Ozone Depression Research Articles

Evaporation and Fragmentation of the Electrified Droplets in the Polar Clouds during Spring Season as a Key Mechanism of the Ozone Depression Formation

This study focuses on the role of the charged particles in the formation of the springtime ozone depression in the polar atmosphere. Analysis of experimental data collected in the polar atmosphere indicates that the small charged particles, predominantly ion clusters, can play a key role in the ozone molecules destruction and springtime ozone depression. The formation of these particles increases strongly during the spring season in the process of evaporation and fragmentation of the cloud-charged droplets in the lower stratosphere and upper troposphere. Additionally, small charged particles can also affect the formation and accumulation of chlorine monoxide under cold conditions of the lower stratosphere. At the same time, the chlorine mechanism of ozone destruction cannot completely explain the ozone depression formation, which probably takes place not only inside the polar vortex in the lower stratosphere but outside it also, both at the altitudes of the lower stratosphere and upper troposphere. The assumption that the charged particles play an important role in the process of ozone depression formation was put forward by previous studies, but in this research work, this assumption has been additionally confirmed, which is the springtime growth of ion clusters concentration as a result of the droplet's evaporation and defragmentation in the polar atmosphere is a key mechanism of the ozone depression formation. We simulated the process of evaporation and fragmentation in the case of a 10-micron size droplet, which implies the possible catalytic cycles of ozone destruction with the ion clusters. For the first time, the role of the Earth's magnetic field and the Polar vortex wind in the unipolar charge accumulation on the cloud particles in the lower stratosphere and upper troposphere not only inside the Polar vortex but also outside of it was substantiated. This fact in our point of view can give rise to the large-scale springtime ozone depression, spreading over the midlatitudes, which size is vastly greater than it is commonly supposed.

Experimental measurements and correlation of isothermal vapor-liquid equilibria for HFC-32 + HFO-1234ze (E) and HFC-134a + HFO-1234ze (E) binary systems

Currently, refrigeration industry is facing the challenge of developing new highly efficient alternative refrigerants with zero ozone depression potential (ODP) and global warming potential (GWP) lower than 150. Mixtures, composed of hydrofluoro-olefins (HFOs) with either hydrofluorocarbons (HFCs) or natural refrigerants, are of great interest, because they could meet both thermodynamic and environmental requirements. This work investigated the phase behavior of two low GWP binary refrigerants containing trans-1,3,3,3-tetrafluoropropene (HFO-1234ze (E)) and two HFCs. Isothermal vapor-liquid equilibrium (VLE) data for two binary mixtures of difluoroethane (HFC-32) + HFO-1234ze (E) and 1,1,1,2-Tetrafluoroethane (HFC-134a) + HFO-1234ze (E) were measured by a static-analysis apparatus at four temperatures ranging from (283.15 to 323.14) K. The VLE data of HFC-32 + HFO-1234ze (E) system was compared with literature, and good consistence was obtained. The experimental VLE data were correlated by Peng-Robinson (PR) equation of state (EOS) combined with van der Waals (vdW) mixing rules. The binary interaction parameters of two mixtures were obtained, and correlation deviation was acceptable. Our work provides fundamental thermodynamics properties of new mixed refrigerants which are crucial to evaluate their cycle performance and optimize the design of refrigeration system.

Temperature and ozone anomalies as indicators of volcanic soot in the stratosphere

The role of volcanogenic aerosols in the formation of ozone and temperature anomalies in the tropical stratosphere recorded after the eruption of Mount Pinatubo in June, 1991, is analyzed in the work on the basis of 30-year balloon measurement data series at the Hilo station (Hawaii). Positive temperature and negative ozone deviations in vertical profiles ≥2σ from normal annual are considered as anomalies. The stratospheric anomalies observed in the second half of 1991 agree well with the presence of volcanic ash remaining in the stratosphere for about six months. However, temperature anomalies and stratospheric ozone depression, observed during next 2–3 years, cannot be explained by long-lived sulfuric acid aerosol. A mechanism is suggested for the formation of long-lived volcanic soot particles in the stratosphere due to thermal decomposition of methane in the eruption column, which actively absorb solar radiation and destroy ozone on their surfaces. The largest ozone anomaly observed in the lower stratosphere in the second half of 1992 is explained by the soot deposition rate calculated accounting for the high efficiency of ozone destruction on its surface.

Possible mechanism of ozone depletion on ice crystals in the polar stratosphere

Developed is a new mechanism of photochemical reactions taking account of the dipole interaction between the molecules and the “sharp” inhomogeneities of electrified ice crystals in polar stratospheric clouds. This mechanism enables to explain the ozone depression formation during the winter-spring period in the polar stratosphere.

