Impact Of O3 Research Articles

Spatio-temporal variation of O3 concentration and exposure risk assessment in key regions of China, 2015–2021

In recent years, the increasing Ozone (O3) concentration has become a significant concern for human life and health. In this study, O3 concentration data at 10 km resolution and population density data at 1 km resolution for China were utilized. Methods such as the Global Moran's I index, Getis-Ord Gi* index, and population exposure risk index, to analyze the spatial-temporal variation, meteorological influences, aggregation characteristics, exposure risk levels and health impact of O3 in China and six key regions from 2015 to 2021. The results revealed an increasing trend with a bimodal fluctuation pattern, peak in May and August. Only Pearl River Delta (PRD) showed the highest in autumn, five other key regions were highest O3 concentration in the summer. And the spatial autocorrelation in China is obvious among regions. Among the five meteorological factors, temperature and sunshine duration predominantly influenced O3 concentration in China. Relative humidity was the main factor affecting O3 concentration in Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD) and Sichuan Basin (SCB), while precipitation had the greatest impact on FenWei Plain (FWP) and Hexi Corridor (HXC) and exhibited a positive correlation. Wind speed in PRD showed a strong negative correlation with O3 concentration. The Ri exhibited significant differences between the eastern and western sides of the Hu Huanyong line, demonstrating a distribution pattern of "high in the east and low in the west". Through this research, we aim to provide valuable insights for public health policies and the prevention and control of regional air pollution.

Facilitating Electrochemical Ozone Production and Chlorine Evolution Reaction by Synergistic Effect of Multicomponent Metal Oxides

AbstractThe concomitant degradation of organic contaminants using green oxidants, NaClO and O3, exhibits great potential to mitigate the deleterious impact of organic pollutants. In this work, the electrochemical ozone production (EOP) and chlorine evolution reaction (CER) performed by highly active electrocatalysts composed of Ce‐Ni‐Sb‐SnO2 and Ru‐Ir‐Ce‐Ni‐Sb‐SnO2, respectively, are presented. Ce‐Ni‐Sb‐SnO2 exhibits high selectivity with a 43.9% Faraday efficiency in EOP. Incorporating Ru and Ir in Ru‐Ir‐Ce‐Ni‐Sb‐SnO2 improves CER performance, achieving outstanding Faraday efficiency of up to 98.3%. Additionally, it achieves a low overpotential of ≈80 mV at 10 mA cm−2 with 0.3 m NaCl (pH = 6). Theoretical calculations reveal the significant impact of multicomponent oxides on reaction intermediate adsorption. Ce, Ni, Sb doping on SnO2 enhances O2 and O3 adsorption for optimal EOP performance, while Ru and Ir doping on Ce‐Ni‐Sb‐SnO2 enhances Cl adsorption, boosting CER performance. Further investigations into the decomposition of pesticides and antibiotics demonstrate that the collaborative impact of O3 and NaClO elicits a significantly more robust kinetic degradation rate in comparison to their individual influences. This work aims to shed light on the synthesis of multicomponent metal oxides as potential precursors for the cost‐effective preparation of O3 and NaClO for electrochemical advanced oxidation processes.

Stratospheric dynamics modulates ozone layer response to molecular oxygen variations

Photolysis of molecular oxygen (O2) sustains the stratospheric ozone layer and is thereby protecting living organisms on Earth by absorbing harmful ultraviolet radiation. In the past, atmospheric O2 levels were not constant, and their variations are thought to be responsible for the extinction of some species due to the thinning of the ozone layer. Over the Phanerozoic Eon (last ∼500 Mio years), the O2 volume mixing ratio ranged between 10% and 35% depending on the level of photosynthetic activity of plants and oceans. Previous estimates, mostly performed by simplified 1-D models, showed different ozone (O3) responses to atmospheric O2 changes within this range, such as monotonically positive or negative correlations, or displaying a maximum in the O3 column around a certain O2 level. Here, we assess the ozone layer sensitivity to atmospheric O2 varying between 5% and 40% with a state-of-the-art 3-D chemistry-climate model (CCM). Our findings show that the O3 layer thickness maximizes around the current mixing ratio of O2, 21% ± 5%, while lower or higher levels of O2 result globally in a reduction of total column O3. At low latitudes, the total column O3 is less sensitive to O2 variations, because of the “self-healing” effect, namely, a vertical dipole in the tropical ozone response. Mid- and high-latitude O3 columns that are largely affected by transport of O3 from the tropics, however, are much more sensitive to O2 with changes up to 20 DU even for small (±5%) O2 perturbations. We show that these variations are largely driven by the radiative impact of O3 on stratospheric temperatures and on the strength of the Brewer-Dobson circulation (BDC), indicating chemistry-radiation-transport feedback. High O2 cases result in an acceleration of the BDC and vice versa, which always works in favor of the negative part of the O3 anomaly dipole in the tropics being more effectively transported to the mid- and high-latitudes than the positive one. Although there are other factors strongly influencing O3/O2 relationship on the Phanerozoic Eon timescales that have not been considered here, our results and the presented mechanism bring useful insights for other studies focusing on the long-term O3/O2 relationship.

