Effects Of Tropospheric Ozone Research Articles

Tropical tropospheric ozone distribution and trends from in situ and satellite data

Abstract. Tropical tropospheric ozone (TTO) is important for the global radiation budget because the longwave radiative effect of tropospheric ozone is higher in the tropics than midlatitudes. In recent decades the TTO burden has increased, partly due to the ongoing shift of ozone precursor emissions from midlatitude regions toward the Equator. In this study, we assess the distribution and trends of TTO using ozone profiles measured by high-quality in situ instruments from the IAGOS (In-Service Aircraft for a Global Observing System) commercial aircraft, the SHADOZ (Southern Hemisphere ADditional OZonesondes) network, and the ATom (Atmospheric Tomographic Mission) aircraft campaign, as well as six satellite records reporting tropical tropospheric column ozone (TTCO): TROPOspheric Monitoring Instrument (TROPOMI), Ozone Monitoring Instrument (OMI), OMI/Microwave Limb Sounder (MLS), Ozone Mapping Profiler Suite (OMPS)/Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2), Cross-track Infrared Sounder (CrIS), and Infrared Atmospheric Sounding Interferometer (IASI)/Global Ozone Monitoring Experiment 2 (GOME2). With greater availability of ozone profiles across the tropics we can now demonstrate that tropical India is among the most polluted regions (e.g., western Africa, tropical South Atlantic, Southeast Asia, Malaysia and Indonesia), with present-day 95th percentile ozone values reaching 80 nmol mol−1 in the lower free troposphere, comparable to midlatitude regions such as northeastern China and Korea. In situ observations show that TTO increased between 1994 and 2019, with the largest mid- and upper-tropospheric increases above India, Southeast Asia, and Malaysia and Indonesia (from 3.4 ± 0.8 to 6.8 ± 1.8 nmol mol−1 decade−1), reaching 11 ± 2.4 and 8 ± 0.8 nmol mol−1 decade−1 close to the surface (India and Malaysia–Indonesia, respectively). The longest continuous satellite records only span 2004–2019 but also show increasing ozone across the tropics when their full sampling is considered, with maximum trends over Southeast Asia of 2.31 ± 1.34 nmol mol−1 decade−1 (OMI) and 1.69 ± 0.89 nmol mol−1 decade−1 (OMI/MLS). In general, the sparsely sampled aircraft and ozonesonde records do not detect the 2004–2019 ozone increase, which could be due to the genuine trends on this timescale being masked by the additional uncertainty resulting from sparse sampling. The fact that the sign of the trends detected with satellite records changes above three IAGOS regions, when their sampling frequency is limited to that of the in situ observations, demonstrates the limitations of sparse in situ sampling strategies. This study exposes the need to maintain and develop high-frequency continuous observations (in situ and remote sensing) above the tropical Pacific Ocean, the Indian Ocean, western Africa, and South Asia in order to estimate accurate and precise ozone trends for these regions. In contrast, Southeast Asia and Malaysia–Indonesia are regions with such strong increases in ozone that the current in situ sampling frequency is adequate to detect the trends on a relatively short 15-year timescale.

Modeling the effects of tropospheric ozone on the growth and yield of global staple crops with DSSAT v4.8.0

Abstract. Elevated surface ozone (O3) concentrations can negatively impact growth and development of crop production by reducing photosynthesis and accelerating leaf senescence. Under unabated climate change, future global O3 concentrations are expected to increase in many regions, adding additional challenges to global agricultural production. Presently, few global process-based crop models consider the effects of O3 stress on crop growth. Here, we incorporated the effects of O3 stress on photosynthesis and leaf senescence into the Decision Support System for Agrotechnology Transfer (DSSAT) crop models for maize, rice, soybean, and wheat. The advanced models reproduced the reported yield declines from observed O3-dose field experiments and O3 exposure responses reported in the literature (O3 relative yield loss RMSE <10 % across all calibrated models). Simulated crop yields decreased as daily O3 concentrations increased above 25 ppb, with average yield losses of 0.16 % to 0.82 % (maize), 0.05 % to 0.63 % (rice), 0.36 % to 0.96 % (soybean), and 0.26 % to 1.23 % (wheat) per ppb O3 increase, depending on the cultivar O3 sensitivity. Increased water deficit stress and elevated CO2 lessen the negative impact of elevated O3 on crop yield, but potential yield gains from CO2 concentration increases may be counteracted by higher O3 concentrations in the future, a potentially important constraint to global change projections for the latest process-based crop models. The improved DSSAT models with O3 representation simulate the effects of O3 stress on crop growth and yield in interaction with other growth factors and can be run in the parallel DSSAT global gridded modeling framework for future studies on O3 impacts under climate change and air pollution scenarios across agroecosystems globally.