Analysis of Refrigerants Properties and Alternative

With the question of Ozone Depression Potential and Global Warming Potential popping out day by day, the Freon refrigerant alternative has become one of the current research contents of refrigerant. Based on the given Freon refrigerant R22, R134a and natural refrigerant CO2, the differences of their properties were compared, and the relevant alternative refrigerants conducted an investigation. The results show that the natural refrigerant CO2 instead of Freon refrigerant has good application prospects; it provides basic data to develop new products, which enhance the COP of air conditioner and heat pump.

Characterizations of ozone and related compounds under the influence of maritime and continental winds at a coastal site in the Yangtze Delta, nearby Shanghai

In this study, some distinct characteristics of surface ozone and related compound (NO, NO 2, and CO) levels during maritime winds (MW) and continental winds (CW) at a coastal site in the Yangtze Delta, nearby Shanghai, were presented and discussed. The frequency of MW was higher in spring and summer and lower in autumn and winter. The ozone level during MW was much higher than those during CW in each season, while the primary pollutant levels presented the opposite result. There may be ozone depression processes during CW at the site caused by relatively fresh primary pollutants, which are transported from urban Shanghai. In contrast, pollutants during MW were more aged, so the ozone depression processes were weak and the ozone level was high. Due to the lack of fresh NO, the daily ozone maximum was lagged, and the early morning ozone minimum was obscured during MW. Ozone concentrations during CW presented evident “weekend effect”, while the concentrations during MW showed obvious anti-“weekend effect”. Just like in urban Shanghai, “weekend effect” during CW in the site is mainly associated with “VOCs-limited” and the change of NO 2/NO ratio. The ozone anti-“weekend effect” during MW might be associated with the high NO x concentrations in weekend, which were caused by the recirculation of the pollutants carried over in weekdays from urban areas during CW.

The Chemistry of Drying an Aqueous Solution of Salts

The fate of salts in drying aqueous solution was investigated. In the drying of acidic solutions, weak acid ions and chloride ions combine with protons and evaporate, depending on the proton concentration. In the drying of alkaline solutions, weak acid ions evaporate or remain as salts depending on the ratio of the concentrations of excess nonvolatile cations (the difference between concentrations of nonvolatile cation and nonvolatile anion) to volatile anions defined as DeltaCA. Under neutral and alkaline conditions, the fate of nitrite depends not only on DeltaCA but also on the drying speed. Nitrite is converted to N2, which is formed by reacting nitrite with ammonium (denitrification), NO and NO2, HONO and salts. In urban areas, nitrite and ammonium can appear in high concentrations in dew. HONO in the atmosphere affects the ozone concentration, but dew formation decreases the concentration of HONO. If chemical denitrification occurs, nitrogen species will decrease in the environment, and as a result, the ozone concentration could decrease. Ozone levels show an ozone depression when dew formed, and a Box model simulation showed an ozone depression by decreasing HONO levels.

Oxygen and Hydrogen Isotopic Signatures of Large Atmospheric Ice Conglomerations

Specific studies about the stable isotope composition (18O/16O and D/H) of atmospheric icy conglomerations are still scarce. The present work offers, for the first time, a very detailed analysis of oxygen and hydrogen isotopic signatures of unusually large ice conglomerations, or “megacryometeors”, that fell to the ground in Spain during January 2000. The hydrochemical analysis is based on the bulk isotopic composition and systematic selective sampling (deuterium isotopic mapping) of eleven selected specimens. δ18O and δD (V-SMOW) of all samples fall into the Meteoric Water Line matching well with typical tropospheric values. The distribution of the samples on Craig's line suggests either a variation in condensation temperature and/or different residual fractions of water vapour (Rayleigh processes). Three of the largest megacryometeors exhibited unequivocally distinctive negative values (δ18O = −17.2%0 and δD = −127 %0 V-SMOW), (δ18O = −15.6%0 and δD = −112%0 V-SMOW) and (δ18O = −14.4%0 and δD = −100%0 V-SMOW), suggesting an atmospheric origin typical of the upper troposphere. Theoretical calculations indicate that the vertical trajectory of growth was lower than 3.2 km. During the period in which the fall of megacryometeors occurred, anomalous atmospheric conditions were observed to exist: a substantial lowering of the tropopause with a deep layer of saturated air below, ozone depression and strong wind shear. Moreover, these large ice conglomerations occurred during non-thunderstorm conditions, suggesting an alternative process of ice growth was responsible for their formation.

Relationship between total ozone amounts and stratospheric temperature at Syowa, Antarctica

Using statistical methods, the relationship has been studied between total ozone and 100‐mbar temperatures at Syowa Station, Antarctica (69°S, 40°E), based on data obtained in 1961–1981 and 1982–1988, the time of ozone depletion in Antarctica. Results indicate a strong, positive correlation between total ozone and 100‐mbar stratospheric temperatures during September‐March for all years, but lower ozone values at 100‐mbar stratospheric temperatures colder than about −60°C during the 1982–1988 period. Ozone destruction by heterogeneous photochemical processes is the main cause of ozone depletion over Syowa during the 1980's, with a lesser contribution from a change in air dynamics (heat, ozone, and momentum transport to Antarctica during the austral spring) that increased polar vortex stability, thereby promoting photochemical ozone depression within the vortex.

