Major Atmospheric Pollutants Research Articles

Improvement of PM2.5 and O3 forecasting by integration of 3D numerical simulation with deep learning techniques

Air pollution is a major impediment to the sustainable development of cities and society. Governed by emission characteristics and meteorological conditions, the formation and destruction of fine particulate matter (PM2.5) and ozone (O3) are complicated, and accurate predictions of the concentrations of these two major secondary atmospheric pollutants remain challenging. In this study, by combining meteorological and air pollutant data from ground observations and the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) model simulations, a deep learning model structure based on long short-term memory layers (LSTM) was developed and applied to predict the PM2.5 and O3 concentrations in the future 48 h period. The forecasting improvement was extended to the whole Greater Bay Area by introducing a spatial correction (SC) method to the CMAQ simulation results. Compared with the original CMAQ forecast, the new method gained a 26% reduction in mean absolute error (MAE) and a 33% reduction in root mean square error (RMSE), respectively, in terms of PM2.5; it also achieved a 40% reduction in MAE and a 34% reduction in RMSE in terms of O3. SC method, applied to the whole GBA region, also reduced the overall MAE and RMSE by 10% and 17% in terms of PM2.5 and by 31% and 25% in terms of O3, respectively. Using an AI approach, our study provides new perspectives for further improving air quality forecasting from both temporal and spatial perspectives, thus increasing the smartness and resilience of the cities and promoting environmentally sustainable development in the area.

Influence of atmospheric in-cloud aqueous-phase chemistry on the global simulation of SO<sub>2</sub> in CESM2

Abstract. Sulfur dioxide (SO2) is a major atmospheric pollutant and precursor of sulfate aerosols, which influences air quality, cloud microphysics, and climate. Therefore, better understanding the conversion of SO2 to sulfate is essential to simulate and predict sulfur compounds more accurately. This study evaluates the effects of in-cloud aqueous-phase chemistry on SO2 oxidation in the Community Earth System Model version 2 (CESM2). We replaced the default parameterized SO2 aqueous-phase reactions with detailed HOx, Fe, N, and carbonate chemistry in cloud droplets and performed a global simulation for 2014–2015. Compared with the observations, the results incorporating detailed cloud aqueous-phase chemistry greatly reduced SO2 overestimation. This overestimation was reduced by 0.1–10 ppbv (parts per billion by volume) in most of Europe, North America, and Asia and more than 10 ppbv in parts of China. The biases in annual simulated SO2 mixing ratios decreased by 46 %, 41 %, and 22 % in Europe, the USA, and China, respectively. Fe chemistry and HOx chemistry contributed more to SO2 oxidation than N chemistry. Higher concentrations of soluble Fe and higher pH values could further enhance the oxidation capacity. This study emphasizes the importance of detailed in-cloud aqueous-phase chemistry for the oxidation of SO2. These mechanisms can improve SO2 simulation in CESM2 and deepen understanding of SO2 oxidation and sulfate formation.

Study on the photoionization and dissociative photoionization of ortho-, meta-, para-bromofluorobenzenes using VUV synchrotron radiation

Bromofluorobenzene(BrFPh) is one of the major volatile atmospheric pollutants. In this paper, using the VUV synchrotron radiation as the excitation source, the photoionization time of flight mass spectra of ortho-, meta-, para-BrFPh moleclues were recorded and the mass spectra illustrated that BrFPh molecule would be ionized into C6H4BrF+ and then dissociate into C6H4F+ and Br atom under the synchrotron radiation. Then the photoionization efficiency (PIE) curves of each parent ions and fragment ions were obtained by plotting the ion intensity versus photon energy. And the photoionization energies of three isomers of BrFPh molecules were determined to be 9.10 eV, 9.16 eV, 8.98 eV. Meanwhile, the photodissociation energies of o-, m-, p-C6H4BrF+ ions were determined to be 3.71 eV, 3.50 eV and 3.63 eV, respectively. Furthermore, the photoionization and photodissociation energies of them were also calculated based on DFT via B3LYP/6–311++G basis set. The theoretical results are in excellent agreement with the experimental values, and could provide important theoretical support for the experimental analysis of the photoionization and dissociative photoionization process of BrFPh molecules.

