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International audience; Ozone, PM10 and PM2.5 concentrations over Paris, France and Stockholm, Sweden were modeled at 4 and 1 \unit{km} horizontal resolutions respectively for the present and 2050 periods employing decade-long simulations. We account for large-scale global climate change (RCP-4.5) and fine resolution bottom-up emission projections developed by local experts and quantify their impact on future pollutant concentrations. Moreover, we identify biases related to the implementation of regional scale emission projections over the study areas by comparing modeled pollutant concentrations between the fine and coarse scale simulations. We show that over urban areas with major regional contribution (e.g., the city of Stockholm) the bias due to coarse emission inventory may be significant and lead to policy misclassification. Our results stress the need to better understand the mechanism of bias propagation across the modeling scales in order to design more successful local-scale strategies. We find that the impact of climate change is spatially homogeneous in both regions, implying strong regional influence. The climate benefit for ozone (daily average and maximum) is up to -5 % for Paris and -2 % for Stockholm city. The joined climate benefit on PM2.5 and PM10 in Paris is between -10 and -5 % while for Stockholm we observe mixed trends up to 3 % depending on season and size class. In Stockholm, emission mitigation leads to concentration reductions up to 15 % for daily average and maximum ozone and 20 % for PM and through a sensitivity analysis we show that this response is entirely due to changes in emissions at the regional scale. On the contrary, over the city of Paris (VOC-limited photochemical regime), local mitigation of NOx emissions increases future ozone concentrations due to ozone titration inhibition. This competing trend between the respective roles of emission and climate change, results in an increase in 2050 daily average ozone by 2.5 % in Paris. Climate and not emission change appears to be the most influential factor for maximum ozone concentration over the city of Paris, which may be particularly interesting in a health impact perspective.

The ozone-initiated oxidation of 1,2-dichlorobenzene catalysed by manganese supported on metal oxide (γ-Al2O3 and SiO2) at ambient temperature and pressure conditions is reported in this study. Wet impregnation method was used to synthesise various percentages of Mn loading on γ-Al2O3 and SiO2 supports. The catalysts were characterised by FT-IR, SEM, EDX, TEM, ICP-OES, BET and XRD techniques. All the reactions were conducted in an impinger glass reactor using 25 mL pure 1,2-dichlorobenzene and 0.25 g of the catalysts. The reaction products were characterised by GC–MS and FT-IR for quantitative and qualitative identification of the products. The 2.5, 5, 7.5 and 10 % of Mn impregnated on γ-Al2O3 and SiO2 were found to be more active than γ-Al2O3 and SiO2 supports. The 5 % Mn/SiO2 catalyst was found to be the most active catalyst in the ozonation reaction of 1,2-dichlorobenzene with a percentage conversion of 44 % and percentage selectivity of 88 % towards the main product mucochloric acid. Whereas, 5 % Mn/γ-Al2O3 catalyst resulted in the percentage conversion of 40 % and percentage selectivity of 86 % towards the main product mucochloric acid. The activity of the catalysts is attributed to manganese loaded on γ-Al2O3 and SiO2 supports.

Ozone pollution and high temperatures have adverse health impacts that can be amplified by the combined effects of ozone and temperature. Moreover, changes in weather patterns are expected to alter ozone pollution episodes and temperature extremes. In particular, atmospheric blocking is a high-impact, large-scale phenomenon at mid-high latitudes that has been associated with temperature extremes. This study examines the impact of atmospheric blocking on the ozone and temperature dependence among measurement stations over Europe during the period 1999–2015. We use a copula-based method to model the dependence between the two variables under blocking and non-blocking conditions. This approach allows us to examine the impact of blocks on the joint probability distribution. Our results showed that blocks lead to increasing strength in the upper tail dependence of ozone and temperature extremes (> 95th percentile) in north-west and central Europe (e.g. the UK, Belgium, Netherlands, Luxembourg, Germany and the north-west of France). The analysis of the probability hazard scenarios revealed that blocks generally enhance the probability of compound ozone and temperature events by 20 % in a large number of stations over central Europe. The probability of ozone or temperature exceedances increases 30 % (on average) under the presence of atmospheric blocking. Furthermore, we found that, in a number of stations over north-western Europe, atmospheric blocking increases the probability of ozone exceedances by 30 % given high temperatures. Our results point out the strong influence of atmospheric blocking on the compounding effect of ozone and temperature events, suggesting that blocks might be considered a relevant predicting factor when assessing the risks of ozone-heat-related health effects.

New particle formation (NPF) events are an increasingly interesting topic in air quality and climate science. In this study, the particle number size distributions, and the frequency of NPF events over Hefei were investigated from November 2018 to February 2019. The proportions of the nucleation mode, Aitken mode, and accumulation mode were 24.59%, 53.10%, and 22.30%, respectively, which indicates the presence of abundant ultrafine particles in Hefei. Forty-six NPF events occurred during the observation days, accounting for 41.82% of the entire observation period. Moreover, the favorable meteorological conditions, potential precursor gases, and PM2.5 range of the NPF events were analyzed. Compared to non-NPF days, the NPF events preferentially occurred on days with lower relative humidity, higher wind speeds, and higher temperatures. When the PM2.5 was 15–20, 70–80, and 105–115 μg/m3, the frequency of the NPF events was higher. Nucleation mode particles were positively related to atmospheric oxidation indicated by ozone when PM2.5 ranged from 15 to 20 μg/m3, and related to gaseous precursors like SO2 and NO2 when PM2.5 was located at 70-80 and 105–115 μg/m3. On pollution days, NPF events did not directly contribute to the increase in the PM2.5 in the daytime, however, NPF events would occur during the night and the growth of particulate matter contributes to the nighttime PM2.5 contents. This could lead to pollution that lasted into the next day. These findings are significant to the improvement of our understanding of the effects of aerosols on air quality.

The assimilation of carbon by terrestrial vegetation via photosynthesis, or gross primary productivity (GPP), is a vital part of the carbon cycle. This process may be hampered locally by drought stress on vegetation. In a warming climate with droughts occurring more frequently, quantifying the associated deficit in carbon uptake, as attempted in this study, becomes crucial for refined regional greenhouse gas budgets. These are needed, for example, in assessing CO2 mitigation strategies involving forestation or avoidance of land-use change. In summer 2018, a drought paired with temperatures above average prevailed on the British Iles and most other parts of transalpine Europe. Using satellite images of solar-induced chlorophyll fluorescence (SIF) from the Global Ozone Monitoring Experiment-2 (GOME-2) and GOSIF data, which is based on satellite images from the Orbiting Carbon Observatory 2 (OCO-2), a GPP deficit of −98 ± 19 gC m−2 between June and September 2018 and −139 ± 25 gC m−2 for the whole year 2018 was retrieved for the British Iles. The latter corresponds to ~44 TgC, or 44% of the mass of carbon released by anthropogenic CO2 emissions 2018 in the United Kingdom.

To ensure the safety of drinking water, ozone (O3) has been extensively applied in drinking water treatment plants to further remove natural organic matter (NOM). However, the surface water and groundwater near the coastal areas often contain high concentrations of bromide ion (Br−). Considering the risk of bromate (BrO3−) formation in ozonation of the sand-filtered water, the inhibitory efficiencies of hydrogen peroxide (H2O2) and ammonia (NH3) on BrO3− formation during ozonation process were compared. The addition of H2O2 effectively inhibited BrO3− formation at an initial Br− concentration amended to 350 µg/L. The inhibition efficiencies reached 59.6 and 100% when the mass ratio of H2O2/O3 was 0.25 and > 0.5, respectively. The UV254 and total organic carbon (TOC) also decreased after adding H2O2, while the formation potential of trihalomethanes (THMsFP) increased especially in subsequent chlorination process at a low dose of H2O2. To control the formation of both BrO3− and THMs, a relatively large dose of O3 and a high ratio of H2O2/O3were generally needed. NH3 addition inhibited BrO3− formation when the background ammonia nitrogen (NH3 N) concentration was low. There was no significant correlation between BrO3− inhibition efficiency and NH3 dose, and a small amount of NH3 N (0.2 mg/L) could obviously inhibit BrO3− formation. The oxidation of NOM seemed unaffected by NH3 addition, and the structure of NOM reflected by synchronous fluorescence (SF) scanning remained almost unchanged before and after adding NH3. Considering the formation of BrO3− and THMs, the optimal dose of NH3 was suggested to be 0.5 mg/L.