Effect of tropospheric ozone and its protectants on gas exchange parameters, antioxidant enzymes and quality of Garlic (Allium sativum. L).

An experimental study was conducted to assess the detrimental effect of ground-level ozone (O3) on garlic physiology and to find out appropriate control measures against ground-level O3, at TNAU-Horticultural Research farm, Udhagamandalam. Elevated ground ozone levels significantly decreased garlic leaf chlorophyll, photosynthetic rate, stomatal conductance, total soluble solids and pungency. The garlic chlorophyll content was highest in ambient ozone level and lowest in elevated ozone@200ppb, highest stomatal conductance was recorded in ambient ozone with foliar spray of 3%Panchagavya, and the lowest was observed in elevated ozone@200ppb. Since the elevated O3 had reduced in garlic photosynthetic rate significantly the lowest was observed in elevated O3@200ppb and the highest photosynthetic rate was observed in ambient Ozone with foliar spray 3% of panchagavya after a week. The antioxidant enzymes of garlic were increased with increased concentration of tropospheric ozone. The highest catalase (60.97µg of H2O2/g of leaf) and peroxidase (9.13 ΔA/min/g of leaf) concentration was observed at 200ppb elevated ozone level. Garlic pungency content was highest in ambient ozone with foliar spray of 0.1% ascorbic acid and the lowest was observed under elevated O3@200ppb. Highest total soluble solids were observed in ambient ozone with foliar spray of 3%Panchagavya and the lowest observed in elevated ozone@200ppb. Thus, tropospheric ozone has a detrimental impact on the physiology of crops, which reduced crop growth and yield. Under elevated O3 levels, ascorbic acid performed well followed by panchagavya and neem oil. The antioxidant such as catalase and peroxidase had positive correlation among themselves and had negative correlation with chlorophyll content, stomatal conductance, photosynthetic rate, pungency and TSS. The photosynthetic rate has high positive correlation with chlorophyll content, pungency and TSS. Correlation analysis confirmed the negative effects of tropospheric ozone and garlic gas exchange parameters and clove quality. The ozone protectants will reduce stomatal opening by which the entry of O3 in to the cell will be restricted and other hand they also will alleviate ROS and allied stresses.

Evidence for tropospheric ozone effects on rice production in Bangladesh

Although Bangladesh is known to be burdened with elevated tropospheric ozone levels, little is known about its effects on food security. We conducted field experiments in four highly polluted rice growing environments of Bangladesh in three cropping seasons (2020−2022), in which we grew 20 different rice varieties with or without application of the ozone protectant ethylene diurea (EDU). The average daytime ozone concentrations at the study sites during the rice growing seasons ranged from 53 ppb to 84 ppb, with the lowest concentrations occurring in the year 2020. EDU increased rice grain yields significantly by an average of 10.4 % across all seasons and locations, indicating that plants were stressed under ambient ozone concentrations. EDU was effective in distinguishing ozone-tolerant from ozone-sensitive varieties, in which yield increased by up to 21 %. Likewise, the EDU treatment positively affected vegetation indices representing chlorophyll (NDVI), the chorophyll:carotenoid ratio (Lic2), and pigments of the xanthophyll cycle (PRI). Stomatal conductance was increased significantly by an average of around 10 % among all varieties when plants were treated with EDU. In all physiological traits, significant genotype by treatment interactions occurred, indicating that different varieties varied in their responses to ozone stress. Our study demonstrates that rice production in Bangladesh is severely affected by tropospheric ozone, and calls for the breeding of tolerant rice varieties as well as mitigation measures to reduce air pollution.

