High Ozone Concentrations Research Articles

Diurnal hourly near-surface ozone concentration derived from geostationary satellite in China

Near-surface O3 is a harmful atmospheric pollutant and a key component of urban photochemical pollution. The availability of satellite ozone concentration products is predominantly restricted to daytime, resulting in a lack of understanding of nighttime ozone pollution (e.g. nocturnal ozone enhancement events). This research leverages 5-km bright temperatures derived from Advanced Himawari Images (AHI) on the Himawari-8 satellite, in conjunction with auxiliary data, to estimate 24-h near-surface O3 concentrations in China at a resolution of 5 km for 2020. The model achieves an average 5-fold cross-validation R2 of 0.92. Comparative analysis with on-site observations reveals that the model has low relative errors between 8:00 and 21:00 LT. The estimated O3 maps depict a consistent 24-h variation pattern, characterized by high and most fluctuating concentrations during the daytime, reaching a peak around 16:00 LT, which is primarily due to the increased photochemical reactions and the O3 accumulation in the mid-afternoon. In the daytime of summer, high surface ozone concentrations are mainly contributed by June. The elevated levels of O3 are predominantly found in central China, particularly in the Beijing-Tianjin-Hebei region and Inner Mongolia. It can also be seen that although the highest average daytime surface O3 concentration occurs in summer, the highest nighttime concentration is observed in spring, which may be attributed to the frequent occurrence of horizontal transport and vertical mixing of O3. This study holds promise in providing comprehensive round-the-clock surface O3 data across China, thereby enhancing our understanding of diurnal ground-level O3 variations.

Ozonated Aloe Vera: A Novel Topical Agent for Improved Wound Healing and Reduced Scar Formation on TGF-β Modulation Invivo Study

Background: Chronic wounds and impaired wound healing represent a significant healthcare burden. Aloe vera has been recognized for its therapeutic potential in wound healing, and the combination with ozone, and ozonated aloe vera, may offer synergistic effects. This study investigated the effects of ozonated aloe vera oil on wound healing and scar formation, focusing on TGF-β modulation in a rat model. Methods: Full-thickness skin defects were created on 50 Sprague Dawley rats, which were randomly divided into five groups: (1) control (untreated), (2) aloe vera oil, (3) ozonated aloe vera oil (600 mg/ml ozone), (4) ozonated aloe vera oil (1200 mg/ml ozone), and (5) ozonated aloe vera oil (1800 mg/ml ozone). Wound healing was assessed macroscopically by measuring wound area reduction and microscopically by evaluating TGF-β expression through immunohistochemical staining on days 3, 7, and 14. Results: Ozonated aloe vera oil significantly accelerated wound healing compared to the control and aloe vera oil alone groups (p < 0.05). The highest ozone concentration (1800 mg/ml) showed the most rapid wound closure and the lowest TGF-β expression on day 14 (p < 0.05). Histological analysis revealed enhanced collagen organization and reduced inflammatory cell infiltration in ozonated aloe vera oil treated wounds. Conclusion: Ozonated aloe vera oil effectively promotes wound healing and reduces scar formation in a rat model. The modulation of TGF-β signaling plays a crucial role in these effects. Ozonated aloe vera oil holds promise as a novel topical agent for improved wound management.