The flow and tracer transport in an ozone contactor is simulated by using computational fluid dynamics. The standard k- model, RNG k- model, realizable k- model and SST k- model are used to describe turbulence. A step change method is used to simulate the residence time distribution. The residence time and cumulative residence time are compared with laboratory experiments. All turbulence models can capture the feature of the residence time distribution and cumulative residence time distribution. The residence time distribution in the initial period is sensitive to the used turbulence model, which can affect the value of Morrill dispersion index. The standard k- model behaves better among four turbulence models. HIGHLIGHTS RTD in the initial period is sensitive to turbulence models.; MDI is greatly affected by turbulence models.; The standard k-ɛ model behaves better among four turbulence models.

Nitryl chloride (ClNO 2 ) is an important chlorine reservoir in the atmosphere that affects the oxidation of volatile organic compounds (VOCs) and the production of RO x radicals and ozone (O 3 ). This study presents measurements of ClNO 2 and related compounds at urban, polluted rural, and polluted lower tropospheric (mountaintop) sites in the winter of 2017–2018 over the North China Plain (NCP). The nocturnal concentrations of ClNO 2 were lower at the urban and polluted rural sites but higher at the polluted lower tropospheric site. The winter concentrations of ClNO 2 were generally lower than the summer concentrations that were previously observed at these sites, which was due to the lower nitrate radical (NO 3 ) production rate ( P (NO 3) ) and the smaller N 2 O 5 uptake coefficients ( γ (N 2 O 5) ) in winter, despite the higher ratios of dinitrogen pentoxide (N 2 O 5 ) to NO 3 in winter. Significant daytime peaks of ClNO 2 were observed at all the sites during the winter campaigns, with ClNO 2 mixing ratios of up to 1.3 ppbv. Vertical transport of ClNO 2 from the residual layers and prolonged photochemical lifetime of ClNO 2 in winter may explain the elevated daytime concentrations. The daytime-averaged chlorine radical (Cl) production rates ( P (Cl)) from the daytime ClNO 2 were 0.17, 0.11, and 0.12 ppbv h −1 at the polluted rural, urban, and polluted lower tropospheric sites, respectively, which were approximately 3–4 times higher than the campaign-averaged conditions. Box model calculations showed that the Cl atoms liberated during the daytime peaks of ClNO 2 increased the RO x levels by up to 27 %–37 % and increased the daily O 3 productions by up to 13 %–18 %. Our results provide new insights into the ClNO 2 processes in the lower troposphere impacted by fresh and intense anthropogenic emissions and reveal that ClNO 2 can be an important daytime source of Cl radicals under certain conditions in winter.

The reaction of ozone with sea-salt derived bromide is relevant for marine boundary layer atmospheric chemistry. The oxidation of bromide by ozone is enhanced at aqueous interfaces. Ocean surface water and sea spray aerosol are enriched in organic compounds, which may also have a significant effect on this reaction at the interface. Here, we assess the surface propensity of cationic tetrabutylammonium at the aqueous liquid-vapor interface by liquid microjet X-ray photoelectron spectroscopy (XPS) and the effect of this surfactant on ozone uptake to aqueous bromide solutions. The results clearly indicate that the positively charged nitrogen group in tetrabutylammonium (TBA), along with its surface activity, leads to an enhanced interfacial concentration of both bromide and the bromide ozonide reaction intermediate. In parallel, off-line kinetic experiments for the same system demonstrate a strongly enhanced ozone loss rate in the presence of TBA, which is attributed to an enhanced surface reaction rate. We used liquid jet XPS to obtain detailed chemical composition information from the aqueous-solution-vapor interface of mixed aqueous solutions containing bromide or bromide and chloride with and without TBA surfactant. Core level spectra of Br 3d, C 1s, Cl 2p, N 1s, and O 1s were used for this comparison. A model was developed to account for the attenuation of photoelectrons by the carbon-rich layer established by the TBA surfactant. We observed that the interfacial density of bromide is increased by an order of magnitude in solutions with TBA. The salting-out of TBA in the presence of 0.55 M sodium chloride is apparent. The increased interfacial bromide density can be rationalized by the association constants for bromide and chloride to form ion-pairs with TBA. Still, the interfacial reactivity is not increasing simply proportionally with the increasing interfacial bromide concentration in response to the presence of TBA. The steady state concentration of the bromide ozonide intermediate increases by a smaller degree, and the lifetime of the intermediate is 1 order of magnitude longer in the presence of TBA. Thus, the influence of cationic surfactants on the reactivity of bromide depends on the details of the complex environment at the interface. ISSN:2472-3452

Photolysis of oxygenated volatile organic compounds (OVOCs) produces a primary source of free radicals, including OH and inorganic and organic peroxy radicals (HO2 and RO2), consequently increasing photochemical ozone production. The amplification of radical cycling through OVOC photolysis provides an important positive feedback mechanism to accelerate ozone production. The large production of OVOCs near the surface helps promote photochemistry in the whole boundary layer. This amplifier effect is most significant in regions with high nitrogen oxides (NOx) and VOC concentrations such as Wangdu, China. Using a 1-D model with comprehensive observations at Wangdu and the Master Chemical Mechanism (MCM), we find that OVOC photolysis is the largest free-radical source in the boundary layer (46%). The condensed chemistry mechanism we used severely underestimates the OVOC amplifier effect in the boundary layer, resulting in a lower ozone production rate sensitivity to NOx emissions. Due to this underestimation, the model-simulated threshold NOx emission value, below which ozone production decreases with NOx emission decrease, is biased low by 24%. The underestimated OVOC amplifier effect in a condensed mechanism implies a low bias in the current 3-D model-estimated efficacy of NOx emission reduction on controlling ozone in polluted urban and suburban regions of China.

International audience; Grapevine trunk diseases can infect nursery plants at different stages of propagation. Here, we evaluated the efficiency of aqueous ozone against two fungi associated with trunk diseases (Phaeoacremonium minimum and Phaeomoniella chlamydospora). The effect of ozone on the plant growth is also studied. Aqueous ozone completely suppressed spore germination in vitro. In planta fungal development was reduced six weeks post-inoculation. In the nursery, ozone treatment was comparable to the usual chemical treatment. Irrigation with aqueous ozone had no negative effects on plant growth. These anti-fungal properties and the absence of phytotoxicity make ozone a promising alternative for controlling microbial infection in nurseries.

Ozone (O3) plays essential roles in stratosphere and helps reduce the amount of harmful ultraviolet arriving the Earth’s surface. However, O3 is also a strong oxidant and causes troubles to human health in troposphere, especially in the confined space, such as indoor environment. Recently, O3 abatement materials have become research hotspots due to the urgent environmental demands. Catalysis is a facile strategy that can eliminate indoor airborne O3 efficiently and economically. Thus, this review summarizes the recent progresses of O3 decomposition catalysts. The catalysts covered here are categorized as follows: zeolite, metal organic frameworks (MOFs), metal oxides, noble metals. Manganese–based catalysts display higher efficiency and are mainly discussed. Generally, the active sites of O3 decomposition catalysts are described as Lewis acid sites (e.g., zeolite), metal sites (e.g., MOFs), oxygen vacancy sites (e.g., MnO2) in the previous work. In this review, we ascribe all the active sites to unsaturated metal sites and their Lewis acidity. Possible evidence from the experimental and theoretical perspectives are proposed. Furthermore, the strategy to circumvent deactivation caused by peroxides (O22–) accumulation and water molecular competition are also elaborated. Finally, perspective is presented on the challenges and opportunities of exploring existing and new O3 decomposition catalysts.

