[1] Since 1996, quality assurance experiments of electrochemical concentration cell (ECC) ozonesondes of two different model types (SPC-6A and ENSCI-Z) have been conducted in the environmental simulation facility at the Research Centre Juelich within the framework of the Juelich Ozone Sonde Intercomparison Experiment (JOSIE). The experiments have shown that the performance characteristics of the two ECC-sonde types can be significantly different, even when operated under the same conditions. Particularly above 20 km the ENSCI-Z sonde tends to measure 5–10% more ozone than the SPC-6A sonde. Below 20 km the differences are 5% or less, but appear to show some differences with year of manufacture. There is a significant difference in the ozone readings when sondes of the same type are operated with different cathode sensing solutions. Testing the most commonly used sensing solutions showed that for each ECC-manufacturer type the use of 1.0% KI and full buffer gives 5% larger ozone values compared with the use of 0.5% KI and half buffer, and as much as 10% larger values compared with 2.0% KI and no buffer. For ozone sounding stations performing long term measurements this means that changing the sensing solution type or ECC-sonde type can easily introduce a change of ±5% or more in their records, affecting determination of ozone trends. Standardization of operating procedures for ECC-sondes yields a precision better than ±(3–5)% and an accuracy of about ±(5–10)% up to 30 km altitude.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2006JD007308

Assessment of the performance of ECC‐ozonesondes under quasi‐flight conditions in the environmental simulation chamber: Insights from the Juelich Ozone Sonde Intercomparison Experiment (JOSIE)

Nanoporous gold as non-enzymatic sensor for hydrogen peroxide

Trace quantities of ozone and nitrogen dioxide, 1.5 ppm, catalyzed the rapid oxidation of unsaturated fatty acids. Nitrogen dioxide-catalyzed oxidations were dependent upon the NO2 concentration in the atmosphere. Both thin films and aqueous emulsions of fatty acids are oxidized by NO2 through a mechanism akin to the spontaneous autoxidation in air. Phenolic antioxidants, including vitamin E, retarded the oxidation. Ozone catalyzed a more rapid and complete oxidation than NO2 by a direct attack upon the double bonds of the fatty acid. Phenolic antioxidants are protective only in aqueous emulsions where the oxidation proceeds by peroxidation as well. Oxidation of essential tissue polyunsaturated fatty acids by O3 and NO2 is a likely common mechanism of toxicity.

Oxidation of unsaturated fatty acids by ozone and nitrogen dioxide. A common mechanism of action

[1] On the basis of extensive laboratory and field tests of electrochemical concentration cell (ECC) ozonesondes, a height-dependent artifact in ozone profile measurements was found that is primarily due to side reactions of the phosphate buffers used in the “standard” 1% potassium iodide sensing solution. The influence of the buffers was revealed as a result of new, direct measurements of the ozonesonde pump flow rate efficiency made in an environmental chamber using an oil bubble flowmeter developed at National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL). The new flow rate measurements give pump efficiency correction factors that are 2 and 15% greater at 100 and 5 hPa, respectively, than those used in currently recommended procedures. Profile measurements using ozonesondes with differing ECC sensor solutions, on dual-sonde balloons and experiments in a simulation chamber, show that the impact of the buffers is most pronounced above the ozone partial pressure maximum. The effect is about a 10–15% overmeasurement of ozone at an altitude of 30 km. Careful consideration must be given to the combination of the sensing solution composition and pump efficiency correction if representative ozone profiles are to be obtained from ozonesonde measurements.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2001JD000557

Electrochemical concentration cell (ECC) ozonesonde pump efficiency measurements and tests on the sensitivity to ozone of buffered and unbuffered ECC sensor cathode solutions

Selected organisms with public health significance were placed in a reaction chamber for treatment by ozonation, by ozonation and sonication, by sonication, or by sonication during oxygenation. Vesicular stomatitis virus, encephalomyocarditis virus, GDVII virus, Staphylococcus aureus, Pseudomonas fluorescens, Salmonella typhimurium, enteropathogenic Escherichia coli, Vibrio cholerae, and Shigella flexneri were inactivated by treatment with ozone. When microorganisms were suspended in phosphate-buffered saline, they were inactivated rapidly by treatment with ozone. However, microorganisms suspended in secondary effluent from a wastewater treatment plant required longer contact times with ozone for complete inactivation. Simultaneous treatments by ozonation and sonication reduced the contact time for complete inactivation of microorganisms in secondary effluent. Treatment by sonication alone or sonication and oxygenation did not inactivate microorganisms. Therefore, the simultaneous treatment of microorganisms in secondary effluent with ozone and sonication resulted in a synergistic effect.

Inactivation of Viruses and Bacteria by Ozone, With and Without Sonication

A basic technique of kinetic colorimetry was developed for determining oxidants in mixtures. An appropriate reagent to produce a slowly developed color was added. Components were resolved graphically using a plot of logarithm of undeveloped color (maximum absorbance minus that at given time) vs. reaction time. Iodometric microdeterminations were thus made of liquid dilutions of various oxidants. This technique was applied to study the stoichiometry of iodide reagents with low concentrations of ozone in air. Reactions appeared to involve both hypoiodite and perphosphate. The most satisfactory reagent was 1% potassium iodide in neutral phosphate buffer. Comparisons were made with an independent method found to be specific for ozone in gaseous mixtures, based on converting ozone to nitrogen dioxide by reaction with excess nitric oxide. These methods should be valuable for differentiating natural smog oxidant into its components; the kinetic colorimetry technique should have broad analytical applications in making specific determinations, even if the available reactions are nonspecific.

Iodometric Microdetermination of Organic Oxidants and Ozone. Resolution of Mixtures by Kinetic Colorimetry

(1959). Microdetermination of Ozone in Smog Mixtures: Nitrogen Dioxide Equivalent Method. American Industrial Hygiene Association Journal: Vol. 20, No. 5, pp. 379-386.

Nathan. Gilbert

Papers

Iodometric Microdetermination of Organic Oxidants and Ozone. Resolution of Mixtures by Kinetic Colorimetry

Microdetermination of ozone in smog mixtures: nitrogen dioxide equivalent method.