Predictive Model for O3 in Shanghai Based on the KZ Filtering Technique and LSTM

In this study, a Kolmogorov-Zurbenko （KZ） filter was proposed to decompose the original ozone （O3） sequence to improve the accuracy of ozone long-term series prediction and select relevant meteorological features. Furthermore, the enhanced maximal minimal redundancy （mRMR） feature selection technique was combined with the support vector regression （SVR） approach to select the most illuminating meteorological features. Subsequently, from May to August 2023, during high ozone concentration periods, a long short-term memory network （LSTM） was utilized to assess and predict high ozone concentration periods at the monitoring stations of Jingan （urban area）, Pudong-Chuansha （suburban area）, and Dianshan Lake （suburban area） in Shanghai. The results showed that pressure, temperature, humidity, boundary layer height, and wind direction were the best combinations of O3 baseline and short-term components, as chosen by feature screening. The R2 values for Jingan Station, Pudong-Chuansha Station, and Dianshan Lake Station were 0.86, 0.83, and 0.85, respectively. The RMSE values were 18.26, 18.74, and 20.02 μg·m-3, respectively. These findings suggest that decomposing the original O3 sequence improved the prediction accuracy of ozone concentrations. Additionally, as indicated by the R2 and RMSE values found for every monitoring station, feature screening preserved the model's predictive performance.

A prospective study on the cardiorespiratory effects of air pollution among residents of the Tibetan Plateau

The Tibetan Plateau is characterized by high ozone concentration which poses a significant public health concern. However, the causal evidence linking ozone pollution to adverse cardiopulmonary health impacts, as well as the understanding of its underlying biological mechanisms, remains limited. Additionally, exposure levels to particulate and other gaseous air pollutants along with their associated health effects in this region are largely unknown. To address these gaps, we conducted a prospective follow-up study in Tibet from May 2021 to November 2021. In consideration of the potential synergistic effects of chronic hypobaric hypoxia, two Tibetan cities with different altitudes, Lhasa (3650 m) and Nyingchi (3000 m), were chosen to implement atmospheric monitoring and health measurement. We employed cutting-edge, high-precision instruments at stationary monitoring sites to measure ambient air pollution and collected particle samples. Portable devices were used to monitor personal exposure levels of ozone and black carbon. A total of 212 healthy Tibetan college students participated in up to four clinical visits, yielding 774 visits in total, during which functional endpoints were measured and biological samples were collected. The primary aim of this study is to evaluate the cardiorespiratory effects of ambient ozone under hypoxic conditions, where its impact may be amplified due to the region's unique environmental characteristics. The secondary aim is to provide a comprehensive assessment of other air pollutants, including their exposure levels, sources, and health effects. By addressing these aims, the study offers valuable insights into air quality and its health implications in this unique high-altitude setting. This paper outlines the research motivation, measurement framework, and preliminary findings.

Ozone stress-induced DNA methylation variations and their transgenerational inheritance in foxtail millet.

Elevated near-surface ozone (O3) concentrations have surpassed the tolerance limits of plants, significantly impacting crop growth and yield. To mitigate ozone pollution, plants must evolve a rapid and effective defense mechanism to alleviate ozone-induced damage. DNA methylation, as one of the most crucial epigenetic modifications, plays a pivotal role in maintaining gene stability, regulating gene expression, and enhancing plant resilience to environmental stressors. However, the epigenetic response of plants to O3 stress, particularly DNA methylation variations and their intergenerational transmission, remains poorly understood. This study aims to explore the epigenetic mechanisms underlying plant responses to ozone stress across generations and to identify potential epigenetic modification sites or genes crucial in response to ozone stress. Using Open Top Chambers (OTCs), we simulated ozone conditions and subjected foxtail millet to continuous ozone stress at 200 nmol mol-1 for two consecutive generations (S0 and S1). Results revealed that under high-concentration ozone stress, foxtail millet leaves exhibited symptoms ranging from yellowing and curling to desiccation, but the damage in the S1 generation was not more severe than that in the S0 generation. Methylation Sensitive Amplified Polymorphism (MSAP) analysis of the two generations indicated that ozone stress-induced methylation variations ranging from 10.82% to 13.59%, with demethylation events ranged from 0.52% to 5.58%, while hypermethylation occurred between 0.35% and 2.76%. Reproductive growth stages were more sensitive to ozone than vegetative stages. Notably, the S1 generation exhibited widespread demethylation variations, primarily at CNG sites, compared to S0 under similar stress conditions. The inheritance pattern between S0 and S1 generations was mainly of the A-A-B-A type. By recovering and sequencing methylation variant bands, we identified six stress-related differential amplification sequences, implicating these variants in various biological processes. These findings underscore the potential significance of DNA methylation variations as a critical mechanism in plants' response to ozone stress, providing theoretical insights and references for a comprehensive understanding of plant adaptation mechanisms to ozone stress and the epigenetic role of DNA methylation in abiotic stress regulation.

