2-D Modeling and Calculations of Stratospheric Ozone and Influences of Convection, Diffusion, and Time

An engineering system approach of 2-D cylindrical model of transient mass balance calculations of ozone and other concerned chemicals along with fourteen photolysis, ozone-generating and ozone-depleting chemical reaction equations was developed, validated, and used for studying the ozone concentrations, distribution and peak of the layer, ozone depletion and total ozone abundance in the stratosphere. The calculated ozone concentrations and profile at both the Equator and a 60˚N location were found to follow closely with the measured data. The calculated average ozone concentration was within 1% of the measured average, and the deviation of ozone profiles was within 14%. The monthly evolution of stratospheric ozone concentrations and distribution above the Equator was studied with results discussed in details. The influences of slow air movement in both altitudinal and radial directions on ozone concentrations and profile in the stratosphere were explored and discussed. Parametric studies of the influences of gas diffusivities of ozone DO3 and active atomic oxygen DO on ozone concentrations and distributions were also studied and delineated. Having both influences through physical diffusion and chemical reactions, the diffusivity (and diffusion) of atomic oxygen DO was found to be more sensitive and important than that of ozone DO3 on ozone concentrations and distribution. The 2-D ozone model present in this paper for stratospheric ozone and its layer and depletion is shown to be robust, convenient, efficient, and executable for analyzing the complex ozone phenomena in the stratosphere. .

Effects of Chlorine and Chlorine Monoxide on Stratospheric Ozone Depletion

This paper presents a system approach of mass balance calculations of ozone and other species under diffusion-convection-reaction processes to study the impacts of major ozone-depleting chemicals, chlorine (Cl) and chlorine monoxide (ClO), and the effect of photolysis on ozone concentrations, ozone depletion, total ozone abundance, and ozone layer along the altitude in the stratosphere. The calculated ozone concentrations and profile of the layer followed a similar trend and were generally in good agreement with the measurements above the tropical area. The calculated peak of the layer was at the same mid-stratosphere at Z = 30 km with a peak concentration and total ozone abundance about 20% higher than the measured peak concentration of 8.0 ppm and total abundance of 399 DU. In the presence of Cl and ClO, the calculated ozone concentrations and total abundance were substantially reduced. Cl generally depleted more uniformly of ozone across the altitude, while ClO reduced substantially the ozone in the upper stratosphere and thus shifted the peak of the layer to a much lower elevation at Z = 14 km. Although both ClO and Cl are active ozone-depleting chemicals, ClO was found to have a more pronounced impact on ozone depletion and distribution than Cl. The possible explanations of these interesting phenomena were discussed and elaborated. The approach and calculations in this paper were shown to be useful in providing an initial insight into the structure and behavior of the complex ozone layer.

Calculations and Sensitivity Analysis of Chlorine-,NO_(x)-,and Bromine-Depleting Cycles of Stratospheric Ozone

This paper presents an engineering system approach using a 2D model of conservation of mass to study the dynamics of ozone and concerned chemical species in the stratosphere.By considering all fourteen photolysis,ozone-generating,and-depleting chemical reactions,the model calculated the transient,spatial changes of ozone under different physical-chemical-radiative conditions.Validation against the measured data demonstrated good accuracy,close match of our model with the observed ozone concentrations at both 20°S and 90°N locations.The deviation in the average concentration was less than 1% and in ozone profiles less than 17%.The impacts of various chlorine-(Cl),nitrogen oxides-(NO_(x)),and bromine-(Br)depleting cycles on ozone concentrations and distribution were investigated.The chlorine catalytic depleting cycle was found to exhibit the most significant impact on ozone dynamics,confirming the key role of chlorine in the problem of ozone depletion.Sensitivity analysis was conducted with levels of 25%,50%,100%,200%,and 400% of the baseline value.The combined cycles(Cl+NO_(x)+Br)showed the most significant influence on ozone behavior.The total ozone abundance above the South Pole could decrease by a small 3%,from 281 DU(Dubson Units)to 273 DU for the 25% level,or by a huge thinning of 60%to 114 DU for the 400% concentration level.When the level of chlorine gases increased beyond 200%,it would cause ozone depletion to a level of ozone hole(below 220 DU).The 2D Ozone Model presented in this paper demonstrates robustness,convenience,efficiency,and executability for analyzing complex ozone phenomena in the stratosphere.

