Destruction Of Atmospheric Ozone Research Articles

Destruction of Atmospheric Ozone in Ox, HOx, NOx, ClOx, BrOx, and IOx Catalytic Cycles

Data on the relative contribution of the Ox, HOx, NOx, ClOx, BrOx, and IOx catalytic cycles to atmospheric ozone destruction are given for June and January 2000 at a latitude of 50° N in the height range of 0–50 km. The height profiles of the components of the above families have been calculated using the SOCRATES two-dimensional interactive model and the one-dimensional photochemical model developed at the Tal’rose Institute of Energy Problems of Chemical Physics, Russian Academy of Sciences. The initial data for the calculations are taken to be the atmospheric content of greenhouse gases according to the Intergovernmental Panel on Climate Change RCP 4.5 scenario for 2000. The ozone destruction rate is calculated using an algorithm proposed earlier by the author to determine the rate of the limiting stage of the catalytic cycle.

Geophysical Consequences of Tropospheric Particulate Heating: Further Evidence that Anthropogenic Global Warming is Principally Caused by Particulate Pollution

The climate science community and the United Nations’ Intergovernmental Panel on Climate Change have misinformed world governments by failing to acknowledge tropospheric particulate geoengineering that has been ongoing with ever-increasing duration and intensity for decades, and by treating global warming solely as a radiation-balance issue, which has resulted in a seriously incomplete understanding of the fundamental factors that affect Earth’s surface temperature. Here we review the consequences of tropospheric particulate heating by absorption of short- and long-wave solar radiation and long-wave radiation from Earth’s surface. Generally, black carbon absorbs light over the entire solar spectrum; brown carbon absorbs near-UV wavelengths and, to a lesser extent, visible light; iron oxides are good absorbers, the most efficient being magnetite. Pyrogenic coal fly ash, both from coal burning and from tropospheric jet-spraying geoengineering (for military purposes and/or climate engineering), contains carbon and iron oxides, hematite and magnetite. The recently published climate-science paradigm shift discloses that the main cause of global warming is not carbon dioxide heat retention, but particulate pollution that absorbs radiation, heats the troposphere, and reduces the efficiency of atmospheric-convective heat removal from Earth’s surface. In addition to the World War II data, three other independent lines of supporting evidence are reviewed: (1) Passage overhead of the Mt. St. Helens volcanic plume; (2) Radiosonde and aethalometer investigations of Talukdar et al.; and, (3) convection suppression over the tropical North Atlantic caused by the Saharan-blown dust. The risks associated with the placement of aerosol particulates into the stratosphere, whether lofted naturally, inadvertently, or deliberately as proposed for solar radiation management, poses grave risks, including the destruction of atmospheric ozone. To solve global warming humanity must: (1) Abruptly halt tropospheric particulate geoengineering; (2) Trap particulate emissions from coal-fired industrial furnaces (especially in India and China) and from vehicle exhaust; and, (3) Reduce particulate-forming fuel additives.

Unresolved Problems in the Chemistry of the Middle Atmosphere

In this paper, we consider the unresolved problems of chemistry of the middle atmosphere related to the atmospheric lifetime of the Ox family and its O3, O(3P), and O(1D) components, as well as problems associated with the odd oxygen loss in the Ox, HOx, NOx, ClOx, and BrOx catalytic cycles. We showed that modern interpretations of the odd oxygen concept do not allow obtaining reliable data on the atmospheric lifetime of an odd oxygen family and its components, which is of fundamental importance for the chemistry of the middle atmosphere. Existing methods for determining the rate of ozone depletion in the above cycles are also shown not to have taken into account the chain nature of atmospheric ozone destruction, which leads to significant errors in the results of calculations made using them. We provide the algorithm for a correct estimate of the atmospheric lifetime of the Ox family, as well as an algorithm for calculating the rate of ozone depletion in the Ox, HOx, NOx, ClOx, and BrOx cycles, which is also used to calculate the atmospheric lifetime of the Ox family.

Environmental Control of Vanadium Haloperoxidases and Halocarbon Emissions in Macroalgae.