A Preliminary Fuzzy Inference System for Predicting Atmospheric Ozone in an Intermountain Basin

High concentrations of ozone in the Uinta Basin, Utah, can occur after sufficient snowfall and a strong atmospheric anticyclone creates a persistent cold pool that traps emissions from oil and gas operations, where sustained photolysis of the precursors builds ozone to unhealthy concentrations. The basin’s winter-ozone system is well understood by domain experts and supported by archives of atmospheric observations. Rules of the system can be formulated in natural language (“sufficient snowfall and high pressure leads to high ozone”), lending itself to analysis with a fuzzy-logic inference system. This method encodes human expertise as machine intelligence in a more prescribed manner than more complex, black-box inference methods such as neural networks, increasing user trustworthiness of our model prototype before further optimization. Herein, we develop an ozone forecasting system, Clyfar, informed by an archive of meteorological and air-chemistry measurements. This prototype successfully demonstrates proof-of-concept despite rudimentary tuning. We describe our framework for predicting future ozone concentrations if input values are drawn from numerical weather prediction forecasts rather than observations as Clyfar initial conditions. We evaluate inferred values for one winter, finding our prototype demonstrates mixed performance but promise after optimization to deliver useful forecast guidance for decision-makers when forecast data are used as input. This early version model is the basis of ongoing optimization through machine learning.

Molecular Mechanisms of Ozonized Nigella sativa Oil in Wound Repair: Albumin as Biomarker in Rat Model

Background: Wound healing is a complex physiological process that can be impaired in various conditions. Nigella sativa oil, rich in bioactive compounds like thymoquinone, has shown promise in promoting wound healing. Ozone therapy, through the generation of reactive oxygen species (ROS), has also been explored for its potential to accelerate wound repair. This study aimed to investigate the molecular mechanisms underlying the effects of ozonized Nigella sativa oil on wound healing, with a focus on albumin as a biomarker of tissue regeneration in a rat model. Methods: Full-thickness skin wounds were created on the backs of Sprague Dawley rats. The rats were randomly divided into four groups: a control group receiving no treatment, and three treatment groups receiving topical applications of ozonized Nigella sativa oil at different ozone concentrations (1400 mg/ml, 1800 mg/ml, and 2200 mg/ml) for 7 days. Wound healing was assessed by measuring wound closure rates and histological analysis. Albumin levels in wound tissue were quantified using immunohistochemistry. Additionally, the expression of key genes involved in wound healing, including growth factors, cytokines, and matrix metalloproteinases, was evaluated using quantitative real-time PCR. Results: Ozonized Nigella sativa oil significantly accelerated wound closure compared to the control group. Histological analysis revealed improved tissue regeneration and collagen deposition in the treated groups. Albumin levels were significantly elevated in the wound tissue of rats treated with ozonized Nigella sativa oil, particularly at the highest ozone concentration. Furthermore, the expression of growth factors (VEGF, TGF-β), pro-inflammatory cytokines (IL-1β, TNF-α), and matrix metalloproteinases (MMP-2, MMP-9) was modulated in a manner consistent with enhanced wound healing. Conclusion: Ozonized Nigella sativa oil promotes wound healing in a rat model through multiple molecular mechanisms, including the stimulation of albumin synthesis, growth factor expression, and controlled inflammation. These findings suggest that ozonized Nigella sativa oil may have therapeutic potential for enhancing wound repair in clinical settings.