Towards robust on-site ammonia emission measuring techniques based on inverse dispersion modeling

Ammonia is recognized as one of the major atmospheric pollutants affecting air and ecosystem quality. The application of N fertilizers is a major source of NH3 emissions. It is necessary to develop simple, accurate and low cost measurement techniques to obtain representative data for a wide range of regions and agricultural practices. This information would improve national inventories and support decision-making processes regarding strategies for NH3 emission abatement. Measurement techniques can be complex, adjusted to specific conditions, labor-intensive and costly. This work analyses different methods aimed at reaching a balance between the accuracy and precision required for measurements and their complexity. Three techniques were tested under: semiopen passive chambers (SOCs) and an inverse dispersion model (IDM) combined with two different NH3 air concentration measuring techniques: ALPHA® passive samplers and acid bubblers. Different setups were evaluated testing different heights over the emitting surface. These techniques were assessed using micrometeorological mass balance integrated horizontal flux (IHF) with passive flux samplers as a reference method. The SOC results showed a close linear relationship with the IHF results (R2=0.784, p<0.01), although emissions after 16 days were 10.6% higher. The bLS IDM with acid bubblers showed promising results, although they were labor-demanding and required a power supply. The IDM with ALPHA® samplers placed at a 1.25-m height was demonstrated to embrace precision and close agreement with the IHF observations in our experimental conditions (R2=0.768, p<0.01; no difference from line 1:1; mean bias: 0.041 kg N ha−1h−1 and rRMSE: 46.1%). However, these data require special attention for periods of drastically changing weather, when the NH3 fluxes determined with air concentration samplers moved away from the overall emission pattern. Longer sampling intervals and the assumption of neutral atmospheric conditions in IDM may decrease costs, simplify the procedure and provide a cost-efficient alternative to the IHF method.

“Military Parade Blue Skies” in Beijing: Decisive Influence of Meteorological Factors on Transport Channel and Atmospheric Pollutant Concentration Level

The severity of high atmospheric pollution has been a major social problem in northern China. To improve the air quality in the Beijing–Tianjin–Hebei (BTH) region and guarantee a suitable environment during the military parade and other celebrating activities for the 70th anniversary of the victory for anti-Fascist Warcraft in the year 2015, a series of strict air quality control policies were carried out. To analyze the reduction extents of PM2.5 and organic matter components during the control period and to examine the meteorological conditions in this region and their decisive influence on the air quality, PM2.5 samples were collected and the Lagrangian particle dispersion model FLEXPART was performed to calculate potential source locations within the BTH region. PM2.5, organic carbon (OC), elementary carbon (EC), and three species types were specifically analyzed. Although the results showed that PM2.5, OC, and EC reduced by 64.55%, 48.74%, and 60.75% during the control period, the air mass transport patterns showed great difference at certain periods, which altered the dominant transport direction of air mass and the potential source region of pollutants and organic matters. This alteration completely changed major atmospheric pollutants sources contribution and caused huge concentration changes. Parallel cases also showed that meteorological conditions could avoid massive atmospheric transported from a major emission source region to a receptor site. The meteorological conditions changed the main contribution source region in control and non-control periods and proved the air quality control measures were less necessary in some southern Hebei cities during special events periods.

Effect of Port Activities on the Physicochemical and Microbiological Quality of Surface Water in Warri and Onne Port Terminals, Nigeria

