High Ozone Concentrations Research Articles

The large-scale atmospheric circulation pattern over Asia associated with formation of extremely high surface ozone concentrations in the region of Tomsk (Western Siberia)

The large-scale atmospheric circulation pattern over Asia associated with formation of extremely high surface ozone concentrations in the region of Tomsk (Western Siberia)

臭氧胁迫冬小麦叶片高光谱特征和叶绿素含量估算

PDF HTML阅读 XML下载 导出引用 引用提醒 臭氧胁迫冬小麦叶片高光谱特征和叶绿素含量估算 DOI: 10.5846/stxb202201200196 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(42130714) Hyperspectral characteristics and chlorophyll content estimation of winter wheat under ozone stress Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为无损、快速监测臭氧胁迫下冬小麦叶片叶绿素含量,建立叶绿素含量与光谱指标的定量关系,基于自由式臭氧浓度增加系统平台观测了臭氧浓度升高下拔节期、开花期及灌浆期冬小麦叶片的叶绿素含量和光谱特征。通过线性回归、人工神经网络(ANN)以及偏最小二乘回归(PLSR)模型对臭氧胁迫下叶片高光谱特征进行了叶绿素含量的估算。结果表明:臭氧胁迫冬小麦叶片的光谱曲线特征出现绿峰"红移"和红边位置"蓝移"现象。相比于拔节期和开花期,小麦叶片在灌浆期受到臭氧的影响更大。臭氧胁迫下叶绿素含量与部分光谱特征参数及遥感植被指数存在显著相关关系,所有模型均取得了较高的估算精度(R2>0.8),其中以光谱特征参数为建模参量的偏最小二乘回归模型精度最高。该方法可用于臭氧胁迫下冬小麦叶片叶绿素含量的估测,动态监测作物的臭氧胁迫。 Abstract:To quantify the O3-induced damage non-destructively and rapidly, it is important to build up the relationship between the chlorophyll content and spectral characteristics. In this study, the winter wheat leaves under ozone stress were measured at the jointing, flowering and grain filling stages, respectively. The field experiment was conducted through the free-air ozone concentration elevation system (O3-FACE) platform located at Jiangdu, Yangzhou, Jiangsu Province. Hyperspectral estimation of chlorophyll content under ozone stress was made using linear regression model, artificial neural network (ANN) model and partial least squares regression (PLSR) model, respectively. The results showed that the green peak of the leaf spectrum under ozone stress showed a "red shift", while the red edge of the leaves spectrum showed a "blue shift". Elevated ozone affected wheat leaves more at grain filling stage than jointing and flowering stages. There was a significant correlation between chlorophyll content and most spectral characteristics or vegetation spectral indexes under ozone stress with high estimation accuracy (R2>0.8). Among all models, the highest accuracy was achieved by the PLSR model based on spectral characteristics. The PLSR model can be used to estimate the chlorophyll content of winter wheat exposed to high ozone concentration and thus quantify the damage induced by ozone stress. 参考文献 相似文献 引证文献

Ozone disinfection efficiency against airborne microorganisms in hospital environment: a case study.

Even though ozone has shown its potential for air disinfection in hospital environment, its more frequent use has earned attention only with the COVID-19 pandemic due to its proven antimicrobial effect and low cost of production. The aim of this study was to determine its antimicrobial efficiency against the most common bacterial species in a real-life setting, that is, in the air of one postoperative room of the General Hospital Dr Ivo Pedišić (Sisak, Croatia). Air was sampled for aiborne bacteria before and after treatment with the ozone concentration of 15.71 mg/m3 for one hour. The most dominant Gram-positive bacteria of the genera Micrococcus, Staphylococcus, and Bacillus were reduced by 33 %, 58 %, and 61 %, respectively. The genus Micrococcus proved to be the most resistant. Considering our findings, we recommend longer air treatment with higher ozone concentrations in combination with mechanical cleaning and frequent ventilation.