Ozone Sterilizer for Treatment and Health Care

Ozone is a green broad-spectrum bactericidal disinfectant, and a trace amount of ozone in the atmosphere makes many viruses and bacteria lose their biochemical activity and infectivity. Nature produces trace amounts of ozone in the air through lightning to purify the ecological environment. The product of ozone decomposition is oxygen, without secondary pollution. Ozone sterilizer is widely used in the epidemic prevention and control of intensive breeding farms and achieved remarkable results. If the concentration and action time of ozone can be accurately controlled, then ozone can quickly eliminate pathogens, without harming the normal cells in the human body. How to use medical ozone for epidemic prevention, treatment and health care is a subject worthy of serious study, which should arouse the attention of the experts in the field.

Preserving the Ozone Layers: Battling Illegal Trade in Ozone-Depleting Substances

The depletion of the ozone layer, a vital shield protecting the Earth from harmful ultraviolet (UV) radiation, is now a worldwide environmental concern. Human activities, particularly the release of ozone depleting substances (ODS), have led to the thinning of this protective layer over recent decades. Simultaneously, illegal trade has emerged as a global challenge, giving rise to economic issues, losses of tax revenue, heightened criminal activities, health risks, and environmental hazards. The depletion of the ozone layer, a critical shield protecting the Earth from harmful ultraviolet (UV) radiation, has become a global environmental concern. This paper delves into the legal dimensions surrounding ozone-depleting substances (ODS), their impact on the ozone layer, and the subsequent risk of skin cancer. As countries navigate international agreements, domestic regulations, and enforcement mechanisms, the intricate interplay between legal frameworks and the health implications of ozone layer depletion comes to the forefront. The paper highlights particular instances of illegal trade in ozone depleting substances, drawing from data reported by the parties to the Montreal Protocol. Notably, China stands out as a significant source of contraband ODS, with other countries such as Bulgaria, Lithuania, Poland, and France reporting numerous cases. Analyzing these case instances offers insights into the efficacy of legal frameworks and enforcement measures. The paper offers a comprehensive set of recommendations to strengthen global control and enforcement against the illegal trade of ozone depleting substances. These recommendations span diverse aspects such as production monitoring, customs collaboration, mutual verification, cross-border agreements, public-private partnerships, international cooperation, detection equipment, global regulatory standards, resource allocation, public awareness campaigns, alternative substance development, and controlling the trade at its source. By applying these recommendations and enhancing enforcement measures, we aim to protect the ozone layer and create a healthier and safer world for future generations and achieve sustainable development goals.

Study on the spatial and temporal evolutionary characteristics of ozone concentration and the impact of human activities in China in 2019

Ozone(O_(3))pollution has a profound impact on human health,vegetation development,and the ecological environment,making it a critical focus of global academic research.In recent years,O_(3)pollution in China has been on a steady rise,with ozone emerging as the sole conventional pollutant to consistently increase in concentration without any decline.This study conducted a quantitative analysis of O_(3)concentrations across 367 Chinese cities in 2019,examining spatial autocorrelation and local clustering of O_(3)levels,and investigated the diverse relationships between human activity factors and O_(3)concentration.The seasonal fluctuation of O_(3)exhibited the“M-type”pattern,with peak concentrations in winter and the lowest levels in summer.The center of O_(3)pollution migrated southeastward,with the area of highest concentration progressively shifting south along the eastern coast.Moreover,O_(3)concentration showed a strong positive correlation with population density,road freight volume,and industrial emissions,suggesting that human activities,vehicle emissions,and industrial operations are significant contributors to O_(3)production.The results provide comprehensive information on the characteristics,causes,and occurrence mechanism of O_(3)in Chinese cities that can be utilized by global government departments to formulate strategies to prevent and control O_(3)pollution.