Impact of Elevated Ozone on Cabbage

Tropospheric ozone (O3) is a pervasive greenhouse gas and air pollutant known for its detrimental effects on human health and vegetation. In the recent years, tropospheric ozone has been rising steadily on the account of rapid urbanization and globalization. Hence, a study to investigate the impact of elevated ozone levels on cabbage cultivars have been initiated. The cultivars Tekila and Primero, which are extensively grown in the high-altitude region of the Western Ghats, India were used as test crop, where ozone levels are a growing concern. The study employed a comprehensive experimental design, encompassing ozone stress (200 ppb), cabbage varieties (Tekila and Primero), and different growth stages of the cabbage plants. Ozone fumigation at 200 ppb was used to simulate elevated ozone conditions, reflecting potential future scenarios. To assess the extent of impact both physiological and biochemical parameters were extensively analyzed. The results revealed that elevated ozone concentrations had a significant negative impact on both cabbage cultivars. Photosynthetic rate, stomatal conductance, and chlorophyll content declined progressively as ozone exposure continued, leading to maximum reductions of 71.2, 81.03 and 32.98% respectively. However, protective mechanisms were activated in response to ozone stress, including increased proline by 32.24%, ascorbic acid by 64.75%, catalase by 3.58%, and peroxidase activities by 56%, suggesting the cabbage plants' efforts to mitigate oxidative damage. Overall, this study highlights the vulnerability of cabbage cultivars to elevated ozone levels and emphasizes the need for effective mitigation strategies to safeguard crop productivity and ensure sustainable agriculture in regions facing escalating ozone pollution. Further research is essential to develop and implement solutions that can protect vital crops like cabbage from the adverse effects of tropospheric ozone.

Short-term effects of tropospheric ozone and other environmental factors on emergency admissions due to pregnancy complications: A time-series analysis in the Madrid Region

Air pollution has been linked to adverse neonatal outcomes, mainly in the case of prolonged exposures. This study focuses on the short-term effects on maternal health.We conducted a retrospective ecological time-series study in the Madrid Region covering the period 2013–2018. The independent variables were mean daily concentrations of tropospheric ozone (O3), particulate matter (PM10/PM2.5) and nitrogen dioxide (NO2), as well as noise levels. The dependent variables were daily emergency hospital admissions due to complications in pregnancy, childbirth and the puerperium. Poisson generalised linear regression models were fitted to quantify the relative and attributable risks, controlling for trend, seasonality, the autoregressive nature of the series, and a number of meteorological factors.There were 318 069 emergency hospital admissions due to obstetric complications across the 2191 days of study. Of this total: 13 164 (95%CI: 9930–16 398) admissions were attributable to exposure to O3, the only pollutant to show a statistically significant (p < 0.05) association with admissions due to hypertensive disorders; and 10 575 (95%CI: 3573–17 566) admissions were attributable to daytime noise levels, while admissions due to hyperemesis gravidarum and vomiting were related to exposure to night noise. Other pollutants which also displayed statistically significant associations were: NO2 concentrations, with admissions due to vomiting and preterm labour; PM10 concentrations, with premature rupture of membranes: and PM2.5 concentrations, with total complications.Exposure to a range of air pollutants, and ozone in particular, is associated with a higher number of emergency hospital admissions due to gestational complications. Hence, surveillance of environmental effects on maternal health should be intensified, and plans and strategies to minimise these should be drawn up.

Effectiveness of ethylene diurea in ameliorating ozone stress in blackgram varieties (Vigna mungo L.)

