从中国首台紫外-可见光高光谱卫星仪器反演得到的高空间分辨率臭氧廓线

Understanding the vertical distribution of ozone is crucial when assessing both its horizontal and vertical transport,as well as when analyzing the physical and chemical properties of the atmosphere.One of the most effective ways to obtain high spatial resolution ozone profiles is through satellite observations.The Environmental Trace Gases Monitoring Instrument(EMI)deployed on the Gaofen-5 satellite is the first Chinese ultraviolet-visible hyperspectral spectrometer.However,retrieving ozone profiles using backscattered radiance values measured by the EMI is challenging due to unavailable measurement errors and a low signal-to-noise ratio.The algorithm developed for the Tropospheric Monitoring Instrument did not allow us to retrieve 87%of the EMI pixels.Therefore,we developed an algorithm specific to the characteristics of the EMI.The fitting residuals are smaller than 0.3%in most regions.The retrieved ozone profiles were in good agreement with ozonesonde data,with maximum mean biases of 20%at five latitude bands.By applying EMI averaging kernels to the ozonesonde profiles,the integrated stratospheric column ozone and tropospheric column ozone also showed excellent agreement with ozonesonde data,The lower layers(0-7.5 km)of the EMI ozone profiles reflected the seasonal variation in surface ozone derived from the China National Environmental Monitoring Center(CNEMC).However,the upper layers(9.7-16.7 km)of the ozone profiles show different trends,with the ozone peak occurring at an altitude of 9.7-16.7 km in March,2019.A stratospheric intrusion event in central China from August 11 to 15,2019,is captured using the EMI ozone profiles,potential vorticity data,and relative humidity data.The increase in the CNEMC ozone co ncentration showed that downward transport enhanced surface ozone pollution.

Himalayas as a global hot spot of springtime stratospheric intrusions:Insight from isotopic signatures in sulfate aerosols

Downward transport of stratospheric air into the troposphere(identified as stratospheric intrusions)could potentially modify the radiation budget and chemical of the Earth's surface atmosphere.As the highest and largest plateau on earth,the Tibetan Plateau including the Himalayas couples to global climate,and has attracted widespread attention due to rapid warming and cryospheric shrinking.Previous studies recognized strong stratospheric intrusions in the Himalayas but are poorly understood due to limited direct evidences and the complexity of the meteorological dynamics of the third pole.Cosmogenic^(35)S is a radioactive isotope predominately produced in the lower stratosphere and has been demonstrated as a sensitive chemical tracer to detect stratospherically sourced air mass in the planetary boundary layer.Here,we report 6-month(April–September 2018)observation of^(35)S in atmospheric sulfate aerosols(^(35)SO_(4)^(2-))collected from a remote site in the Himalayas to reveal the stratospheric intrusion phenomenon as well as its potential impacts in this region.Throughout the sampling campaign,the^(35)SO_(4)^(2-)concentrations show an average of 1,070±980 atoms/m^(3).In springtime,the average is 1,620±730 atoms/m^(3),significantly higher than the global existing data measured so far.The significant enrichments of^(35)SO_(4)^(2-)measured in this study verified the hypothesis that the Himalayas is a global hot spot of stratospheric intrusions,especially during the springtime as a consequence of its unique geology and atmospheric couplings.In combined with the ancillary evidences,e.g.,oxygen-17 anomaly in sulfate and modeling results,we found that the stratospheric intrusions have a profound impact on the surface ozone concentrations over the study region,and potentially have the ability to constrain how the mechanisms of sulfate oxidation are affected by a change in plateau atmospheric properties and conditions.This study provides new observational constraints on stratospheric intrusions in the Himalayas,which would further provide additional information for a deeper understanding on the environment and climatic changes over the Tibetan Plateau.

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.

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.

Effects of Coagulation and Ozonation Pretreatments on Biochemical Treatment of Fluid Catalytic Cracking Wastewater

Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and denitrification reactions, was used to assess their possible biodegradation. Because of the negative effects of high salt concentration (3%), heavy metals and toxic organic matter on microorganisms’ activities, some techniques consisting of dilution, coagulation and flocculation, and ozonation pretreatments, were gradually tested to evaluate chemical oxygen demand (COD), ammonia-nitrogen (ammonia-N) and total nitrogen (TN) removal rates. In this process of FCC wastewater, starting with university-domesticated sludge, the ammonia-N and TN removal rates were worst. However, when using domesticated SBR’s sludge and operating with five-fold daily diluted influent (thus reducing salt concentration), the ammonia-N removal reached about 57% while the TN removal rate was less than 37% meaning an amelioration of the nitrification process. However, by reducing the dilution factors, these results were inflected after some days of operation, with ammonia-N removal decreasing and TN barely removed meaning a poor nitrification. Even by reducing heavy metals concentration with coagulation/flocculation process, the results never changed. Thereafter, by using ozonation pre-treatment to degrade the detected organic matter of di-tert-butylphenol and certain isoparaffins, COD, ammonia-N and TN removal rates reached 92%, 62% and 61%, respectively. These results showed that the activities of the microorganisms were increased, thus indicating a net denitrification and nitrification reactions improvement.