Surface ozone in global cities:A synthesis of basic features,exposure risk,and leading meteorological driving factors

Long-term exposure to high surface ozone(O_(3))concentrations,a complex oxidative atmospheric pollutant,can adversely impact human health.Based on O_(3)monitoring data from 261 cities worldwide in 2020,generalized additive model(GAM)and spatial data analysis(SDA)methods were applied in this study to quantitatively evaluate the spatiotemporal distribution of O_(3)concentration,exposure risk,and dominant meteorological factors.Results indicated that over 40%of the cities worldwide were exposed to harmful O_(3)concentration ranges(40-60μg/m^(3)),with most cities distributed in China and India.Moreover,significant seasonal variations in global O_(3)concentrations were observed,presenting as summer(45.6μg/m^(3))>spring(47.3μg/m^(3))>autumn(38.0μg/m^(3))>winter(33.6μg/m^(3)).Exposure analysis revealed that approximately 12.2%of the population in 261 cities were exposed to an environment with high O_(3)concentrations(80-160μg/m^(3)),with about 36.32 million people in major countries.Thus,the persistent increase in high O_(3)levels worldwide is a critical factor contributing to threats to human health.Furthermore,GAM results indicated temperature,relative humidity,and wind speed as primary determinants of O_(3)variability.The synergy of meteorological factors is critical for understanding O_(3)changes.Our findings are important for enforcing robust air quality policies and mitigating public risk.

Effect of Ozone Treatment on Microbiological Properties of Stored Wheat

In this study, ozone gas was applied to samples of durum wheat stored in four experimental groups (durum wheat without any treatment for comparison, durum wheat treated with ozone, purified durum wheat, and purified durum wheat treated with ozone). Two groups were treated with ozone gas at 3 ppm concentration for 1 hour. Groups were then placed in air-tight glass jars and stored for 6 months at variable temperatures between 24.7°C to 34.8°C. Microbiological (total count bacteria, yeast/molds and coliform) and physical properties (moisture, color and ash) evaluated. Ozone application statistically caused a significant reduction in the numbers of bacteria, yeast, molds and coliforms. Ozone application, washing process and storage temperature are the major factors affecting the microbial counts. No significant differences were determined in moisture and ash contents of samples after ozone treatment. The color measurement results showed that color values of wheat samples were affected by ozone treatment, storage and washing.

Forecast Method of Ozone Concentration in Yulin City Based on Meteorological Conditions

Based on the monitoring data of ozone(O 3)concentration,conventional meteorological data and reanalysis products in Yulin City from 2018 to 2019,the weather situation of O 3 pollution was classified through case analysis and mathematical statistics.At 500 hPa,the weather situation was divided into continental high pressure type,subtropical high type and mixed type.At 850 hPa,it was divided into southwest air flow type,east air flow type and south air flow type.The correlation between meteorological element and O 3 concentration were analyzed,and factors with good correlation such as temperature,air pressure and wind speed were selected to establish regression equations.The fitting effect was good,and O 3 concentration could be objectively predicted.

The effect of ozone on pine forests in South-Eastern France from 2017 to 2019

In South-Eastern forests of France,risks linked to the effects of tropospheric ozone(O_(3))are real;its annual impact has been observed specifically near the coastline and in high altitude mountains during the period 2017-2019.In this study,the risk assessment of O_(3)pollutant was carried out using two approaches based on forest response indicators such as O_(3)specific foliar visible injury and by stomatal O_(3)flux.Phytotoxic O_(3)dose values(POD_(0))were obtained by the DO_(3)SE model.The model requires hourly O_(3)concentration for POD_(0)calculation.A modified approach that uses measurements from passive samplers(monthly average O_(3)concentration)was tested for the calculation of POD_(0)and test results showed good agreement with the POD_(0)calculated using hourly O_(3)data.In the model input file,the average O_(3)concentration is used for POD_(0),and this could be useful for POD_(0)calculation when the active monitor is limited.In this study,a flux-based assessment provided better correlation with O_(3)specific leaf injury,which is also species-specific.Foliar visible injury in response to O_(3)indicates that Pinus cembra and Pinus halepensis are more affected and therefore more sensitive than Pinus sylvestris.The POD_(0)and stomatal conductance(Gsto)seem to be induced by environmental factors,primarily rainfall and the soil water potential(fSWP).The correlation between the O_(3)flux metric and environmental variables with forest response indicators by Spearman rank test confirms P.cembra as one of the most sensitive species to O_(3).