Activities around the port terminals such as cargo handling, and others has environmental implications both inside and outside the port area which may in turn pose severe risks to the environment and water resources resulting to adverse effect on the physicochemical and microbiological quality of the water body. Hence this study was aimed at determination of the effect of port activities on the physicochemical and microbiological quality of surface water at Warri and Onne Port terminals. Surface water samples were collected during wet and dried season between January to June from Onne and Warri port terminals, using sterile containers and transported in an ice packed container to Department of Microbiology laboratory of the Rivers State University for microbiological and physicochemical analyse using standard methods. Statistical analyses were carried out using ANOVA and All pairs tukey-kramer. Results of the Physicochemical Characteristics of the surface water of the dry season ranged as follows; pH (5.6±0.15 to 6.08±0.22),Temperature (27.6±4.278 to 30±1ºC), Electric conductivity (14168±1.90to 2138±27.871 µs/cm), Total dissolved solid (2622±1.70 to 974.2±9.09 mg/l ),Total suspended solid (7.6±0.54 to 111±21.284 mg/l), Dissolved oxygen (2.08±0.19 to 2.68±0.31 mg/l ), Biological oxygen demand (0.78±0.19 to 1.2±0.45 mg/l ), Chemical oxygen demand (1.56±0.38 to 2.4±0.90 mg/l),Turbidity (0.2±0 to 1.36±0.336 NTU),Bromine (0.3±0.01 to 0.6±0 mg/l), Chlorine (&lt;0.001±0 to 0.3±0 mg/l),Nitrate (0.32±0.15 to 5.98±0.74 mg/l ), Sulphate (3.32±0.75 to 694±1.9 mg/l) Phosphate (0.634±0.42 to 2.316±0.44 mg/l ), similar trends were recorded during the wet season. There were significant differences ( P&lt;0.05) between the wet and dry seasons. The mean values of the microbiological results ranged from 1.6±0.77 x 106 to 5.6±2.17 x 106 cfu/ml (Total heterotrophic bacterial count), 0.8 ±2.51 x 104 to 5.6±2.77 x 104 cfu/ml (Total heterotrophic Fungal count), 0.2 ±1.14 x 104 to 3.6 ±1.52 cfu/ml (Hydrocarbon utilizing Bacteria counts) 0.3 ±1.52 x 104 to 1.2 ±2.05cfu/ml (Hydrocarbon utilizing Fungal counts), 0.2±0.71x 104 to 0.6±0.89 x 104cfu/ml (Salmonella spp.). 0.4±0.55 x 104 cfu/ml (Shigella spp), 0.3 ±2.19 x 104 to 1.6±5.13 x 104 cfu/ml (Vibrio spp.) 1.6 ±14.7 x 104 to 2.1±6.39 x 104 cfu/ml Staphylococci spp), 3.9±0.81 x 104 to 4.6 ±1.79 x 104cfu/ml (total coliform), 1.8±0.44 x 104 to 2.7 ±1.03 x 104cfu/ml (feacal coliform). Higher counts were recorded during the wet season compared to dry season. In this study, nine bacteria isolates belonging to the genera and species:- E.coli, Vibrio, Pseudomonas, Klebsiella, Bacillus sp., Shigella, Staphylococcus, Salmonella, and Proteus, Six fungal isolates, namely, Penicillium sp Candida sp, Mucor sp, Aspergillus, Rhizopus spp, and Yeast were obtained. The results obtained in this study Port terminal houses several companies with beehive of activities which generate various industrial wastes which causes adverse environmental effects which consequently are major atmospheric and water pollution around port terminals. Therefore, proper waste management system should be maintained to avoid emergence of virulent pathogens.

COVID-19’s lockdown effect on air quality in Indian cities using air quality zonal modeling

The complete lockdown due to COVID-19 pandemic has contributed to the improvement of air quality across the countries particularly in developing countries including India. This study aims to assess the air quality by monitoring major atmospheric pollutants such as AOD, CO, PM2.5, NO2, O3 and SO2 in 15 major cities of India using Air Quality Zonal Modeling. The study is based on two different data sources; (a) grid data (MODIS- Terra, MERRA-2, OMI and AIRS, Global Modeling and Assimilation Office, NASA) and (b) ground monitoring station data provided by Central Pollution Control Board (CPCB) / State Pollution Control Board (SPCB). The remotely sensed data demonstrated that the concentration of PM2.5 has declined by 14%, about 30% of NO2 in million-plus cities, 2.06% CO, SO2 within the range of 5 to 60%, whereas the concentration of O3 has increased by 1 to 3% in majority of cities compared with pre lockdown. On the other hand, CPCB/SPCB data showed more than 40% decrease in PM2.5 and 47% decrease in PM10 in north Indian cities, more than 35% decrease in NO2 in metropolitan cities, more than 85% decrease in SO2 in Chennai and Nagpur and more than 17% increase in O3 in five cities amid 43 days pandemic lockdown. The restrictions of anthropogenic activities have substantial effect on the emission of primary atmospheric pollutants.