Unravelling the impacts of stratospheric intrusions on near-surface ozone during the springtime ozone pollution episodes in Lhasa, China

While air pollution due to fine particulate matter (PM2.5) has been effectively controlled in China; the photochemical pollution characterized by elevated ozone (O3) has emerged as a major concern for air quality improvement. Except for ozone, Lhasa is one of the cleanest cities in China with the lowest annual PM2.5 concentration in 2017. The levels of major air pollutants in Lhasa are much lower than those of other cities in the eastern region of China, especially in May, when the O3 concentration peaks. This study was based on multi-source observations in combination with the Goddard Earth Observing System coupled with chemistry (GEOS-Chem) and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) models to explore the causes of O3 pollution in Lhasa in May 2023. The results indicated that during the high O3 episodes, the concentrations of O3 precursors were low in Lhasa. Surrounding cities in other parts of the Tibetan Plateau also experienced high ozone concentrations despite being in different airsheds, suggesting that the O3 pollution in Lhasa was caused by regional transport rather than purely local emissions. Stratospheric intrusion events modulated by the westerly jet led to elevated ozone in the troposphere above Lhasa City. The results of the GEOS-Chem model indicated that horizontal advection, turbulence, diffusion, and other effects led to high concentrations of ozone in the near-surface above Lhasa. Vertical transport was the dominant factor leading to ozone concentration increases during high ozone days, with a contribution of 6.33 Gg/day. In addition, high-altitude air masses with a maximum altitude of over 8000 m, were observed arriving in Lhasa during the high ozone days. This study revealed that stratospheric intrusions have a greater contribution to the high O3 concentration in Lhasa in spring and provided a scientific basis for mitigating O3 pollution in the plateau cities.

Pilot scale application of a hybrid process based on ozone and BAF process: Performance evaluation for livestock wastewater treatment in a real environment

Environmental pollution was generated continuously because of the slack standard of effluent from livestock wastewater treatment even though the specific treatment process was applied. Despite the continuous ecological pollution caused by livestock wastewater effluent, a comprehensive treatment process for livestock wastewater effluent has not been investigated. This study utilized an ozone-biological aerated filter (BAF) hybrid process at a pilot scale (1st ozone–BAF–2nd ozone), with a 1 m3/day capacity for real-livestock wastewater treatment. Compared with each process configuration, the single-ozone process showed effective performance in removing chromaticity, but the removal ratio of suspended solids, organic matter (OM), and trace-organic compounds (TrOCs) was insufficient, even at high ozone concentrations. The ozone–BAF hybrid process improved the removal ratios of suspended solids and biochemical oxygen demand (BOD) by 61.61 and 17.70 %, respectively, due to aeration and filtration by the BAF; however, TrOC removal ratios remained low, at <75 %. The removal ratios of TrOCs of the 1st ozone–2nd ozone hybrid process were better than those of the ozone–BAF hybrid process (by 28.2–77.9 %) owing to enhanced oxidation from increased ozone exposure to livestock wastewater. Nevertheless, the removal ratios of suspended solids and BOD were below 40 %. Owing to the complementarity between the BAF and 2nd ozone process, the removal ratios of chromaticity, suspended solids, and TrOCs reached 98, 95, and 92 %, respectively, by the optimized 1st ozone–BAF–2nd ozone hybrid process. Our results highlight the necessity of developing a new hybrid process based on ozone and BAF for treating livestock wastewater, and provide guidelines for livestock wastewater treatment.

Efficiency of ozone compared to commercial sanitizers for hatching eggs from older breeders