Distribution Characteristics of Ozone and the Relationship with Typhoon Processes in the Northwest Pacific Ocean

Based on the vertical ozone reanalysis data and total ozone column data derived from the European Centre for Medium-Range Weather Forecasts,the spatial and temporal distribution characteristics of ozone on each isobaric surface in the troposphere over the Northwest Pacific Ocean were analyzed,and the backward trajectory method was used to track the influence of typhoon on the distribution of ozone.The results show that the updraft near the typhoon center transported the air with low O_(3)content in the lower layer to the upper layer,which reduced O_(3)content in the upper layer and formed a low-value area of O_(3).The variation trend of total ozone column in the regions where typhoons"Megi"and"Fengshen"occurred was analyzed by the case analysis method.It is found that there was a low-value area of total ozone column anomaly near the typhoon center,and there was a certain correlation between typhoon intensity PDI and total ozone column anomaly at the development and maturity stages of typhoons.

Preliminary Investigation of Total Ozone Column and Its Relationship with Atmospheric Variables

This study attempts to investigate the interaction between lower and upper atmosphere, employing daily data of Total Ozone Column (TOC) and atmospheric parameter (cloud cover) over Nigeria from 1998-2012;in order to study the dynamic effect of ozone on climate and vice versa. This is due to the fact that ozone and climate influence each other and the understanding of the dynamic effect of the interconnectivity is still an open research area. Monthly mean daily TOC and cloud cover data were obtained from the Earth Probe Total Ozone Mass Spectroscopy (EPTOMS) and the International Satellite Cloud Climatology Project (ISCCP)-D2 datasets respectively. Bivariate analysis and Mann Kendall trend tests were used in data analysis. MATLAB and ArcGIS software were employed in analyzing the data. Results reveal that TOC increased spatially from the coastal region to the north eastern region of the country. Seasonally, the highest value of TOC was observed at the peak of rainy season when cloud activity is very high, while the lowest value was recorded in dry season. These variations were attributed to rain producing mechanisms and atmospheric phenomena which influence the transport and distribution of ozone. Furthermore, the statistical analysis reveals significant relationship between TOC and low and middle cloud covers in contrast to high cloud cover. This relationship is consistent with previous studies using other atmospheric variables. This study has given scientific insight which is useful in understanding the coupling of the lower and upper atmosphere.

Spatiotemporal variations of ozone exposure and its risks to vegetation and human health in Cyprus:an analysis across a gradient of altitudes

Ground-level ozone(O_(3)) aff ects vegetation and threatens environmental health when levels exceed critical values,above which adverse eff ects are expected.Cyprus is expected to be a hotspot for O_(3)concentrations due to its unique position in the eastern Mediterranean,receiving air masses from Europe,African,and Asian continents,and experiencing a warm Mediterranean climate.In Cyprus,the spatiotemporal features of O_(3) are poorly understood and the potential risks for forest health have not been explored.We evaluated O_(3) and nitrogen oxides(NO and NO 2)at four regional background stations at different altitudes over 2014−2016.O_(3) risks to vegetation and human health were estimated by calculating accumulated O_(3)exposure over a threshold of 40 nmol mol^(−1)(AOT40)and cumulative exposure to mixing ratios above 35 nmol mol^(−1)(SOMO35)indices.The data reveal that mean O_(3)concentrations follow a seasonal pattern,with higher levels in spring(51.8 nmol mol^(−1))and summer(53.2 nmol mol^(−1))and lower levels in autumn(46.9 nmol mol^(−1))and winter(43.3 nmol mol^(−1)).The highest mean O_(3)exposure(59.5 nmol mol^(−1)) in summer occurred at the high elevation station Mt.Troodos(1819 m a.s.l.).Increasing(decreasing)altitudinal gradients were found for O_(3)(NO x),driven by summer–winter diff erences.The diurnal patterns of O_(3) showed little variation.Only at the lowest altitude O_(3) displayed a typical O_(3) diurnal pattern,with hourly diff erences smaller than 15 nmol mol^(−1).Accumulated O_(3) exposures at all stations and in all years exceeded the European Union’s limits for the protection of vegetation,with average values of 3-month(limit:3000 nmol mol^(−1)h)and 6-month(limit:5000 nmol mol^(−1)h)AOT40 for crops and forests of 16,564 and 31,836 nmol mol^(−1)h,respectively.O_(3) exposures were considerably high for human health,with an average SOMO35 value of 7270 nmol mol^(−1) days across stations and years.The results indicate that O_(3) is a major environmental and public health issue in Cyprus,and policies must be adopted to mitigate O_(3) precursor emissions at local and regional scales.