Atmospheric non-methane hydrocarbons (NMHCs) play an important role in the formation of secondary organic aerosols and ozone. After a multidecadal global decline in atmospheric mole fractions of ethane and propane – the most abundant atmospheric NMHCs – previous work has shown a reversal of this trend with increasing atmospheric abundances from 2009 to 2015 in the Northern Hemisphere. These concentration increases were attributed to the unprecedented growth in oil and natural gas (O&NG) production in North America. Here, we supplement this trend analysis building on the long-term (2008–2010; 2012–2020) high-resolution (∼3 h) record of ambient air C2–C7 NMHCs from in situ measurements at the Greenland Environmental Observatory at Summit station (GEOSummit, 72.58 ∘ N, 38.48 ∘ W; 3210 m above sea level). We confirm previous findings that the ethane mole fraction significantly increased by +69.0 [+47.4, +73.2; 95 % confidence interval] ppt yr−1 from January 2010 to December 2014. Subsequent measurements, however, reveal a significant decrease by −58.4 [−64.1, −48.9] ppt yr−1 from January 2015 to December 2018. A similar reversal is found for propane. The upturn observed after 2019 suggests, however, that the pause in the growth of atmospheric ethane and propane might only have been temporary. Discrete samples collected at other northern hemispheric baseline sites under the umbrella of the NOAA cooperative global air sampling network show a similar decrease in 2015–2018 and suggest a hemispheric pattern. Here, we further discuss the potential contribution of biomass burning and O&NG emissions (the main sources of ethane and propane) and conclude that O&NG activities likely played a role in these recent changes. This study highlights the crucial need for better constrained emission inventories.

Zhengzhou is one of the most haze-polluted cities in Central China with high organic carbon emission, which accounts for 15%-20% of particulate matter (PM2.5) in winter and causes significantly adverse health effects. Volatile organic compounds (VOCs) are the precursors of secondary PM2.5 and O3 formation. An investigation of characteristics, sources and health risks assessment of VOCs was carried out at the urban area of Zhengzhou from 1st to 31st December, 2019. The mean concentrations of total detected VOCs were 48.8 ± 23.0 ppbv. Alkanes (22.0 ± 10.4 ppbv), halocarbons (8.1 ± 3.9 ppbv) and aromatics (6.5 ± 3.9 ppbv) were the predominant VOC species, followed by alkenes (5.1 ± 3.3 ppbv), oxygenated VOCs (3.6 ± 1.8 ppbv), alkyne (3.5 ± 1.9, ppbv) and sulfide (0.5 ± 0.9 ppbv). The Positive Matrix Factorization model was used to identify and apportion VOCs sources. Five major sources of VOCs were identified as vehicular exhaust, industrial processes, combustion, fuel evaporation, and solvent use. The carcinogenic and non-carcinogenic risk values of species were calculated. The carcinogenic and non-carcinogenic risks of almost all air toxics increased during haze days. The total non-carcinogenic risks exceeded the acceptable ranges. Most VOC species posed no non-carcinogenic risk during three haze events. The carcinogenic risks of chloroform, 1,2-dichloroethane, 1,2-dibromoethane, benzyl chloride, hexachloro-1,3-butadiene, benzene and naphthalene were above the acceptable level (1.0 × 10−6) but below the tolerable risk level (1.0 × 10−4). Industrial emission was the major contributor to non-carcinogenic, and solvent use was the major contributor to carcinogenic risks.

Nitrous acid (HONO) is an important precursor to hydroxyl radical (OH) that determines atmospheric oxidative capacity and thus impacts climate and air quality. Wildfire is not only a major direct source of HONO, it also results in highly polluted conditions that favor the heterogeneous formation of HONO from nitrogen oxides (NOx= NO + NO2) and nitrate on both ground and particle surfaces. However, these processes remain poorly constrained. To quantitatively constrain the HONO budget under various fire and/or smoke conditions, we combine a unique dataset of field concentrations and isotopic ratios (15N / 14N and 18O / 16O) of NOx and HONO with an isotopic box model. Here we report the first isotopic evidence of secondary HONO production in near-ground wildfire plumes (over a sample integration time of hours) and the subsequent quantification of the relative importance of each pathway to total HONO production. Most importantly, our results reveal that nitrate photolysis plays a minor role (<5 %) in HONO formation in daytime aged smoke, while NO2-to-HONO heterogeneous conversion contributes 85 %–95 % to total HONO production, followed by OH + NO (5 %–15 %). At nighttime, heterogeneous reduction of NO2 catalyzed by redox active species (e.g., iron oxide and/or quinone) is essential (≥ 75 %) for HONO production in addition to surface NO2 hydrolysis. Additionally, the 18O / 16O of HONO is used for the first time to constrain the NO-to-NO2 oxidation branching ratio between ozone and peroxy radicals. Our approach provides a new and critical way to mechanistically constrain atmospheric chemistry and/or air quality models on a diurnal timescale.

Three oxidants (sodium hypochlorite [NaClO], ozone, and ultraviolet rays) were combined with powdered activated carbon (PAC) and ultrafiltration (UF) for advanced treatment of the secondary effluen...

We analysed the biogenic volatile organic compound (BVOC) emissions from rapeseed leaf litter and their potential to create secondary organic aerosols (SOAs) under three different conditions, i.e., (i) in the presence of UV light irradiation, (ii) in the presence of ozone, and (iii) with both ozone and UV light. These experiments were performed in a controlled atmospheric simulation chamber containing leaf litter samples, where BVOC and aerosol number concentrations were measured for 6 d. Our results show that BVOC emission profiles were affected by UV light irradiation which increased the summed BVOC emissions compared to the experiment with solely O3. Furthermore, the diversity of emitted VOCs from the rapeseed litter also increased in the presence of UV light irradiation. SOA formation was observed when leaf litter was exposed to both UV light and O3, indicating a potential contribution to particle formation or growth at local scales. To our knowledge, this study investigates, for the first time, the effect of UV irradiation and O3 exposure on both VOC emissions and SOA formation for leaf litter samples. A detailed discussion about the processes behind the biological production of the most important VOC is proposed.

The longest ozone column measurement series are based on the Dobson sun spectrophotometers developed in the 1920s by Prof. G. B. W. Dobson​​​​​​​. These ingenious and robustly designed instruments still constitute an important part of the global network presently. However, the Dobson sun spectrophotometer requires manual operation, which has led to the discontinuation of its use at many stations, thus disrupting long-term records of observation. To overcome this problem, MeteoSwiss developed a fully automated version of the Dobson spectrophotometer. The description of the data acquisition and automated control of the instrument is presented here with some technical details. The results of different tests performed regularly to assess the instrument's good working conditions are illustrated and discussed. Compared to manual operation, automation results in a higher number of daily measurements with lower random error and additional housekeeping information to characterize the measuring conditions. The automated Dobson instrument allows for continuous observation of the ozone column with a resolution of ∼ 1 DU under clear-sky conditions.