Vanadium-dependent haloperoxidases (V-HPO), able to catalyze the reaction of halide ions (Cl-, Br-, I-) with hydrogen peroxide, have a great influence on the production of halocarbons, which in turn are involved in atmospheric ozone destruction and global warming. The production of these haloperoxidases in macroalgae is influenced by changes in the surrounding environment. The first reported vanadium bromoperoxidase was discovered 40years ago in the brown alga Ascophyllum nodosum. Since that discovery, more studies have been conducted on the structure and mechanism of the enzyme, mainly focused on three types of V-HPO, the chloro- and bromoperoxidases and, more recently, the iodoperoxidase. Since aspects of environmental regulation of haloperoxidases are less well known, the present paper will focus on reviewing the factors which influence the production of these enzymes in macroalgae, particularly their interactions with reactive oxygen species (ROS).

Halogen Bonding in the Complexes of CH3I and CCl4 with Oxygen-Containing Halogen-Bond Acceptors.

Methyl iodine (CH3I) and carbon tetrachloride (CCl4) are both important volatile precursors for atmospheric ozone destruction. CH3I and CCl4 can act as halogen bond donors to form molecular complexes with atmospheric organic species, such as 2,5-dihydrofuran, tetrahydrofuran, and acetone. This study characterized the halogen bonds in the CH3I and CCl4 complexes using matrix isolation infrared spectroscopy and density functional theory calculations. With the combination of vibrational frequencies in spectra and the calculated interaction energies, frequencies and atoms-in-molecules analyses, we confirmed the formation of halogen-bonded complexes. CH3I as a halogen-bond donor is comparable or slightly weaker than CCl4, and furans involving ether oxygens are better halogen acceptors than acetone. The results help to understand the possibilities of formation of atmospheric molecular complexes that may influence the atmospheric chemical activities and enhance the aerosol formation.

Multi-photon dissociation dynamics of Freon 114B2 under UV radiation by femtosecond laser pulse

The ozone layer which absorbs harmful solar UV radiation is a necessary umbrella for human beings and biosphere. A large amount of alkyl halide including freon exhausted by human into the atmosphere poses a great threat to the ozone layer. Freon dissociates into the product of halogen radical, like Br and Cl, induced by UV sunlight radiation, which is found to be the main culprit for the destruction of atmospheric ozone. In this paper, time-of-flight (TOF) mass spectrometry and velocity map imaging technique are employed for investigating the multiphoton dissociation dynamics of Freon F114B2 (C2F4Br2) induced by femtosecond UV radiation at 267 nm. Fragment mass spectra of C2F4Br2 under UV radiation at 266 nm are obtained by TOF mass spectrometry. Three daughter ions C2F4Br+, C2F4+ and CF2Br+are discovered together with the parent ions C2F4Br2+. And three corresponding photodissociation mechanisms are concluded as follows: 1) C2F4Br2+C2F4Br++Br with single CBr bond breaking and direct production of Br radical; 2) C2F4Br2+C2F4++2Br with double CBr bonds breaking and production of two Br radical; 3) C2F4Br2+CF2Br++CF2Br with CC bond breaking. Velocity map images of the strongest daughter ion C2F4Br+with CBr breaking are measured by imaging apparatus. The kinetic energy distribution of C2F4Br+ ions is obtained from the measured velocity map images. And it can be well fitted by three Gaussian curves which describe normal distribution. It indicates that the production of the fragment C2F4Br+ stems from three different dissociation channels. Additional photodissociation dynamics is obtained by analyzing the angular distribution of the measured image. The values of anisotropy parameter are measured to be 0.1 (for the low energy channel), 0.8 (for the middle energy channel) and 1.4 (for the high energy channel) for the fragment C2F4Br+, respectively. The ratios of parallel transition to perpendicular transition are determined for three different channels. In addition, density functional theory calculations are also performed for further analysis and discussion. The optimized geometries of ground state and ionic state of C2F4Br2 are obtained and compared at the level of B3LYP/6-311G++(d, p). The calculated information about ionic states, including energy level and oscillator strength for the ionic excited states, are given.