Estimation of near-surface ozone concentration and analysis of main weather situation in China based on machine learning model and Himawari-8 TOAR data

Ozone (O3) is an important greenhouse gas in the atmosphere. Stratospheric ozone protects human beings, but high near-surface ozone concentrations threaten environment and human health. Owing to the uneven distribution of ground-monitoring stations and the low time resolution of polar orbiting satellites, it is difficult to accurately evaluate the refinement and synergistic pollution of near-surface ozone in China. Besides, atmospheric circulation patterns also affect ozone concentrations greatly. In this study, a new generation of geostationary satellite is used to estimate the hourly near-surface ozone concentration with a spatial resolution of 0.05°. First, the Pearson correlation coefficient and maximum information coefficient were used to study the correlation between the top of atmospheric radiation (TOAR) of Himawari-8 satellite and O3 concentration; seven TOAR channels were selected. Second, based on an interpretable deep learning model, the hourly ozone concentration in China from September 2015 to August 2021 was obtained using the TOAR-O3 model. Finally, the self-organizing map method was used to determine six major summer weather circulation patterns in China. The results showed that (1) the near-surface O3 concentration can be accurately estimated; the R2 (RMSE: μg/m3) values of the daily, monthly, and annual tenfold cross validation results were 0.91 (12.74), 0.97 (5.64), and 0.98 (1.75), respectively. The feature importance of the model showed that the temperature, TOAR, and boundary layer height contributed 38 %, 22 %, and 13 %, respectively. (2) The O3 concentration showed obvious spatiotemporal difference and gradually increased from 10:00 to 15:00 (Beijing time) every day. In most areas of China, O3 concentration had increased significantly. (3) The O3 concentration in northern China was the highest under the circulation pattern of the Meiyu front over the Yangtze River Delta, while in southern China, it was the highest under the circulation pattern of the northeast cold vortex controlling most of China.

Physicochemical characteristics of lodging susceptibility of rice cultivars in response to ozone exposure

High tropospheric ozone concentrations reduce rice yield and grain quality, which imposes a serious threat to food security in Asia. This study aimed at determining the effect of ozone on rice lodging, an unpredictable constraint for achieving high yield and good quality in rice production under climate change. Two rice cultivars with different ozone sensitivity were exposed to ozone concentration of 80 ppb (8 h per day) and control conditions (13 ppb) in natural-light fumigation chambers from tillering to maturity. The pushing resistance of intact plants and the lodging-related culm traits were examined. Ozone exposure significantly decreased the in-situ pushing resistance of intact plant or single culm in the ozone-sensitive cultivar YD6, but had no effects in the ozone-tolerant cultivar WYJ27. Ozone reduced breaking resistance and bending moment to a similar magnitude, resulting in no change of lodging index when averaged across all rice basal internodes. In general, WYJ27 was less responsive to ozone than YD6. Negative ozone effects on lodging-related culm traits of YD6 included reductions in the internode dry weight as well as the dry weight per unit internode length, decreases in internode diameter, cross section area and culm wall thickness of basal internodes, and reduced concentrations of soluble sugar and starch. Correlation analysis indicated that ozone-induced decrease in culm strength of YD6 was mainly attributed to the thinner internodes and the smaller culm density due to less nonstructural carbohydrate deposition. The ozone-sensitivity of YD6 was confirmed by its high yield reduction of 25 %, caused by an 11 % decrease in spikelet number per panicle and a 10 % decrease in fulfilled grain weight. The results suggested that rice ozone sensitivity in yield was in consistent with that in stem strength, which could result in no change of lodging index under greenhouse conditions. The realistic lodging susceptibility of these cultivars in response to ozone pollution in open paddy fields, where rice was often subjected to wind and rain during ripening stage, needs further investigation.

Cost-effective equipment for surface pre-treatment for cleaning and excitation of substrates in semiconductor technology