Impacts of ground-level ozone on sugarcane production

Sugarcane is a vital commodity crop often grown in (sub)tropical regions which have been experiencing a recent deterioration in air quality. Unlike for other commodity crops, the risk of air pollution, specifically ozone (O3), to this C4 crop has not yet been quantified. Yet, recent work has highlighted both the potential risks of O3 to C4 bioenergy crops, and the emergence of O3 exposure across the tropics as a vital factor determining global food security. Given the large extent, and planned expansion of sugarcane production in places like Brazil to meet global demand for biofuels, there is a pressing need to characterize the risk of O3 to the industry. In this study, we sought to a) derive sugarcane O3 dose-response functions across a range of realistic O3 exposure and b) model the implications of this across a globally important production area. We found a significant impact of O3 on biomass allocation (especially to leaves) and production across a range of sugarcane genotypes, including two commercially relevant varieties (e.g. CTC4, Q240). Using these data, we calculated dose-response functions for sugarcane and combined them with hourly O3 exposure across south-central Brazil derived from the UK Earth System Model (UKESM1) to simulate the current regional impact of O3 on sugarcane production using a dynamic global vegetation model (JULES vn 5.6). We found that between 5.6 % and 18.3 % of total crop productivity is likely lost across the region due to the direct impacts of current O3 exposure. However, impacts depended critically on the substantial differences in O3 susceptibility observed among sugarcane genotypes and how these were implemented in the model. Our work highlights not only the urgent need to fully elucidate the impacts of O3 in this important bioenergetic crop, but the potential implications air quality may have upon tropical food production more generally.

Ambient ozone exposure and depression among middle-aged and older adults: Nationwide longitudinal evidence in China.

Epidemiological studies have linked long-term ozone (O3) exposure with depression in developed countries. However, available literature is sparse and exists great heterogeneities. We aimed to investigate the association of long-term O3 exposure with depression among Chinese middle-aged and older adults. We designed a repeated measurement study based on longitudinal data from four waves (2011, 2013, 2015, and 2018) of the China Health and Retirement Longitudinal Study (CHARLS). Annual mean O3 concentrations assessed through machine learning-based spatiotemporal models were assigned to each participant at city level. Depression score was measured using the 10-item Center for Epidemiologic Studies Depression scale (CES-D-10), with scores above the cut-off point of ten defined as depressive symptom. Mixed-effects models were used to evaluate the impact of O3 on depression score and depressive symptom, and quantify the concentration-response (C-R) relationships. Subgroup analyses were performed to examine the potential effect modifications. A total of 19,582 participants with 60,125 visits were included in our analysis, with mean depression score of 8.1 (standard deviation: 6.3). Multivariable-adjusted mixed-effects model estimated a 6.34% (95% confidence interval [CI]: 3.34%, 9.43%) increase in depression score and an odds ratio (OR) of 1.29 (95% CI: 1.16, 1.45) for depressive symptom associated with per 10-μg/m3 rise in annual mean O3 exposure. Significantly elevated risks were identified only at high concentrations (approximately ≥90μg/m3). Participants who suffered from chronic diseases had a significant increased risk of depression (% Change in depression score: 8.42% [95% CI: 4.79%, 12.17%], and OR: 1.42 [95% CI: 1.24, 1.62]), and an evident effect modification was identified for depressive symptom (P=0.01). Our study provided novel evidence that long-term O3 exposure could be a risk factor for depression among Chinese middle-aged and older adults. Our findings may have significant implications for formulating policies in reducing disease burden of depression by controlling air pollution.