ABSTRACT Tropospheric ozone, a phytotoxic air pollutant, has inadvertently increased since industrial era and its effect on agricultural crops has gained urgent scientific attention. The present study aims to evaluate the response of blackgram varieties (Vigna mungo L.) exposed to elevated ozone stress (100 ppb) with antiozonant (Ethylene diurea at 300 ppm). The study was conducted during two seasons and the effectiveness of ethylene diurea (EDU) was explored in terms of plant physiology, biochemistry, antioxidant enzymes, growth, yield and spectral reflectance of blackgram varieties. Ethylene diurea ameliorates the ozone stress by increasing photosynthetic rate by 40.78 and 37.21% in season I and 43.03 and 35.77% in season II for VBN3 and VBN8, respectively, and antioxidant enzyme superoxide dismutase by 24.31 and 19.42% in season I and 22.59 and 18.59% in season II for VBN3 and VBN8, respectively. The growth indices and yield traits were significantly increased with the application of EDU and the effect was more pronounced in sensitive cultivar (VBN3) compared to the tolerant (VBN8) one. Spectral reflectance, a non-destructive study, further validates the effect of tropospheric ozone on blackgram varieties. Newly identified spectral indices [R566, R573], and [R564, R586] demonstrated the greatest potential in detecting ozone sensitivity of blackgram varieties.

The effects of tropospheric ozone on plant species: New perspectives

The effect of tropospheric ozone on the physiology of plants has been well established using physicochemical analysis and visual assessment. One of the main metabolic processes, in plants that is affected by ozone, is photosynthesis. This in turn affects a number of secondary processes required for the survival of plants. This study focused on two main aspects; the qualitative determination of damage through visual assessment and the quantification of damage through the determination of the content of chlorophyll and other quality parameters using spectrophotometric techniques in a number of plant species. Three distinct setups were considered, mainly rural, urban and semiurban, representing the topography of the islands of Malta and Gozo. It was observed that chlorosis was not the sole factor contributing to the yellowing of the leaves. Another important finding was the correlation between ozone levels (50.18-69.35 ppb) and the anthocyanin content (2.57-28.99 mg/kg) of leaves. From the three plant species that were extensively studied (Nerium oleander, Pinus halepensis and Schinus terebinthifolius), the N. oleander exhibited promising results as a bioindicator for ozone-induced damage. Due to the presence of this ornamental plant in rural and urban areas, it can be used by researchers and authorities as a tool for assessment of tropospheric ozone levels.

Interactive effects of tropospheric ozone and blast disease (Magnaporthe oryzae) on different rice genotypes

Rising tropospheric ozone concentrations can cause rice yield losses and necessitate the breeding of ozone-tolerant rice varieties. However, ozone tolerance should not compromise the resistance to important biotic stresses such as the rice blast disease. Therefore, we investigated the interactive effects of ozone and rice blast disease on nine different rice varieties in an experiment testing an ozone treatment, blast inoculation, and their interaction. Plants were exposed to an ozone concentration of 100 ppb for 7 h per day or ambient air throughout the growth period. Half of the plants were simultaneously infected with rice blast inoculum. Grain yield was significantly reduced in the blast treatment (17%) and ozone treatment (37%), while the combination of both stresses did not further decrease grain yields compared to ozone alone. Similar trends occurred for physiological traits such as vegetation indices, normalized difference vegetation index (NDVI), photochemical reflectance index (PRI), Lichtenthaler index 2 (Lic2), and anthocyanin reflectance index 1 (ARI1), as well as stomatal conductance and lipid peroxidation. Ozone exposure mitigated the formation of visible blast symptoms, while blast inoculation did not significantly affect visible ozone symptoms. Although different genotypes showed contrasting responses to the two types of stresses, no systematic pattern was observed regarding synergies or trade-offs under the two types of stresses. Therefore, we conclude that despite the similarities in physiological stress responses to ozone and blast, the tolerance to these stresses does not appear to be genetically linked in rice.