This article presents a cost-effective ultraviolet-ozone cleaner (UV/O3 Cleaner) for surface pre-treatment of substrates in the field of semiconductor technology. The cleaner consists of two chambers, the upper one contains the electronics, including the time counter. The lower chamber contains the two UV sterilisation lamps and a UV reflector of anodized aluminium, which confines the area of high Ozone concentration in the area of interest. The device is successfully used for surface cleaning and modification of different materials. To this end, the two important wavelengths 253.7 nm (excitation of organic residues) and 184.9 nm (production of ozone from the atmospheric environment as a strong oxidant) were first detected. The effectiveness of UV/O3 cleaning is demonstrated by improving the properties of indium tin oxide (ITO) for OLED fabrication. The contact angle of water to ITO could be reduced from 90° to 3° and for diiodomethane, it was reduced from 55° to 31° within the 10 min of irradiation. This greatly improved wettability for polar and non-polar liquids can increase the flexibility in further process control. In addition, an improvement in wettability is characterized by measuring the contact angles for titanium dioxide (TiO2) and polydimethylsiloxane (PDMS). The contact angle of water to TiO2 decreased from 70° to 10°, and that of diiodomethane to TiO2 from 54° to 31°. The wettability of PDMS was also greatly increased. Here, the contact angle of water was reduced from 109° to 24° and the contact angle to diiodomethane from 89° to 49°.Article HighlightsWe report a cost-effective dry-cleaning device for surface cleaning and modification based on ultraviolet-ozone irradiation.Contact angle measurements show an increase of wettability for different materials due to surface modification.The UVO3 pre-treatment improves layer formation and optoelectrical properties of OLEDs.

Effect of distance tip gap on screw electrode of ozone generator: simulation and experimental study

Ozone generation using screw-type electrodes with different distance peak to peak was studied, with the view to comparing the effectiveness of the two technologies in improving for high ozone concentration. Current density, heat flux, and distribution electric potential were performed by using simulation software Ansys. These simulations indicate that the screw-type electrode with a distance of 2 mm generates the higher current density, the result is the same as the initial assumption that the screw distance 2 mm will be better than distance 1.5 mm because it has lower heat flux. Experimental work confirms that a screw model with a distance of 2 mm also has high ozone concentration than a distance 1.5 mm screw model due to current density making electric field strength also higher to produce high ozone concentration, as was also noted by previous authors.

Evaluation of targeted oxidative stress induced by oxygen-ozone in vitro after ischemic induction

ABSTRACT Encephalic vascular accident, or stroke, is the most common pathology of the central nervous system in humans, the second leading cause of death and physical and cognitive disabilities, in developing countries. It presents as an ischemic (more common) or hemorrhagic form. Ozone therapy has been shown to be effective in neuromodulation, neuroprotection, and nerve regeneration. The present study aimed to evaluate the effect of targeted mild ozone after inducing cerebral ischemia in vitro. Neuroblastoma lineage cells (SH-SY5Y) and canine amniotic membrane stem cells were subjected to 24 hours of hypoxia in an incubator culture chamber. The cells were evaluated by MTT assay, colorimetric assay spectrophotometry, fluorescence microscopy, and flow cytometry. Treatment with low concentrations of ozone (2–10 µg/mL), indicated a possible neuroregenerative effect at low concentrations, correlated with lower levels of apoptosis and oxidative stress compared to cells not subjected to hypoxia. High concentrations of ozone (18–30 µg/mL) promoted an increase in rate of apoptosis and cell death. We developed a novel protocol that mimics ozone therapy for ischemic stroke, using ozonized culture medium after hypoxia induction. Although more studies are needed, we conclude that ozone has a dose-dependent hormetic effect and can reverse the effect of ischemia in vitro at low concentrations.

The ozone-activated peroxymonosulfate process for the removal of a mixture of TrOCs with different ozone reactivity at environmentally relevant conditions: Technical performance, radical exposure and online monitoring by spectral surrogate parameters

Secondary effluent from wastewater treatment plants contains (bio)recalcitrant trace organic contaminants (TrOCs) that are discharged into the environment. Ozonation can offer a solution for TrOCs removal from effluent and has been extensively investigated with respect to reaction mechanisms, performance and control strategies in view of full-scale application. The ozone-activated peroxymonosulfate process (O3/PMS) is a relatively new and promising upgrade of ozonation for which research under real conditions is, however, still lacking. Therefore, this work focuses on the removal of 11 TrOCs with different ozone reactivity at environmentally relevant concentrations in effluent by using O3/PMS. At short reaction times, the hydroxyl radical exposure is approximately 2 times higher in O3/PMS than during ozonation at O3 concentrations exceeding the instantaneous ozone demand (IOD). The radical production during O3/PMS is even noticeable at ozone concentrations lower than the IOD, which indicates that radical reaction pathways are more important during the IOD phase in O3/PMS than during ozonation. At longer reaction times, also direct PMS oxidation enhances the removal of some TrOCs at low ozone concentrations (< IOD). However, the extra TrOCs removal during O3/PMS is overall limited compared to ozonation, i.e. up to 24 % extra removal at 0.5 min reaction time and the highest ozone concentration (12.3 mg/L). In a second part of this research, spectral surrogate models based on UV absorbance at 254 nm (UVA254) and fluorescence were developed for the prediction of TrOCs removal. The intensity of both surrogates decreased in a similar way as a function of the applied ozone concentration in both the ozonation and O3/PMS process. However, the regression parameters of the surrogate models and particularly the location of the inflection point show differences between both advanced oxidation processes.