Ozonation Vs sequential solar driven processes as simultaneous tertiary and quaternary treatments of urban wastewater: A life cycle assessment comparison

Solar driven advanced oxidation processes (S-AOPs) have been successfully investigated in the last years as tertiary and quaternary treatment of urban wastewater for simultaneous inactivation of microorganisms and removal of contaminants of emerging concern (CECs), respectively. However, the lack of data about the comparison with consolidated technologies, including also the evaluation of their impact on the environment, has contributed to humper their application at full scale so far. In this study, the environmental impact of a new S-AOP, namely sequential treatment (ST) with sunlight/H2O2 and solar photo-Fenton (SPF) at neutral pH (using Ethylenediamine-N, N′-disuccinic acid (EDDS) as chelating agent) operated at pilot scale in a raceway pond reactor, was compared to a pilot scale ozonation (O3) treatment unit in terms of simultaneous bacteria inactivation and CECs removal, through a Life Cycle Assessment (LCA). Different urban wastewater treatment plant (UWWTP) sizes and scenarios (namely effluent disposal and reuse) were evaluated. While the reuse scenario resulted in a higher impact compared to the disposal scenario in the construction/deconstruction phase, due to the more stringent limits that resulted in longer treatment time and a higher consumption of raw materials, the positive impact on water resources saving compared to disposal makes the reuse scenario a more sustainable solution. Despite O3 disinfection by-products were taken into account, ST resulted in a higher toxicity to human health (0.27·10−9 DALYs Vs 2.11 10−9 DALYs, respectively) due to the higher residual concentration of the target CECs. However, it is noteworthy that both values are significantly lower than the acceptable DALYs value (≤10−6). Chemicals, energy, groundwater consumption and residual CECs can affect resources 1125 and 1874 times more for O3 treatment than for the ST, for disposal and reuse scenarios, respectively. The total impact of O3 on the human health was 13 and 19 times higher compared to ST, for disposal and reuse scenarios, respectively, due to the higher energy and chemical consumption. According to the LCA results, ST resulted in a better overall environmental performance compared to O3 and it is a more sustainable and attractive solution in particular for small UWWTPs.

A remote sensing based method for assessing the impact of O3 on the net primary productivity of terrestrial ecosystems in China

O3 pollution in China has been increasing in recent years, but the process of O3 impact on net primary productivity of terrestrial ecosystems remains unclear. We attempts to explore a remote sensing-based method to assess the impact of O3 on NPP of China’s terrestrial ecosystems by combining MODIS NPP and the latest ground observation data of O3 concentration. By comparing the NPP data of MODIS image pixels with the 6-year average AOT40 data of corresponding pixels, we extracted the signal data that highlighted the effects of O3 on NPP and established the response relationships between AOT40 and NPP. It was found that NPP was significantly negatively correlated with AOT40 in farmland and grassland ecosystems in China (farmland: r = 0.8674, p < 0.003, grassland: r = 0.7181, p < 0.03). Then the response relationships were adopted to evaluate the effect in China in 2014. The results showed that the estimated percentage of O3-induced NPP decline was in the range of 5%–35%. Among them, the most significant declines were found in farmland ecosystems, with the vast majority of declines in 10%–35%. The decrease rate of evergreen coniferous forests ranked second, mostly in the range of 15%–20%. The grassland ecosystems declined at a lower rate, almost between 5% and 15%. And the evergreen broad-leaved forests has the lowest decline rate, most distributed in 0%–5%. The highest percentage decreases were mainly found in the Beijing-Tianjin-Hebei region and Shandong Province. And the decline rate of farmland ecosystems was significantly higher than other ecosystem types.

Current ambient ozone levels mitigate the effect of Puccinia striiformis on wheat: Is Mediterranean wheat ready for pre-industrial background ozone levels?