Multi-photon dissociation dynamics of Freon 1110 induced by femtosecond laser pulse

The ozone layer which absorbs harmful solar UV radiation is an essential umbrella for human beings. However, a large number of exhausts of chlorine compounds including freon released by people in the atmosphere pose a great threat to the ozone layer. Freon dissociates into the product of chlorine radicals induced by UV sunlight radiation, which are found to be the main culprit for the destruction of atmospheric ozone. In this paper, time-of-flight mass spectrometry and velocity map imaging technique are coupled for investigating the multiphoton dissociation dynamics of Freon 1110 (C2Cl4, Tetrachloroethylene) induced by ultrafast short laser pulse on a femtosecond time scale at 800 nm. Fragments mass spectra of C2Cl4 are measured by time-of-flight mass spectrometry. Together with the parent ion C2Cl4+, two dominant fragment ions C2Cl3+ and C2Cl2+ are discovered in the multi-photon ionization and dissociation process in the experiment. By analyzing the above mass spectra, two corresponding photodissociation mechanisms are discussed and listed as follows: 1) C2Cl4+C2Cl3+ +Cl with single CCl bond breaking and direct production of Cl radical; 2) C2Cl4+C2Cl2+ +2Cl with double CCl bonds breaking and production of two Cl radicals. Also, ion images of these two observed fragment ions C2Cl3+ and C2Cl2+ are measured by velocity map imaging apparatus. The kinetic energy distributions of these two fragment ions are determined from the measured velocity map images. The kinetic energy distributions of both C2Cl3+ and C2Cl2+ can be well fitted by two Gaussion distributions. It indicates that both fragments C2Cl3+ and C2Cl2+ are from two production channels. The peak energies for each channel are fitted. More detailed photodissociation dynamics is obtained by analyzing the angular distribution of the generated fragment ions. The anisotropy parameter values are measured to be 0.46 (low energy channel) and 0.52 (high energy channel) for the fragment C2Cl3+, and 0.41 (low energy channel) and 0.66 (high energy channel) for the fragment C2Cl2+, respectively. The ratios between parallel transition and perpendicular transition are determined for all the observed channels for producing fragments C2Cl3+ and C2Cl2+. In addition, density functional theory calculations at a high-precision level are also performed on photodissociation dynamics for further analysis and discussion. The optimized geometries of ground state and ionic state of C2Cl4 are obtained and compared with density functional theory calculation at the level of B3LYP/6-311G++(d,p). The different structures of the ground and ionic states are given and discussed. The calculated information about ionic states of C2Cl4, including energy level and oscillator strength for the ionic excited states, is also given for analyzing the photodissociation dynamics of the C2Cl4 ions.

Stereodynamical Origin of Anti-Arrhenius Kinetics: Negative Activation Energy and Roaming for a Four-Atom Reaction.

The OH + HBr → H2O + Br reaction, prototypical of halogen-atom liberating processes relevant to mechanisms for atmospheric ozone destruction, attracted frequent attention of experimental chemical kinetics: the nature of the unusual reactivity drop from low to high temperatures eluded a variety of theoretical efforts, ranking this one among the most studied four-atom reactions. Here, inspired by oriented molecular-beams experiments, we develop a first-principles stereodynamical approach. Thermalized sets of trajectories, evolving on a multidimensional potential energy surface quantum mechanically generated on-the-fly, provide a map of most visited regions at each temperature. Visualizations of rearrangements of bonds along trajectories and of the role of specific angles of reactants' mutual approach elucidate the mechanistic change from the low kinetic energy regime (where incident reactants reorient to find the propitious alignment leading to reaction) to high temperature (where speed hinders adjustment of directionality and roaming delays reactivity).