Adverse associations of long-term exposure to ambient ozone with molecular biomarkers of aging alleviated by residential greenness in rural Chinese adults.

Both ambient ozone exposure and residential greenness are linked to the aging process. However, their interactive effect on molecular biomarkers of aging (telomere length (TL) and mitochondrial DNA copy number (mtDNA-CN)) remains unclear. This study was conducted among 6418 rural Chinese adults. The concentration of ambient ozone was assessed using a random forest model. Residential greenness was represented by the normalized difference vegetation index (NDVI). Molecular biomarkers of aging (relative TL and relative mtDNA-CN) were determined by quantitative real-time polymerase chain reaction. Generalized linear regression models were applied to investigate the independent and combined effects of ambient ozone and residential greenness on relative TL and relative mtDNA-CN. The estimated percent changes and 95% confidence intervals (CIs) of relative TL in response to per-unit increase in ambient ozone were -22.43% (-23.74%, -21.18%), -14.19% (-15.63%, -12.72%) and -4.50% (-6.57%, -2.27%) for participants with low (NDVI≤0.53), moderate (0.54-0.55) and high (≥0.56) residential greenness exposure, respectively, while the corresponding figures of relative mtDNA-CN were -12.63% (-13.84%, -11.31%), -9.52% (-10.60%, -8.33%) and 2.12% (0.20%, 4.19%). Furthermore, negative interactive effects between ambient ozone and residential greenness exposure on molecular biomarkers of aging were observed (Pfor interaction<0.001 for relative TL, and 0.098 for relative mtDNA-CN). Long-term exposure to high concentrations of ambient ozone and low residential greenness was associated with decreased mtDNA-CN and shortened TL. The adverse effect of ambient ozone exposure on molecular biomarkers of aging may be attenuated by increased residential greenness.

Evaluation of Ambient Ozone Effect in Bean and Petunia at Two Different Sites under Natural Conditions: Impact on Antioxidant Enzymes and Stress Injury

Tropospheric ozone is a harmful air pollutant and greenhouse gas that adversely affects living organisms. The effect of long-term ozone stress on the activity of SOD, APX, and GuPX, as well as lipid peroxidation and membrane injury in bean and petunia growing at a city site and in a forest, characterised by different ozone concentrations, was examined. The experiments were conducted in three growing seasons with different tropospheric ozone concentrations and meteorological conditions. Plants’ exposition to increased ozone concentration resulted in enhanced activity of antioxidant enzymes, level of lipid peroxidation, and membrane injury. In all years, higher ozone levels and solar radiation were observed at the forest site. The pattern of the changes in enzyme activity was dependent on ozone concentrations as well as on environmental conditions and varied from year to year. In the second year with the highest ozone concentration, the activity of GuPX and SOD increased the most. However, despite higher ozone concentration in the forest, a larger increase in APX and SOD activity in both species and GuPX activity in bean was recorded at the city site. The present results revealed that plant response to ozone might vary in different locations not only due to differences in ozone concentration but also because of the impact of other environmental factors, such as solar radiation and temperature.

Machine-Learning-Based Near-Surface Ozone Forecasting Model with Planetary Boundary Layer Information.