深圳市大气污染时空分布及其与景观格局的关系

气溶胶和臭氧是我国大部分地区的两种主要大气污染物，对城市生态环境和人类身体健康影响严重。以深圳市为研究区，利用大气监测站点提供的监测数据和普通kriging空间插值法，从年、季、月尺度上开展近5年（2015-2019）深圳全市PM_2.5和臭氧的时空分布研究，通过皮尔逊分析和显著性检验从月尺度上分析土地覆盖类型及其景观格局对大气污染的影响。结果表明：（1）近5年内深圳市PM_2.5浓度总体呈现下降趋势，臭氧浓度则先降后升，二者季节性和月度差异显著。（2）PM_2.5和臭氧在年、季、月尺度上空间差异明显，全市PM_2.5浓度整体为西北高、东南低；臭氧浓度西北、东南较高，其余区域相对较低。（3）植被占比的增多对PM_2.5浓度有明显的抑制和调控作用，植被斑块间距离越近，对PM_2.5浓度的调控作用越明显；水体占比的增高会导致臭氧浓度增高和变化幅度增大。研究结果可为城市大气污染防治和景观格局规划管理提供参考。;Aerosols and ozone are two major atmospheric pollutants in most regions of China, which have serious impacts on the city ecological environment and human health. Taking Shenzhen as the study area, the spatial and temporal distribution of PM_2.5 and ozone in the last five years (2015-2019) were studied at annual, seasonal, and monthly scales using monitoring data provided by observation stations and the ordinary Kriging spatial interpolation method. In addition, the landcover and its landscape were analyzed at monthly scales by Pearson analysis and significance test. The results show that: (1) in the past five years, PM_2.5 concentration in Shenzhen show a general decreasing trend, while ozone concentration increase after an early decrease, they both have significant seasonal and monthly differences. (2) The spatial differences between PM_2.5 concentration and ozone concentration on the annual, seasonal and monthly scales are obvious, and the PM_2.5 concentration is overall high in the northwest and low in the southeast of Shenzhen, while ozone concentration is higher in the northwest and southeast but relatively low in the rest of Shenzhen. (3) The increase of vegetation occupancy has a significant inhibitory and regulatory effect on PM_2.5 concentration, and the closer the distance between vegetation patches, the regulatory effect on PM_2.5 concentration becomes more obvious; the increase in the proportion of water bodies may lead to higher and more variable ozone concentration. This study can provide reference for urban air pollution control and landscape pattern planning and management.

A Novel Method for Regional NO2 Concentration Prediction Using Discrete Wavelet Transform and an LSTM Network.

Achieving accurate predictions of urban NO2 concentration is essential for effectively control of air pollution. This paper selected the concentration of NO2 in Tianjin as the research object, concentrating predicting model based on Discrete Wavelet Transform and Long- and Short-Term Memory network (DWT-LSTM) for predicting daily average NO2 concentration. Five major atmospheric pollutants, key meteorological data, and historical data were selected as the input indexes, realizing the effective prediction of NO2 concentration in the next day. Firstly, the input data were decomposed by Discrete Wavelet Transform to increase the data dimension. Furthermore, the LSTM network model was used to learn the features of the decomposed data. Ultimately, Support Vector Regression (SVR), Gated Regression Unit (GRU), and single LSTM model were selected as comparison models, and each performance was evaluated by the Mean Absolute Percentage Error (MAPE). The results show that the DWT-LSTM model constructed in this paper can improve the accuracy and generalization ability of data mining by decomposing the input data into multiple components. Compared with the other three methods, the model structure is more suitable for predicting NO2 concentration in Tianjin.

