Partial Ozone Research Articles

Systematic errors of total ozone retrievals using the 9.7‐micron channel Earth radiance

A systematic analysis of the TIROS Operational Vertical Sounder (TOVS) used as a lower stratospheric ozone monitor is realized. The total ozone retrieved from the TOVS radiances appears to be sensitive to the vertical distribution of ozone. This dependency is first studied using radiative transfer calculations. Poor information on ozone above 40 hPa is available and thus a partial ozone column over the atmospheric layer 400–40 hPa is derived. Systematic errors of the total and partial ozone column retrievals are investigated using comparisons with Total Ozone Mapping Spectrometer observations and four‐dimensional ozone fields derived from data assimilation experiments. The latitudinal and seasonal differences over the year 1998 are inside the interval (+35, −35) Dobson Units (DU) for the total ozone column and inside (+15, −15) DU for the partial one. This work, now limited to observations over oceans, has to be extended to other conditions for a better understanding of differences between infrared ozone measurements and ultraviolet ozone measurements.

Ozonation of an azo dye C.I. Remazol Black 5 and toxicological assessment of its oxidation products

The effect of ozonation (20.5 mg l −1) on the degradation processes of an azo dye, Remazol Black 5 (RB5; CI) was studied. Conventional parameters such as chemical oxygen demand (COD), total organic carbon (TOC), pH, conductivity, colour removal, biodegradability (BOD 5/28), and toxic potential of the dye and its degradation products were monitored during the process. The results obtained indicated that ozonation is a highly effective way to remove the colour of a corresponding dye solution. However, a considerable organic load still remained as indicated by high COD and TOC residues. The COD, TOC reductions were about 40% and 25% for 6 h ozonation of 2 g l −1 RB5 aqueous solution. During the ozonation process the rapid decrease of pH and the sharp increase of conductivity indicated the formation of acidic by-products and small fragments and ions which were identified by high performance ion chromatography. The BOD 28 data revealed that first by-products after partial ozonation (10–150 min) of RB5 were more biodegradable than the parent compound and ozonation can enhance the biodegradability of azo dyes. During the first 150 min of total 360 min of oxidation, the formation of first by-products with high toxic potential took place as it could be confirmed by two acute toxicity-screening tests, the bioluminescence test ( Vibrio fischerii) and the neutral red cytotoxicity assay (rat hepatoma cells). The significant enhancement of microbial biodegradability after long-term ozonation could also be seen as a decrease of toxic intermediates in correlation with the ozonation time as indicated in BOD 28 biological degradation test results.

Ozonation application in activated sludge systems for a textile mill effluent

The study investigates the effect of partial ozonation of textile wastewater, both at the inlet (pre-ozonation) and the outlet (post-ozonation) of biological treatment, for the optimization of COD and color removals, both typical polluting parameters associated with the textile industry. Pre-ozonation provides at optimum contact time of 15 minutes 85% color removal, but only 19% COD reduction. Removal of the soluble inert COD fraction remains at 7%, indicating selective preference of ozone for simpler compounds. Post-ozonation is much more effective on the breakdown of refractory organic compounds and on color removal efficiency. Ozonation after biological treatment results in almost complete color removal and a 14% soluble inert COD reduction. The polishing effect of post-ozonation also proves quite attractive from an economical standpoint, involving approximately 50% of the ozone utilization at the same ozone flux rate and contact time, yet providing a lower soluble residual COD level.