Depletion of stratospheric ozone in the Southern Hemisphere (SH) during the late twentieth century cooled local air temperature, which resulted in stronger stratospheric westerly winds near 60° S and altered SH surface climate. However, Antarctic ozone has been recovering since around 2001 thanks to the implementation of the Montreal Protocol, which banned production and consumption of ozone-depleting substances. Here we show that the post-2001 increase in ozone has resulted in significant changes to trends in SH temperature and circulation. The trends are generally of opposite sign to those that resulted from stratospheric ozone losses, including a warming of the SH polar lower stratosphere and a weakening of the SH stratospheric polar vortex. Observed post-2001 trends of temperature and circulation in the stratosphere are about 50–75% smaller in magnitude than the trends during the ozone depletion era. The response is broadly consistent with expectations based on modelled depletion-era trends and variability of both ozone and reactive chlorine. The differences in observed stratospheric trends between the recovery and depletion periods are statistically significant (P

The influence of relative humidity (RH) on the condensational growth of organic aerosol particles remains incompletely understood. Herein, the RH dependence was investigated via a series of experiments for α-pinene ozonolysis in a continuously mixed flow chamber in which recurring cycles of particle growth occurred every 7 to 8 h at a given RH. In 5 h, the mean increase in the particle mode diameter was 15 nm at 0% RH and 110 nm at 75% RH. The corresponding particle growth coefficients, representing a combination of the thermodynamic driving force and the kinetic resistance to mass transfer, increased from 0.35 to 2.3 nm2 s-1. The chemical composition, characterized by O:C and H:C atomic ratios of 0.52 and 1.48, respectively, and determined by mass spectrometry, did not depend on RH. The Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) was applied to reproduce the observed size- and RH-dependent particle growth by optimizing the diffusivities Db within the particles of the condensing molecules. The Db values increased from 5 α-1 × 10-16 at 0% RH to 2 α-1 × 10-12 cm-2 s-1 at 75% RH for mass accommodation coefficients α of 0.1 to 1.0, highlighting the importance of particle-phase properties in modeling the growth of atmospheric aerosol particles.

Fire is an important source of ozone (O3) precursors. The formation of surface O3 can cause damage to vegetation and reduce stomatal conductance. Such processes can feed back to inhibit dry deposition and indirectly enhance surface O3. Here, we apply a fully coupled chemistry–vegetation model to estimate the indirect contributions of global fires to surface O3 through O3–vegetation feedback during 2005–2012. Fire emissions directly increase the global annual mean O3 by 1.2 ppbv (5.0 %) with a maximum of 5.9 ppbv (24.4 %) averaged over central Africa by emitting a substantial number of precursors. Considering O3–vegetation feedback, fires additionally increase surface O3 by 0.5 ppbv averaged over the Amazon in October, 0.3 ppbv averaged over southern Asia in April, and 0.2 ppbv averaged over central Africa in April. During extreme O3–vegetation interactions, such a feedback can rise to >0.6 ppbv in these fire-prone areas. Moreover, large ratios of indirect-to-direct fire O3 are found in eastern China (3.7 %) and the eastern US (2.0 %), where the high ambient O3 causes strong O3–vegetation interactions. With the likelihood of increasing fire risks in a warming climate, fires may promote surface O3 through both direct emissions and indirect chemistry–vegetation feedbacks. Such indirect enhancement will cause additional threats to public health and ecosystem productivity.

The evolution of the analytical techniques allowed the detection of pollutants so called contaminants of emerging concern (CEC). Water scarcity is a reality lived by some populations. Thus, water reuse is mandatory to minimize this problematic. This implies that wastewater treatments must be improved. The Advanced Oxidation Processes (AOP) such as photocatalysis and ozonation can be suitable solutions for CECs abatement. Also, TiO2 powder catalyst is an important material in this field. However, its powder form presents a huge obstacle for industrial application, and the solution may be to support this material. This work studies the degradation of a mixture of 3 parabens by photocatalysis, catalytic and photocatalytic ozonation using TiO2 nanotube arrays (NTs). The studied catalysts were produced using electrolyte solutions with different ages, so the nanotubes growth ocurred at 5 (NTs_5) and 20 (NTs_20) anodization cycles. The toxicological assessment for the initial mixture, final samples and along the reaction time was performed using the cress seeds Lepidium sativum and the bacteria Aliivibrio fischeri. The photocatalysis with UVA radiation led to 50 % and 35 % parabens removal for NTs_5 and NTs_20 catalysts. This can be related to the different dimensional characteristics of the nanotubes. Ozone technologies led to total parabens degradation with an improvement when catalytic ozonation was applied. The use of NTs as catalysts in ozonation also reduced the transferred ozone dose (TOD) required for total parabens abatement when compared to single ozonation. The main parabens degradation mechanism seems to be via direct pathway by molecular ozone. Regarding the toxicity assessment, the toxicity did not change significatively, which can be explained by the intermediate’s formation.

Volcanoes emit halogens into the atmosphere that undergo complex chemical cycling in plumes and cause destruction of ozone. We present a case study of the Mount Etna plume in the summer of 2012, when the volcano was passively degassing, using aircraft observations and numerical simulations with a new 3D model “WRF-Chem Volcano” (WCV), incorporating volcanic emissions and multi-phase halogen chemistry. Measurements of SO2 – an indicator of plume intensity – and ozone were made in the plume a few tens of kilometres from Etna, revealing a strong negative correlation between ozone and SO2 levels. From these observations, using SO2 as a tracer species, we estimate a mean in-plume ozone loss rate of 1.3×10−5 molecules of O3 per second per molecule of SO2. This value is similar to observation-based estimates reported very close to Etna's vents, indicating continual ozone loss in the plume up to at least tens of kilometres downwind. The WCV model is run with nested grids to simulate the plume close to the volcano at 1 km resolution. The focus is on the early evolution of passively degassing plumes aged less than 1 h and up to tens of kilometres downwind. The model is able to reproduce the so-called “bromine explosion”: the daytime conversion of HBr into bromine radicals that continuously cycle in the plume. These forms include the radical BrO, a species whose ratio with SO2 is commonly measured in volcanic plumes as an indicator of halogen ozone-destroying chemistry. The species BrO is produced in the ambient-temperature chemistry, with in-plume BrO / SO2 ratios on the order of 10−4 mol/mol, similar to those observed previously in Etna plumes. Wind speed and time of day are identified as non-linear controls on this ratio. Sensitivity simulations confirm the importance of near-vent radical products from high-temperature chemistry in initiating the ambient-temperature plume halogen cycling. Heterogeneous reactions that activate bromine also activate a small fraction of the emitted chlorine; the resulting production of chlorine radical Cl strongly enhances the methane oxidation and hence the formation of formaldehyde (HCHO) in the plume. Modelled rates of ozone depletion are found to be similar to those derived from aircraft observations. Ozone destruction in the model is controlled by the processes that recycle bromine, with about three-quarters of this recycling occurring via reactions between halogen oxide radicals. Through sensitivity simulations, a relationship between the magnitude of halogen emissions and ozone loss is established. Volcanic halogen cycling profoundly impacts the overall plume chemistry in the model, notably hydrogen oxide radicals (HOx), nitrogen oxides (NOx), sulfur, and mercury chemistry. In the model, it depletes HOx within the plume, increasing the lifetime of SO2 and hence slowing sulfate aerosol formation. Halogen chemistry also promotes the conversion of NOx into nitric acid (HNO3). This, along with the displacement of nitrate out of background aerosols in the plume, results in enhanced HNO3 levels and an almost total depletion of NOx in the plume. The halogen–mercury model scheme is simple but includes newly identified photo-reductions of mercury halides. With this set-up, the mercury oxidation is found to be slow and in near-balance with the photo-reduction of the plume. Overall, the model findings demonstrate that halogen chemistry has to be considered for a complete understanding of sulfur, HOx, reactive nitrogen, and mercury chemistry and of the formation of sulfate particles in volcanic plumes.