Effects of tropospheric ozone on groundnut (Arachis hypogea L.) cultivars: Role of plant age and antioxidative potential

Ozone (O3) is a secondary atmospheric pollutant present in the tropospheric environment. Ozone enters in internal tissue of leaf through stomata and produces reactive oxygen species (ROS) which damages cellular membrane, alter gene expression and metabolic activities and ultimately caused death of the plant tissues. Certain defensive mechanism occurs in the internal part of leaves to eliminate generated ROS. However, there is significant change in the levels and kind of defence traits as plants develop from the seedling to juvenile to mature and senescent stages. A field study was conducted for two consecutive seasons with five cultivars of groundnut (Arachis hypogea L cv. TG-37A, TPG-41, TAG-24, GG-20, and Dh-86) to assess the intra-specific variation in defensive response against ozone at various plant developmental stage. Results of the study showed that ozone significantly affected biomass and primary metabolites, generate ROS and increases membrane permeability in all the groundnut cultivars. In response to ROS, groundnut cultivars produced non-enzymatic and enzymatic antioxidants. Study found that the severity of the effect varied among the cultivars and by developmental stages. Cultivar Dh-86 showed higher antioxidative activity and least biomass sensitivity to ozone. Although accumulation of non-enzymatic antioxidants was present to provided defence against ozone, activity of enzymatic antioxidants varied at different growth stages and corresponds to the biomass sensitivity. Study concluded that the ozone phytotoxicity is dependent on the antioxidative potential of the cultivars and the growth stage of the plant. Further, the activity of APX played a measure role for age dependent plant sensitivity in groundnut.

The effects of tropospheric ozone on oaks: A global meta-analysis

Tropospheric ozone (O3) levels are still elevated in many regions of the world including Northern Hemisphere forests areas, and are predicted to increase further due to anthropogenic activities and climate change. Oaks are major woody angiosperms in the Northern Hemisphere in terms of biodiversity, ecological dominance, and economic values. This meta-analysis shows overwhelming evidence of the O3 effects on 51 growth, anatomical, biomass, physiological and biochemical parameters of 14 deciduous or evergreen oak species distributed all around the Northern Hemisphere. Although no large impacts were observed on biomass, suggesting an O3 tolerance by oaks, some impairments were found at physiological level that might negatively affect carbon sequestration and water vapour transfer to the atmosphere. This outcome suggests the need to incorporate this phenomenon into future projection studies dealing with how atmospheric change and forest biomes will interact in effecting climatic change. Among the antioxidants used by oaks to respond to O3, phenols seem to have a crucial role. Deciduous species resulted more affected by O3 than evergreen ones, as well as oaks native to Eurasia, in comparison with those from North-America. Experiments performed in less controlled environments showed more O3 deleterious effects, especially under higher AOT40 levels, but negative impacts were also reported for acute O3 exposures. Most of the reviewed studies with additional treatments to O3 exposure investigated the interaction(s) between O3 and drought, but the negative effects induced by drought seemed not to be exacerbated by the pollutant. However, more combined experiments on the impact of O3 and co-occurring stressors on woody species are necessary. Another major issue is the lack of experiments on adult trees. To better understand O3 impacts, and to reinforce the strength of O3 impact predictions, O3 controlled experiments on young individuals should be combined with long-term experiments on mature trees grown in open-air conditions.

Effects of ozone phytotoxicity in reducing the yield and nutritional quality of chilli (Capsicum annuum L.)

This study was designed to assess the effects of tropospheric ozone (O3) on the yield and nutritional quality of chilli (Capsicum annuum L. cv. Pusa Jwala) using ethylene diurea (EDU) under field conditions in Peshawar, Pakistan. Average O3 concentration ranged between 38 and 68 ppb which is high enough to cause phytotoxic effects. Accumulated ozone exposure over a threshold of 40 ppm h (AOT40) value calculated for 3-month period was found to be substantially higher, i.e., 7.3 ppm h. Various growth and yield parameters analyzed on weekly basis showed that the plant height (6.3%), number of flowers (15%), fruits (36%), and total dry biomass (30%) and its nutritional quality parameters such as mean crude protein, fat, and fiber showed 24%, 100%, and 12% better results in EDU-treated plants as compared with control, respectively. However, mineral contents showed no significant difference (p < 0.05) for both the groups. The results of this study concluded that ambient O3 is a threat to the selected plant species thus affecting its quality and yield and EDU remains successful in protecting the chilli (Capsicum annuum L.) against the negative effects of tropospheric ozone.