Surface ozone is one of six air pollutants designated as harmful by National Ambient Air Quality Standards because it can adversely impact human health and the environment. Thus, ozone forecasting is a critical task that can help people avoid dangerously high ozone concentrations. Conventional numerical approaches, as well as data-driven forecasting approaches, have been studied for ozone forecasting. Data-driven forecasting models, in particular, have gained momentum with the introduction of machine learning advancements. We consider planetary boundary layer (PBL) height as a new input feature for data-driven ozone forecasting models. PBL has been shown to impact ozone concentrations, making it an important factor in ozone forecasts. In this paper, we investigate the effectiveness of utilization of PBL height on the performance of surface ozone forecasts. We present both surface ozone forecasting models, based on multilayer perceptron (MLP) and bidirectional long short-term memory (LSTM) models. These two models forecast hourly ozone concentrations for an upcoming 24-h period using two types of input data, such as measurement data and PBL height. We consider the predicted values of PBL height obtained from the weather research and forecasting (WRF) model, since it is difficult to gather actual PBL measurements. We evaluate two ozone forecasting models in terms of index of agreement (IOA), mean absolute error (MAE), and root mean square error (RMSE). Results showed that the MLP-based and bidirectional LSTM-based models yielded lower MAE and RMSE when considering forecasted PBL height, but there was no significant changes in IOA when compared with models in which no forecasted PBL data were used. This result suggests that utilizing forecasted PBL height can improve the forecasting performance of data-driven prediction models for surface ozone concentrations.

Effects of Brush-Type Ionizer Materials on Virus Inactivation.

Many studies have found that bioaerosols are harmful to humans. In particular, infectious viruses, such as the virus that causes COVID-19, are increasing. Therefore, the research on methods for reducing bioaerosols is becoming progressively more important. The purpose of this study was to improve the existing electrostatic precipitator, which generates high concentrations of ozone, by reducing bioaerosols effectively without significant ozone production. A brush-type ionizer was studied as a replacement for the existing electrostatic precipitator. The study, which was conducted at the laboratory scale, determined the amounts of ions generated with different ionizer materials (carbon, copper, and stainless steel) and voltages (−1, −2, and −3 kV), as well as it compared the virus inactivation efficiency under the various conditions. As a result, about two million ions were produced when a voltage of −3 kV was applied to all of the materials, and 99.9 ± 0.2% and 98.8 ± 0.6% virus inactivation efficiencies were confirmed in the cases of carbon and copper, respectively. In addition, an assessment of the effect of flow velocity confirmed that the inactivation efficiency decreased as the flow velocity increased. However, the results for the flow velocities of 0.2 and 0.4 m/s had similar trends. Therefore, this system can be used with flow velocities up to 0.4 m/s.

Preparation of nano/microcapsules of ozonated olive oil in chitosan matrix and analysis of physicochemical and microbiological properties of the obtained films

In order to meet one of the greatest problems of food technology, i.e. unwanted food spoilage caused by the action of microorganisms, active or intelligent packaging is being created and used with increasing frequency. At the same time, substitutes for plastics are being sought in order to protect the environment. Biodegradable polymer composites seem to be an extremely promising material that could replace synthetic materials in the future. By encapsulating biologically active substances in a polymer matrix, directional action and controlled release of the substance are possible. The use of ozone, which has become more and more popular especially recently, allows to limit the growth of microorganisms, and the production of ozone derivatives of unsaturated fats allows to reduce the short time of its decomposition.The aim of this study was to analyse the physicochemical and bacteriostatic properties of innovative chitosan-based films containing encapsulated nanocapsules of ozonated olive oil in two concentrations. The morphology and size of the obtained nanocapsules were determined using Scanning Electron Microscopy and DLS. The largest particle size was observed for the film containing the lower ozone concentration – up to 4900 nm, in the control film 3500 nm, for the film with the highest ozone concentration, the particle size was the smallest, with the majority in the range of 100–1000 nm. Ozone content was determined by peroxidation number. The properties of the composites were characterised by infrared (IR) which proved that chitosan is a good matrix for the formation of capsules and ultraviolet (UV) which showed that the obtained composite absorbs light in the range of blue and near ultraviolet light, and the addition of nanocapsules of ozonated olive oil increased the degree of absorption and decreased the transparency. We also performed photoluminescence spectroscopy before and after storage of pork meat proving that films are sensitive to the physico-chemical and biochemical transformation products formed as a result of meat spoilage. The study of the microbiological properties included the analysis of the microbiological quality of pork meat stored under the obtained films as a function of time. The films have a bactericidal and bacteriostatic effect and the addition of ozonated olive oil capsules increases the bactericidal effect against Gram-negative bacteria. Contact angles, Water Vapour Transmission Rate and transparency were also determined and they were subjected to enzymatic hydrolysis. Water absorption, solubility and liquid absorption capacity were determined. All tested samples show high hydrophobicity and low solubility, and the ozone content directly influences these parameters.