A compound was observed using airborne proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) measurements in the emission plumes from the Daesan petrochemical facility in South Korea. The compound was detected at m/z 43.018 on the PTR-TOF-MS and was tentatively identified as ketene, a rarely measured reactive volatile organic compound (VOC). Estimated ketene mixing ratios as high as ∼ 50 ppb (parts per billion) were observed in the emission plumes. Emission rates of ketene from the facility were estimated using a horizontal advective flux approach and ranged from 84–316 kg h−1. These emission rates were compared to the emission rates of major known VOCs such as benzene, toluene, and acetaldehyde. Significant correlations (r2 > 0.7) of ketene with methanol, acetaldehyde, benzene, and toluene were observed for the peak emissions, indicating commonality of emission sources. The calculated average ketene OH reactivity for the emission plumes over Daesan ranged from 3.33–7.75 s−1, indicating the importance of the quantification of ketene to address missing OH reactivity in the polluted environment. The calculated average O3 production potential for ketene ranged from 2.98–6.91 ppb h−1. Our study suggests that ketene, or any possible VOC species detected at m/z 43.018, has the potential to significantly influence local photochemistry, and therefore, further studies focusing on the photooxidation and atmospheric fate of ketene through chamber studies are required to improve our current understanding of VOC OH reactivity and, hence, tropospheric O3 production.

In recent years, the sanitization of environments, devices, and objects has become mandatory to improve human and environmental safety, in addition to individual protection and prevention measures. International studies considered ozone one of the most useful and easy sanitization methods for indoor environments, especially hospital environments that require adequate levels of disinfection. The purpose of this work was to evaluate the microclimate influence on sanitizing procedure for indoor settings with ozone, to prevent infections and ensure the safe use of the environments. The concentration of ozone was measured during sanitization treatment and estimation of microorganisms’ survival on the air and different contaminated plates after the sanitization operations were performed. The results demonstrated a significant reduction in the microbial count that always fell below the threshold value in different conditions of distance, temperature, and relative humidity.

International audience; Rising air pollution by surface ozone (O 3) in China has induced extensive efforts to control ozone generation in major urban and industrial areas, yet mechanisms ruling the ozone production and loss are not well understood. In particular, ozone levels are strongly influenced by meteorological factors such as relative humidity, but this has been explored only in local situations, and the effect of relative humidity on ozone levels in warm seasons on a large scale in China is still unknown. Here we studied surface ozone, relative humidity, temperature, and other meteorological variables in 74 major cities in China during 2017-2018, focusing on the warm seasons in seven regions. Results show that ozone levels decrease with increasing relative humidity in all cities, with an average correlation coefficient of − 0.58, ranging from − 0.17 in Zhangjiakou to − 0.84 in Hengshui. At high relative humidity levels, above 75%, average ozone levels ranged from 44.6 to 122.5 μg m −3 , which is lower than Chinese quality threshold of hourly average ozone level of 200 μg m −3. The decreases of ozone with relative humidity were more pronounced at high temperature, above 30 °C, than below 25 °C. The increases of ozone with temperature were more pronounced at low relative humidity, below 40%. Overall, our findings reveal that mechanisms ruling surface ozone levels are similar on a large scale. This is promising to design common methods of climate engineering to protect human health.

We developed incremental reactivity (IR) scales for 116 volatile organic compounds (VOCs) in a Chinese megacity (Guangzhou) and elucidated their application in calculating the ozone (O3) formation potential (OFP) in China. Two sets of model inputs (emission-based and observation-based) were designed to localize the IR scales in Guangzhou using the Master Chemical Mechanism (MCM) box model and were also compared with those of the US. The two inputs differed in how primary pollutant inputs in the model were derived, with one based on emission data and the other based on observed pollutant levels, but the maximum incremental reactivity (MIR) scales derived from them were fairly similar. The IR scales showed a strong dependence on the chemical mechanism (MCM vs. Statewide Air Pollution Research Center), and a higher consistency was found in IR scales between China and the US using a similar chemical mechanism. With a given chemical mechanism, the MIR scale for most VOCs showed a relatively small dependence on environmental conditions. However, when the NOx availability decreased, the IR scales became more sensitive to environmental conditions and the discrepancy between the IR scales obtained from emission-based and observation-based inputs increased, thereby implying the necessity to localize IR scales over mixed-limited or NOx-limited areas. This study provides recommendations for the application of IR scales, which has great significance for VOC control in China and other countries suffering from serious O3 air pollution.

A green analytical method for the determination of Cu and Zn in rice samples was developed. This method was based on an ozone-assisted extraction (OAE) in diluted acid media. A novel closed system was designed for this purpose that allowed four simultaneous sample treatments being safe for the laboratory environment. The method consisted in 0.5 g of the sample, 15 minutes of ozonation, and 3 minutes of centrifugation. The obtained supernatant was ready for Cu and Zn determinations by flame atomic absorption spectrometry. Detection limits were 0.20 and 0.08 mg kg−1 for Cu and Zn, respectively, with a precision (RSD) better than 5% for both elements. A certified reference material of rice flour was analyzed for trueness evaluation, and the mean recoveries (%) were 100.4 (Cu) and 95.9 (Zn). Several commercial rice samples were analyzed using this method, and the results were compared with those obtained using traditional microwave-assisted digestion (MAE). Both methods yielded comparable results. Cu and Zn levels were in accordance with reported values in other regions. The OAE resulted to be simple and economical and with results equivalent with those obtained using traditional sample preparation procedures as MAE with the advantage of being in good agreement with the principles of green analytical chemistry.

The relationship between the dynamics of the atmospheric pollutants and meteorological conditions has been analyzed during the COVID-19 pandemic in Moscow in spring, 2020. The decrease in traffic emissions during the lockdown periods from March 30th until June 8th played an important role in the decrease (up to 70%) of many gaseous species and aerosol PM10 concentrations and in the increase of surface ozone (up to 18%). The analysis of the pollutant concentrations during the lockdown showed much smoother diurnal cycle for most of the species due to the reduced intensity of traffic, especially during rush hours, compared with that before and after the lockdown. The specific meteorological conditions with low temperatures during the lockdown periods as well as the observed smoke air advection have made a considerable contribution to the air quality. After removing the cases with smoke air advection the decrease in concentration of many pollutants was observed, especially in NOx and PM10. The analysis of Pearson partial correlation coefficients with fixed temperature factor has revealed a statistically significant negative correlation between the Yandex self-isolation indices (SII), which can be used as a proxy of traffic intensity, and daily concentrations of all pollutants, except surface ozone, which has a statistically significant positive correlation with SII caused by specific photochemical reactions. In situations with SII>2.5 more favorable conditions for surface ozone generation were observed due to smaller NOx and the higher O3 /NOx ratios at the same ratio of VOC/NOx. In addition, this may also happen, since during the Arctic air advection, which was often observed during the lockdown period, the growth of ozone could be observed due to the downward flux of the ozone-rich air from the higher layers of the atmosphere.

China is confronting increasing ozone (O3) pollution that worsens air quality and public health. Extreme O3 pollution occurs more frequently under special events and unfavorable meteorological conditions. Here we observed significantly elevated maximum daily 8 h average (MDA8) O3 (up to 98 ppb) during the Chinese National Day holiday (CNDH) in 2018 throughout China, with a prominent rise by up to 120 % compared to the previous week. The air quality model shows that increased precursor emissions and regional transport are major contributors to the elevation. In the Pearl River Delta region, the regional transport contributed up to 30 ppb O3 during the CNDH. Simultaneously, aggravated health risk occurs due to high O3, inducing 33 % additional deaths throughout China. Moreover, in tourist cities such as Sanya, daily mortality even increases significantly from 0.4 to 1.6. This is the first comprehensive study to investigate O3 pollution during the CNDH at the national level, aiming to arouse more focus on the O3 holiday impact of the public.