Increasing surface ozone is a main concern for crop production in the Global Change framework, especially in the Mediterranean basin where climate conditions favor its photochemical formation. Meanwhile, increasing common crop diseases, such as yellow rust, one of the most important pathogens affecting global wheat production has been detected in the area in recent decades. However, the impact of O3 on the occurrence and impact of fungal diseases is scarcely understood.A close-to-field-conditions assay (Open Top Chamber facility) situated in a Mediterranean cereal rainfed farming area was carried out to study the impact of increasing O3 levels and N-fertilization on spontaneous fungal outbreaks in wheat. Four O3-fumigation levels reproducing pre-industrial to future pollutant atmospheres with additional 20 and 40 nL L−1 over the ambient levels were considered (7 h-mean ranging from 28 to 86 nL L−1). Two top N-fertilization supplementations (100 and 200 kg ha−1) were nested within the O3 treatments; foliar damage, pigment content and gas exchange parameters were measured. Pre-industrial natural background O3 levels strongly favored the yellow rust infection, where the O3-polluted levels currently observed at the farm highly benefited the crop, mitigating the presence of rust by 22 %. However, future expected high O3-levels neutralized the beneficial infection-controlling effect by inducing early wheat senescence, decreasing the chlorophyll index of the older leaves by up to 43 % under the higher O3 exposure. Nitrogen promoted the rust infection by up to 49.5 % without interacting with the O3-factor. Achieving future air quality standards might require considering new varietal improvement programs, to be able to adapt crops to an increased pathogen tolerance without requiring the assistance provided by O3-pollution.

Effects of ozone, drought and heat stress on wheat yield and grain quality

Tropospheric ozone (O3) is a gaseous phytotoxic plant stressor known to reduce wheat (Triticum aestivum) crop yields at current concentrations. O3 is predicted to increase in many crop-growing regions, together with higher frequencies of heatwaves and droughts. In this study, wheat crops were exposed to two levels of O3 (ambient and ∼70 ppb) in combination with ambient or elevated temperature (+8 °C) and two watering regimes (well-watered and 50% reduced water supply) during the grain-filling period. With this experimental setup, we assessed the interactive effects between O3, temperature and water supply on wheat yield and grain quality, and measured leaf gas exchange to explore the underlying mechanisms. Overall, O3, warming and drought all decreased grain yield and average grain mass but increased grain concentration of N and other nutrient elements. Increasing daytime O3 from 25 to 73 ppb resulted in a 25% yield reduction in treatments with ambient temperature and well-watered soil. Drought reduced the impact of O3 on light-saturated photosynthesis, grain mass, total aboveground biomass and grain concentrations of K, Ca, Mg, Mo. In contrast, concentrations of K and Ca increased to a larger extent when O3 stress was combined with elevated temperature. Grain concentrations of N, Ca and Zn were closely and negatively related to grain yield regardless of O3, heat and drought stress, likely explained by the reduction in grain filling period, with starch accumulation reduced to a larger extent than that of these elements. P, K, Mg, Mn, Mo concentrations were weakly related to grain yield, but were clearly altered by environmental stress. The modifying effect of water availability is crucial to include in assessments of O3 impacts on global food production in relation to climate change, considering effects on wheat yield variables and grain nutrient concentrations.

The impact of monthly air pollution exposure and its interaction with individual factors: Insight from a large cohort study of comprehensive hospitalizations in Guangzhou area.

Although the association between short-term air pollution exposure and certain hospitalizations has been well documented, evidence on the effect of longer-term (e. g., monthly) air pollution on a comprehensive set of outcomes is still limited. A total of 68,416 people in South China were enrolled and followed up during 2019-2020. Monthly air pollution level was estimated using a validated ordinary Kriging method and assigned to individuals. Time-dependent Cox models were developed to estimate the relationship between monthly PM10 and O3 exposures and the all-cause and cause-specific hospitalizations after adjusting for confounders. The interaction between air pollution and individual factors was also investigated. Overall, each 10 μg/m3 increase in PM10 concentration was associated with a 3.1% (95%CI: 1.3%-4.9%) increment in the risk of all-cause hospitalization. The estimate was even greater following O3 exposure (6.8%, 5.5%-8.2%). Furthermore, each 10 μg/m3 increase in PM10 was associated with a 2.3%-9.1% elevation in all the cause-specific hospitalizations except for those related to respiratory and digestive diseases. The same increment in O3 was relevant to a 4.7%-22.8% elevation in the risk except for respiratory diseases. Additionally, the older individuals tended to be more vulnerable to PM10 exposure (P interaction: 0.002), while the alcohol abused and those with an abnormal BMI were more vulnerable to the impact of O3 (P interaction: 0.052 and 0.011). However, the heavy smokers were less vulnerable to O3 exposure (P interaction: 0.032). We provide comprehensive evidence on the hospitalization hazard of monthly PM10 and O3 exposure and their interaction with individual factors.