Review of Recent After-Treatment Technologies for De-NOx Process in Diesel Engines

The removal of nitrogen oxides (NOx), which are major atmospheric pollutants, in exhaust gas after-treatment systems, has been studied extensively. The catalytic reduction of NOx in lean-burn environments is challenging in diesel after-treatment technology. The most relevant catalytic NOx reduction technologies for diesel engines are summarized in this review paper, focusing on current catalytic after-treatment systems for compliance with emission standards. Four promising after-treatment technologies for the abatement of tail-pipe NOx emissions are discussed: (i) lean NOx trap (LNT) and LNT combined with selective catalytic reduction (SCR) (LNT + SCR), (ii) Urea/NH3-SCR, (iii) Hydrocarbon-SCR (HC-SCR), and (iv) CO/H2-SCR. The relevant reaction mechanisms and current major challenges are reviewed in detail. The effects of the active phases and support modifications of the respective catalysts are examined to evaluate their contribution to the after-treatment systems. Major issues in practical applications, such as hydrothermal aging, chemical poison, and metallic additives for improving de-NOx performance, are extensively reviewed in this paper.

Spatial and temporal variations of open straw burning based on fire spots in northeast China from 2013 to 2017

Open straw burning releases significant amounts of particulate matter (PM) and trace gases into the air and thus is an important source of atmospheric pollutants in China. In this study, based on fire spots in northeast China from 2013 to 2017, we analyzed pollution concentration degree (PCD) and pollution concentration period (PCP), and assessed spatial and temporal variations of open straw burning. Straw types and burning areas were then determined according to the distributions of fire spots and land use dataset. The amounts of several major atmospheric pollutants (PM10, PM2.5, CO, NOx and NMVOCs (non-methane volatile organic compounds)) emitted into the atmosphere from open straw burning were estimated according to crop production, Residue/Grain ratio (R/G), combustion efficiency and emission factor. Open straw burning occurred frequently in dry and paddy fields, mainly in areas of West and Northeast Heilongjiang Province, Midwest Jilin Province and Central Liaoning Province. The temporal variations of open straw burning tended to be dispersed with PCD varying from >0.8 during 2013–2015 to <0.4 during 2017 and PCP changing from 28.2 to 36.0 during autumn-winter seasons of 2013–2015 to 5.4–7.9 during winter-spring seasons of 2016–2017. During the five-year period (2013–2017), the total straw yield reached 628.7 million tons, of which 10.9 million tons were open burned in northeast China. The total amounts emitted from open straw burning were 108.9, 106.9, 552.9, 36.9 and 99.4 thousand tons for PM10, PM2.5, CO, NOx and NMVOCs, respectively. Among these emissions, corn straw burning contributed 81.7%, 81.6%, 71.4%, 86.8% and 74.9% while rice straw burning contributed 18.2%, 18.4%, 28.5%, 13.2% and 25.0%, respectively. Emissions from open straw burning have significant impacts on pollutants ambient concentrations, especially for PM2.5 in the autumn-winter seasons as indicated by their good correlations (p < 0.05).

Analysis of surface and vertical measurements of O3 and its chemical production in the NCP region, China

Abstract Ozone has become a major atmospheric pollutant in the North Central Plain (NCP) of China. Comprehensive measurements concerning the vertical profiles and photochemical formation mechanisms of typical O3 pollution episode during August 8–13, 2018 were conducted in the NCP. A maximum hourly ozone concentration of 346 μg/m3 was observed on Aug 10, in which the surface O3 photochemistry was under a strong VOC-limited regime, and the ratio of VOC to NOX ranged from 4:1 to 4:3, with ethylene, toluene, xylene, and propene providing large contributions to O3 chemical production. The vertical measurements of O3, NOX, and the planetary boundary layer (PBL) height suggested that there were three different layers of photochemical O3 production from the surface to 1.1 km. The first layer was from the surface to 200 m, with high NO concentrations leading to a strong conversion between O3 and NO2. The surface O3 concentration was significantly lower than at 220 m during nighttime and early morning, with an average O 3 of approximately 60 μg/m3 and the maximum vertical gradient appearing in the early morning. Diurnal variations of NO2 and N O 2 were significantly inversely correlated with O3 and O 3 . In the second vertical layer between 200 m and 1000 m the value of d[O3]/dt ranged from 10 to 40 μg/m3/h, and the maximum chemical production of O3 occurred at 300 m. The third layer was located outside the PBL height, where O3 precursors with short chemical lifetimes rapidly decreased, producing weak chemical O3 production.