This study aimed to evaluate the potential of ozone as a sanitizer compared to commercial sanitizers for hatching eggs stored in hatching machines using different turning systems. The eggs (n = 120) were distributed in a completely randomized design using a factorial scheme (6x2) where the treatments were constituted by different sanitizers applied (non-treated eggs, Ozone 1.6 mg L-1, Ozone 3.2 mg L-1, Cyphenothrin, UVC, and paraformaldehyde) and two turning systems (vertical and horizontal) with 10 eggs each, with the egg considered as a replicate. Data collected were subjected to the Tukey test at 0.05. We observed a very similar performance in the incubation yield results of the hatching machines with different turning systems, where the hatching percentage of eggs stored in the hatching machine using vertical turning presented better (p &lt; 0.05) results. Comparing ozone to other sanitizers, we observed that paraformaldehyde and UVC provided better (p &lt; 0.05) hatching percentage. However, both ozone concentrations used also presented good hatching percentage results. Chicks from treated eggs, except those from eggs treated with the highest ozone concentration (3.2 mg L-1), were heavier (p &lt; 0.05) at hatch. Chicks from eggs treated with the low concentration of ozone (1.6 mg L-1) presented, in several scenarios, higher (p &lt; 0.05) weight at hatch than chicks from eggs treated with sanitizers commonly used, especially paraformaldehyde and UVC. Conclusively, ozone can be used as a sanitizer to treat eggs from older breeders, presenting potential to replace commonly used sanitizers stored in hatching machines using both vertical and horizontal turning systems.

The Relationship of Surface Ozone Pollution with Meteorological Conditions in Determining Episode Periods

Jakarta, the capital city of Indonesia, is located in a tropical region with abundant sunlight and high temperatures year-round. Ozone and particulate matter (PM) are critical parameters causing unhealthy air pollution. Meteorological data were obtained from the NASA Power website. This study aims to explore the relationship between ozone formation and meteorological factors in Jakarta. Ozone air quality data were measured using the Backman model 950A ozone Analyzer, which detects concentrations as low as 0.05 ppm, with measurements taken every 40 seconds. From January to October 2023, ozone concentrations increased during the dry months of May to October, with the highest hourly value recorded at 263 μg/m³. During this period, average temperatures ranged from 27-29°C, rainfall was 0.3-5.6 mm, wind speeds were 3.14-4.64 m/s, wind direction was 92-171 degrees, and air humidity was 74-82%. Significant episodes were identified on (i) May 5-9, (ii) July 12-15, (iii) September 6-7, (iv) September 13-14, (v) September 21-22, and (vi) October 29-30, 2023. Daily, monthly, and seasonal ozone variations aligned with meteorological conditions, showing higher concentrations during the dry months. Further studies, including photochemical modeling, are required to identify dominant factors causing high ozone concentrations during these episodes. Understanding NOx or VOC emission sensitivities is crucial for effective ozone abatement strategies in Jakarta.

Kolmogorov-Zurbenko filter coupled with machine learning to reveal multiple drivers of surface ozone pollution in China from 2015 to 2022

Near-surface ozone pollution is a significant concern in China. Its meteorological drivers are uncontrolled, stressing an urgent need to quantify the anthropogenic-driven components. This study employs explainable machine learning (ML) algorithms to predict ozone concentrations, emphasizing the anthropogenic-driven trends after accounting for meteorological effects. Results present that radiation is the most important meteorological factor affecting ozone pollution in the Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SCB), while temperature is dominant for the North China Plain (NCP). Even at lower temperatures, stronger solar radiation can still lead to the accumulation of higher ozone concentrations. The anthropogenic-driven ozone concentration showed an upward trend in China, with an interannual growth rate of 2.61 μg/m3 a−1 from 2015 to 2022. Nonetheless, its rising trend experienced a post-2019 downturn, due to the COVID-19 lockdown and emission reduction strategies. It started to rise in 2022. Regionally, NCP has the highest ozone concentration, the SCB has the most pronounced increase in 2022, but the PRD has no noticeable variation and no significant seasonal change after 2019. As for precursor emissions, the urban areas in China are mostly located in the VOC-limited (volatile organic component) and transitional regimes, highlighting that VOC control is more cost-effective.