The risk of respiratory incidents in response to the increase of ozone concentration in the ambient air, in the Silesian Voivodeship, in 2016-2017.

Due to the high level of urbanization and industrialization, Silesian Voivodeship remains a region with the poorest quality ambient air, especially in the winter season in which alarm levels are constantly being exceeded. However, in the summertime, there are observed short-term episodes of high ozone concentrations for which their impact on the population health is poorly documented. The aim of the study was to assess the risk of daily respiratory health problems related to an increased pollutants concentration typical for photochemical smog. In the ecological type of study, secondary epidemiological data were used. They were obtained from the National Health Fund (NFZ) in Katowice and included the number of outpatient visits in primary health care and hospitalizations due to respiratory diseases (J00-J99) and selected acute respiratory incidents registered between 01/01/2016 and 31/08/2017 in the Silesian Voivodeship. In the summertime of both years (2016 and 2017), there were observed short-term episodes of photochemical smog in the study region. Obtained results show a significant increase in the risk of outpatient visits due to total respiratory diseases, and also due to acute pharyngitis, acute laryngotracheitis, bronchitis, and asthma in response to the increase in ozone concentration. Similarly, a significant increase in the risk of hospitalization for all respiratory diseases was found, however, it appeared with a delay of at least two to three weeks. In the case of hospitalization due to bronchitis statistically significant risk was observed 2-4 days after the increase in exposure. The occurrence of registered respiratory incidents was confirmed in response to the increase in ozone concentration, characteristic of the summertime in the Silesian Voivodeship.

Observed sensitivities of PM2.5 and O3 extremes to meteorological conditions in China and implications for the future.

Frequent extreme air pollution episodes in China accompanied with high concentrations of particulate matters (PM2.5) and ozone (O3) are partly supported by meteorological conditions. However, the relationships between meteorological variables and pollution extremes can be poorly estimated solely based on mean pollutant level. In this study, we use quantile regression to investigate meteorological sensitivities of PM2.5 and O3 extremes, benefiting from nationwide observations of air pollutants over 2013-2019 in China. Results show that surface winds and humidity are identified as key drivers for high PM2.5 events during both summer and winter, with greater sensitivities at higher percentiles. Higher humidity favors the hydroscopic growth of particles during winter, but it tends to decrease PM2.5 through wet scavenging during summer. Surface temperature play dominant role in summer O3 extremes, especially in VOC-limited regime, followed by surface winds and radiation. Sensitivities of O3 to meteorological conditions are relatively unchanging across percentiles. Under the fossil-fueled development pathway (SSP5-8.5) scenario, meteorological conditions are projected to favor winter PM2.5 extremes in North China Plain (NCP), Yangtze River Delta (YRD) and Sichuan Basin (SCB), mainly due to enhanced surface specific humidity. Summer O3 extremes are likely to occur more frequently in the NCP and YRD, associated with warmer temperature and stronger solar radiation. Besides, meteorological conditions over a relatively longer period play a more important role in the formation of pollution extremes. These results improve our understanding of the relationships between extreme PM2.5 and O3 pollution and meteorology, and can be used as a valuable reference of model predicted air pollution extremes.

Relationship of Surface Ozone (O3) with its precursors and meteorological parameters over New Delhi, India

In the present study, continuous measurements of Surface Ozone (O3), Oxides of Nitrogen (NOx (NO+ NO2)), and carbon monoxide (CO), monitored at five different locations in Delhi National Capital Region have been studied for the period 2013 – 2019. The five monitoring locations used are namely IMD Lodi Road, IGI Airport Palam, CV Raman Dheerpur, CRRI Mathura Road, and NCMRWF Noida. The average hourly concentration of O3, NO, NO2, CO, NOx (NO + NO2), and OX(NO2 +O3) are found in the range of 32.44 ppb to 36.57 ppb, 19.46 to 28.09 ppb, 20.83 to 26.89 ppb,1.67 to 1.89 ppm,43.04 to 54.99 ppb, and 54.06 to 60.99 ppb respectively during the study period. Diurnal variation of NOx and CO Concentrations show higher values during the morning (0600-0900h) and late evening (1900-2400h) hours while the highest concentrations of ozone have been observed during afternoon hours. The relationship between NO, NO2, and surface O3 as a function of NOx has also been examined during daylight hours (0500hrs IST to 1900 hrs IST) and chemical coupling of the three species i.e. NO, NO2 and O3 have been studied. The ground-level concentration of Ozone has been found to decrease with increasing NOx concentration during the daytime. The variations in concentrations of oxidants (NO2 + O3) with the concentration of [NOx] have been studied to examine the contributing pollution sources of oxidants at all the study sites. The average rate of change of O3 concentrations (dO3/dt) has been examined at all five locations. The monthly and diurnal variation of oxidants [OX] at all the study locations has shown a strong positive correlation with temperature whereas a negative correlation with humidity.