Nitric oxide enhanced reduction in a rotating drum biofilter coupled with absorption by FeII(EDTA)

AbstractBACKGROUND: The ongoing emission of nitric oxide (NO) is a serious persistent environmental problem, because it contributes to atmospheric ozone destruction and global warming. A novel and effective system was developed for the complete treatment of NO from flue gases. The system features NO absorption by FeII(EDTA) and biological denitrification in a rotating drum biofilter (RDB).RESULTS: After 100 mg L−1 FeII(EDTA) was added to the nutrient solution, the results show that the NO removal efficiency was improved from 70.56% to 80.15%, the optimal temperature improved from 32.5 °C to 40.5 °C, and the pH improved from 7.5 to 8.0–8.3. A maximum NO removal efficiency of 96.5% was achieved when 500 mg L−1 FeII(EDTA) was used in the nutrient solution.CONCLUSION: This experiment demonstrates that FeII(EDTA) could not only improve the mass transfer efficiency of NO from gas to liquid, but also serve as an electron donor for the biological reduction of NO to N2. The new integrated treatment system seemed to be a promising alternative for the complete treatment of NO from flue gases. © 2012 Society of Chemical Industry

Radiotracer Experiments on Biological Volatilization of Organic Iodine from Coastal Seawaters

Biological volatilization of iodine from seawaters was studied using a radiotracer technique. Seawater samples were incubated aerobically in serum bottles with radioactive iodide tracer (125I), and volatile organic and inorganic iodine were collected with activated charcoal and silver wool trap, respectively. Iodine was volatilized mainly as organic iodine, and inorganic iodine volatilization was not observed. Influence of light intensity on the volatilization was determined, but no significant differences were observed under light (70,000 lux) and dark conditions. The effect of the chemical form of iodine on the volatilization was determined, and the results suggested that volatilization preferentially occurs from iodide (I−) but not from iodate (IO3 −). Volatilization did not occur when the samples were autoclaved or filtered through a 0.22-μm pore size membrane filter. Incubation of the samples with antibiotics caused decreased volatilization. Conversely, enhanced volatilization was observed when the samples were incubated with yeast extract. Fifty-nine marine bacterial strains were then randomly isolated from marine environments, and their iodine-volatilizing capacities were determined. Among these, 19 strains exhibited significant capacities for volatilizing iodine. 16S ribosomal RNA gene comparisons indicated that these bacteria are members of Proteobacteria (α and γ subdivisions) and Cytophaga-Flexibacter-Bacteroides group. One of the strains, strain C-19, volatilized 1 to 2% of total iodine during cultivation, and the gaseous organic iodine was identified as methyl iodide (CH3I). These results suggest that organic iodine volatilization from seawaters occurs biologically, and that marine bacteria participate in the process. Considering that volatile organic iodine emitted from the oceans causes atmospheric ozone destruction, biological iodine volatilization from seawater is of great importance. Our results also contribute to prediction of movement and diffusion of long-lived radioactive iodine (129I) in the environment.

Bacteria mediate methylation of iodine in marine and terrestrial environments.

Methyl iodide (CH(3)I) plays an important role in the natural iodine cycle and participates in atmospheric ozone destruction. However, the main source of this compound in nature is still unclear. Here we report that a wide variety of bacteria including terrestrial and marine bacteria are capable of methylating the environmental level of iodide (0.1 microM). Of the strains tested, Rhizobium sp. strain MRCD 19 was chosen for further analysis, and it was found that the cell extract catalyzed the methylation of iodide with S-adenosyl-L-methionine as the methyl donor. These results strongly indicate that bacteria contribute to iodine transfer from the terrestrial and marine ecosystems into the atmosphere.

Solubility of HBr in H2SO4/H2O and HNO3/H2SO4/H2O Solutions

The solubility of HBr in H2SO4/H2O and HNO3/H2SO4/H2O solutions was determined by measuring the HBr vapor pressure over stirred bulk solutions using tunable diode laser spectrometry. The experimental results for the solubility of HBr in sulfuric acid solutions show good agreement with experimental literature data. However, there is a factor 2−6 discrepancy between experimental and model values. The solubility of HBr in sulfuric acid was parameterized as a function of the H2SO4 concentration and temperature in the range 53−75 wt % H2SO4 and 195−250 K, respectively. The solubility of HBr in ternary HNO3/H2SO4/H2O solutions was determined for the first time. An increase in the solubility was observed on exchanging H2SO4 by HNO3 at constant water weight fraction. This observation is in qualitative agreement with model calculations, however, the observed solubility change was much larger than predicted by the model calculations. The solubility of HBr in ternary solutions was parameterized as a function of both the concentration of HNO3/H2SO4 and the temperature. The relations derived can be used for atmospheric modeling of the influence of heterogeneous HBr reactions on atmospheric ozone destruction.

