers. Both highly acidic fog and ambient ozone depressed green pepper growth and yield responses via the inhibition of photosynthesis. Applications of highly acidic fog (i.e. two exposures of pH 1.68 fog per week for 11 weeks) caused a significant depression of net photosynthesis, reduction in leaf buffering capacity, and an extensive amount of leaf injury. These alterations closely paralleled decreases in growth and yield on a percentage basis. In contrast, ambient ozone had similar impacts on net photosynthesis, growth and yield, but enhanced leaf buffering capacity, and caused no visible injury. The pollutant-specific differences in plant response are discussed with respect to whole-plant carbon metabolism and physiological compensation. PMID:16666330

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.

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 ...

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.

Multivariate Analysis To Quantify Species in the Presence of Direct Interferents: Micro-Raman Analysis of HNO 3 in Microfluidic Devices

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

Lines, Amanda M.; Nelson, Gilbert L.; Casella, Amanda J.

Microfluidic devices are a growing field with significant potential for application to small scale processing of solutions. Much like large scale processing, fast, reliable, and cost effective means of monitoring the streams during processing are needed. Here we apply a novel Micro-Raman probe to the on-line monitoring of streams within a microfluidic device. For either macro or micro scale process monitoring via spectroscopic response, there is the danger of interfering or confounded bands obfuscating results. By utilizing chemometric analysis, a form of multivariate analysis, species can be accurately quantified in solution despite the presence of overlapping or confounded spectroscopic bands.more » This is demonstrated on solutions of HNO 3 and NaNO 3 within micro-flow and microfluidic devices.« less

Ozone-initiated chemistry in an occupied simulated aircraft cabin.

PubMed

Weschler, Charles J; Wisthaler, Armin; Cowlin, Shannon; Tamás, Gyöngyi; Strøm-Tejsen, Peter; Hodgson, Alfred T; Destaillats, Hugo; Herrington, Jason; Zhang, Junfeng; Nazaroff, William W

2007-09-01

We have used multiple analytical methods to characterize the gas-phase products formed when ozone was added to cabin air during simulated 4-hour flights that were conducted in a reconstructed section of a B-767 aircraft containing human occupants. Two separate groups of 16 females were each exposed to four conditions: low air exchange (4.4 (h-1)), <2 ppb ozone; low air exchange, 61-64 ppb ozone; high air exchange (8.8 h(-1)), <2 ppb ozone; and high air exchange, 73-77 ppb ozone. The addition of ozone to the cabin air increased the levels of identified byproducts from approximately 70 to 130 ppb at the lower air exchange rate and from approximately 30 to 70 ppb at the higher air exchange rate. Most of the increase was attributable to acetone, nonanal, decanal, 4-oxopentanal (4-OPA), 6-methyl-5-hepten-2-one (6-MHO), formic acid, and acetic acid, with 0.25-0.30 mol of quantified product volatilized per mol of ozone consumed. Several of these compounds reached levels above their reported odor thresholds. Most byproducts were derived from surface reactions with occupants and their clothing, consistent with the inference that occupants were responsible for the removal of >55% of the ozone in the cabin. The observations made in this study have implications for other indoor settings. Whenever human beings and ozone are simultaneously present, one anticipates production of acetone, nonanal, decanal, 6-MHO, geranyl acetone, and 4-OPA.

Solubility limits of dibutyl phosphoric acid in uranium-nitric acid solutions

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

Pierce, R.A.

2000-01-04

The Savannah River Site has enriched uranium (EU) solution that has been stored since being purified in its solvent extraction processes. The concentrations in solution are approximately 6 g/L U and 0.1 M nitric acid. Residual tributylphosphate in solution has slowly hydrolyzed to form dibutyl phosphoric acid (HDBP) at concentrations averaging 30--50 mg/L. Dibutyl phosphoric acid, in turn, is in equilibrium with (HDBP){sub 2} and DBP{sup {minus}}. Uranium can form compounds with the dibutylphosphate ion (DBP{sup {minus}}) which have limited solubility, thereby creating a nuclear criticality safety issue. Literature reports and earlier SRTC tests have shown that it is feasiblemore » to precipitate U-DBP solid during the storage and processing of EU solutions. As a result, a series of solubility experiments were run at nitric acid concentrations from 0--4.0 M HNO{sub 3}, uranium at 0--90 g/L, and temperatures from 0--30 C. The data shows temperature and nitric acid concentration dependence consistent with what would be expected. With respect to uranium concentration, U-DBP solubility passes through a minimum between 6 and 12 g/L U at the acid concentrations and temperatures studied. However, the minimum shows a slight shift toward lower uranium concentrations at lower nitric acid concentrations. The shifts in solubility are strongly dependent upon the overall ionic strength of the solution. The data also reveal a shift to higher DBP solubility above 0.5 M HNO{sub 3} for both 6 g/L and 12 g/L uranium solutions. Analysis of U-DBP solids from the tests identified distinct differences between precipitates from less than 0.5 M solutions and those from greater than 4 M acid. Analyses identified UO{sub 2}(DBP){sub 2} as the dominant compound present at low acid concentrations in accordance with literature reports. As the acid concentration increases, the crystalline UO{sub 2}(DBP){sub 2} shows molecular substitutions and an increase in amorphous content.« less

Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO 3 − aerosol during the 2013 Southern Oxidant and Aerosol Study