Does Ozone Pollution Share the Same Formation Mechanisms in the Bay Areas of China?

As important regions of transition between land and sea, the three bay areas of Bohai Bay (BHB), Hangzhou Bay (HZB), and Pearl River Estuary (PRE) in China often suffer from severe photochemical pollution despite scarce anthropogenic emissions. To understand the causes of high ozone (O3) concentrations, the high O3 episode days associated with special synoptic systems in the three bays were identified via observations and simulated by the weather research and forecasting coupled with community multiscale air quality (WRF-CMAQ) model. It was revealed that the interaction between synoptic winds and mesoscale breezes resulted in slow wind speeds over the HZB and PRE, where air pollutants transported from upwind cities gained a long residence time and subsequently participated in intensive photochemical reactions. The net O3 production rates within the bay areas were even comparable to those in surrounding cities. This finding was also applicable to BHB but with lower net O3 production rates, while high levels of background O3 and the regional transport from farther upwind BHB partially elevated the O3 concentrations. Hence, these three bay areas served as O3 "pools" which caused the accumulation of air pollutants via atmospheric dynamics and subsequent intense photochemical reactions under certain meteorological conditions. The results may be applicable to other similar ecotones around the world.

Development of a Miniature Mass Spectrometry System for Point-of-Care Analysis of Lipid Isomers Based on Ozone-Induced Dissociation.

Disorder of lipid homeostasis is closely associated with a variety of diseases. Although mass spectrometry (MS) approaches have been well developed for the characterization of lipids, it still lacks an integrated and compact MS system that is capable of rapid and detailed lipid structural characterization and can be conveniently transferred into different laboratories. In this work, we describe a novel miniature MS system with the capability of both ozone-induced dissociation (OzID) and collision-induced dissociation (CID) for the assignment of sites of unsaturation and sn-positions in glycerolipids. A miniature ozone generator was developed, which can be operated at a relatively high pressure. By maintaining high-concentration ozone inside the linear ion trap, OzID efficiency was significantly improved for the identification of C═C locations in unsaturated lipids, with reaction times as short as 10 ms. Finally, the miniature OzID MS system was applied to the analysis of C═C locations and sn-positions of lipids from biological samples. Direct sampling and fast detection of changes in phospholipid isomers were demonstrated for the rapid discrimination of breast cancer tissue samples, showing the potential of the miniature OzID MS system for point-of-care analysis of lipid isomer biomarkers in complex samples.

Clustering-based spatial transfer learning for short-term ozone forecasting

Ground-level ozone is a critical atmospheric pollutant, and high concentrations of ozone can damage human health, affect plant growth and cause ecological harm. Traditional chemical transport models and popular machine learning models have difficulty in predicting ozone concentrations, especially in times with high concentrations. We proposes a clustering-based spatial transfer learning Multilayer Perceptron (SPTL-MLP) to predict ozone concentration at the target observation station for the next three days. We use k-means clustering algorithm to find similar stations and train them together to get a base model for spatial transfer learning. For practical applications, a weighted loss function has been designed with an extra emphasis on reducing prediction errors of high ozone concentrations. Evaluation using historical data of stations in Germany shows that our SPTL-MLP model has a smaller error (reduced by 9.13%) and higher prediction accuracies of ozone exceedances (improved by 8.21% and 16.9%) compared to MLP (without spatial transfer). The results demonstrate the effectiveness of the SPTL-MLP in the short-term ozone forecast. It can be used for timely warning of ozone exceedances and help governments to detect air quality.