The GEOS ozone data assimilation system: Specification of error statistics

AbstractA global three‐dimensional ozone data assimilation system has been developed at the Data Assimilation Office of the NASA Goddard Space Flight Center. The Total Ozone Mapping Spectrometer (TOMS) total ozone data and the Solar Backscatter Ultraviolet/2 (SBUV/2) partial ozone profile observations are assimilated. The assimilation, into an off‐line ozone transport model, is done using the global Physical‐space Statistical Analysis Scheme. This system became operational in December 1999.A detailed description of the statistical analysis scheme and, in particular, of the forecast‐ and observation‐error covariance models is given. A new global anisotropic horizontal forecast‐error correlation model accounts for a varying distribution of observations with latitude. Correlations are largest in the zonal direction in the tropics where data are sparse. Forecast‐error variance is assumed to be proportional to the ozone field. The forecast‐error covariance parameters were determined by maximum‐likelihood estimation. The error covariance models are validated using χ2 statistics.The analysed ozone fields in the winter 1992 are validated against independent observations from ozone sondes and the Halogen Occultation Experiment (HALOE). The difference between the mean HALOE observations and the analysis fields is less than 10% at pressure levels between 70 and 0.2 hPa. The global root‐mean‐square difference between TOMS observed and forecast values is less than 4%. The global root‐mean‐square difference between SBUV observed and analysed ozone between 50 and 3 hPa is less than 15%.

The GEOS ozone data assimilation system: Specification of error statistics

A global three-dimensional ozone data assimilation system has been developed at the Data Assimilation Office of the NASA/Goddard Space Flight Center. The Total Ozone Mapping Spectrometer (TOMS) total ozone and the Solar Backscatter Ultraviolet (SBUV) or (SBUV/2) partial ozone profile observations are assimilated. The assimilation, into an off-line ozone transport model, is done using the global Physical-space Statistical Analysis Scheme (PSAS). This system became operational in December 1999. A detailed description of the statistical analysis scheme, and in particular, the forecast and observation error covariance models is given. A new global anisotropic horizontal forecast error correlation model accounts for a varying distribution of observations with latitude. Correlations are largest in the zonal direction in the tropics where data is sparse. Forecast error variance model is proportional to the ozone field. The forecast error covariance parameters were determined by maximum likelihood estimation. The error covariance models are validated using x squared statistics. The analyzed ozone fields in the winter 1992 are validated against independent observations from ozone sondes and HALOE. There is better than 10% agreement between mean Halogen Occultation Experiment (HALOE) and analysis fields between 70 and 0.2 hPa. The global root-mean-square (RMS) difference between TOMS observed and forecast values is less than 4%. The global RMS difference between SBUV observed and analyzed ozone between 50 and 3 hPa is less than 15%.

Variations in ozone profiles during the period of solar proton events from October 19–31,1989

Ozone deepletion was the main effect revealed up to now after penetration of Solar Cosmic Rays (SCR) in the middle atmosphere. Making use of satellite data (collected from 19 to 31 October1989) to examine the ozone profiles we established: i.) The partial ozone pressure (POP) decreased between 23–25 km, ii.) POP increased between 18–19 km. The study was performed on the base of data about POP and temperature at altitudes 25.5 km, 24.5 km, 23.5 km, 19.5 km, 18.5 km and 11.5 km. The orbits of the satellite covered the belt 30°–90° N and 20°–40° E. Data about high energetic protons were taken from the Solar Geophysical Data (1989). The measurements were carried out with the Neutron Monitor in Kiel, Germany. Seven energy bins were herein used: 4.2–8.7 MeV, 8.7–14.5 MeV, 15–44 MeV, 39–82 MeV, 82–200 MeV, 110–500 MeV, 640–850 MeV.

Effects of increased solar ultraviolet radiation on materials

Synthetic polymers such as plastics, as well as naturally occurring polymer materials such as wood, are extensively used in building construction and other outdoor applications where they are routinely exposed to sunlight. The UV-B content in sunlight is well known to affect adversely the mechanical properties of these materials, limiting their useful life. Presently their outdoor lifetimes depend on the use of photostabilizers in the case of plastics and on protective surface coatings in the case of wood. Any increase in the solar UV-B content due to a partial ozone depletion would therefore tend to decrease the outdoor service life of these materials. It is the synergistic effect of increased UV radiation with other factors such as the temperature that would determine the extent of such reduction in service life. The increased cost associated with such a change would be felt unevenly across the globe. Those developing countries that depend on plastics as a prime material of construction and experience high ambient temperatures are likely to be particularly affected in spite of the relatively small fractional decrease in ozone at those locations. Assessment of the damage to materials, associated with ozone depletion, requires a knowledge of the wavelength dependence as well as the dose-response characteristics of the polymer degradation processes of interest. While the recent literature includes some reliable spectral sensitivity data, little dose-response information has been reported, so it is difficult to make such assessments reliably at the present time. This is particularly true for the naturally occurring materials popularly used in construction applications. To maintain polymers at the same useful lifetime in spite of increased solar UV-B content, the amount of photostabilizers used in the formulations might be increased. This strategy assumes that conventional stabilizers will continue to be effective with the spectrally altered UV-B-enhanced solar radiation. While the present understanding of the degradation chemistry suggests the strategy to have merit, its effectiveness, in an altered solar radiation environment, has not been demonstrated for common polymers. The availability of these data is crucial for reliably estimating the cost of mitigating the increased damage to materials as a result of a possible partial depletion of the ozone layer using this approach.