Microanalysis of ozone depression of motor activity

Ozone, the principal oxidant in photochemical smog, impairs athletic performance and induces complaints of fatigue and lethargy. It also reduces motor activity in rodents. A detailed analysis of this finding was attempted. Eight male Long-Evans rats were housed in cages attached to running wheels located within a 2-m 3 exposure chamber. Each revolution of a wheel closed a switch with the time between switch closures recorded by an attached computer. The rats were exposed for 6-hr periods during the nocturnal phase of their light cycle to ozone concentrations of 0.12, 0.25, 0.50, and 1.0 ppm. Five days or more separated successive exposures. The 3 days preceding an exposure served as control observations. Ozone produced initial decrements in the number of revolutions and a progressively greater decrease with continued exposure. Statistically significant depression took place at 0.12 ppm. Analysis of the individual components of wheel running revealed differential susceptibility to ozone. An increase in the interval between bursts of running was primarily responsible for the decrease in the number of revolutions; this interval was also more sensitive to disruption than either time per revolution or burst length at low concentrations. After termination of exposure to low concentrations of ozone, animals showed increased running. At the higher concentrations, running remained suppressed below control values for several hours. A new multivariate graphical technique, the biplot, is presented as a way to simultaneously display the relationships among many complex variables.

Stratospheric ozone response to a solar proton event: Hemispheric asymmetries

Ozone depression in the polar stratosphere during the energetic solar proton event on 4 August 1972 was observed by the backscattered ultraviolet (BUV) experiment on the Nimbus 4 satellite. Distinct asymmetries in the columnar ozone content, the amount of ozone depressions and their temporal variations above 4 mb level (∼38 km) were observed between the two hemispheres. The ozone destroying solar particles precipitate rather symmetrically into the two polar atmospheres due to the geomagnetic dipole field These asymmetries can be therefore ascribed to the differences mainly in dynamics and partly in the solar illumination and the vertical temperature structure between the summer and the winter polar atmospheres. The polar stratosphere is less disturbed and warmer in the summer hemisphere than the winter hemisphere since the propagation of planetary wave from the troposphere is inhibited by the wind system in the upper troposphere, and the air is heated by the prolonged solar insolation. Correspondingly, the temporal variations of stratospheric ozone depletion and its recovery appear to be smooth functions of time in the (northern) summer hemisphere and the undisturbed ozone amount is slighily, less than that of its counterpart. On the other hand, the tempotal variation of the upper stratospheric ozone in the winter polar atmosphere (southern hemisphere) indicates large amplitudes and irregularities due to the disturbances produced by upward propagating waves which prevail in the polar winter atmosphere. These characteristic differences between the two polar atmospheres are also evident in the vertical distributions of temperature and wind observed by balloons and rocker soundings.

Differential effects of ozone on in vivo nitrate reduction in soybean cultivars. I. Response to exogenous sugars

Two cultivars of soybeans (Glycine max (L.) Merr.) differing widely in their resistance to ozone were exposed to 0.5 μl/ℓ ozone for 2 h in growth chambers. In vivo nitrate reduction was depressed by more than 50% in the primary leaves of Dare, the ozone-sensitive cultivar, but was not significantly altered in Hood, the ozone-resistant cultivar. Sucrose, up to 1.5% (w/v), added to excised seedlings of the Dare cultivar during exposure to ozone eliminated the ozone depression of in vivo nitrate reductase activity and also reduced foliar injury. Addition of two glycolytic intermediates, glyceraldehyde-3-phosphate and fructose-1,6-diphosphate, to the infiltration medium recovered some in vivo nitrate reduction in treated Dare leaves. The levels of extractable nitrate reductase and glyceraldehyde-3-phosphate dehydrogenase in the primary leaves of both cultivars were unaltered by ozone fumigations. These observations led to the conclusion that ozone depression of in vivo nitrate reduction is not due to ozone inactivation of nitrate reductase or of the enzymes coupling nitrate reduction to glycolysis, but may be caused by an inadequate supply of photosynthetic sugars. It was also noted that ozone depression of in vivo nitrate reduction only occurred with treatments which subsequently caused the development of visible foliar injury.

Ozone Alteration of Nitrate Reduction in Soybean

AbstractSoybeans [Glycine max (L.) Merr.] were harvested at various periods after a 2 h exposure to determine the effects of ozone on nitrate reductase and selected metabolites related to nitrate reduction. Ozone initially depressed the concentrations of reducing sugars, amino acids, and nitrate reductase activity. On subsequent days following exposure, amino acid and protein levels were higher than the respective controls while the levels of reducing sugars and nitrate reductase activity returned to control levels. The ozone depression of nitrate reduction was not the result of a direct ozone reaction with the nitrate reductase protein but rather an interference with reactions that supplied the NAD(P)H needed for nitrate reduction.