A technical feasibility study was carried out at the wastewater treatment plant (WWTP) Hamm-West in 2018, which included preliminary planning for the improvement of the plant, using different advanced wastewater technologies. The results of the technical feasibility study show that the application of activated carbon or ozone, in combination with an additional filtration system, can not only remove organic micropollutants efficiently but can also significantly improve the quality of other standard parameters in the WWTP effluent. This technical feasibility study, along with seven other studies, is part of the module-based approach the Emschergenossenschaft and Lippeverband (EGLV) is pursuing in order to improve wastewater treatment plants with advanced treatment systems. Finally, the module-based approach can be used to pair the most suitable WWTPs with the best applicable technologies to improve the treatment process in the whole Lippe catchment area. HIGHLIGHTS Advanced wastewater treatment for organic micropollutants.; Module-based approach.; Wastewater and stormwater treatment plants.; Technical feasibility study.; Holistic approach.

New particle formation (NPF) is thought to contribute half of the global cloud condensation nuclei. A better understanding of the NPF at different altitudes can help assess the impact of NPF on cloud formation and corresponding physical properties. However, NPF is not sufficiently understood in the upper mixing layer because previous studies mainly focused on ground-level measurements. In this study, the developments of aerosol size distribution at different altitudes are characterized based on the field measurement conducted in January 2019 in Beijing, China. We find that the partition of nucleation-mode particles in the upper mixing layer is larger than that at the ground, which implies that the nucleation processing is more likely to happen in the upper mixing layer than that at the ground. Results of the radiative transfer model show that the photolysis rates of the nitrogen dioxide and ozone increase with altitude within the mixing layer, which leads to a higher concentration of sulfuric acid in the upper mixing layer than that at the ground. Therefore, the nucleation processing in the upper mixing layer should be stronger than that at the ground, which is consistent with our measurement results. Our study emphasizes the influence of aerosol–radiation interaction on the NPF. These results have the potential to improve our understanding of the source of cloud condensation nuclei on a global scale due to the impacts of aerosol–radiation interaction.

The present study evaluates the efficacy of ozonated water for the removal of pesticide residues in grapes and green bell peppers. Fruit fortified with pesticides (azoxystrobin, chlorothalonil, chlorpyrifos, cypermethrin, hexaconazole and methyl parathion) were subjected to 15 and 30 min aqueous ozone treatment. GC analysis of ozonated fruits showed a 48.67% to 96.95% decrease in pesticide residues of different pesticides. Methyl paraoxon, a toxic degradation product of methyl parathion, was detected in the ozonated water sample. To assess the effect of ozonation on the nutraceutical quality of fruits, the concentrations of eleven polyphenols and ascorbic acid were analyzed. The individual polyphenols showed different trend in 15 and 30 min treatment. Overall, there was an increase in the levels of all the polyphenols in grapes after 30 min ozonation treatment. In peppers, there was a net increase in quercetin, quercetin-3-O-glucoside, rutin and kaempferol in 30 min while other polyphenols were decreased. The ascorbic acid content of both the fruits was decreased by more than 70% upon ozonation. Thus, ozonation treatment was effective in pesticide removal. However, it changed the nutraceutical quality of grapes and green bell peppers.

Our quantitative understanding of natural tropospheric ozone concentrations is limited by the paucity of reliable measurements before the 1980s. We utilize the existing measurements to compare the long-term ozone changes that occurred within the marine boundary layer at northern and southern midlatitudes. Since 1950 ozone concentrations have increased by a factor of 2.1 ± 0.2 in the Northern Hemisphere (NH) and are presently larger than in the Southern Hemisphere (SH), where only a much smaller increase has occurred. These changes are attributed to increased ozone production driven by anthropogenic emissions of photochemical ozone precursors that increased with industrial development. The greater ozone concentrations and increases in the NH are consistent with the predominant location of anthropogenic emission sources in that hemisphere. The available measurements indicate that this interhemispheric gradient was much smaller and was likely reversed in the pre-industrial troposphere with higher concentrations in the SH. Six Earth system model (ESM) simulations indicate similar total NH increases (1.9 with a standard deviation of 0.3), but they occurred more slowly over a longer time period, and the ESMs do not find higher pre-industrial ozone in the SH. Several uncertainties in the ESMs may cause these model–measurement disagreements: the assumed natural nitrogen oxide emissions may be too large, the relatively greater fraction of ozone injected by stratosphere–troposphere exchange to the NH may be overestimated, ozone surface deposition to ocean and land surfaces may not be accurately simulated, and model treatment of emissions of biogenic hydrocarbons and their photochemistry may not be adequate.

We evaluated the SARS-CoV-2-inactivation activity of ozonated glycerol (OG). When a viral solution with 1% fetal bovine serum (FBS) was mixed with test solutions at a ratio of 1:19 and incubated for 20 s, OG with ozone concentrations of over 1000 ppm inactivated ≥ 94.38% of the virus. Extension of the reaction time to 1 h led to the inactivation of ≥ 99.82% of the virus (the viral titer was below the detection limit). Extension to 24 h resulted in concentrations over 200 ppm OG inactivating ≥ 99.87% of the virus (the viral titers were below the detection limit). Next, viral solutions with 1, 20, and 40% FBS were mixed with test solutions at a ratio of 1:19 and incubated for 5 min. Whereas the virucidal activity of 500 ppm OG was very limited in the presence of 1% FBS (79.47% inactivation), it increased in the presence of 20 and 40% FBS (95.13 and 97.95% inactivation, respectively; the viral titers were not below the detection limit). Meanwhile, over 1000 ppm OG inactivated ≥ 99.44% of the virus regardless of the FBS concentration (the viral titers were below the detection limit). Extension of the reaction time to 1 h led to 500 ppm OG inactivating ≥ 99.91 and ≥ 99.95% of the virus with 20 and 40% FBS, respectively (the viral titers were below the detection limit). These results suggested that OG might be useful as a virucidal agent against SARS-CoV-2.

We present an updated fuel-based oil and gas (FOG) inventory with estimates of nitrogen oxide (NOx) emissions from oil and natural gas production in the contiguous US (CONUS). We compare the FOG inventory with aircraft-derived ("top-down") emissions for NOx over footprints that account for ∼25% of US oil and natural gas production. Across CONUS, we find that the bottom-up FOG inventory combined with other anthropogenic emissions is on average within ∼10% of top-down aircraft-derived NOx emissions. We also find good agreement in the trends of NOx from drilling- and production-phase activities, as inferred by satellites and in the bottom-up inventory. Leveraging tracer-tracer relationships derived from aircraft observations, methane (CH4) and non-methane volatile organic compound (NMVOC) emissions have been added to the inventory. Our total CONUS emission estimates for 2015 of oil and natural gas are 0.45 ± 0.14 Tg NOx/yr, 15.2 ± 3.0 Tg CH4/yr, and 5.7 ± 1.7 Tg NMVOC/yr. Compared to the US National Emissions Inventory and Greenhouse Gas Inventory, FOG NOx emissions are ∼40% lower, while inferred CH4 and NMVOC emissions are up to a factor of ∼2 higher. This suggests that NMVOC/NOx emissions from oil and gas basins are ∼3 times higher than current estimates and will likely affect how air quality models represent ozone formation downwind of oil and gas fields.