Rice yield losses due to O3 pollution in China from 2013 to 2020 based on the WRF-CMAQ model

High ground-level ozone (O3) concentrations has been shown to inhibit crops growth and decrease their yields. Current indicators for assessing the impact of O3 on crop yields are usually based on the ambient concentration, without considering recently suggested flux-based indicators (especially stomatal flux) for ecological risk assessment. This study applied the WRF-CMAQ model system, the parameterized Jarvis stomatal conductance model, and the O3 flux model to simulate the changes of O3 uptake flux in rice stomata in major rice growing areas in China during 2013–2020. The yield losses of rice caused by O3 pollution were estimated using both exposure-based (AOT40) and flux-based (PODγ) indicators. The rice yield losses experienced an overall increasing and decreasing trend in 2013–2018 and 2018–2020, respectively. The yield losses estimated by AOT40 were 3.5–5.9% for single rice, 1.8–3.5% for double-early rice, and 2.4–5.4% for double-late rice during 2013–2020, while the losses based on PODγ were 5.1–13.0%, 2.1–10.6%, and 6.7–15.9%, respectively. The yearly rice yield losses based on AOT40 and PODγ were 5.9–11.4 Mt (million metric tons) and 8.0–28.0 Mt for 2013–2020, respectively. This study can provide an important reference for avoiding the impact of O3 pollution and climate change on rice yield in the future.

Ambient ozone – New threat to birds in mountain ecosystems?

Mountain ecosystems are inhabited by species with specific characteristics enabling survival at high altitudes, which make them at risk from various pressures. In order to study these pressures, birds represent excellent model organisms due to their high diversity and position at the top of food chains. The pressures upon mountain bird populations include climate change, human disturbance, land abandonment, and air pollution, whose impacts are little understood. Ambient ozone (O3) is one of the most important air pollutants occurring in elevated concentrations in mountain conditions. Although laboratory experiments and indirect course-scale evidence suggest its negative effects on birds, population-level impacts remain unknown. To fill this knowledge gap, we analysed a unique 25-years long time series of annual monitoring of bird populations conducted at fixed sites under constant effort in a Central European mountain range, the Giant Mountains, Czechia. We related annual population growth rates of 51 bird species to O3 concentrations measured during the breeding season and hypothesized (i) an overall negative relationship across all species, and (ii) more negative O3 effects at higher altitudes due to increasing O3 concentration along altitudinal gradient. After controlling for the influence of weather conditions on bird population growth rates, we found an indication of the overall negative effect of O3 concentration, but it was insignificant. However, the effect became stronger and significant when we performed a separate analysis of upland species occupying the alpine zone above treeline. In these species, populations growth rates were lower after the years experiencing higher O3 concentration indicating an adverse impact of O3 on bird breeding. This impact corresponds well to O3 behaviour and mountain bird ecology. Our study thus represents the first step towards mechanistic understanding of O3 impacts on animal populations in nature linking the experimental results with indirect indications at the country-level.

The Interactive Effects of Nitrogen Addition and Ozone Pollution on Cathay Poplar-Associated Phyllosphere Bacterial Communities

Ground-level ozone (O3) can adversely impact tree productivity and the service functions of forest ecosystems. The deposition of atmospheric nitrogen (N) can enhance nutrient availability and mitigate the O3-mediated impairment of plant–soil–microbe systems. Interactions between plants and associated microbial communities are integral to the ability of these plants to resist environmental stressors, yet studies examining the impact of increased O3 and N levels, alone or in combination, on these phyllosphere bacterial communities have been lacking to date. Accordingly, this study was conducted to examine the impact of O3 (charcoal-filtered air vs. non-filtered ambient air + 40 ppb of O3), N addition (0, 50, and 100 kg N ha−1 year−1), and a combination of these treatments on the phyllosphere bacterial communities associated with Cathay poplars. Higher O3 levels were found to significantly reduce the relative abundance of Gammaproteobacteria phyla while increasing the relative abundance of the dominant Alphaproteobacteria and Betaproteobacteria, with these effects being independent of N levels. Consistently, while marked differences in the composition of phyllosphere bacterial communities were observed as a function of O3 treatment conditions, they were largely similar across N treatments. Higher O3 levels contributed to significant reductions in α diversity, including both observed OTUs and phylogenetic diversity, when no N or low levels of N were added. α diversity was not affected by the N addition irrespective of O3 levels. A significant correlation was observed between photosynthesis rates and both α diversity and phyllosphere bacterial community composition, indicating a close relationship between photosynthetic activity and this microbial community. Together, these data offer new ecological insights regarding O3-induced changes in the makeup of bacterial communities present on plant surfaces, providing a foundation for efforts to formulate novel management strategies aimed at adapting environmental stressors under conditions of O3 pollution and in N-enriched environments.