Combined biological and chemical treatment of highly concentrated residual dyehouse liquors

The combined biological and chemical treatment of highly concentrated reactive azo dye-containing residual dyehouse liquors with recalcitrant compounds was investigated in a sequencing batch reactor (SBR). The plant consists of a batch reactor in which the anoxic and aerobic phases are carried out by sequenced steps. Water-soluble reactive dyes were reductively cleft and decolorized by a facultative anaerobic bacterial mixed culture under anoxic conditions. Complete decolorization was observed up to concentrations of nearly 20 g dye/L without addition of an external auxiliar substrate. Mineralization of the cleavage products occurs with the same bacterial mixed culture in the same reactor under aerobic conditions. The biomass used for the anoxic treatment is grown in this aerobic phase by the use of split flows with readily biodegradable compounds. Because of the recalcitrant toxic character of some remaining substances, further aerobic mineralization was initiated by partial oxidation with ozone. Partial ozonization in a circulated stream with biological post-treatment of the transformed substances led to an increased reaction selectivity, to a better biological degradation and not least to a lower consumption of ozone. Due to this purification procedure involving highly concentrated residual dyehouse liquors a total decolorization and an overvall degradation of nearly 90% in DOC was achieved.

Combined biological and chemical treatment of highly concentrated residual dyehouse liquors

The combined biological and chemical treatment of highly concentrated reactive azo dye-containing residual dyehouse liquors with recalcitrant compounds was investigated in a sequencing batch reactor (SBR). The plant consists of a batch reactor in which the anoxic and aerobic phases are carried out by sequenced steps. Water-soluble reactive dyes were reductively cleft and decolorized by a facultative anaerobic bacterial mixed culture under anoxic conditions. Complete decolonization was observed up to concentrations of nearly 20 g dye/L without addition of an external auxiliar substrate. Mineralization of the cleavage products occurs with the same bacterial mixed culture in the same reactor under aerobic conditions. The biomass used for the anoxic treatment is grown in this aerobic phase by the use of split flows with readily biodegradable compounds. Because of the recalcitrant toxic character of some remaining substances, further aerobic mineralization was initiated by partial oxidation with ozone. Partial ozonization in a circulated stream with biological post-treatment of the transformed substances led to an increased reaction selectivity, to a better biological degradation and not least to a lower consumption of ozone. Due to this purification procedure involving highly concentrated residual dyehouse liquors a total decolonization and an overvall degradation of nearly 90% in DOC was achieved.

Changes of Ozone Content at Middle Latitudes During Forbush Decreases in Cosmic Rays

The variations of total ozone at Alma-Ata (43°N, 76 °E) and ozone profiles obtained by balloon sounding at Tateno (36°N, 140°E), Wallops Island (38°N, 75°W) and Cagliari (39°N, 9°E) in the periods of Forbush decreases (FD) in galactic cosmic rays have been analysed. A decrease of total ozone was observed in the initial stage of the FD and an increase 10–11 days later. The average total deviations calculated using the superposed epoch method for 9 FD events are equal to 30 D. U. in the positive and to −18 D. U. in the negative phase. The changes of average ozone profiles, associated with 26 FD events, are more significant in the lower stratosphere and upper troposphere. The decrease of the partial ozone pressure at a height of 12–15 km is about 30 υmb. These vertical variations of ozone coincide with the average changes of the respective temperature profiles. A cooling, on the average, of 3°C was observed at 12–15 km, and a heating of 4°C below this level.