Responses of a semi-natural grassland community of tropical region to elevated ozone: An assessment of soil dynamics and biomass accumulation

Despite knowing the phytotoxic effects of tropospheric ozone (O3), which is of global concern, there is no study so far reported about its impacts on grassland community of tropical regions. Therefore, we assessed the responses of a semi-natural grassland community of Indo-Gangetic plains to elevated O3 exposure (Ambient + 20 ppb) compared to ambient after three years of exposure using open-top chambers. Percent decreases were found in above (26%; p ≤ 0.002) and belowground (30%; p ≤ 0.003) biomass under elevated compared to ambient O3 exposure. Percent decrements in total organic carbon (TOC; 24%; p ≤ 0.001), total nitrogen (29%; p ≤ 0.001) and available phosphorus (11%; p ≤ 0.002) in the soil were also observed under elevated O3 exposure. Exposure at elevated O3 reduced soil microbial biomass and activities of β-glucosidase, amylase, urease and phosphatase, while polyphenol oxidase and peroxidase showed enhancement in their activities, showing negative effects on belowground soil health. Percent reduction in root shoot ratio (10%; p ≤ 0.05) depicts that less C-allocation towards root system led to a reduction in TOC in the soil, which could affect C-sequestration under elevated O3 condition in the semi-natural grasslands. Elevated O3 also affected enzymes participating in N and P-cycles, causing reductions in total nitrogen and phosphorus. The study concludes that projected O3 concentrations have serious implications for aboveground biomass as well as belowground soil health in tropical areas, identified as hotspots of O3 in the world.

Macro- and microscopic leaf injury triggered by ozone stress in beech foliage (Fagus sylvatica L.)

The diversity of structural injury underlying visible symptoms by ozone stress resulted from the succession of degenerative processes and programmed-cell death events, depending on the ozone uptake and varying on a year-to-year basis. The effects of tropospheric ozone (O3) on the vegetation will remain a lasting concern during the twenty-first century, and deeper understanding of functional and structural responses to O3 in plant foliage in a changing environment is needed. Comprehensive analysis of the O3 injury spectrum, with a view to functional understanding of cellular processes in response to varying O3 doses. Characterization of macro- and microscopic symptoms in the sun crown foliage of adult trees exposed to ambient and twice ambient O3 levels in a Free Air O3 Enrichment (FACE) experiment using light and electron microscopy. Visible injury triggered by O3 resulted from (i) degenerative processes of varying severity (photobleaching, accelerated cell senescence, ACS), (ii) programmed cell death with disruption of cell content (hypersensitive reaction–like, HR-like) and occasional leakage of cellular debris into the apoplast, (iii) overlapping degenerative and disruptive processes, primarily in the upper mesophyll and within organelles prone to oxidative stress (chloroplasts and mitochondria) and (iv) necrosis in lower mesophyll with leakage of cellular debris in the intracellular space. Especially the degenerative and disruptive traits showed contrasting structural features. In the case of stippling symptoms, the structural variability was particularly high, as a consequence of interactions between early degenerative and late disruptive processes. These findings thus confirmed the close dependency of processes—and a further spectrum of ozone injury—on rates of ozone uptake. Such relationships and development of injury, as observed in the case of beech (Fagus sylvatica L.) foliage, are expected to be basically similar in other broadleaved tree species.