Response of tropical trees to elevated Ozone: a Free Air Ozone Enrichmentstudy.

Tropospheric ozone (O3) has become one of the main urban air pollutants. In the present study, we assessed impact of ambient and future ground-level O3 on nine commonly growing urban tree species under Free Air Ozone Enrichment (FAOE)condition. During the study period, meanambient and elevated ozone (EO3) concentrations were 48.59 and 69.62ppb, respectively. Under EO3 treatment,stomatal density (SD) significantly decreased and guard cell length (GCL) increased in Azadirachta indica, Bougainvillea spectabilis, Plumeria rubra, Saraca asoca and Tabernaemontana divaricata, while SD increased and GCL decreased in Ficus benghalensis and Terminalia arjuna. Proline levels increased in all the nine plant species under EO3 condition. EO3 significantly reduced photosynthetic rate, stomatal conductance (gs), and transpiration rates (E). Only A. indica and N. indicum showed higher gs and E under EO3 treatment. Water use efficiency (WUE) significantlyincreased in F. benghalensis anddecreased in A. indica and T. divaricata. Air Pollution Tolerance Index (APTI) significantly increased in Ficus religiosa and S. asoca whereas it decreased in B. spectabilis and A. indica. Of all the plant species B. spectabilis and A. indica were the mostsensitive to EO3 (high gs and less ascorbic acid content) whileS. asoca and F. religiosa were the mosttolerant (lowgs and more ascorbic acid content). The sensitivity of urban tree species to EO3 is a cause ofconcern and should be considered for future urban forestry programmes. Our study should guidemore such studies toidentify tolerant trees for urban air pollution abatement.

The Effects of Elevated Tropospheric Ozone on Carbon Fixation and Stable Isotopic Signatures of Durum Wheat Cultivars with Different Biomass and Yield Stability.

Tropospheric ozone (O3) enrichment caused by human activities can reduce important crop yields with huge economic loss and affect the global carbon cycle and climate change in the coming decades. In this study, two Italian cultivars of durum wheat (Claudio and Mongibello) were exposed to O3 (80 ppb, 5 h day-1 for 70 consecutive days), with the aim to investigate the changes in yield and biomass, ecophysiological traits, and stable carbon and nitrogen isotope values in plants, and to compare the stable isotope responses under environmental stressors. Both cultivars showed a relative O3 tolerance in terms of photosynthetic performance, but in cultivar Mongibello, O3 was detrimental to the grain yield and plant biomass. The δ13C values in the leaves of plants identified that the impact of O3 on CO2 fixation by RuBisCO was dominant. The δ15N value showed significant differences between treatments in both cultivars at seven days from the beginning of the exposure, which could be considered an early indicator of ozone pollution. Under increasingly frequent extreme climates globally, the relationships among stable isotope data, ecophysiological traits, and agronomic parameters could help breed future cultivars.