Large-scale ozone episodes in Europe: Decreasing sizes in the last decades but diverging changes in the future

Episodes of high near-surface ozone concentrations tend to cover large areas for several days. They are strongly dependent on meteorology, precursor emissions, and the ambient photochemical conditions. This study introduces a new pseudo-Lagrangian algorithm that identifies the spatiotemporal patterns of episodes, allowing for a good characterization of their areal extent and an assessment of their drivers. The algorithm has been used to identify ozone episodes in Europe from April to September over the last twenty years (2003–2022) in the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis as well as in the historical simulation (1950–2014) and four shared socio-economic pathways (SSPs, spanning 2015–2100) of three Earth system models (UKESM1-0-LL, EC-Earth3-AerChem and GFDL-ESM4). While the total number of episodes has increased in recent years, the frequency of large episodes has decreased following European precursor emission reductions. The analysis of the 100 largest episodes shows that they tend to occur in Northern Europe during spring and in the center and south of the continent from June onwards. Most of the top 10 episodes occurred in the first years of the century and were associated with high temperatures, enhanced solar radiation, and anticyclonic conditions. Despite the decrease in large episodes in recent years, there is uncertainty regarding future European episodes. Episodes of reduced size are found for SSPs with weak greenhouse forcing and low precursor emissions, whereas episode sizes increase in scenarios with high methane concentrations and enhanced radiative forcing, even exceeding the maximum historical size. However, the three models project episodes of different sizes for any given scenario, probably associated with their differing warming trends and the varying level of complexity in the implementation of processes. These results point to the need to implement both effective climate and air quality policies to address the ozone air pollution problem in Europe in a warming climate.

The impact of evolving synoptic weather patterns on multi-scale transport and sources of persistent high-concentration ozone pollution event in the Yangtze River Delta, China

High-concentration ozone pollution pose threats to ecosystems and human health. However, there is limited research on the impact of the alternating evolution of synoptic weather patterns (SWPs) on the multi-scale transport processes and sources of ozone. From June 14 to 18, 2018, a rare consecutive ozone pollution plagued in Hefei and broader Yangtze River Delta region (YRD). This study investigates the meteorological factors and sources using in-situ observational data and WRF-Chem model simulations. Analysis reveals a northeastern low-pressure system moving from north to south generated a cold front. This moving cold front facilitated the vertical transport of warm air masses carrying high-concentration ozone originating from North China. Subsequently, Ozone-rich air masses (ORMs) were transported over the YRD, influenced by the eastward movement of the Mongolian high-pressure system. Based on WRF-Chem model with NOx tagging mechanisms and WRF-FLEXPART backward simulations, it is confirmed that a notable atmospheric transport originated from North China region (NCR) to Hefei, especially on June 15. As the Mongolian high-pressure weakens and shifts east-southward, it carried ORMs generated by NOx emissions from the YRD, accumulating over the sea within the range of 120°E to 126°E and 25°N to 30°N. Both WRF-chem model results and TRopospheric Ozone and Precursors from Earth System Sounding (TROPESS) Chemistry Reanalysis dataset Version 2 (TCR-2) revealed the existence of ORMs in this geographic range. Subsequently, the ORMs carried out to sea by the weakened high-pressure system were reintroduced inland, influenced by southeast winds brought about by the peripheral circulation of typhoon “Gaemi”. In summary, the alternating evolution of SWPs significantly influences multi-scale ozone transport from both the NCR and the YRD regions, making substantial contributions to this prolonged episode. These findings offer valuable insights for improving regional ozone pollution prevention and control mechanisms.

Ozone exceedance forecasting with enhanced extreme instance augmentation: A case study in Germany

Accurately forecasting ozone levels that exceed specific thresholds is pivotal for mitigating adverse effects on both the environment and public health. However, predicting such ozone exceedances remains challenging due to the infrequent occurrence of high-concentration ozone data. This research, leveraging data from 57 German monitoring stations from 1999 to 2018, introduces an Enhanced Extreme Instance Augmentation Random Forest (EEIA-RF) approach that significantly improves the prediction of days when the maximum daily 8-hour average ozone concentrations exceed 120μg/m3. A pre-trained machine learning model is used to generate additional high-concentration data, which, combined with selectively reduced low-concentration data, forms a new dataset for training a refined model. This method achieved an improvement of at least 8% in the accuracy of predicting days with ozone exceedances across Germany. Our experiment underscores the approach’s value in enhancing atmospheric modeling and supporting public health advisories and environmental policy-making related to ozone pollution.