Modeling the effects of tropospheric ozone on wheat growth and yield

Abstract Elevated tropospheric ozone (O3) concentrations can negatively impact wheat growth by reducing photosynthesis and accelerating leaf senescence. Future global O3 concentrations are expected to increase in many regions, which will further limit global wheat production. However, few crop models consider the effects of O3 stress on wheat. We incorporated the effects of O3 stress on photosynthesis and leaf senescence into the DSSAT-NWheat crop model and reproduced an observed experiment and reported yield declines from the literature. Simulated wheat yields decreased as daily O3 concentrations increased above 25 ppb, with yield losses ranging from 0.26% to 0.95% per ppb O3 increase, depending on the cultivar O3 sensitivity. The model reproduced known wheat physiological responses from the combination of O3 stress with water deficit and elevated atmospheric CO2 concentration. Increased water deficit stress and elevated atmospheric CO2 both reduce the negative impact of O3, but yield benefits from elevated CO2 can be lost due to elevated O3 concentrations. The O3-modified NWheat model simulates the effects of O3 stress on wheat growth and yield in interaction with other growth factors and can be used for studies on climate change and O3 impacts.

Closing the global ozone yield gap: Quantification and cobenefits for multistress tolerance.

Increasing both crop productivity and the tolerance of crops to abiotic and biotic stresses is a major challenge for global food security in our rapidly changing climate. For the first time, we show how the spatial variation and severity of tropospheric ozone effects on yield compare with effects of other stresses on a global scale, and discuss mitigating actions against the negative effects of ozone. We show that the sensitivity to ozone declines in the order soybean>wheat>maize>rice, with genotypic variation in response being most pronounced for soybean and rice. Based on stomatal uptake, we estimate that ozone (mean of 2010-2012) reduces global yield annually by 12.4%, 7.1%, 4.4% and 6.1% for soybean, wheat, rice and maize, respectively (the "ozone yield gaps"), adding up to 227Tg of lost yield. Our modelling shows that the highest ozone-induced production losses for soybean are in North and South America whilst for wheat they are in India and China, for rice in parts of India, Bangladesh, China and Indonesia, and for maize in China and the United States. Crucially, we also show that the same areas are often also at risk of high losses from pests and diseases, heat stress and to a lesser extent aridity and nutrient stress. In a solution-focussed analysis of these results, we provide a crop ideotype with tolerance of multiple stresses (including ozone) and describe how ozone effects could be included in crop breeding programmes. We also discuss altered crop management approaches that could be applied to reduce ozone impacts in the shorter term. Given the severity of ozone effects on staple food crops in areas of the world that are also challenged by other stresses, we recommend increased attention to the benefits that could be gained from addressing the ozone yield gap.

Short-term effect of tropospheric ozone on daily mortality in Spain

BackgroundStudies that seek to link the impact of ozone with mortality display a number of uncertainties. This study sought to ascertain the functional relationship between ozone and mortality, and analyse its short-term impact on daily natural-, respiratory- and circulatory-cause mortality in Spain. MethodsWe analysed data on daily natural- (ICD 10: A00-R99), respiratory- (ICD 10: J00-J99) and circulatory-cause mortality (ICD 10: I00-I99) for each of Spain's 52 provinces across the period 2000–2009. We calculated the impact of ozone on mortality by reference to relative risks (RRs) using generalised linear models, and performed an overall meta-analysis. Attributable mortality was calculated on the basis of RRs. ResultsA quadratic relationship was observed and the existence of a threshold value identified in 33 of the 46 monitoring stations judged to be valid for ozone data, this threshold value was located above the 80th percentile. The overall RRs for 10 μg/m3 increases in concentrations of the O3 threshold value were as follows: 1.033 (95%CI: 1.023–1.044) for natural causes; 1.089 (95%CI: 1.058–1.120) for respiratory causes; and 1.025 (95%CI: 1.018–1.033) for mortality circulatory causes. The annual total of natural-cause ozone-attributable deaths was 499 (95%CI: 277–717), 126 of which (95%CI: 54–194) were due to respiratory causes and 167 (95%CI: 39–293) to circulatory causes. ConclusionsHigh ozone concentrations display a quadratic relationship with daily mortality. While this effect is more pronounced in respiratory causes, there is also a short-term effect on natural- and circulatory-cause mortality.

Ozone pollution will compromise efforts to increase global wheat production.