Effect of the elevated ozone on greening tree species of urban: Alterations in C-N-P stoichiometry and nutrient stock allocation to leaves and fine roots

Anthropogenic ground-level ozone (O3) pollution can alter the phosphorus (P), carbon (C), and nitrogen (N) of terrestrial plants’ ecological stoichiometry, which in turn affects forest productivity, nutrient utilization, and carbon sink capacity. However, there is still quite a lot of uncertainty regarding the impact of high O3 levels on C-N-P stoichiometry in organs with a rapid turnover (i.e., fine roots and leaves) across varied functional types. This study investigated the effects of O3 on the stoichiometry of C-N-P nutrient allocation of stocks to various plant organs, with a special focus on tree species frequently employed for urban greening. The impact of O3 on C-N-P stoichiometry among different functional tree types was subsequently evaluated by reviewing the published literature. Under a pooling of all species, elevated O3 decreased and leaf C and P concentrations increased, thereby decreasing the leaf C: P ratio. Elevated O3 increased the N concentration in fine roots, thereby decreasing the C: N ratio, although no significant impact was observed in leaves. Elevated O3 significantly reduced the leaf stocks of C (CSleaf) and N (NSleaf), however, there was no observed variation in these stocks in fine roots. The content of P, C, and N in fine roots and leaves in evergreen broadleaf species exceeded those in deciduous species. Elevated O3 significantly reduced CSleaf, NSleaf, and PSleaf in deciduous broadleaf species, whereas there was a significant reduction for the same in evergreen species. The literature analysis further demonstrated a larger O3-induced increment in leaf P concentration in deciduous species as compared to evergreen species. Elevated O3 significantly increased the difference in C and N stocks between fine roots and leaves in deciduous broadleaf species, whereas this difference was observed to decrease in evergreen species. The results of this study can facilitate an improved understanding of ecological stoichiometric responses of urban greening tree species under O3 stress and the resulting nutrient use strategies.

Parenchymal and Inflammatory Cell Responses to Single and Repeated Ozone Exposure in Healthy and Surfactant Protein-C Mutant Lung.

Mutations in the alveolar epithelial-specific gene encoding for surfactant protein C (SP-C) are linked to pulmonary disease. Ozone (O3) is a ubiquitous pollutant known to exacerbate stress through oxidative injury and inflammation. To comprehend the structural, functional, and immunological impact of single and repeated O3 exposure, SP-CWT and surfactant protein-C I73T mutant (SP-CI73T) mice were exposed to air or O3 (0.8 ppm, 3 h, up to ×4 consecutive days). O3 was associated with mitochondrial and autophagic activation (PINK1, LC3B, and p62), focal remodeling, and inflammation localized at the terminal bronchiole-to-alveolar junctions. Histological damage was exacerbated by repeated exposure. Single O3 challenge resulted in transient elastin fiber loss, whereas repeated exposure resulted in marked increases in elastance in SP-CI73T mice. Flow cytometric analysis revealed increases in classical monocyte and monocyte-derived macrophages recruitment in conditions of repeated exposure, which peaked earlier (24 h) in SP-CI73T mice. Immunohistochemical analysis also showed clustering of Arg-1+ and CD206+ activated cells within regions of remodeled lung. Lymphoid cell analysis identified CX3CR1-B220+ B cells accumulating after single (24/72 h). Repeated exposure produces a switch in the phenotype of these B cells CX3CR1+ (72 h) only in SP-CWT mice. SP-CI73T mutants also displayed depletion in NK1.1+ NKp46+ natural killer cells in lung, as well as bone marrow, blood, and spleen. These results illustrate the cumulative impact of O3 on lung structure and function in healthy lung, and aberrant myeloid and lymphoid recruitment in SP-C mutants responding to challenge. Together, this work highlights the significance of modeling environmental exposure across the spectrum of genetic susceptibility, consistent with human disease.

