Elevated Ozone Concentrations Research Articles

Changes in first- and second-order sensitivities of ozone concentration to its precursors over the Yangtze River Delta region of China due to COVID-19 lockdown: Insights from CMAQ-HDDM modeling study

Elevated ozone (O3) concentration during the COVID-19 lockdown is a matter of great concern, but the changes of its sensitivities to key precursors remains unclear. This study utilized the Community Multiscale Air Quality (CMAQ) model coupled with the Higher-order Decoupled Direct Method in Three Dimensions (HDDM-3D) and the process analysis (PA) modules to reveal in detail the changes in O3-precursors sensitivities and the contribution of major chemical and physical processes to O3 formation/loss during the month-long COVID-19 lockdown in early 2020 over the Yangtze River Delta (YRD) region of China. The results indicate that the contributions (absolute value) of gas-phase chemistry to O3 and Ox (i.e., O3+NO2) were reduced by 35–50% and 8–24%, respectively, under lockdown-specific (LCD) scenario compared with the business-as-usual (BAU) scenario in the highly urbanized areas of eastern and central YRD. Under the BAU (LCD) scenario, the first-order and second-order O3-NOx sensitivities averaged about −25 (−36) μg/m3 and about 8 (28) μg/m3, respectively. These 1st- and 2nd-order sensitivities of O3 to NOx were both intensified due to COVID-19 lockdown, which potentially contributed to O3 increases of between 5 and 10 μg/m3. In other words, the concentration of O3 and its rate of increase were both amplified due to COVID-19 lockdown. Overall, this study highlighted a significant wintertime “NOx reduction disbenefit” phenomenon over YRD because of both strong 1st-order (negative) and 2nd-order (positive) O3 sensitivities to NOx emissions, which were further reinforced due to COVID-19 lockdown.

Role of Elevated Ozone on Development and Metabolite Contents of Lemongrass [Cymbopogon flexuosus (Steud.) (Wats.)

The present study was conducted to assess the effect of elevated ozone stress on the development and metabolite contents of lemongrass, a medicinal plant. The experimental plant was exposed to two elevated ozone concentrations (ambient + 15 ppb, and ambient + 30 ppb) using open-top chambers. Samplings were carried out at 45 and 90 days after transplantation (DAT), for the analysis of different characteristics, while the metabolite contents of leaves and essential oils were analyzed at 110 DAT. Both the doses of elevated ozone had notable negative effects on the carbon fixation efficiency of plants, resulting in a significant reduction in plant biomass. Enzymatic antioxidant activity increased during the second sampling, which suggests that the scavenging of reactive oxygen species was more prominent in lemongrass during the later developmental stage. The results of the present study showed a stimulated diversion of resources towards the phenylpropanoid pathway, which is made evident by the increase in the number and contents of metabolites in foliar extract and essential oils of plants grown at elevated ozone doses, as compared to ambient ozone. Elevated ozone not only upregulated the contents of medicinally important components of lemongrass, it also induced the formation of some pharmaceutically active bio compounds. On the basis of this study, it is expected that increasing ozone concentrations in near future will enhance the medicinal value of lemongrass. However, more experiments are required to validate these findings.

Two decades of fumigation data from the Soybean Free Air Concentration Enrichment facility

The Soybean Free Air Concentration Enrichment (SoyFACE) facility is the longest running open-air carbon dioxide and ozone enrichment facility in the world. For over two decades, soybean, maize, and other crops have been exposed to the elevated carbon dioxide and ozone concentrations anticipated for late this century. The facility, located in East Central Illinois, USA, exposes crops to different atmospheric concentrations in replicated octagonal ~280 m2 Free Air Concentration Enrichment (FACE) treatment plots. Each FACE plot is paired with an untreated control (ambient) plot. The experiment provides important ground truth data for predicting future crop productivity. Fumigation data from SoyFACE were collected every four seconds throughout each growing season for over two decades. Here, we organize, quality control, and collate 20 years of data to facilitate trend analysis and crop modeling efforts. This paper provides the rationale for and a description of the SoyFACE experiments, along with a summary of the fumigation data and collation process, weather and ambient data collection procedures, and explanations of air pollution metrics and calculations.

Estimation of Stratospheric Intrusions During Indian Cyclones

AbstractDeep convection associated with tropical cyclones leads to stratosphere‐troposphere exchange (STE), which affects the upper‐tropospheric ozone concentrations in the vicinity of the cyclones. This study estimates the ozone enhancements over India due to the North Indian Ocean (NIO) cyclones‐driven STE. Indicators such as stratospheric fraction and potential vorticity calculated using the reanalysis data sets suggest that roughly 70% of the cyclones show anomalously high stratospheric intrusions. Aircraft observations over different locations across India also show elevated ozone concentrations in the mid‐to‐upper troposphere on cyclone days. Further, ozone and stratospheric ozone tracer concentrations from Goddard Earth Observing System‐Chemistry simulations and the Copernicus Atmosphere Monitoring Service reanalysis data sets show up to 40 ppb of excess upper tropospheric ozone over India, of which stratospheric ozone accounts for roughly 60%. Stratospheric intrusion due to the Bay of Bengal and the Arabian Sea cyclones affected the upper tropospheric ozone amounts over North and South India, respectively. The stratospheric ozone was observed to propagate downwards into the troposphere, often reaching ∼600 hPa and, in some cases, even the surface.

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.

Assessing the contribution of open crop straw burning to ground-level ozone and associated health impacts in China and the effectiveness of straw burning bans

In recent years, ozone pollution in China has been shown to increase in frequency and persistence despite the concentrations of fine particulate matter (PM2.5) decreasing steadily. Open crop straw burning (OCSB) activities are extensive in China and emit large amounts of trace gases during a short period that could lead to elevated ozone concentrations. This study addresses the impacts of OCSB emissions on ground-level ozone concentration and the associated health impact in China. Total VOCs and NOx emissions from OCSB in 2018 were 798.8 Gg and 80.6 Gg, respectively, with high emissions in Northeast China (31.7%) and North China (23.7%). Based on simulations conducted for 2018, OCSB emissions are estimated to contribute up to 0.95 µg/m3 increase in annual averaged maximum daily 8-hour (MDA8) ozone and up to 1.35 µg/m3 for the ozone season average. The significant impact of OCSB emissions on ozone is mainly characterized by localized and episodic (e.g., daily) changes in ozone concentration, up to 20 µg/m3 in North China and Yangtze River Delta region and even more in Northeast China during the burning season. With the implementation of straw burning bans, VOCs and NOx emissions from OCSB dropped substantially by 46.9%, particularly over YRD (76%) and North China (60%). Consequently, reduced OCSB emissions result in an overall decrease in annual averaged MDA8 ozone, and reductions in monthly MDA8 ozone could be over 10 µg/m3 in North China. The number of avoided premature death due to reduced OCSB emissions (considering both PM2.5 and ozone) is estimated to be 6120 (95% Confidence Interval: 5320–6800), with most health benefits gained over east and central China. Our results illustrate the effectiveness of straw burning bans in reducing ozone concentrations at annual and national scales and the substantial ozone impacts from OCSB events at localized and episodic scales.

Cultivar assortment index (CAI): a tool to evaluate the ozone tolerance of Indian Amaranth (Amaranthus hypochondriacus L.) cultivars.

The adverse impact of climate change on crop yield has accelerated the need for identification of crop cultivars resistant to abiotic stress. In the present study, a cultivar assortment index (CAI) was generated for the evaluation of forty Amaranthus hypochondriacus cultivars response to elevated ozone (EO) concentrations (AO + 30ppb) in Free Air Ozone Enrichment (FAOE) facility using the parameters viz. foliar injury, gaseous exchange attributes, namely, net photosynthetic rate, stomatal conductance, transpiration rate, intercellular carbon dioxide, and water use efficiency along with above ground biomass and grain yield attributes. The dataset was used to identify key indicator parameters responsive to EO through principal component analysis (PCA) and further transformed to obtain linear score and weighted score. The CAI varied from 70.49 to 193.43. Cultivars having CAI value less than 151 were ozone tolerant (OT) whereas cultivars with CAI values between 150 and 170 were moderately tolerant (MOT). The cultivars exhibiting CAI values above 170 were ozone sensitive (OS). The cultivars exhibited differential sensitivity to EO with IC-5994 (CAI = 187.26) being the most affected cultivar whereas IC-5576 (CAI = 83.38) and IC-5916 (CAI = 70.49) being the least affected ones. The CAI, based on linear score and weighted score, offers easy identification of ozone sensitive (OS) and ozone tolerant (OT) cultivars. This index could help researchers to define a clear and strong basis for identification of OT cultivars which will reduce the time required for preliminary screening and further evaluation of crop cultivars for the development of climate smart crops.

Further transformation of the primary ozonation products of tramadol- and venlafaxine N-oxide: Mechanistic and structural considerations

Ozonation has been used to effectively remove micropollutants from the secondary effluent in several wastewater treatment plants. It is known that ozonation transforms tertiary amine compounds into their respective N-oxides, however in an earlier study a mass balance could not be closed at elevated ozone concentrations, leading to the assumption that more ozonation products are possible. This study was conducted to elucidate which (hitherto unknown) ozonation products can be formed from venlafaxine and tramadol when ozonating wastewater. Ozonation experiments were performed with tramadol and venlafaxine N-oxide in two different set-ups. Both tramadol- and venlafaxine N-oxide degraded during ozonation in pure (deionized) water in both semi-continuous and batch mode ozonation set-ups. 13 and 17 new transformation products were detected from tramadol- and venlafaxine N-oxide respectively, using high resolution mass spectrometry with ESI(+) ionization. Empirical chemical formulas were proposed based on the determination of the exact masses and interpretation of the product ion spectra. These transformation products result from the addition of one to three oxygen atoms and removal of C, –CH2, C2H2, C3H6, etc., from the parent molecule, respectively. Quenching experiments suggested that most of the transformation products originated from the direct reaction with ozone (eight for tramadol N-oxide and ten for venlafaxine N-oxide), whereas fewer products originated from the reaction with OH radicals (three for tramadol N-oxide and three for venlafaxine N-oxide). Reaction mechanisms and chemical structures of products are proposed, based on the available active sites and past literature on ozone reaction mechanisms. The experimental results are compared to theory and literature on ozone reactive sites and ozone reaction mechanisms. All in all this shows that there can be multiple ozonation products, and ozonation pathways can be complex, even if initially only one ozonation product is formed.

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.

Variation in leaf transcriptome responses to elevated ozone corresponds with physiological sensitivity to ozone across maize inbred lines.

We examine the impact of sustained elevated ozone concentration on the leaf transcriptome of 5 diverse maize inbred genotypes, which vary in physiological sensitivity to ozone (B73, Mo17, Hp301, C123, and NC338), using long reads to assemble transcripts and short reads to quantify expression of these transcripts. More than 99% of the long reads, 99% of the assembled transcripts, and 97% of the short reads map to both B73 and Mo17 reference genomes. Approximately 95% of the genes with assembled transcripts belong to known B73-Mo17 syntenic loci and 94% of genes with assembled transcripts are present in all temperate lines in the nested association mapping pan-genome. While there is limited evidence for alternative splicing in response to ozone stress, there is a difference in the magnitude of differential expression among the 5 genotypes. The transcriptional response to sustained ozone stress in the ozone resistant B73 genotype (151 genes) was modest, while more than 3,300 genes were significantly differentially expressed in the more sensitive NC338 genotype. There is the potential for tandem duplication in 30% of genes with assembled transcripts, but there is no obvious association between potential tandem duplication and differential expression. Genes with a common response across the 5 genotypes (83 genes) were associated with photosynthesis, in particular photosystem I. The functional annotation of genes not differentially expressed in B73 but responsive in the other 4 genotypes (789) identifies reactive oxygen species. This suggests that B73 has a different response to long-term ozone exposure than the other 4 genotypes. The relative magnitude of the genotypic response to ozone, and the enrichment analyses are consistent regardless of whether aligning short reads to: long read assembled transcripts; the B73 reference; the Mo17 reference. We find that prolonged ozone exposure directly impacts the photosynthetic machinery of the leaf.

Response of Ginkgo biloba growth and physiological traits to ozone stress

Ginkgo biloba , the main greening tree species in Beijing, was used to study the effects of elevated ozone (O 3 ) concentrations on physiology and ecology using an open-top air chamber (OTC). We set three O 3 concentration gradients (NF: normal atmospheric O 3 concentration; NF40: normal atmospheric O 3 concentration plus 40 nmol/mol; NF80: normal atmospheric O 3 concentration plus 80 nmol/mol). Based on the theoretical basis of the coupling of O 3 and transpiration through stomata, the O 3 uptake from the leaf surface of G. biloba was studied under artificial control. The results showed that with the O 3 concentration increased, the leaves of G. biloba were damaged, stomatal density, stomatal aperture, stomatal size, net photosynthetic rate, transpiration rate, stomatal conductance, and chlorophyll content decreased, while intercellular CO 2 concentrations and relative conductivity increased. The monthly and daily variations in the liquid flow density of G. biloba decreased with the increase in O 3 concentration. Similarly, water consumption and the ozone uptake rate ( F O3) of G. biloba decreased with the increase in O 3 concentration: Water consumption by the entire tree under the NF40 and NF80 ozone concentrations decreased compared to NF, the rates of decline were 68.77% and 78.38%, respectively. The rates of F O3 decrease were 15.48% and 31.04%, respectively.

The Spectral Compositions of Light Changes Physiological Response of Chinese Cabbage to Elevated Ozone Concentration.

The effects of ozone combined with other environmental factors remain an important topic of the research, both in connection with climate change and the possibility of using modern solutions in horticulture. In our experiment, we compared the influence of ozone (100 ppb) on photosynthesis and changes in the pigment composition of Chinese cabbage (Brassica rapa subsp. pekinensis) leaves depending on the spectral composition of light. We used white LED light (WL), a combination of red + green + blue (RGBL) with a dominant red component and white +blue (WBL) with a dominant blue component in comparison with the classic sodium lamp lighting (yellow light—YL). The values of the parameters describing the light-dependent phase of photosynthesis and the parameters of the gas exchange, as well as non-photosynthesis pigment contents, show that the spectral composition strongly differentiates the response of Chinese cabbage leaves to ozone. In general, the efficiency of photochemical reactions was the highest in YL, but after O3 fumigation, it decreased. In plants growing in WL and WBL, the increase of O3 concentration stimulated light photosynthesis reactions and led to the enhancement of transpiration, stomatal conductance and intracellular CO2 concentration. Changes in photosynthetic activity were accompanied by an increase in the content of anthocyanins and flavonols.

Identifying the dominant driver of elevated surface ozone concentration in North China plain during summertime 2012–2017

The increasingly serious surface ozone (O3) pollution in North China Plain (NCP) has received wide attention. However, the contribution of the changes for each emission source to the elevated O3 concentration, as well as the direct and indirect effect of meteorological condition variation on increased O3 level have not been comprehensively analyzed. This study applied the Community Multiscale Air Quality (CMAQ) model coupled with the integrated source apportionment method (ISAM) to quantify changes in daily maximum 8–h average O3 concentration (MDA8 O3) under different air pollutants emissions and meteorological conditions during summertime 2012–2017. The results showed that incoordinate NOx/VOC emission control sustainably increased MDA8 O3 by 2.2–36.2 μg/m3 in the NCP, of which emission changes from industrial and transportation sectors were the predominant contributors (−0.6–19.5 μg/m3 for industrial sector and 1.2–18.1 μg/m3 for transportation, respectively). In contrast, MDA8 O3 decreased by 2.5–9.2 μg/m3 for the power plants. The effect of changes in meteorological condition on MDA8 O3 exhibited significantly spatial and temporal variation and unfavorable meteorological fields were shown in 2014, 2016, and 2017, which enhanced MDA8 O3 by −2.5–23.1, −5.3–20.7, and −7.2–25.8 μg/m3, respectively. In addition, the changed meteorological factors indirectly affected the biogenic emission thus prompting the increases of MDA8 O3 by −3.9–4.9 μg/m3 in the NCP during 2012–2017. The sensitive simulations suggested that more aggressive control measures about VOC reduction in industrial and transportation sectors should be implemented to further mitigate the O3 pollution under unfavorable meteorological condition.

Effect of Elevated Tropospheric Ozone on Vigna Mungo L. Varieties

ABSTRACT Tropospheric ozone (O3) is widely recognized as the most critical, regional atmospheric pollutant causing significant losses to agricultural productivity due to its phytotoxicity over agricultural areas and is expected to increase in future. In view of rising tropospheric ozone concentration over Indian regions, the present study aimed to evaluate the effect of elevated ozone stress on pulse crop blackgram (Vigna mungo L.), which contributes the major share of protein. The blackgram varieties namely CO 6, VBN 1, VBN 2, VBN 3, VBN 5, VBN 6, VBN 7, and VBN 8 were grown in open top chambers and factorial completely randomized block design was followed. The plants were exposed to elevated ozone concentration (50 and 100 ppb) from 10.00 h to 17.00 h over 10 days at flowering stage, with a weighted average ozone concentration of 50.1 and 101.2 ppb. Both the elevated ozone treatments significantly affected the plant physiological, biochemical, growth, and yield traits of all test varieties. On an average across eight blackgram varieties, decrease in chlorophyll content by 33.83 and 42.41%, stomatal conductance by 28.25 and 40.51% and photosynthetic rate by 29.43 and 42.30% exposed to 50 and 100 ppb ozone were observed, respectively. Correspondingly, the number of pods per plant decreased by 30.82 and 32.65%, 100 grain weight by 7.75 and 21.23% and plant weight by 16.03 and 21.23%, respectively, which were significant at 5% level. Furthermore in the observed traits, significantly higher reduction was observed in VBN3, while the least reduction was observed in VBN8. The path analysis displayed that all the observed physiological, biochemical, growth, and yield traits positively regulated the yield except leaf injury percentage, malondialdehyde, and proline content. The principal component analysis of two elevated ozone treatments confirmed VBN8 as ozone tolerant and VBN3 as ozone sensitive variety. Hence, cultivation of VBN8 variety at ozone hotspot regions would be the best option to overcome ozone induced yield loss.

Invasive herbaceous respond more negatively to elevated ozone concentration than native species

AbstractAimMany studies show that increase in ground‐level ozone (O3) has adverse effects on plant growth. Due to high phenotypic plasticity, invasive species is considered to be more adaptable to elevated O3 than native species. This idea is only tested by the very limited studies comparing invasive weeds with crops. However, whether it holds remains unclear when comparing invasive species with their co‐occurring native species in natural systems.LocationChina.MethodsWe performed an open‐top chamber experiment growing six congeneric pairs of invasive and native species with and without competition under ambient (approximately 43 ppb) and elevated O3 (approximately 89 ppb) concentrations to test whether the growth responses to elevated O3 concentrations differ between invasive and native species.ResultsOur results revealed that elevated O3 had a significant negative effect on both invasive and native species. In particular, elevated O3 reduced the aboveground biomass and damaged the leaves of invasive species significantly more than those of native species.Main conclusionsOur study indicates that elevated O3 concentration has a stronger adverse effect on invasive species than on native species. Therefore, increasing O3 pollution might suppress plant invasion, and thus invasive species might expand their distribution more easily to the area with lower O3 pollution in the future.

Oceanic phytoplankton are a potentially important source of benzenoids to the remote marine atmosphere

Benzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions.

Elevated Tropospheric Ozone Concentration Alters Soil CO2 Emission: A Meta-Analysis

Elevated tropospheric ozone (O3) concentration may substantially influence the below-ground processes of terrestrial ecosystems. Nevertheless, a comprehensive and quantitative understanding of O3 impacts on soil CO2 emission remains elusive, making the future sources or sinks of soil C uncertain. In this study, 77 pairs of observations (i.e., elevated O3 concentration treatment versus control) extracted from 16 peer-reviewed studies were synthesized using meta-analysis. The results depicted that soil CO2 efflux was significantly reduced under short-term O3 exposure (≤1 year, p < 0.05), while it was increased under extended duration (>1 year, p < 0.05). Particularly, soil CO2 emission was stimulated in nonagricultural ecosystems, in the free-air CO2 enrichment (FACE) experiment, and in the soils of lower pH. The effect sizes of soil CO2 efflux were significantly positively correlated with experimental duration and were significantly negatively correlated with soil pH, respectively. The ozone effect on soil CO2 efflux would be enhanced at warm temperatures and high precipitation. The duration of O3 exposure was the fundamental factor in analyzing O3 impacts on soil CO2 emission.

Bioenergy sorghum maintains photosynthetic capacity in elevated ozone concentrations.

Elevated tropospheric ozone concentration (O3) significantly reduces photosynthesis and productivity in several C4 crops including maize, switchgrass and sugarcane. However, it is unknown how O3 affects plant growth, development and productivity in sorghum (Sorghum bicolor L.), an emerging C4 bioenergy crop. Here, we investigated the effects of elevated O3 on photosynthesis, biomass and nutrient composition of a number of sorghum genotypes over two seasons in the field using free‐air concentration enrichment (FACE), and in growth chambers. We also tested if elevated O3 altered the relationship between stomatal conductance and environmental conditions using two common stomatal conductance models. Sorghum genotypes showed significant variability in plant functional traits, including photosynthetic capacity, leaf N content and specific leaf area, but responded similarly to O3. At the FACE experiment, elevated O3 did not alter net CO2 assimilation (A), stomatal conductance (g s), stomatal sensitivity to the environment, chlorophyll fluorescence and plant biomass, but led to reductions in the maximum carboxylation capacity of phosphoenolpyruvate and increased stomatal limitation to A in both years. These findings suggest that bioenergy sorghum is tolerant to O3 and could be used to enhance biomass productivity in O3 polluted regions.

Uticaj aerozagađenja na egzacerbacije hronične opstruktivne bolesti pluća

Chronic obstructive pulmonary disease (COPD) is one of the greatest global public health challenges, emerging as the third leading cause of death by 2030. Acute exacerbations of COPD (AECOPD) contribute to the accelerated deterioration of lung function, reduced quality of life and higher hospitalizations and mortality rates. The cause of exacerbation is usually an infectious agent, but the impact of exposure to environmental factors is being studied more thoroughly. Among them, atmospheric pollutants emerged as the most important ones. Multiple studies showed that elevated concentrations of particulate matter (PM), sulphur dioxide (SO2), nitric dioxide (NO2) and ozone (O3) in the atmosphere, have the most significant negative effect on patients with COPD, increasing hospitalisations and mortality rates due to COPD. While examining their effect on AECOPD, it is important to consider the mutual interactions of different air pollutants, as well as interactions with meteorological factors. In order to decrease the burden of COPD, it is necessary to implement all strategies that will reduce the incidence of COPD, including global reduction of air pollution. That will require the support of the world's most developed economies, a significant renewal of the necessary resources and, finally, radical social change.

Response of Blackgram Cultivars to Elevated Tropospheric Ozone

As a secondary pollutant, Tropospheric ozone is inadvertently increasing every year, thereby causing severe loss to agricultural crops. The present study aimed at evaluating the response of tropospheric ozone against blackgram varieties. Eight ruling blackgram varieties (V.B.N. 1, V.B.N. 2, V.B.N. 3, V.B.N. 5, V.B.N. 6, V.B.N. 7, V.B.N. 8 and CO 6) were exposed to elevated tropospheric ozone concentration (50 ppb) in an open-top chamber. The exposure was given during 31 days after sowing (D.A.S.) to 40 D.A.S. for seven hours (10.00 h-17.00 h). The changes in physiological, biochemical, growth, and yield traits were observed by comparing them with control (ambient condition). Results indicate that physiological, biochemical, growth, and yield traits significantly differed under ozone stress. Amongst all varieties, the reduction of all observed traits was higher in V.B.N. 3 and least in V.B.N. 8. The reduction of photosynthetic rate, stomatal conductance, and chlorophyll content was higher in V.B.N. 3 (33.57, 29.17 and 35.67 %) and least in V.B.N. 8 (26.23, 22.92 and 31.78 %). In the case of biochemical traits, in V.B.N. 3, the malondialdehyde and proline content increased twice and ascorbic acid declined by 39.85 %. However, in V.B.N. 8, malondialdehyde and proline content increased by 78.26 and 89.01 %; while ascorbic acid decreased by 36.31 % only. Similarly, 100-grain weight reduced in V.B.N. 3 by 8.69 % while it was only 5.37 % in V.B.N. 8. The current investigation revealed that V.B.N. 3 is highly sensitive, while V.B.N. 8 is tolerant to ozone stress.