Impact of the Urban Heat Island Effect on Ozone Pollution in Chengdu City,China

With the advancement of urbanization,the urban heat island effect and ozone pollution have become hot issues in urban research.The urban heat island effect can impact ozone conversion,but its mechanism of action is unclear.In this study,the effects of the urban heat island effect on ozone concentration in Chengdu City,China,were investigated by comparing the ozone concentration under different heat island levels with ozone data from March 2020 to February 2021 and the temperature and wind field data of ERA5-Land during the same period.The results showed that:1)regarding the distribution characteristics,the ozone concentration in Chengdu presented a‘high in summer and low in winter’distribution.The ozone concentration in summer(189.54µg/m^(3))was nearly twice that in winter(91.99µg/m^(3)),and the ozone diurnal variation presented a‘single peak and single valley’distribution,with a peak at 16:00.2)For the characteristics of the heat island effect,the heat island intensity in Chengdu was obviously higher in spring than in other seasons,and the diurnal variation showed a‘single peak and single valley’distribution,with the peak and trough values appearing at 9:00 and 17:00,respectively.Spatially,the eastern part of Chengdu was a heat island,while the western and northwestern parts were mostly cold island.3)The correlation analysis between heat island intensity and ozone concentration showed a significant positive correlation but with a 7–8 h time lag.Ambient air temperature was not the main factor affecting ozone concentration.The heat island effect impacts the ozone concentration in two ways:changing the local heat budget to promote ozone generation and forming local urban wind,which promotes ozone diffusion or accumulation and forms different areas of low and high ozone values.

Increasing Surface UV Radiation in the Tropics and Northern Mid-Latitudes due to Ozone Depletion after 2010

Excessive exposure to ultraviolet(UV)radiation harms humans and ecosystems.The level of surface UV radiation had increased due to declines in stratospheric ozone in the late 1970s in response to emissions of chlorofluorocarbons.Following the implementation of the Montreal Protocol,the stratospheric loading of chlorine/bromine peaked in the late 1990s and then decreased;subsequently,stratospheric ozone and surface UV radiation would be expected to recover and decrease,respectively.Here,we show,based on multiple data sources,that the May–September surface UV radiation in the tropics and Northern Hemisphere mid-latitudes has undergone a statistically significant increasing trend[about 60.0 J m^(–2)(10 yr)^(–1)]at the 2σlevel for the period 2010–20,due to the onset of total column ozone(TCO)depletion[about−3.5 DU(10 yr)^(–1)].Further analysis shows that the declines in stratospheric ozone after 2010 could be related to an increase in stratospheric nitrogen oxides due to increasing emissions of the source gas nitrous oxide(N_(2)O).

Modelling,Validation,and Calculations of Stratospheric Ozone Dynamics and Latitudinal Changes

This paper presents an engineering system approach of 2-D cylindrical model of mass balance calculations with convection,diffusion,and all potential photolysis,ozone generating and depleting chemical reactions considered.This model was developed,validated,and tested under different conditions for the stratospheric ozone.The calculated ozone concentrations and profile in the stratosphere at both the Equator and mid-latitudinal location of 40°S were found to exhibit a similar and close profile and peak value of the published measured data.The discrepancy between the calculations and measurements for the average ozone concentration was shown to be less than 1%and the variation of distributions to be less than 19%.The latitudinal changes of ozone concentrations,distribution,and peak of the layer were found to shift from 9.41 ppm at mid-altitude of z=30 km at the Equator,to 7.81 ppm at z=34.5 km at 40°S,to 5.78 ppm at higher altitude z=39 km at the South Pole.The total ozone abundances at strategic latitudes at 0°S,20°S,40°S,60°S,and 90°S,were found to remain stable and not much changed,from 305 DU to 335 DU,except a smaller value of 288 DU at the South Pole.The possible explanations of ozone profile change and peak shifting as affected by solar/UV radiation,latitudinal locations,and ozone-depleting reactions were discussed and elaborated.The 2-D ozone Model presented in this paper is a robust,efficient,executable,and validated model for studying the complex ozone phenomena in the stratosphere.