Tropospheric ozone (O3), as an air pollutant is increasing at an alarming rate in urban areas. The concentration of ozone is affected by precursor pollutants, such as particulate matter (PM10, PM2.5), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon dioxide (CO2), and nitric oxide (NO), and meteorological parameters, such as air temperature (AT), relative humidity (RH), global solar radiation (SR), wind direction (WD), and wind speed (WS) of the area. Ozone is a secondary pollutant and strong oxidizing agent injurious to human health. The present study aimed to identify the most crucial factors that influence ozone formation and to develop an ozone prediction model using artificial neural network with optimal inputs. The data obtained from Limbayat, real-time air pollutants monitoring station of Surat city, have been used to evolve the model, followed by feature selection techniques, namely, sensitivity analysis, Boruta algorithm, and recursive feature elimination algorithm (RFE). Finally, 6/14 influencing parameters have been identified using an attribute selection approach. Interestingly, “hour of the day” was found the most prominent and governing parameter among the 14 parameters after applying various feature selection techniques in the experiments. The result showed that the efficiency of the prediction model was 79.4% when six parameters were used in the machine learning algorithms.

Cuticular hydrocarbons (CHCs) are important, multi-function components of the insect epicuticle. In Drosophila spp., CHCs provide protection from desiccation and serve as semiochemicals for both intra- and interspecific communication. We developed a non-lethal method for the modification of Drosophila CHCs profiles through the exposure of live insects to a high dose of ozone gas (~ 45,000 ppm). Drosophila suzukii that were treated with ozone showed a 1.63–3.10 fold reduction in unsaturated hydrocarbons with these CHCs shown to regenerate over 108 h. Changes in CHCs were correlated with significantly reduced desiccation resistance in both male and female D. suzukii at one h after ozone treatment. Interestingly, individuals treated with ozone showed increased desiccation resistance in comparison to controls at 108 h after ozone treatment. The methodology reported in this paper provides a novel approach to investigate the biosynthesis and functions of CHCs during the lifespan of an insect.

Based on the formaldehyde (HCHO) inversion data of OMI satellite sensor from 2009 to 2019, this paper discusses the spatial and temporal distribution of HCHO column concentration over the Qinghai-Tibet Plateau in the past 11 years and explores the factors affecting the dynamic distribution of atmospheric HCHO column concentration over the Qinghai-Tibet Plateau in combination with meteorological, aerosol, ozone, and other data. The results show that the average concentration of HCHO column in the Qinghai-Tibet Plateau is 8.84 × 1015 molec/cm2 in the past 11 years, which is relatively low, and the annual variation rate of HCHO column is 7.79%, showing a slight upward trend. The seasonal changes show a trend of Autumn < Winter < Spring < Summer. The monthly variation is more obvious than the seasonal variation. The spatial distribution showed a decreasing trend from southeast to northwest. Residual analysis showed that 83.77% of the area was frequently affected by natural factors. Correlation analysis found that the natural factors including precipitation, air temperature, and atmospheric activities for a greater influence on the column experiment the distribution of the concentration of the Qinghai-Tibet Plateau and human factors, such as biomass, the distribution of fossil fuel combustion, and emissions to HCHO, play a promoting role. Through the backward trajectory analysis, it can be seen that the transboundary atmospheric transport activity has a prominent contribution to the distribution of HCHO in the southern region of the Qinghai-Tibet Plateau. Hurst index study found that in the future, the concentration of HCHO column in 53.03% of the Qinghai-Tibet Plateau will decrease, but in some areas, such as the eastern and northern parts of the Qinghai-Tibet Plateau, it will increase.

Surface ozone (O3) pollution during summer (June–August) over eastern China has become more severe in recent years, resulting in a co-occurrence of surface O3 and PM2.5 (particulate matter with aerodynamic diameters ≤ 2.5 µm in the air) pollution. However, the mechanisms regarding how the synoptic weather pattern (SWP) might influence this compound pollution remain unclear. In this study, we applied the T-mode principal component analysis (T-PCA) method to objectively classify the occurrence of four SWPs over eastern China, based on the geopotential heights at 500 hPa during summer (2015–2018). These four SWPs over eastern China were closely related to the western Pacific subtropical high (WPSH), exhibiting significant intra-seasonal and interannual variations. Based on ground-level air quality observations, remarkable spatial and temporal disparities of surface O3 and PM2.5 pollution were also found under the four SWPs. In particular, there were two SWPs that were sensitive to compound pollution (Type 1 and Type 2). Type 1 was characterized by a stable WPSH ridge with its axis at about 22∘ N and the rain belt located south of the Yangtze River Delta (YRD); Type 2 also exhibited WPSH dominance (ridge axis at ∼ 25∘ N) but with the rain belt (over the YRD) at a higher latitude compared to Type 1. In general, SWPs have played an important role as driving factors of surface O3–PM2.5 compound pollution in a regional context. Our findings demonstrate the important role played by SWPs in driving regional surface O3–PM2.5 compound pollution, in addition to the large quantities of emissions, and may also provide insights into the regional co-occurring high levels of both PM2.5 and O3 via the effects of certain meteorological factors.

Conventional antimicrobial therapies are less effective against pythiosis. Therefore, the goal of this study was to characterize the effects of two ozone (O3) presentations on the growth of canine ...

The increasing emission of nitrogen oxides exerts large impacts on vegetation by raising surface ozone (O3) concentrations and enhancing atmospheric nitrogen (N) deposition. We established a free-air O3 concentration elevation and enhanced N deposition system (O3-N-FACE) in Beijing, China, to investigate long-term effects of elevated O3 and N deposition on poplar plantation. Eight square plots with a side length of 16 m were randomly allocated to elevated O3 (E-O3) and ambient air (AA) treatments. Ozone generated by electric discharge in pure oxygen is mixed with clean and dry air, and released from small holes on the tubes installed above the plant canopy at a rate controlled to keep O3 concentration in E-O3 plots by 50% higher than that in AA plots. Each O3 treatment plot consisted of four subplots with a factorial combination of 2 lines of poplar clones and 2 levels of N deposition rate. In enhanced N deposition subplots, we sprayed urea solution on the plantation floor at a rate of 60 kg ha−1 year−1. We hereby present the system performances during the growing seasons of 2018 and 2019: the first 2 years of experiment. The mean daytime O3 concentrations of E-O3 plots were 38% and 31% higher than AA plots in 2018 and 2019, respectively. And, in 2019, the accumulated O3 exposure over 40 ppb (AOT40) in E-O3 plots was 70% higher than that in AA plots. The hourly mean O3 concentrations in E-O3 plots were within 20% of the target for 83% of time on average across the four E-O3 plots. Within the E-O3 plots, spatial distribution of the hourly O3 concentration exhibited the maximum deviation at 24% in 2019. We concluded that performance of this system is better than other similar facilities for trees and suitable for a long-term experiment of enhanced O3 and N.

Iodide-adduct chemical ionization mass spectrometry (I-CIMS) is a widely used technique in the atmospheric chemistry community to detect oxygenated volatile organic compounds (OVOCs) in real time. In this work, we report the occurrence of secondary ion chemistry from interactions between a strong oxygen donor (such as O3 and peracids) and acidic OVOCs (such as carboxylic acids and organic hydroperoxides) in the ion-molecule reaction (IMR) region of I-CIMS. Such interactions can lead to acidic organic molecules (HA or HB) clustering with [IO]- (e.g., [HA + IO]-) and dimer adducts ([A + B + I]-), in addition to the well-known iodide clusters ([HA + I]-). This ion chemistry was probed using common chemical standards as well as the gas-phase oxidation products of α-pinene and isoprene in a flowtube reactor. The results show that secondary ion chemistry can lead to misinterpretations of molecular compositions and distributions of the gas-phase products and an overestimation of the elemental O/C ratio overall. Nevertheless, the varying degrees of signal change in response to the secondary ion chemistry might be a clue to inform OVOCs' functionalities. Specifically, in the α-pinene ozonolysis system, the extents of ion signal reduction in the presence of additional acids in the IMR suggest that C9H14O4 produced in the gas phase is a peracid, rather than the often-assumed pinic acid. Thus, we suggest that the potential application of the secondary ion chemistry to inform organic functionalities is promising, which could help better understand the molecular compositions of gas-phase OVOCs and the reaction mechanisms therein.