Projecting ozone impact on crop yield in Taiwan under climate warming

Ozone is a primary air pollutant that impairs photosynthesis and reduces crop yields, an effect that received little attention in Taiwan, especially under the context of climate warming. This study predicted the impact of surface O3 on cash crop yields, specifically in wheat, potatoes, and tomatoes, under 2 °C and 4 °C climate warming scenarios in Taiwan via high-resolution simulations. The simulated O3 concentration (daytime mean) over Taiwan's croplands during the growing seasons was around 35–52 ppb, and it increased by 0.9 and 2.1 ppb under 2 °C and 4 °C warming for wheat and potatoes. In contrast, more minor changes of around 0.4 ppb were found for tomatoes.The O3 concentrations were converted to AOT40 (Accumulated Ozone exposure over a threshold of 40 ppb) and POD3 (Phytotoxic Ozone Dose above a threshold of 3 nmol O3 m−2) metrics to estimate changes in relative yield (RY). The mean RYPOD3 (RYAOT40) reductions over irrigated cropland for wheat, tomatoes, and potatoes under current climate and O3-stress conditions are 27.5 % (19.1 %), 14.7 % (3.8 %), and 8.2 % (1.6 %), respectively. Under 2 °C warming, the additional reductions would be 2.7 % (1.8 %) for wheat, 4.1 % (0.3 %) for tomatoes, and 2.4 % (0.4 %) for potatoes; the values under 4 °C warming become 4.7 % (4.1 %) for wheat, 8.1 % (0.6 %) for tomatoes, and 5.2 % (0.8 %) for potatoes. The contribution of RYPOD3 reduction was separated into O3-induced and climate-induced effects. The former dominated the additional yield reduction under a 2 °C warming climate, yet, the latter prevailed under 4 °C warming. Further analysis indicated that the temperature rise enhances ozone uptake flux; still, the amplified water vapor deficit and more incoming solar radiation can offset it and weakens the overall meteorological effect, especially from 2 °C to 4 °C warming conditions. Such effects demonstrated a nonlinear effect related to the co-dependence of the ozone uptake flux, which requires attention in agriculture policymaking.

CO2 fertilization of crops offsets yield losses due to future surface ozone damage and climate change

Tropospheric ozone (O3) is harmful to plant productivity and negatively impacts crop yields. O3 concentrations are projected to decrease globally in the optimistic Representative Concentration Pathway of 2.6 W m–2 (RCP2.6) but increase globally following the high-emission scenario under the RCP8.5, with substantial implications for global food security. The damaging effect of O3 on future crop yield is affected by CO2 fertilization and climate change, and their interactions for RCP scenarios have yet to be quantified. In this study, we used the Joint UK Land Environment Simulator modified to include crops (JULES-crop) to quantify the impacts, and relative importance of present-day and future O3, CO2 concentration and meteorology on crop production at the regional scale until 2100 following RCP2.6 and RCP8.5 scenarios. We focus on eight major crop-producing regions that cover the production of wheat, soybean, maize, and rice. Our results show that CO2 alone has the largest effect on regional yields, followed by climate and O3. However, the CO2 fertilization effect is offset by the negative impact of tropospheric O3 in regions with high O3 concentrations, such as South Asia and China. Simulated crop yields in 2050 were compared with Food and Agriculture Organisation (FAO) statistics to investigate the differences between a socioeconomic and a biophysical process-based approach. Results showed that FAO estimates are closer to our JULES-crop RCP8.5 scenario. This study demonstrates that air pollution could be the biggest threat to future food production and highlights an urgent policy need to mitigate the threat of climate change and O3 pollution on food security.

Elevated Ozone Concentration and Nitrogen Addition Increase Poplar Rust Severity by Shifting the Phyllosphere Microbial Community.

Tropospheric ozone and nitrogen deposition are two major environmental pollutants. A great deal of research has focused on the negative impacts of elevated O3 and the complementary effect of soil N addition on the physiological properties of trees. However, it has been overlooked how elevated O3 and N addition affect tree immunity in face of pathogen infection, as well as of the important roles of phyllosphere microbiome community in host–pathogen–environment interplay. Here, we examined the effects of elevated O3 and soil N addition on poplar leaf rust [Melampsora larici-populina] severity of two susceptible hybrid poplars [clone ‘107’: Populus euramericana cv. ‘74/76’; clone ‘546’: P. deltoides Í P. cathayana] in Free-Air-Controlled-Environment plots, in addition, the link between Mlp-susceptibility and changes in microbial community was determined using Miseq amplicon sequencing. Rust severity of clone ‘107’ significantly increased under elevated O3 or N addition only; however, the negative impact of elevated O3 could be significantly mitigated when accompanied by N addition, likewise, this trade-off was reflected in its phyllosphere microbial α-diversity responding to elevated O3 and N addition. However, rust severity of clone ‘546’ did not differ significantly in the cases of elevated O3 and N addition. Mlp infection altered microbial community composition and increased its sensitivity to elevated O3, as determined by the markedly different abundance of taxa. Elevated O3 and N addition reduced the complexity of microbial community, which may explain the increased severity of poplar rust. These findings suggest that poplars require a changing phyllosphere microbial associations to optimize plant immunity in response to environmental changes.