Influence of ozonation on the mutagenic activity of benzidine in water

In this study, benzidine was treated with ozone to determine the effectiveness of degradation and the genetic properties of ozone byproducts. Several types of ozonation were studied, partial ozonation, ozonation at about 99.9% and total ozonation. Disappearance of parent compounds and appearance of ozone byproducts were measured by high performance liquid chromatography (HPLC) coupled with spectrofluorimetry and UV spectrophotometry. A plate incorporation mutagenicity assay using Salmonella typhimurium strain was used to test the ozone byproducts in presence and in absence of metabolic activation system.

Effects of ozonation on mutagenic activity of polycyclic aromatic hydrocarbons

In this study, four polycyclic aromatic hydrocarbons were tested. Benzo(a)pyrene (B(a)P), Chrysene (CH), 7,12-dimethylbenzo(a)-anthracene (DMBA) and 3-methylcholanthrene (MCA) in hexane were treated with ozone to determine the effectiveness of degradation and to evaluate the genetic properties of ozone byproducts. Two types of ozonation were carried out: partial ozonation and total ozonation. The disappearance of parent compounds and the appearance of ozone byproducts were measured by high performance liquid chromatography (HPLC) coupled with spectrofluorimetry and U.V. spectrophotometry. Plate incorporation mutagenicity assay, using a Salmonella typhimurium strain, was used to test the ozone byproducts with and without metabolic activation.

In situ growth of high temperature superconductor thin films with evaporation techniques using an ozone jet

High-quality YBa/sub 2/Cu/sub 3/O/sub 7/ thin films were grown in situ on various substrates (SrTiO/sub 3/, Al/sub 2/O/sub 3/, and Si) using MBE (molecular beam epitaxy) techniques and an ozone jet. The yttrium and copper are evaporated from electron-gun sources and the barium is evaporated from a Knudsen cell. All sources are controlled by a single mass spectrometer feedback system to obtain the correct fluxes at high partial ozone pressures. During deposition, the partial ozone pressure at the substrate position is estimated to be 10/sup -3/ -10/sup -2/ mbar. The substrate holder temperature is 700 degrees C. The real substrate temperature is estimated to be lower than 650 degrees C. The films are analyzed with R(T), X-ray diffraction, and RBS (Rutherford backscattering) measurements. Scanning electron microscope photographs are taken of the surface. The best film so far is grown on SrTiO/sub 3/ and has a T/sub c.onset/ of 88 K and a T/sub c0/ of 80 K. One 200-nm-thick film grown on bare silicon has a T/sub c.onset/ of 88 K and a T/sub c0/ of 60 K. This film shows negligible superconductor-substrate interactions according to the RBS measurements.

In situ growth of high temperature superconductor thin films with evaporation techniques using an ozone jet

High quality YBa 2Cu 3O 7 thin films are grown in situ on various substrates (SrTiO 3, AI 2O 3, Si) using MBE techniques and an ozone jet. The yttrium and copper are evaporated from electron gun sources and the barium is evaporated from a Knudsen cell. All sources are controlled by a single mass spectrometer feedback system to obtain the correct fluxes at high partial ozone pressures. During deposition the partial ozone pressure at the substrate position is estimated to be 10 −3−10 −2 mbar. The substrate holder temperature is 700 °C. The films are analyzed with R(T), X-ray diffraction and RBS measurements. SEM photographs are taken of the surface. The best film so far is grown on SrTiO 3 and has a T c,onset of 88 K and a T cO of 80 K. One 200 nm thick film grown on bare silicon has a T cset of 88 K and a T cO of 60 K. This film shows negligible superconductor-substrate interactions according to the RBS measurements.

Ozonolysis of olefins, IV. Ozonolysis of polyunsaturated fatty esters in HCl/methanol

Ozonolysis of ethyl 5,8,11,14,17-eicosapentaenoate and ethyl 4,7,10,13,16,19-docosahexaenoate in HCl/methanol gave methyl 3,3-dimethoxypropanoate in about 45% yield. The other C-3 fragments dimethyl malonate and 1,1,3,3-tetramethoxypropane were found only in very low quantities. Partial ozonization of methyl linoleate, methyl linolenate and methyl γ-linolenate in HCl/methanol provided a mixture of all expected saturated, mono- and diunsaturated derivatives. Additionally about 1–7% of the methanol addition products of the monounsaturated derivatives could be detected. The different products were separated and identified by GC/MS. A regioselective ozonization of the double bonds could not be achieved.