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.

上海某居民区恶臭污染溯源、臭氧生成潜势及健康风险评估

针对上海某居民区恶臭投诉问题,对恶臭物质来源、特征及其风险评估展开相关研究。利用正定矩阵因子分解(positive matrix factorization,PMF)模型对居民区恶臭点连续监测数据进行来源解析,共识别出3个排放源,分别为餐厨垃圾源(41.24%)、农业源(32.85%)、二次生成和尾气排放混合源(25.91%),确定餐厨垃圾源为居民区恶臭的主要来源。通过分析监测点位间主要致臭物质异味活度值(odor active value,OAV)的相关性,可知居民区受到餐厨垃圾预处理车间和生化车间的恶臭污染为主,全天受影响程度具有间歇式变化特征。通过计算预处理、生化处理和深加工3个车间排气筒的恶臭物质的臭氧生成潜势(ozone formation potential,OFP),可知各物质种类对OFP的贡献率从大到小依次为羰基类(37.46%)、醇类(21.38%)、烯烃类(15.52%)、挥发性脂肪酸类(13.70%)、芳香烃类(4.02%)、含氮化合物(3.90%)、烷烃类(1.77%)、酯类(1.29%)、硫化物(0.95%)、含氯有机物(0.01%),羰基类、醇类、烯烃类、挥发性脂肪酸类为该厂区OFP贡献的代表物质种类。各车间的OFP从高到低依次为预处理车间(27051.82μg/m^(3))、生化车间(7547.51μg/m^(3))、深加工车间(1647.14μg/m^(3)),乙醛、丙烯酸、1-丁烯、甲醛、乙醇、丙烯和苯酚对OFP的贡献率在3个排气筒中均较高,是该餐厨垃圾处理厂区生成臭氧的主要污染物质,并且乙醛对OFP的贡献率最高。敏感点恶臭物质的健康风险评估结果表明,监测期间累计非致癌风险指数与致癌风险指数均超过美国国家环境保护局(U.S.Environmental Protection Agency,U.S.EPA)推荐的安全阈值,主要贡献物质分别为丙烯醛和甲醛。因此,乙醛、丙烯醛和甲醛应作为餐厨垃圾处理厂中恶臭物质的优先监控指标。

Role of Stratospheric Processes in Climate Change: Advances and Challenges

In this review,instead of summarizing all the advances and progress achieved in stratospheric research,the main advances and new developments in stratosphere-troposphere coupling and stratospheric chemistry-climate interactions are summarized,and some outstanding issues and grand challenges are discussed.A consensus has been reached that the stratospheric state is an important source of improving the predictability of the troposphere on sub-seasonal to seasonal(S2S)time scales and beyond.However,applying stratospheric signals in operational S2S forecast models remains a challenge because of model deficiencies and the complexities of the underlying mechanisms of stratosphere-troposphere coupling.Stratospheric chemistry,which controls the magnitude and distribution of many important climate-forcing agents,plays a critical role in global climate change.Convincing evidence has been found that stratospheric ozone depletion and recovery have caused significant tropospheric climate changes,and more recent studies have revealed that stratospheric ozone variations can even exert an impact on SSTs and sea ice.The climatic impacts of stratospheric aerosols and water vapor are also important.Although their quantitative contributions to radiative forcing have been reasonably well quantified,there still exist large uncertainties in their long-term impacts on climate.The advances and new levels of understanding presented in this review suggest that whole-atmosphere interactions need to be considered in future for a better and more thorough understanding of stratosphere-troposphere coupling and its role in climate change.

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).

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.