Continuous and comprehensive atmospheric observations in Beijing: a station to understand the complex urban atmospheric environment

ABSTRACT Due to profound impact on climate and human health, air quality has attracted attention from all levels of the civil society. The key step in the provision of required tools for the society to tackle the complex air quality problem is to characterize it in a comprehensive manner with a long-term perspective. Here, we describe a continuous and comprehensive observation station and its accompanying state-of-the-art instrumentation that was established to investigate the complex urban atmospheric environment in a rapidly developing Chinese Megacity. The station, located in downtown Beijing, aims to study air quality by identifying the major atmospheric pollutants and key processes determining their formation and loss mechanisms. A few hundreds of parameters are continuously measured with the state-of-the-art instruments, including trace gas concentrations, aerosol particle size distributions, and mass concentrations, covering aerosol particle chemical composition from molecules to micrometer-sized aerosol particles. This produced long-term, comprehensive big data with around bytes per year. In this paper, we provide an overview on the facilities of the station, the instrumentation used, the workflow of continuous observations and examples of results from 2018 to 2019 and a basis for establishing a modern long-term, comprehensive atmospheric urban observation station in other megacities.

Comparative study of air quality indices in the European Union towards adopting a common air quality index

This study aims to compare air quality indices applied in European Union countries towards adopting a common air quality index. The urban European cities Rome, Madrid, Paris, London, Berlin, Warsaw, Stockholm, and Oslo were selected. Using the EEA AirBase air quality database, time series data for the major atmospheric pollutants (CO, NO2, SO2, O3, PM10, and PM2.5) were recovered for each city, for most recent years available. Daily averages, maximum hourly values and maximum 8-h averages were calculated for each pollutant. The air quality indices selected were BelAQI, DAQx, DAQI, AtmoIndex, AQIH, and CAQI. The daily value of each air quality indices and the corresponding dominant atmospheric pollutant were determined for each city. A two-stage normalization procedure was applied on air quality indices in a 0–1 range, to allow their direct comparison without altering their structure. All air quality indices exhibited air quality rates over 64% for all cities, thus below the European Union air quality standard. The dominant pollutant was NO2 for both BelAQI and DAQx; O3 for both DAQI and AQIH (with an exception for Warsaw where SO2 was the dominant pollutant). For CAQI, NO2 prevails in Berlin, London, Warsaw, Stockholm, and Oslo, while O3 prevails in Rome, Madrid, and Paris. The dominant pollutant for AtmoIndex was NO2 in Berlin, Warsaw, and Stockholm; O3 in Madrid, Paris, London, and Oslo; PM10 in Rome. A very strong positive statistical correlation ( p &lt; 0.01) was found for all cities between BelAQI and CAQI, and also between CAQI and DAQx. A strong positive statistical correlation ( p &lt; 0.01) was found for all cities between BelAQI and DAQx. A moderate positive correlation was shown between the following pairs of indices: AtmoIndex-DAQI, AtmoIndex-AQIH, DAQI-AQIH, BelAQI-AQIH, and AQIH-CAQI. On the contrary, a weak positive correlation was noticed between the following pairs of indices: BelAQI-DAQI, BelAQI-AtmoIndex, DAQX-DAQI, DAQx-AQIH, DAQI-CAQI, and CAQI-AtmoIndex. After the normalization process that enables the direct comparison of the air quality indices, the main results are the BelAQI presents the largest normalized median (range 0.33–0.5) implying the worst air quality compared to the other air quality indices. The CAQI has a median value of 0.33, the DAQx of 0.25, while the AtmoIndex a median value range of 0.125–0.375, and the DAQI and AQIH of 0.165–0.33. Concluding, the AQIH can be proposed as a common European Union air quality index because: firstly, its calculation comprises all significant atmospheric pollutants including PM2.5, thereby being harmonized with the Directive 2008/50/EC, and, secondly, AQIH does not display extremely low or high (normalized) values compared to the other air quality indices.