Antarctic ozone hole is earlier, deeper, wider

This year, the annual massive destruction of atmospheric ozone over Antarctica has begun earlier, extends to lower altitudes, and is spread over a wider geographical area than ever before. The unprecedented intensity of this year's ozone hole likely results from volcanic aerosols exacerbating the ozone destruction that is catalyzed by chlorine from chlorofluorocarbons (CFCs), scientists theorize. Both U.K. and U.S. researchers report from Antarctica that ozone over their research stations began disappearing earlier and is plunging to lower levels than in previous years. In addition, satellite data from the National Aeronautics & Space Administration show the hole's area is the largest on record—almost as vast as the entire North American continent. Since it began appearing each September about a decade ago, the Antarctic ozone hole has reached its maximum extent and depth in early October before breaking up, usually in November. Within the hole, ozone is almost completely destroyed in the stratosphere fro...

Malignant melanoma risk by nativity, place of residence at diagnosis, and age at migration

Although geographic latitude is clearly linked to the risk of cutaneous malignant melanoma, the chronology of this link is unclear. Based on the 4,611 cases of melanoma with known place of nativity diagnosed in 1972-82 among the non-Latino White residents of Los Angeles County (California, United States) of known place of origin, migrants to Los Angeles from higher US latitudes enjoy relative safety from skin melanoma. This relative safety is largely unaffected by the interval since migration, even after decades of residence in Los Angeles. The same relative protection is enjoyed by native residents of more northerly US communities in comparison with co-resident migrants from the southwestern US. While the observed effect of latitude is consistent with the accepted importance of solar radiation as a determinant of melanoma risk, it suggests that early, rather than late or cumulative, exposure is of most importance. This finding does not affirm the belief that protection of adult skin from exposure to the sun will reduce the risk from melanoma. It does suggest that decades must pass before it will be possible to assess the impact on melanoma risk of any increase in ultraviolet radiation delivered to the earth as a result of the destruction of atmospheric ozone.

Destruction of atmospheric ozone?

Destruction of atmospheric ozone?

Destruction of atmospheric ozone at the ocean surface

A procedure is suggested for the evaluation of the reaction constantK of the destruction of atmospheric ozone at the earth's surface. The method is applicable when the ozone profile on one hand, and the wind speed at a fixed level on the other hand, are measured simultaneously; a logarithmic wind profile is assumed. An application of this method to some of the ozone profiles recently published by Tiefenau and Fabian leads toK ∼ 0.1 cm/sec at the surface of the ocean. This value, if confirmed by measurements at other locations, would require an upward revision of current estimates of the global flux of atmospheric ozone into the earth.

Stratospheric sink for chlorofluoromethanes: chlorine atom-catalysed destruction of ozone

Chlorofluoromethanes are being added to the environment in steadily increasing amounts. These compounds are chemically inert and may remain in the atmosphere for 40–150 years, and concentrations can be expected to reach 10 to 30 times present levels. Photodissociation of the Chlorofluoromethanes in the stratosphere produces significant amounts of chlorine atoms, and leads to the destruction of atmospheric ozone.

Photochemical, advective and turbulent effects on the meridional distribution of ozone

A time-dependent study of the formation, distribution and destruction of atmospheric ozone is made for a meridional plane between 15 km and 45 km under the assumption of zonal symmetry. Included are time-effects of photochemistry, advection and turbulence, using presently available information on theoretical and observational data. The attempt is made to investigate the important part played by pure photochemistry, by the various transport processes and by the combination of both.