First results of regular ozonesondes at Novolazarevskaya Station, 1985

Abstract During the 30th Soviet Antarctic Expedition (1985–86) 66 combined ozonesone/radiosonde releases were made from Novolazarevskaya Station over the period May‐December 1985. The sondes generally reached heights of 30 km. Highest values for partial ozone pressure (up to 150 mPa) were recorded in midwinter (July) at heights of 18–20 km, in association with a zone of intense low temperature (‐85° C). Lowest ozone levels (< 40 mPa) occurred in the Antarctic spring (October‐November) throughout extensive areas of the lower stratosphere (14–20 km). These values represent the lowest values of partial ozone pressure ever recorded from Antarctica.

Statistical characteristics of the vertical ozone distribution in mid-latitudes

The correlation matrix for the vertical ozone distribution and the temperature-ozone cross-correlation matrix, which was calculated from ozone soundings made over Berlin between 1967 and 1970, the statistical structure of the vertical ozone profile (correlation coefficients, average profiles, average standard deviation, relative variability) was derived for the three ozone seasons. The partial ozone pressure does not at all heights follow a normal distribution (e. g. at tropopause level). Generally, the correlation between tropospheric and stratospheric ozone is rather poor. In some layers the highest correlation coefficients, i.e. −0.3 and +0.4, occur in autumn (October to December) and in winter and spring (January to April). The correlation between the ozone amounts of various stratospheric layers is distinct in autumn, less distinct in summer (May to September) and entirely missing from January to April. Conspicuous cross-correlations between temperature and ozone have been found for all three seasons. a) With a negative correlation between tropospheric temperature and middle tropospheric to middle stratospheric ozone (maximum up to −0.8); b) with a rather strong positive correlation between the ozone amount and the temperature in the lower stratosphere (maximum up to +0.84); c) with a positive correlation between the ozone amount of the middle stratosphere and the temperature of the middle stratosphere (maximum up to +0.8). The highest correlation coefficients occur in autumn.

Instrumental study of aldehyde oils and their reaction with selected amines

AbstractUnsaturated aldehyde oils prepared by partial ozonization of soybean oil gave infrared and nuclear magnetic resonance spectra in qualitative accord with the structures expected. Infrared spectra indicated that the unsaturation present was in thetrans form. Reactions of dialdehyde oil with various amines proceeded with surprising ease at room temperatures to give facticelike, crosslinked products.

Omega‐formylalkanoates by ozonization of unsaturated fatty esters

AbstractOzonization of the methyl esters of 11‐eicosenoic, linoleic, erucic and linolenic acids gave a number of different homologous methyl ३‐formylalkanoates. Complete ozonization of the monounsaturated esters formed C11 and C13 compounds with 90% conversion; partial ozonization of the polyunsaturated esters gave C12 and C15 products with maximum conversions at ca. 75% consumption of fatty ester. Thus, methyl linoleate gave 52 and 23% conversions to the 9‐ and 12‐carbon products, and methyl linolenate gave 29, 27 and 19% conversions to the 9‐, 12‐ and 15‐carbon products. Yields of aldehyde or acetal esters in distilled products were 70舑90% in preparative‐scale experiments. Kinetic analysis showed that ozone attack was essentially random. Methanol was used as a participating solvent.

Unsaturated aldehyde oils by the partial ozonization of soybean oil

AbstractAldehyde oils containing an average of one or two aldehyde groups per glyceride molecule were prepared by partial ozonization of soybean oil. Ozonization was carried out in ethyl acetate‐methanol solvent, and reduction of the ozonolysis products was done catalytically with palladium on charcoal in the presence of pyridine. Under these conditions, maximum conversion of unsaturated to carbonyl functionality was achieved without saturation of the unozonized double bonds. The products were oils having three different types of functionality: aldehydic, olefinic, and glyceride ester.