Calculations of Stratospheric Ozone and Effects of Diffusivity

This paper presents a system approach of mass balance of ozone and other species under diffusion-convection-reaction processes to study the ozone layer along the altitude in the stratosphere. The ozone abundance and general distribution above the tropical area were calculated and compared to the published measured data. The peak ozone layer was found to be 21 mPa at 22 km or 9.7 ppm at 30 km, and the involved competing processes depicting the ozone layer were explained in details. In the entire stratosphere from 10 km to 50 km, the calculated ozone distribution displayed a similar profile and trend to the observational data, with the calculation in ppm slightly above the measurement by 12%. The standard deviation of the differences between calculated and measured data was close to 0.25. A sensitivity study of gas diffusivities of molecular ozone D3 and atomic oxygen D1 on changing the ozone abundance and profile in the stratosphere showed that in the upper two-third of the stratosphere, D1 evidently exhibited a pronounced impact on ozone, as much as 24-fold larger than D3. The mechanism leading to this finding was also elaborated. The approach and calculations in this paper are shown to be useful for providing an initial insight into the structure and behavior of the complex ozone layer.

Ozone pollution threatens bird populations to collapse:an imminent ecological threat?

While bird populations are declining,the factors associated with this decline are unclear.Based on laboratory experiments,air pollution has long been recognized as a factor causing oxidative stress and adversely aff ecting bird health.Recently,studies employing an epidemiological approach have reported signifi cant declines in avian populations in Central Europe and the United States due to air pollution,and ozone in particular.We advocate that urgent actions are needed to mitigate these eff ects,which threaten biodiversity and environmental health,and propose a series of measures which can enlighten the path toward mitigating air pollution eff ects on avian populations.

Improvement in discharge characteristics and energy yield of ozone generation via configuration optimization of a coaxial dielectric barrier discharge reactor

Dielectric barrier discharge (DBD) has been widely employed in ozone generation.However,the technology still exhibits relatively low energy yield (E_(Y)) referring to its theoretical value.In this work,E_(Y)of ozone generation was improved by optimizing the mesh number,electrode length,and dielectric material in a coaxial DBD reactor with two wire mesh electrodes.Meanwhile,the discharge characteristics were investigated to elucidate the effect of reactor configuration on E_(Y).Results showed that the discharge characteristics were improved by increasing the mesh number,electrode length,and relative permittivity.When the mesh number was increased from 40 to 100,an improvement of approximately 48%in E_(Y) was obtained.Additionally,higher E_(Y) values were obtained using corundum as the dielectric material relative to polytetrafluoroethylene and quartz.Ultimately,E_(Y) in the optimal DBD reactor could reach 326.77 g·(k W·h)^(-1).Compared with the reported DBD reactor,the coaxial DBD reactor with the mesh electrode and the dielectric material of corundum could effectively improve E_(Y),which lays a foundation for the design of high-efficiency coaxial DBD reactor.

Kinetics of the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation

In this study,high-gravity intensified heterogeneous catalytic ozonation is utilized for treatment of phenol-containing wastewater,and the kinetics of the direct reaction between ozone and phenol in the presence of excess tertiary butanol(TBA)is investigated.It is revealed that the direct reaction between ozone and phenol in the rotating packed bed(RPB)follows the pseudo-first-order kinetics with a reaction rate constant higher than that in the conventional bubbling reactor(BR).Under different conditions of temperature,initial pH,high-gravity factor,and gaseous ozone concentration,the apparent reaction rate constant varies in the range of 0.0160–0.115 min-1.An empirical power-exponential model is established to characterize the effects of these parameters on the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation.