Impact Of Ozone Research Articles

Impact of the Stratospheric Ozone on the Northern Hemisphere Surface Climate During Boreal Winter

AbstractIn this study, we examine the impact of stratospheric ozone on the Northern Hemisphere (NH) surface climate during boreal winter by analyzing the two experiments using Global/Regional Integrated Model system‐Chemistry Climate Model (GRIMs‐CCM) (i.e., LINOZ‐on/‐off experiments) and eight Atmosphere Model Inter‐comparison Project (AMIP) climate models. In LINOZ‐on, ozone concentration in the upper troposphere and lower stratosphere (UTLS) varies with latitudes, being low in the tropics and high in the mid‐to‐high‐latitudes, by adopting a linearized ozone scheme. The LINOZ‐off, however, prescribes constant ozone concentration throughout all latitudes. Cooler surface temperatures over the Eurasian and Asian continents in boreal winter are simulated in LINOZ‐on than that in LINOZ‐off. A reduced mean UTLS temperature gradient in LINOZ‐on, due to the difference of climatological mean ozone concentration, causes a weakened mean zonal wind in the lower stratosphere compared to the LINOZ‐off. This mean wind difference is extended all the way to the surface, resulting in a negative Arctic Oscillation (AO)‐like mean state in the mid‐to‐high latitudes in the LINOZ‐on. Subsequently, it causes cool surface temperatures over the Eurasian and Asian continents by altering horizontal winds. This result is also supported by the comparison between AMIP models with a relatively high and low stratospheric ozone concentration in the mid‐to‐high latitudes. Therefore, a careful attention should be paid to the climatology of stratospheric ozone concentration in climate models to correctly simulate surface climate in the NH in the past and future climate.

Stratospheric Ozone and Climate Forcing Sensitivity to Cruise Altitudes for Fleets of Potential Supersonic Transport Aircraft

AbstractThe possibility of commercial and business supersonic aircraft that fly in the lower stratosphere is being discussed and specific designs are under consideration. Emissions from supersonic transports have raised crucial environmental concerns regarding ozone and climate. The atmospheric response is sensitive to a range of factors regarding aircraft types, designs, and deployment parameters. This study conducts a series of sensitivity experiments of possible future cruise altitudes to evaluate the potential atmospheric response for a fleet of supersonic aircraft assumed to be fully operational in 2050. Cruise emissions in the sensitivity studies were varied in 2 km bands over the 13–23 km altitude range. We show that the supersonic aircraft can induce both ozone increase and decrease depending on altitude primarily as a result of emissions of nitrogen oxides, and the changes in total column ozone depend on the cruise altitude. The total column ozone change is shown to have a small increase flying from 13 to 17 km, with the ozone impact not very dependent on cruise altitude. As cruise altitude transitions from 17 to 23 km, the ozone impact transitions from production to depletion and the column ozone depletion strongly depends on cruise altitude. We also explore the seasonal ozone loss, changes in ozone, and climate radiative forcing per unit of fuel burn as a function of cruise altitude. The climate impact of water vapor emissions shows a larger effect associated with higher cruise altitude, with more than 1 mW m−2 Tg−1 yr for cruise altitudes above 19 km.

Impact of ozone and inlet design on the quantification of isoprene-derived organic nitrates by thermal dissociation cavity ring-down spectroscopy (TD-CRDS)

Abstract. We present measurements of isoprene-derived organic nitrates (ISOP-NITs) generated in the reaction of isoprene with the nitrate radical (NO3) in a 1 m3 Teflon reaction chamber. Detection of ISOP-NITs is achieved via their thermal dissociation to nitrogen dioxide (NO2), which is monitored by cavity ring-down spectroscopy (TD-CRDS). Using thermal dissociation inlets (TDIs) made of quartz, the temperature-dependent dissociation profiles (thermograms) of ISOP-NITs measured in the presence of ozone (O3) are broad (350 to 700 K), which contrasts the narrower profiles previously observed for, for example, isopropyl nitrate (iPN) or peroxy acetyl nitrate (PAN) under the same conditions. The shape of the thermograms varied with the TDI's surface-to-volume ratio and with material of the inlet walls, providing clear evidence that ozone and quartz surfaces catalyse the dissociation of unsaturated organic nitrates leading to formation of NO2 at temperatures well below 475 K, impeding the separate detection of alkyl nitrates (ANs) and peroxy nitrates (PNs). The use of a TDI consisting of a non-reactive material suppresses the conversion of isoprene-derived ANs at 473 K, thus allowing selective detection of PNs. The potential for interference by the thermolysis of nitric acid (HNO3), nitrous acid (HONO) and O3 is assessed.

Gaseous ozone to preserve quality and enhance microbial safety of fresh produce: Recent developments and research needs

Fresh fruits and vegetables are highly perishable and are subject to large postharvest losses due to physiological (senescence), pathologic (decay), and physical (mechanical damage) factors. In addition, contamination of fresh produce with foodborne human pathogens has become a concern. Gaseous ozone has multiple benefits including destruction of ethylene, inactivation of foodborne and spoilage microorganisms, and degradation of chemical residues. This article reviews the beneficial effects of gaseous ozone, its influence on quality and biochemical changes, foodborne human pathogens, and spoilage microorganisms, and discusses research needs with an emphasis on fruits. Ozone may induce synthesis of a number of antioxidants and bioactive compounds by activating secondary metabolisms involving a wide range of enzymes. Disparities exist in the literature regarding the impact of gaseous ozone on quality and physiological processes of fresh produce, such as weight loss, ascorbic acid, and fruit ripening. The disparities are complicated by incomplete reporting of the necessary information, such as relative humidity and temperatures at which ozone measurement and treatment were performed, which is needed for accurate comparison of results among studies. In order to fully realize the benefits of gaseous ozone, research is needed to evaluate the molecular mechanisms of gaseous ozone in inhibiting ripening, influence of relative humidity on the antimicrobial efficacy, interaction between ozone and the cuticle of fresh produce, ozone signaling pathways in the cells and tissues, and so forth. Possible adverse effects of gaseous ozone on quality of fresh produce also need to be carefully evaluated for the purpose of enhancing microbial and chemical safety of fresh produce.

Source impact and contribution analysis of ambient ozone using multi-modeling approaches over the Pearl River Delta region, China

Quantification of source impacts and contributions is a key element for the design of effective air pollution control policies. In this study, O3 source impacts and contributions were comprehensively assessed over the Pearl River Delta (PRD) region of China using brute-force method (BFM), response surface modeling with BFM (RSM-BFM) and differential method (RSM-DM) respectively, high-order decoupled direct method (HDDM), and ozone source apportionment technology (OSAT). The multi-modeling comparison results indicated that under typical nonlinear atmospheric conditions during the O3 formation, BFM, RSM-BFM, and HDDM seemed to be appropriate for assessing the impact of single source emissions; however, the results of HDDM could deviate from those of BFM when the emission reduction ratio was higher than 50 %. Under multi-source control scenarios, the results of source contribution analyses obtained from RSM-DM and OSAT were reasonably well, but the performance of OSAT was limited by its capability in representing the nonlinearity of O3 response to emission reductions of its precursors, particularly NOx. The results of this pilot study in the PRD showed that the RSM-DM appeared to replicate the nonlinearity of O3 chemistry reasonably well (e.g., O3 disbenefits due to local NOx emission reductions in Guangzhou city). Based on the source contribution results, on-road mobile (including both NOx and VOC emissions) and industrial process (mainly VOC emissions) sources were identified as two major contribution sectors by both RSM-DM and OSAT, contributing an average of 31.5 % and 11.4 % (estimated by RSM-DM) and 29.2 % and 13.0 % (estimated by OSAT) respectively to O3 formation in 9 cities of the PRD. Therefore, the reinforced emission reductions on NOx and VOC from on-road mobile and industrial process sources in the central cities (i.e., Guangzhou, Foshan, Dongguan, Shenzhen, and Zhongshan) were suggested to effectively mitigate the ambient O3 levels in the PRD.

Quantifying the impact of ozone on crops in Sub-Saharan Africa demonstrates regional and local hotspots of production loss.

Tropospheric ozone can have a detrimental effect on vegetation, including reducing the quantity of crop yield. This study uses modelled ozone flux values (POD3IAM; phytotoxic ozone dose above 3 nmol m-2 s-1, parameterised for integrated assessment modelling) for 2015, together with species-specific flux-effect relationships, spatial data on production and growing season dates to quantify the impact of ozone on the production of common wheat (Triticum aestivum) and common beans (Phaseolus vulgaris) across Sub-Saharan Africa (SSA). A case study for South Africa was also done using detailed data per province. Results suggest that ozone pollution could decrease wheat yield by between 2 and 13%, with a total annual loss of 453,000 t across SSA. The impact on bean production depended on the season; however, estimated yield losses were up to 21% in some areas of SSA, with an annual loss of ~300,000 t for each of the two main growing seasons. Production losses tended to be greater in countries with the highest production, for example, Ethiopia (wheat) and Tanzania (beans). This study provides an indication of the location of areas at high risk of crop losses due to ozone. Results emphasise that efforts to reduce ozone precursors could contribute to reducing the yield gap in SSA. More stringent air pollution abatement policies are required to reduce crop losses to ozone in the future.

Exploring new strategies for ozone-risk assessment: A dynamic-threshold case study

Tropospheric ozone is a dangerous atmospheric pollutant for forest ecosystems when it penetrates stomata. Thresholds for ozone-risk assessment are based on accumulated stomatal ozone fluxes such as the Phytotoxic Ozone Dose (POD). In order to identify the effect of ozone on a Holm oak forest in central Italy, four flux-based ozone impact response functions were implemented and tested in a multi-layer canopy model AIRTREE and evaluated against Gross Primary Productivity (GPP) obtained from observations of Eddy Covariance fluxes of CO2. To evaluate if a clear phytotoxic threshold exists and if it changes during the year, six different detoxifying thresholds ranging between 0 and 5 nmol O3 m−2 s−1 were tested.The use of species-specific rather than more general response functions based on plant functional types (PFT) increased model accuracy (RMSE reduced by up to 8.5%). In the case of linear response functions, a threshold of 1 nmol m−2 s−2 produced the best results for simulations of the whole year, although the tolerance to ozone changed seasonally, with higher tolerance (5 nmol m−2 s−1 or no ozone impact) for Winter and Spring and lower thresholds in Summer and Fall (0–1 nmol m−2 s−1). A “dynamic threshold” obtained by extracting the best daily threshold values from a range of different simulations helped reduce model overestimation of GPP by 213 g C m−2 y−1 and reduce RMSE up to 7.7%. Finally, a nonlinear ozone correction based on manipulative experiments produced the best results when no detoxifying threshold was applied (0 nmol O3 m−2 s−1), suggesting that nonlinear functions fully account for ozone detoxification. The evidence of seasonal changes in ozone tolerance points to the need for seasonal thresholds to predict ozone damage and highlights the importance of performing more species-specific manipulative experiments to derive response functions for a broad range of plant species.

Validation of meteorological and ground-level ozone WRF-CHIMERE simulations in a mountainous grapevine growing area for phytotoxic risk assessment

Ozone is the most damaging phytotoxic air pollutant to crop yield quantity and quality. This study presents the validation of a simulation with the WRF-CHIMERE modelling system in order to assess the risk of phytotoxicity by tropospheric ozone for an important and characteristic Mediterranean crop, i.e. the grapevine. The study region was the Douro wine region in Portugal, which is characterized by a rugged relief and a Mediterranean climate. The simulation covered a reference grapevine growing season in the Northern Hemisphere (from April to September 2017), during which a particular measuring campaign was also carried out. The validation of the meteorological simulations on a daily and hourly time resolution was performed based on data from three weather stations, namely on temperature, global solar radiation, relative humidity, wind speed and direction values. The ozone phytotoxicity was assessed with data from two measuring stations. A specific grapevine growth parameter based on monitored phenological observations was introduced for ozone stomatal uptake assessment. Concerning meteorology, validation statistics were acceptable and within the range of what has been found in other regional climate modelling simulations. Ground-level ozone-based values were calculated for a better assessment of the phytotoxic risk, in particular cumulative standards for vegetation protection. Stomatal flux estimates were within the range of those measured for the local cultivars in the field campaign when there was not severe water stress limitation. Both field and statistically adjusted model values indicate that considerable areas in the Demarcated Douro Region of Portugal can exceed the critical exposure values for vegetation according to current European legislation standards. Moreover, measured and simulated results indicate an ozone impact on grapevine yield and quality in the target region because the exposure- and flux-based indices exceed the criteria based on current open-top-chamber experimental knowledge.

Impact of ground-level ozone on Mediterranean forest ecosystems health

Given the high ozone concentrations observed in the Mediterranean region during summer, it is crucial to extend our knowledge on the potential ozone impacts on forest health with in situ studies, especially to protect typical endemic forests of the Mediterranean basin.This study is focused on ozone measurements and exposures over the Eastern Adriatic coast and on the calculation of different O3 metrics, i.e., accumulated exposure AOT40 (AOT40dir, AOT40ICP, AOT40pheno) and stomatal O3 fluxes with an hourly threshold of uptake (Y) to represent the detoxification capacity of trees (PODY, with Y = 0, 1, 2 nmol O3 m−2 s−1) used for forest protection. Finally, we provide an assessment of the relationships between the forest response indicators and environmental variables.Passive ozone measurements and monitoring of forest health indicators, namely growth and crown defoliation, were performed for Quercus ilex, Quercus pubescens, Pinus halepensis, and Pinus nigra forests. Results showed that, for all the analysed species, ozone levels were close to reached the upper plausibility limits for passive monitoring of air quality at forest sites (100 ppb), with the highest values found on P. halepensis in the summer period. O3 metrics based on exposure were found to be higher in pine plots than in oak plots, while the highest values of uptake-based metrics were found on P. nigra.Regarding relationships between environmental variables and forest-health response indicators, the crown defoliation was significantly correlated with the soil water content at various depth while the tree growth was correlated with the different O3 metrics. The most important predictors affecting tree growth of Q. pubescens and Q. ilex were AOT40pheno and AOT40dir and POD0 for P. nigra.

Degradation of Structure of Populus tremula Wood during Delignification with Ozone. Thermal Analysis

Transformations of aspen wood under the impact of ozone were investigated by FTIR spectroscopy and simultaneous thermal analysis combined with mass spectrometry (TG/MS) of noncondensable products of pyrolysis. The TG/DTG curves of lignocellulosic materials (LCM) obtained at various values of specific absorption of ozone were analyzed. Simulation of DTG curves with Gaussian components was carried out. It is shown that the content of hemicellulose (HC) and lignin (LG) decreases and the content of cellulose increases under the impact of ozone in wood. FTIR spectroscopy data confirm the destruction of aromatic structures of LG and indicate the formation of oxygen-containing products of biomass ozonation as the specific absorption of ozone increases. Based on the TG/MS analysis of the LCM and the simulation results, the range of ozone consumption corresponding to the predominant destruction of LG and HC, and the range of ozone reactions with the ozonation products of the LCM were established. Degradation of the cellulose structure was found at high ozone consumptions.

Impact of Ambient Particulate Matter and Ozone Exposure of Heart Transplant Recipients on All-Cause Mortality after Heart Transplant

Purpose There is limited evidence on role of air quality on chronic rejection after heart transplant (HT). We investigated the impact of particulate matter concentration (PM≥2.5 μm/m3) and ozone (O3) exposure of recipients on all-cause mortality after HT in the US. Methods UNOS Standard Transplant Analysis and Research (STAR) database (June 30, 2017) identified adult HT recipients between 2005 and 2015, and their zip code of residence at HT. Average ambient PM and daily maximum 8-hour average O3 associated with recipient residencies 1 year after HT were estimated by mapping each zip code to a census tract, using a crosswalk from HUD, downscaled from a 12 × 12-km sq grid resolution detailed chemistry - transport model application using a Bayesian space-time downscaler, and then fused with surface observations. PM concentration was classified into low ( 12 μg/m3); O3 was similarly categorized (low: 42 ppb). Inverse-probability of treatment weighted Cox regression and Kaplan-Meier curves assessed the impact of PM and O3 on 1-year and long-term incidence of all-cause mortality. Results Overall, 17,893 HT patients were included; Median follow-up was 1529 days (IQR 737-2586). 21% of HT recipients had high PM exposure and 20% had high O3 exposure. While estimates were imprecise, both high exposure levels of PM and O3, compared to low exposure, appeared to increase long-term mortality (Table). High PM exposure may also increase 1-year mortality; O3 had no impact on 1-year mortality. Conclusion PM2.5 and O3 conc are only 2 aspects of air quality and appear to increase long term risk of death after HT. Additional research on other air quality measures including isolating primary and secondary components of PM2.5 and focusing on traffic-related air pollutants is warranted for all transplant recipients.

Assessment of Synergistic Impact of Ambient Surface Ozone and Fine Particulate Matter on Experimentally Grown Wheat Crop

The present study aims to understand how increasing surface ozone and fine particulate matter concentrations affect wheat crop productivity under ambient conditions. A pot experiment was conducted spanning over a period of 117 days starting from December 2016 to April 2017 at one of the receptor locations in Delhi characterized with high levels of surface ozone and fine particulate matter. The study site recorded highest concentrations of PM1, PM2.5, PM10 and surface ozone of 159±77 μg m−3, 172±79 μg m−3, 280±108 μg m−3 and 335±18 μg m−3, respectively during the crop cycle indicating the high levels of air pollutants at the site. The crops were treated with ascorbic acid under different experimental setups. A large number of growth, biochemical and yield parameters were evaluated at the vegetative, reproductive and grain formation stage of the crop cycle. Results indicated that the chlorophyll content and harvest yield of crops grown under ambient conditions were ∼23% and ∼14% lower than those of crops grown under controlled environment. Furthermore, a ∼13%, 5%, 15% and 10% decline in root length, plant height, number of tillers and number of leaves was observed in crops that were exposed to only surface ozone in comparison to crops exposed to only fine particulate matter under vegetative stage, respectively. Relative water content, chlorophyll content and air pollution tolerance index observed ∼56%, 23% and 61% decline with fully exposed setup in comparison control setup in the vegetative stage, while ∼57%, 23% and 44% decline was observed in the reproductive stage. Experiments also suggested that surface ozone had a more pronounced influence on overall productivity of wheat crops in comparison to fine particulate matter.

Ozone-Induced Oxidative Stress, Neutrophilic Airway Inflammation, and Glucocorticoid Resistance in Asthma.

Despite recent advances in using biologicals that target Th2 pathways, glucocorticoids form the mainstay of asthma treatment. Asthma morbidity and mortality remain high due to the wide variability of treatment responsiveness and complex clinical phenotypes driven by distinct underlying mechanisms. Emerging evidence suggests that inhalation of the toxic air pollutant, ozone, worsens asthma by impairing glucocorticoid responsiveness. This review discusses the role of oxidative stress in glucocorticoid resistance in asthma. The underlying mechanisms point to a central role of oxidative stress pathways. The primary data source for this review consisted of peer-reviewed publications on the impact of ozone on airway inflammation and glucocorticoid responsiveness indexed in PubMed. Our main search strategy focused on cross-referencing “asthma and glucocorticoid resistance” against “ozone, oxidative stress, alarmins, innate lymphoid, NK and γδ T cells, dendritic cells and alveolar type II epithelial cells, glucocorticoid receptor and transcription factors”. Recent work was placed in the context from articles in the last 10 years and older seminal research papers and comprehensive reviews. We excluded papers that did not focus on respiratory injury in the setting of oxidative stress. The pathways discussed here have however wide clinical implications to pathologies associated with inflammation and oxidative stress and in which glucocorticoid treatment is essential.

Impact of elevated ozone on yield and carbon-nitrogen content in soybean cultivar ‘Jake’

Tropospheric ozone (O3) is a pollutant that leads to significant global yield loss in soybean [Glycine max (L.) Merr.]. To ensure soybean productivity in areas of rising O3, it is important to identify tolerant genotypes. This work describes the response of the high-yielding soybean cultivar ‘Jake’ to elevated O3 concentrations. ‘Jake’ was treated with either low O3 [charcoal-filtered (CF) air, 12 h mean: 20 ppb] or with O3-enriched air (12 h mean: 87 ppb) over the course of the entire growing season. In contrast to the absence of O3-induced leaf injury under low O3, elevated O3 caused severe leaf injury and decreased stomatal conductance and photosynthesis. Although elevated O3 reduced total leaf area, leaf number, and plant height at different developmental stages, above-ground and root biomass remained unchanged. Analyzing carbon and nitrogen content, we found that elevated O3 altered allocation of both elements, which ultimately led to a 15 % yield loss by decreasing seed size but not seed number. We concluded that cultivar ‘Jake’ possesses developmental strength to tolerate chronic O3 conditions, attributes that make it suitable breeding material for the generation of new O3 tolerant lines.

A win-win strategy for simultaneous air-quality benign and profitable emission reduction during chemical plant shutdown operations

Although the flaring system is designed for the safety operation in chemical plants, the intensive flaring will cause not only tremendous raw material loss, but also large amounts of VOCs and NOx, which could escalate regional ozone formation and elevation under the solar radiation. Thus, it will be a win-win situation to preform air-quality conscious flare minimization (FM) for chemical plants, so that both environmental and industrial sustainability could be promoted. In this study, a systematic multi-scale methodology has been established to identify and demonstrate the win-win strategy for simultaneous air-quality benign and profitable emission reduction during chemical plant shutdown (CPS) operations. The major contribution of this study is that process-level dynamic simulations via Aspen Plus Dynamics have been seamlessly integrated with the regional-level air-quality modeling via CAMx to simultaneously accomplish both flare source savings and ozone impact minimization during the CPS operation. Case studies have indicated that the base case of CPS without FM could have a serious effect on the air-quality (1.6 ppb 8-h ozone observed). However, the improved case of CPS based on FM would significantly reduce such an ozone impact (only 0.1 ppb 8-h ozone observed); meanwhile the flare source and CO2 emission reductions, as well as the plant economic savings are respectively 165.2 tons, 479.1 tons, and US$133,945.6.

Improvement of biotreatability of environmentally persistent antibiotic Tiamulin by O3 and O3/H2O2 oxidation processes

ABSTRACT The aim of the work was to assess the efficiency of ozonation and ozonation in combination with H2O2 in jet loop reactor to increase biotreatability of persistent veterinary antibiotic Tiamulin. The efficiency of oxidative processes was monitored by combined approach based on determination of efficiency of wastewater treatment and impact to waste sludge stabilization. Degradation of Tiamulin in model wastewater (100 mg L−1) during oxidation was followed by COD and DOC measurements while changes in biodegradability were determined by respirometric measurements. Biogas production potential was also determined to identify problems related to anaerobic digestion of waste sludge resulted in treatment of Tiamulin-contaminated wastewater. At ozone dose of 69 gozone gCOD −1 and 220 gozone gDOC −1removal for COD and DOC was 26% and 17%, respectively. Better biotreatability was confirmed by respirometric testing. H2O2 addition did not improve removal efficiency (11–13%). The second stage of nitrification was suppressed by the addition of Tiamulin and ozonation again recovered formation. O3/H2O2 treated sample reduced the nitrification, especially formation of in the first phase of the process. Simultaneously, quadratic model was developed to describe the relationship between oxygen uptake rate and changes in ammonium nitrogen concentration due to the oxidative treatment. The positive impact of ozone was also confirmed by ozonation of Tiamulin-contaminated (400 mg L−1) waste sludge where biogas production potential was increased for 6-times. Combination of approaches confirmed, that O3 effectively increase the treatability of Tiamulin in wastewater and sludge while addition of the hydrogen peroxide generally did not improve the performance of the processes.

Solar Ultraviolet Radiation in Pretoria and Its Relations to Aerosols and Tropospheric Ozone during the Biomass Burning Season

Biomass burning has an impact on atmospheric composition as well as human health and wellbeing. In South Africa, the biomass burning season extends from July to October and affects the aerosol loading and tropospheric ozone concentrations which in turn impact solar ultraviolet radiation (UVR) levels at the surface. Using ground-based observations of aerosols, tropospheric ozone and solar UVR (as well as modelled solar UVR) we investigated the impact of aerosols and tropospheric ozone on solar UVR in August, September, and October over Pretoria. Aerosol optical depth (AOD) and tropospheric ozone reached a peak between September and October each year. On clear-sky days, the average relative difference between the modelled and observed solar Ultraviolet Index (UVI) levels (a standard indicator of surface UVR) at solar noon was 7%. Using modelled UVR—which included and excluded the effects of aerosols and tropospheric ozone from biomass burning—aerosols had a larger radiative effect compared to tropospheric ozone on UVI levels during the biomass burning season. Excluding only aerosols resulted in a 10% difference between the modelled and observed UVI, while excluding only tropospheric ozone resulted in a difference of −2%. Further understanding of the radiative effect of aerosols and trace gases, particularly in regions that are affected by emissions from biomass burning, is considered important for future research.

Impact of Ozone Used-Alone and Coagulation Aid Treatment on The Reduction of Trihalomethanes Components

The whole research paper examines the impact of ozone as either a just use-alone and coagulation benefit, mainly upon the reduction of dissolved organic carbon from the water with a moderate rate of DOC 10.75 mg/land CaCO3 calcium hardness 300 mg/l. A raw water sample has been taken from the Tigris River (Baghdad, Iraq) was being adopted in research work. The performance of ozone therapy has been assessed by calculations of DOC, DOC quantities, UV254, as well as total trihalomethane (TTHM). Research findings have shown that with 0.9 mg O3/mg DOC ozone use-alone, approximately 60% UV254 reduction and approximately 28% DOC reduction will occur.DOC fractionation analysis indicates that within the water samples, ozone could alter the composition of DOC, transform the hydrophobic fractions toward hydrophilic fractions and reduce TTHM. Ozone was also responsible for a significant reduction in particle stability as well as the dissolved calcium content. Improved water flocculation and improved DOC removal were triggered by these simultaneous ozonation effects. This resulted in a decrease in the coagulant dosage while the dosage of ozone is considerably higher over 0.3 mg O3/mg DOC has added before ferric sulfate coagulation. The pre-ozonation coagulation method also accomplished favorable removal of TTHM with all tested ozone doses (0 to 0.9 mg O3/mg DOC), resulting in lower TTHM during pre-ozonated coagulated waters unlike those through related ozonated waters.

The impact of elevated ozone on growth, secondary metabolites, production of reactive oxygen species and antioxidant response in an anti-diabetic plant Costus pictus

Tropospheric ozone (O3) is a global air pollutant that causes deleterious effect to the plants. The present objective was to investigate the growth response, foliar injury, reactive oxygen species (ROS) accumulation and metabolites production in Costus pictus D. Don (insulin plant) at two developmental stages under ambient O3 (AO) and ambient + 20 ppb O3 (EO) using the open-top chambers (OTCs). A significant reduction in leaf area and total biomass was observed under EO as compared with AO. EO induced ROS (.O2- and H2O2) and lipid peroxidation led to more significant foliar injury and solute leakage. Image obtained from the fluorescence microscope and biochemical estimations reflected high levels of ROS under EO. A differential response in flavonoids and anthocyanin content, ascorbic acid, and antioxidative enzymes such as catalase (CAT), superoxide dismutase (SOD) and peroxidase (POX) has been observed with the growth stages of C. pictus plant. EO exposure negatively affected thiols and protein contents at all the growth stages. Secondary metabolites (tannins, lignin, saponins and alkaloids) were increased in both leaves and rhizomes due to EO, whereas phytosterols were induced only in rhizomes. Apart from other metabolites, the key bioactive compound (corosolic acid) showed its synthesis to be stimulated under EO at later growth stage. The study concludes that O3 is a potent stimulating factor for changing the levels of secondary metabolites and antioxidants in an antidiabetic C. pictus plants as it can alter its medicinal properties.

Scale-up impact over solar photocatalytic ozonation with benchmark-P25 and N-TiO2 for insecticides abatement in water

The application of photocatalysis, single, catalytic and photocatalytic ozonation was evaluated for the abatement of a mixture of seven insecticides at pilot plant scale to infer the effect of the reactor’s diameter on the process performance. Two different heterogeneous catalysts were used, a laboratory produced (N-TiO2) compared to the benchmarked P25. The photocatalyst P25 presents best performance comparing with N-TiO2 on the insecticide’s abatement for the different technologies applied. Photocatalytic oxidation and ozonation using the highest tube diameter were capable to degrade almost 100% of the initial insecticide’s concentration. The tube diameter has high impact on the required catalyst amount for the photocatalytic oxidation process. The photocatalytic oxidation with P25 for low diameter tube (32 mm) achieved almost 90% of global insecticides degradation with QUV = 25 kJ/L and 200 mg/L of catalyst while for larger tube was achieved the same degradation with only QUV = 8.2 kJ/L and 100 mg/L of catalyst. Moreover, photocatalytic ozonation improved N-TiO2 performance leading to about 65% of global insecticides mixture degradation while photocatalytic oxidation was only able to obtain 35%. However, the impact of ozone on the P25 photocatalytic activity was almost negligible due to the high efficiency of this catalyst under solar radiation.