Drought stress impacts soil microbial nutrient limitation more strongly than O3 pollution

Summer drought conditions generally coincide with exposure to high ground-level concentrations of ozone (O3). These two stressors compromise the availability of water, energy, and nutrients to vegetation and microbial communities present within the soil. However, relatively little is known regarding the responses of rhizosphere and non-rhizosphere soil microbial nutrient acquisition to conditions of drought and O3 exposure. Here, we used ecoenzymatic stoichiometry modeling and vector analyses to decipher the resource constraints on rhizosphere and non-rhizosphere soil microbial metabolic limitation within the soil of hybrid poplars exposed to two watering regimens (well-watered or reduced water of 40 %) and two chronic O3 treatments (charcoal-filtered air or ambient air +40 ppb of O3). Results show that, simulated drought stress resulted in stronger effects on the structure of soil microbial communities and associated enzymatic activity relative to exposure to elevated O3 levels. Exposure to these two stressors induced a microbial phosphorus (P) limitation response, with these limitation effects being more pronounced in the rhizosphere soil relative to non-rhizosphere soil. Structural equation modeling revealed that drought-associated declines in soil water availability and pH values were the primary factors influencing this microbial P limitation. Reduced soil water levels resulted in the exacerbation of microbial P limitation as a consequence of the inhibition of P mineralization and availability of C and N, whereas declining soil pH values had the opposite effect, alleviating microbial P limitations by reducing soil alkalinity and thereby aiding in the dissolution of the insoluble P present in alkaline soil. These results emphasize the complex responses of rhizosphere and non-rhizosphere soil microbial metabolic activity to elevated O3 levels and drought stress, providing invaluable insight into the importance of elemental stoichiometry-driven microbial metabolic variability of nutrient cycling activity at the root-soil interface in O3-polluted and drought-exposed ecosystems.

Optical study on the effect of ozone addition on a diesel/ammonia dual fuel engine with pilot injection

Influenced by the concept of carbon neutrality, ammonia is gaining widespread attention in the transport sector as a zero-carbon fuel. Diesel/ammonia dual fuel engines can achieve stable combustion of ammonia and reduce carbon emissions. To further enhance the low load combustion performance of a diesel/ammonia dual fuel engine, the effect of ozone addition on in-cylinder combustion and flame development was investigated based on an optical engine. Beyond that, ozone addition on pure diesel was also tested to understand the effect of ozone addition on diesel combustion enhancement in diesel/ammonia reactivity controlled compression ignition (RCCI) mode. The results show that the addition of ozone significantly advances the ignition phase, increases the flame area and brightness, and results in a growth in flame luminescence intensity along the radial length and closer to the center of the view field for diesel/ammonia RCCI combustion. In addition, chemical kinetic analysis shows that diesel/ammonia combustion requires higher ozone concentrations to overcome the inhibitory effect of ammonia to reach the upper limit of the promotional effect on the ignition phase and indicated mean effective pressure (IMEP), due to the large amount of OH consumed by ammonia compared to pure diesel. The promotional effect of added ozone on IMEP is similar for different pilot injection ratios (PIRs). At a low PIR and high ozone concentration, the diesel/ammonia RCCI engine achieves the highest IMEP, indicating that ozone addition combined with optimization of diesel injection parameters contributes to improve the performance of the diesel/ammonia RCCI engine at low loads.