Introduction of high-performing crop cultivars and crop/soil water management practices that increase the stomatal uptake of carbon dioxide and photosynthesis will be instrumental in realizing the United Nations Sustainable Development Goal (SDG) of achieving food security. To date, however, global assessments of how to increase crop yield have failed to consider the negative effects of tropospheric ozone, a gaseous pollutant that enters the leaf stomatal pores of plants along with carbon dioxide, and is increasing in concentration globally, particularly in rapidly developing countries. Earlier studies have simply estimated that the largest effects are in the areas with the highest ozone concentrations. Using a modelling method that accounts for the effects of soil moisture deficit and meteorological factors on the stomatal uptake of ozone, we show for the first time that ozone impacts on wheat yield are particularly large in humid rain-fed and irrigated areas of major wheat-producing countries (e.g. United States, France, India, China and Russia). Averaged over 2010-2012, we estimate that ozone reduces wheat yields by a mean 9.9% in the northern hemisphere and 6.2% in the southern hemisphere, corresponding to some 85Tg (million tonnes) of lost grain. Total production losses in developing countries receiving Official Development Assistance are 50% higher than those in developed countries, potentially reducing the possibility of achieving UN SDG2. Crucially, our analysis shows that ozone could reduce the potential yield benefits of increasing irrigation usage in response to climate change because added irrigation increases the uptake and subsequent negative effects of the pollutant. We show that mitigation of air pollution in a changing climate could play a vital role in achieving the above-mentioned UN SDG, while also contributing to other SDGs related to human health and well-being, ecosystems and climate change.

Impact of Tropospheric Ozone on Summer Climate in China

The spatial distribution, radiative forcing, and climatic effects of tropospheric ozone in China during summer were investigated by using the regional climate model RegCM4. The results revealed that the tropospheric ozone column concentration was high in East China, Central China, North China, and the Sichuan basin during summer. The increase in tropospheric ozone levels since the industrialization era produced clear-sky shortwave and clear-sky longwave radiative forcing of 0.18 and 0.71 W m–2, respectively, which increased the average surface air temperature by 0.06 K and the average precipitation by 0.22 mm day–1 over eastern China during summer. In addition, tropospheric ozone increased the land–sea thermal contrast, leading to an enhancement of East Asian summer monsoon circulation over southern China and a weakening over northern China. The notable increase in surface air temperature in northwestern China, East China, and North China could be attributed to the absorption of longwave radiation by ozone, negative cloud amount anomaly, and corresponding positive shortwave radiation anomaly. There was a substantial increase in precipitation in the middle and lower reaches of the Yangtze River. It was related to the enhanced upward motion and the increased water vapor brought by strengthened southerly winds in the lower troposphere.

Effects of Tropospheric Ozone (O3) on Yield and Nutritional Quality of Mung Bean (Vigna radiata Cv. MN 98): Evidence from Pakistan

The effects of ambient ozone concentrations on the yield and nutritional quality of Mung bean (MN-98) grown in Northern Pakistan was assessed using EDU. Passive samplers results revealed that ozone was significantly lower (24.2 ppb) in April compared to May, June (49 ppb). The mean pods number/plants, length/plant, and biomass of both fresh and dry weight of EDU and NEDU treated plants were all significantly not different. The mean biomass for EDU leaves was (4.0 g) and significantly reduced compared to NEDU (2.8 g). The mean root length and shoot biomass of EDU plants compared to NEDU treated plants remained unchanged. However, the total biomass of EDU plants were significantly higher (10.0 g) compared to NEDU (7.3 g). The overall plant biomass was 30% significantly higher than N-EDU plants. The nutritional quality parameters (Ash, Moisture, Fats, Fiber and Protein) reduced significantly in NEDU seeds compared to EDU. The %moisture contents of seeds was (F=0.017; p<0.05), %Ash (F=3.987; p<0.05), %Protein (F=3.467; p<0.05) %Fats (F=2.574; p<0.05), %Fiber content was positively affected by EDU treatment. It was concluded that ozone is directly affecting the growth and quality of summer crops grown in Pakistan that can affect the future food security of the region.