Discussion on the consistency of detection methods of main indexes of workplace air, ambient air and indoor air

Major air pollutants include particulate matter, ozone, sulfur dioxide and nitrogen dioxide, etc. Recent posts have confirmed that air pollution has a variety of adverse health effects on people's health.For professional people, because of occupational hazards of these major atmospheric pollutants also exist in the workplace, is likely to suffer from the double hazards of occupational hazards and air pollutants in the workplace, if similar pollutants are present in the home, the daily exposure concentration of the occupational population may be significantly higher than that of the general population. Exposure limits and testing methods for major atmospheric pollutants (particulate matter or dust, ozone, sulfur dioxide and nitrogen dioxide) are set by relevant standards in workplace air, ambient air and indoor air. However, due to different places and different management departments, there are differences in the detection methods of the same indicators, which brings difficulties to estimate the total daily exposure level. The purpose of this paper is to discuss the "consistency" of the detection method of relevant pollutants in the air, in order to provide scientific basis for estimating the daily exposure level of pollutants in different populations.

Environmental Effective Assessment of Control Measures Implemented by Clean Air Action Plan (2013–2017) in Beijing, China

The Beijing government initiated the Clean Air Action Plan (CAAP) in 2013. Through a series of actions to control air pollution, the emissions of major atmospheric pollutants are reduced to improve urban air quality. In order to evaluate the effectiveness of control measures taken to mitigate atmospheric pollution, we investigated and analyzed the implementation of the CAAP in Beijing from 2013 to 2017, estimating the corresponding reduction in emissions of major air pollutants. The contribution of different control measures to the improvement of air quality was quantified and the experiences of managing air pollution were summarized, which provided references for the continuous improvement of air quality in Beijing and the surrounding areas. The results showed that the emission of SO2, NOX, PM10, PM2.5, and VOCs from air pollution source have been decreased by 119,924, 116,091, 116,810, 46,652, and 97,267 tons after the implementation of the CAAP. The sum of these five air pollutants emissions have been reduced by 39% in 2017 compared with 2013, the largest decrease in SO2 emissions was 87%, which was related to the vigorous control on coal-fired combustion. The control measure with the greatest contribution to decreasing the ambient PM2.5 concentration was the clean energy transformation of coal-fired power plants, which contributed 27% of the total reduced concentration and 6.1 μg/m3 of the average PM2.5 concentration reduction in Beijing. Clean Residential coal use also significantly decreased the PM2.5 concentration by 5.4 μg/m3, which was 23% of the total reduction. In addition, the industrial restructuring and the management of automotive vehicle use and dust could also contribute to efficiently reducing the PM2.5 concentration by 4.0, 3.2, and 2.3 μg/m3, or 17%, 14%, and 10% of the total reduction, respectively. Due to the implementation of control measures of Clean Air Action Plan, the energy and industrial structure of Beijing have been adjusted and optimized, leading to the reduction of pollutant emissions, which is the secret of urban long-term air quality improvement.

Emission Characteristics of Major Atmospheric Pollutants in Changchun City

Based on the technical guide for the preparation of air pollutant emission inventory, this paper makes a statistical analysis of the basic data of air pollution related to the Changchun, and according to the relevant literatures, establishes a list of the main air pollutant emissions from the Changchun 2016 air pollution emission sources (including fine particles, sulfur dioxide and nitrogen oxides). Then the uncertainty analysis is made by Monte Carlo method, and the countermeasures of Changchun air pollution control are put forward. The results showed that the total emission of PM_2.5 in Changchun in 2016 was 70986.45t, and the emissions from the main sources are fixed combustion source, mobile source, process source, biomass burning source and dust source respectively. According to the analysis, we know that coal-based energy consumption structure not only contributes significantly to the emission of one fine particulate matter, but also emits a large number of two fine particulate precursor materials, such as sulfur dioxide, nitrogen oxides. The total sulfur dioxide emission in Changchun in 2016 is 52183.55t, and the total NOx emission is 13.15 million tons. The uncertainty analysis of the Monte Carlo method shows that the uncertainty range of the emission inventory is small and the estimation results are quite credible.