Acetaldehyde is one of the important VOC species of O3 precursors in the atmospheric environment. The influences of relative humidity (RH) and initial VOC/NOx ratio (RCN) on the formation of O3 are studied in smog chamber experiments, and the MCM v3.3.1 mechanism of acetaldehyde is modified based on the experimental results. In low-RH conditions (RH = 11.6%±1.1%), the O3 concentration at 6 h increases first and then decreases with the increase of RCN, and the RCN at the inflection point of O3 concentrations is 3.2. In high-RH experiments (RH = 78.8%±1.0%), variation of the O3 concentration at 6 h with RCN is similar to that in low-RH experiments, but the RCN at the inflection point is 2.8. RH has no significant effect on the O3 concentrations under low RCN ( 3). Compared with the experimental results, original MCM v3.3.1 greatly underestimates the O3 concentrations. Addition of both the photolysis process of peroxyacetyl nitrate and the photolysis process of HNO3 on the reactor surface into the original MCM can reduce the difference between the simulated O3 concentrations and the experimental results at 6 h from 24%−35% and 17%−49% to 6%−26% and 10%−42% under low- and high-RH conditions, respectively. The maximum incremental reactivity (MIR) of acetaldehyde simulated with the modified MCM is 4.0 ppb ppb−1 without considering the effect of other VOCs.

Black carbon (BC) reduces the photolysis coefficient by absorbing solar radiation, thereby affecting the concentration of ozone (O3) near the ground. The influence of BC on O3 has thus received much attention. In this study, Mie scattering and the tropospheric Ultraviolet and Visible radiation model are used to analyze the effect of BC optical properties on radiation. Combined with data of O3 precursors in Nanjing in 2014, an EKMA curve is drawn, and the variations in O3 concentration are further investigated using a zero-dimensional box mechanism model (NCAR MM). When O3 precursors are unchanged, radiation and O3 show a highly similar tendency in response to changing BC optical properties (R=0.997). With the increase of modal radius, the attenuation of fresh BC to radiation and O3 first trends upward before decreasing. In the mixing process, the attenuation of BC to radiation and O3 presents an upward tendency with the increase of relative humidity but decreases rapidly before increasing slowly with increasing thickness of coating. In addition, mass concentration is another major factor. When the BC to PM2.5 ratio increases to 5% in Nanjing, the radiation decreases by approximately 0.13%–3.71% while O3 decreases by approximately 8.13%–13.11%. The radiative effect of BC not only reduces O3 concentration but also changes the EKMA curve. Compared with the NOx control area, radiation has a significant influence on the VOCs control area. When aerosol optical depth (AOD) increases by 17.15%, the NOx to VOCs ratio decreases by 8.27%, and part of the original NOx control area is transferred to the VOCs control area.

As Volatile Organic Compounds (VOCs) are one of the precursors of ozone, their distribution and variable concentrations are highly related to local ozone pollution control. In this study, we obtained vertical profiles of VOCs in Shanghai’s Jinshan district on 8 September and 9 September in 2016 to investigate their distribution and impact on local atmospheric oxidation in the near surface layer. Vertical samples were collected from heights between 50 m and 400 m by summa canisters using an unmanned aerial vehicle (UAV). Concentrations of VOCs (VOCs refers to the 52 species measured in this study) varied minimally below 200 m, and decreased by 21.2% from 100 m to 400 m. The concentrations of VOCs above 200 m decreased significantly in comparison to those below 200 m. The proportions of alkanes and aromatics increased from 55.2% and 30.5% to 57.3% and 33.0%, respectively. Additionally, the proportion of alkenes decreased from 13.2% to 8.4%. Toluene and m/p-xylene were the key species in the formation of SOA and ozone. Principal component analysis (PCA) revealed that the VOCs measured in this study mainly originated from industrial emissions.

Objectives Air pollution can lead to many cardiovascular and respiratory diseases, but the impact of air pollution on pulmonary embolism is still uncertain. We conducted a meta-analysis to assess the relationship between air pollution and pulmonary embolism. Content We searched PubMed, EMBASE, Web of Science, and the Cochran Library for citations on air pollutants (carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone and particulate matter) and pulmonary embolism. A total of nine citations met the inclusion criteria. There is no evidence of bias. CO, SO2, PM10 and PM2.5 had no significant effect on the occurrence of pulmonary embolism. NO2 and O3 can increase the risk of pulmonary embolism to a small extent. Summary This meta-analysis suggests that some air pollutants are associated with an increased risk of pulmonary embolism. Outlook Reducing air pollution and improving air quality can effectively reduce the risk of pulmonary embolism.

The properties and stability of ozone in aqueous solutions of various compositions in the рН range of 0–14 were considered. The effect of anions and cations, which are involved in the redox reactions of actinides, on the stability of ozone and its reactivity has been studied. The reactions of О3 with ions of d- and f-elements were analyzed. Depending on the solution composition and рН value, the reaction can occur directly with the O3 molecule (direct mechanism) and/or with short-lived ion-radical products (•OH, HO 2 • / O 2 − • ${\text{HO}}_{2}^{{\bullet}}/{\text{O}}_{2}^{-{\bullet}}$ , H2O2/ HO 2 − ${\text{HO}}_{2}^{-}$ , O 3 − • ${\text{O}}_{3}^{-{\bullet}}$ ) formed upon ozone decomposition in water (indirect mechanism). Ions with inert coordination sphere react with О3 in the outer-sphere fashion with electron transfer. Polyvalent ions with labile coordination spheres are oxidized in acidic medium via О atom transfer, possibly, with intermediate peroxy addition (H2O2, HNO4, H2SO5, etc.). In alkaline medium, О3 is converted to the O 3 − • ${\text{O}}_{3}^{-{\bullet}}$ radical ion, which is the key oxidant for actinides. The results of studies and the mechanisms of reactions of ozone and its intermediates decomposition products with U, Np, Pu, and Am in various oxidation states and with some transition metals (Fe, Mn, Ag, Co, etc.) in aqueous solutions are presented and discussed.

Ozone therapy is established in clinical applications since many decades, such as treatment of infections or herniated discs. However, in-line monitoring of ozone concentrations is challenging and ...

ALTIUS (Atmospheric Limb Tracker for the Investigation of the Upcoming Stratosphere) is the upcoming stratospheric ozone monitoring limb sounder from ESA's Earth Watch programme. Measuring in the ultraviolet–visible–near-infrared (UV–VIS–NIR) spectral regions, ALTIUS will retrieve vertical profiles of ozone, aerosol extinction coefficients, nitrogen dioxide and other trace gases from the upper troposphere to the mesosphere. In order to maximize the geographical coverage, the instrument will observe limb-scattered solar light during daytime (i.e. bright limb observations), solar occultations at the terminator and stellar/lunar/planetary occultations during nighttime. This paper evaluates the constraint of ALTIUS ozone profiles on modelled stratospheric ozone by means of an observing system simulation experiment (OSSE). In this effort, a reference atmosphere has been built and used to generate ALTIUS ozone profiles, along with an instrument simulator. These profiles are then assimilated to provide ozone analyses. A good agreement is found between the analyses and the reference atmosphere in the stratosphere and in the extra-tropical upper troposphere. In the tropical upper troposphere, although providing significant information in the analyses, the assimilation of ozone profiles does not completely eliminate the bias with respect to the reference atmosphere. The impacts of the different modes of observations have also been evaluated, showing that all of them are necessary to constrain ozone during polar winters where solar/stellar occultations are the most important during the polar night and bright limb data are the most important during the development of the ozone hole in the polar spring.