Degradation of chlorobenzene by non-thermal plasma coupled with catalyst:influence of catalyst,interaction between plasma and catalyst

Non-thermal plasma(NTP)is considered to be a promising technology for the removal of volatile organic compounds;however,its application is limited by low CO_(2) selectivity and undesirable by-products.To overcome these issues,this paper discusses the degradation of chlorobenzene(CB)in systems of NTP coupled with catalysts,and the influence of catalyst locations in the NTP was investigated.In addition,the interaction between plasma and catalyst was also explored.The results indicated that the degradability of CB was remarkably improved through the combination of NTP with catalysts,and the formation of ozone was effectively inhibited.The degradation efficiency increased from 33.9%to 79.6%at 14 kV in the NTPcatalytic system,while the ozone concentration decreased from 437 to 237 mg m^(-3),and the degradation efficiency of in plasma catalysis(IPC)systems was superior to that of the post plasma catalysis system,while the inhibition ability of ozone exhibited an opposing trend.In the IPC system,the degradation efficiency was 87.7%at 14 k V,while the ozone concentration was151 mg m^(-3).Besides,the plasma did not destroy the pore structure and crystal structure of the catalyst,but affected the surface morphology and redox performance of the catalyst.Thus,NTP coupled catalytic system could improve the degradation performance of CB.Furthermore,the plasma discharge characteristics played a major role in the NTP synergistic catalytic degradation of CB.Finally,based on the experiment analysis results,the general reaction mechanism of CB degradation in an IPC reaction system was proposed.

Ground-level ozone(O 3)pollution and its impacts on vegetation:an attribute to Prof.Evgenios Agathokleous

The Journal of Forestry Research(JFR)is pleased to highlight a collection of ten papers published by Prof.Evgenios Agathokleous and colleagues in 2020–2022.In recognition of the current heightened attention into ground-level ozone(O 3)pollution and its impacts on vegetation,this collection addresses eff ects of ozone on plants,methods to counteract plant stress eff ects,and assessment of potential ozone risks.

The Role of Ozone Depletion in the Lack of Cooling in the Antarctic Upper Stratosphere during Austral Winter

Temperature trends in the upper stratosphere are investigated using satellite measurements from Stratospheric Sounding Unit(SSU)outputs and simulations from chemistry-climate models(CCMs)and the Coupled Model Intercomparison Project Phase 6(CMIP6).Observational evidence shows a lack of cooling in the Antarctic,in contrast to strong cooling at other latitudes,during austral winter over 1979-97.Analysis of CCM simulations for a longer period of1961-97 also shows a significant contrast in the upper stratospheric temperature trends between the Antarctic and lower latitudes.Results from two sets of model integrations with fixed ozone-depleting substances(ODSs)and fixed greenhouse gases(GHGs)at their 1960 levels suggest that the ODSs have made a major contribution to the lack of cooling in the Antarctic upper stratosphere.Results from CMIP6 simulations with prescribed GHGs and ozone confirm that changes in the dynamical processes associated with observed ozone depletion are largely responsible for the lack of cooling in the Antarctic upper stratosphere.The lack of cooling is found to be dynamically induced through increased upward wave activity into the upper stratosphere,which is attributed mainly to ODSs forcing.Specifically,the radiative cooling caused by the ozone depletion results in a stronger meridional temperature gradient between middle and high latitudes in the upper stratosphere,allowing more planetary waves propagating upward to warm the Antarctic upper stratosphere.These findings improve our understanding of the chemistry-climate coupling in the southern upper stratosphere.

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.

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.

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.

The dissolution of total suspended solids and treatment strategy of tailwater in a Litopenaeus vannamei recirculating aquaculture system

In recirculating aquaculture systems(RASs),the effective treatment of aquaculture tailwater is essential to maintain the health of the RAS.This study investigated the optimal time and method for tailwater treatment during three periods of the aquaculture of the Litopenaeus vannamei:nursery(0–26 d),middle(27–57 d),and later(57–104 d).The variation of several water parameters during the dissolution of total suspended solid(TSS)in tailwater,applied with the effects of ozone on the microorganism and water quality parameters were investigated.Results showed that the TSS concentrations in tailwater decreased with time,although not significantly(P>0.05),whereas total ammonia nitrogen(TAN),nitrite(NO-2-N),and nitrate(NO_(3)^(-)-N)increased significantly(P<0.05).Therefore,TSS should be removed from the tailwater as early as possible,being most optimal within 4 h.Ozone removed 38.24%–48.95%of TSS,17.78%–90.14%of TAN,and 87.50%–98.90%of NO-2-N after 4 h of treatment.However,it resulted in the significant accumulation of NO_(3)^(-)-N.Moreover,the total number of Vibrio and bacterial counts in aquaculture tailwater was reduced completely by ozone within 4 h.Thus,these results provided technical details and data support for the effective treatment of tailwater from shrimp RAS.

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).