Analysis of nitrogen oxide emissions from modern vehicles using hydrogen or other natural and synthetic fuels in combustion chamber

The paper presents a calculated analysis of the equilibrium emission of nitrogen oxides on the exhaust of carburetor and diesel internal combustion engines. The temperature of fuel oxidation is assumed to be 1,400 °C while the pressure for carburetor and diesel engines is assumed to be 60 atm and 80 atm respectively. The studies have been carried out for natural and synthetic fuels such as hydrogen, ethanol, methanol, petroleum, diesel fuel and methane at the excess air coefficient corresponding to the fuel oxidation temperature of 1,400 °C. In the paper, the method for calculating the equilibrium composition based on the equilibrium constant and mass conservation equations has been applied. It is shown that with an increase in pressure from 1 atm to 60 atm for carburetor engines and up to 80 atm for diesel engines, the reaction of nitrogen dioxide formation may shift towards an increase in NO2. The formation of NO may be not affected by the increase in pressure by virtue of the fact that the reaction proceeds without changes in the amount. It has been determined that NO is the major atmospheric pollutant. However, it would be advisable to use more extensively the fuels characterized by the lowest output of nitrogen dioxide (methane and methanol), since nitrogen dioxide (NO2) related to the 2nd hazard class is appeared to be the most dangerous to humans. It has been revealed that the reduction in oxidation temperature using hydrogen as a fuel for electrochemical current generators may allow reducing nitrogen oxide emissions by more than an order of magnitude as compared to the best results for ICE.

Spatio-temporal evolution of ozone pollution and its influencing factors in the Beijing-Tianjin-Hebei Urban Agglomeration

Ozone has become a major atmospheric pollutant in China as the pattern of urban energy usage has changed and the number of motor vehicles has grown rapidly. The Beijing-Tianjin-Hebei Urban Agglomeration, also known as the Jing-Jin-Ji Urban Agglomeration (hereafter, JJJUA), with a precarious balance between protecting the ecological environment and sustaining economic development, is challenged by high levels of ozone pollution. Based on ozone observation data from 13 cities in the JJJUA from 2014 to 2017, the spatio-temporal trends in the evolution of ozone pollution and its associated influencing factors were analyzed using Moran’s I Index, hot-spot analysis, and Geodetector using ArcGIS and SPSS software. Five key results were obtained. 1) There was an increase in the annual average ozone concentration, for the period 2014–2017. Comparing the 13 prefecture-level cities, ozone pollution in Chengde and Hengshui decreased, while it worsened in the remaining 11 cities. 2) Ozone pollution was worse in spring and summer than in autumn and winter; the peak ozone pollution season was from May to September; the average ozone concentration on workdays was higher than that on non-workdays, showing a counter-weekend effect. 3) Annual average concentrations were high in the central and southern parts of the study region but low in the north. 4) Prominent positive spatial correlations were observed in ozone concentration, with the best correlations shown in summer and autumn; concentrations were high in Baoding and Xingtai but low in Beijing and Chengde. 5) Concentrations of PM10, NO2, CO, SO2, and PM2.5, as well as average wind speed, sunshine duration, evaporation, precipitation, and temperature, all had significant effects on ozone pollution, and interactions between these influencing factors increased it.

NOx AND O3 VARIABILITY AND ITS RELATION WITH WEATHER CONDITIONS IN IAȘI CITY

The paper presents the temporal variability of surface ozone (O3) and its precursors (oxides of nitrogen - NOx) from January 2012 to December 2015. In the same time, this study is aimed to explore the influence of the weather elements on these two major atmospheric pollutants in the area of Iași city. The maximum record of nitrogen oxides reached during the 4 analyzed years was 1200 μ/m-3 on October 27, 2015, a period of the year when atmospheric stability prevails. During the warm season (considered from May to September) the highest concentration of ozone was recorded at 155 μ/m-3. The winds direction from SSE or NNW and the winds speed greater than 2 m/s can significantly increase the concentration of the O3 and NOx respectively. Also, the stable atmospheric conditions can increase especially the concentration of the nitrogen dioxides. The statistical results illustrate a strong Pearson's correlation of surface ozone with solar radiation/maximum air temperature (r &gt;0.5). The correlations were strongest during the summer months. Using the composite method, between warm season and cold season a difference of the pollutants concentration greater than 30 units for NOx was observed. Synoptic conditions associated with high pollution are also described.