Fungicidal effect of gaseous ozone in malting barley: Implications for Fusarium infections and grain germination

Fungal infections pose a challenge in cereal grains, with Fusarium species, especially in malting barley, causing substantial economic losses and quality degradation. We investigated the effect of gaseous ozone on fungal deactivation and grain germination in spring malting barley, with focus on Fusarium spp. Five studies were performed: (1) ozone concentration (10–100 ppm) and exposure time (1–24 h) on high-moisture barley (19.8%); (2) ozone-treated barley stability over 120 days at 4 °C; (3) grain moisture content (12–20%); (4) relative humidity (23%, 54%, and 98%); and (5) temperature (13 °C, 20 °C, and 33 °C). Significant reductions in total fungal count and Fusarium spp. across all treatments were observed. Higher ozone concentrations and longer exposure times yielded greater reductions, with 100 ppm for 24 h achieving 99.2% and 98.2% reductions in total fungal count and Fusarium incidence, respectively. Grain germination exhibited a negative dose-dependent response but remained within recommended values. Ozone-treated barley preserved quality for 60 days in storage. Grain moisture content, relative humidity, and temperature did not significantly affect ozone's efficacy on fungi and grain germination. This study demonstrates ozone's efficacy against fungi while preserving barley germination, suggesting it as an eco-friendly fungicidal alternative.

Recirculated transport mechanism aggravates ozone pollution over the mountainous coastal region: Increased contribution from vertical mixing

In coastal areas where many highly developed metropolis and city agglomeration are located, high ozone (O3) concentrations are one of the most severe environmental problems, which is gravely impacted by the sea-land breeze (SLB) circulation. The complex terrain, such as coastal mountain, complicates SLB circulation and its impact on coastal O3 pollution. Previous studies have shown that coastal mountain intensifies SLB circulation in various regions worldwide, such as the southern California coastal region, the Mediterranean coastal region, and the Beijing-Tianjin-Hebei region. However, the specific impacts of the underlying mechanism on coastal O3 levels, along with a quantified contribution analysis, remain insufficiently explored. Here we present that the coastal mountain terrain in the Western Taiwan Strait of South China induces a three-dimensional O3 transport involving SLB circulation through integrating observational data from 2015 to 2022 and employing WRF-Chem modeling, specifically focusing on the thermally driven sea breeze during the day combined with the up-slope flow generated by the coastal mountain. This flow carries O3-rich air mass, which are caused by both photochemical reactions and cross-boundary transport originating from land and offshore sources. As the air moves inland and up the mountainside, it ultimately forming a layer of high-level O3 aloft. O3 trapped in the layer acts as a reservoir of elevated O3 for the coastal plain and aggravates O3 pollution on the following day via vertical mixing by over 40 μg m−3 h−1. Based on the sensitivity simulation, this work quantifies that the coastal mountain contributes 23.4 % of surface O3 concentrations increase in the coastal urban area. This recirculated transport of O3 has important implications for understanding meteorological drivers on atmospheric environment in complex terrain.

Parsimonious estimation of hourly surface ozone concentration across China during 2015–2020

Surface ozone is an important air pollutant detrimental to human health and vegetation productivity, particularly in China. However, high resolution surface ozone concentration data is still lacking, largely hindering accurate assessment of associated environmental impacts. Here, we collected hourly ground ozone observations (over 6 million records), remote sensing products, meteorological data, and social-economic information, and applied recurrent neural networks to map hourly surface ozone data (HrSOD) at a 0.1° × 0.1° resolution across China during 2015–2020. The coefficient of determination (R2) values in sample-based, site-based, and by-year cross-validations were 0.72, 0.65 and 0.71, respectively, with the root mean square error (RMSE) values being 11.71 ppb (mean = 30.89 ppb), 12.81 ppb (mean = 30.96 ppb) and 11.14 ppb (mean = 31.26 ppb). Moreover, it exhibits high spatiotemporal consistency with ground-level observations at different time scales (diurnal, seasonal, annual), and at various spatial levels (individual sites and regional scales). Meanwhile, the HrSOD provides critical information for fine-resolution assessment of surface ozone impacts on environmental and human benefits.