Fine Particle Concentrations Research Articles

Assessment of atmospheric air quality in urbanised areas of the Southern Urals

ABSTRACT The paper reports a study of the concentration of fine particles in the atmospheric air with a diameter of < 2.5 microns (PM2.5) and solid particles with a diameter of < 10 microns (PM10) of urbanised territories. An environmental monitoring device (DT-9881 M) determined the concentration of dust particles, and the amount of adsorbed dust on the leaves of woody plants was determined by the flushing method. The research established that the concentration of solid particles in the atmospheric air PM2.5/PM10 depended on the intensity of motor traffic. A decrease in the content of PM2.5/PM10 was revealed in plantings where the influence of forest air on human beings was recorded. Measurements on the content of formaldehyde and carbon monoxide at all measurement points gave negative indicators. Green spaces are important to human well-being.

Increasing life expectancy in China by achieving its 2025 air quality target

China is striving to build a “Beautiful China” characterized by clean air. The country has committed to further reducing its national mean fine particle (PM2.5) concentration by 10% from 2020 to 2025, following the substantial improvements in its air quality during the past decade. Meanwhile, the “Healthy China” mission has pledged to increase the national mean life expectancy by one year during the same period. Yet, to what extent will the “Beautiful China” mission contribute to the “Healthy China” vision by reducing the levels of the detrimental PM2.5 is still unclear. Here, by coupling the life table approach and an epidemiological concentration-response model, this study quantifies the potential benefits of achieving China's 2025 air quality target on the national life expectancy. The analysis reveals that the Chinese citizen could expect to extend the average life expectancy by 42.5 days by 2025 due to improved air quality. In addition, if the Chinese government outperforms the planned air quality target, as it usually does, the gains would increase to 65.4 days, ∼18% of the “Healthy China” life expectancy increment task. Further reductions in PM2.5 concentration would lead to accelerated gains in life expectancy both nationally and at the city level, providing strong incentives for the authorities to keep improving air quality. This study reveals the notable benefits on individual life that could be expected from air quality improvement in China and suggests that longer life expectancy is achievable by implementing a health-prioritized air quality management mechanism.

Experimental study on the treatment of desulfurization wastewater from coal-fired power plant by spray evaporation.

In this study, a pilot-scale evaporation tower system was built to treat the desulfurization wastewater by spray evaporation. The distribution characteristics of Cl- in the wastewater evaporation process were investigated. Besides, the morphology and physicochemical property of solid evaporation products from desulfurization wastewater were analyzed. In addition, the emission characteristics of fine particulates were evaluated. The results indicated that the increase of salt content in desulfurization wastewater increased the mass concentrations of Cl- in three phases, but the proportions of it remained almost unchanged, which were about 10%, 55%, and 35% in the gas phase, outlet solid phase, and bottom solid phase respectively. The increase of flue gas temperature can improve the content of Cl- in the gas phase, while the increase of wastewater pH inhibited the formation of gaseous HCl. The solid evaporation products from desulfurization wastewater had a prismatic crystal structure, which mainly included the sulfate and chloride salts, and the main elements including O, Na, Mg, S, Cl, K, and Ca. Besides, the peak values of particle size distribution in the bottom solid phase and outlet solid phase were 7.67 and 0.32μm, respectively. For the particulate matters in flue gas, the spray evaporation of desulfurization wastewater can reduce the particle concentration, promote particle agglomeration, reduce the number concentration of fine particles, and improve the removal effect of PM10. When the inlet particle concentration was 7.62g/m3, it can reduce the particle concentration at the tower outlet to 4.59g/m3 and reduce the number and mass concentrations of PM10 after ESP by about 43.8% and 36.8%.

INVESTIGATION OF THE INTENSIFICATION OF SEPARATION PROCESSES USING THE HEAT OF EXHAUST GASES

The useful use of heat for the above cases is primarily related to the use of heat from the exhaust gases. It should be stressed that in all cases it is necessary to return the maximum amount of waste heat to the process. Part of the heat is usually returned to the working chamber with heated air (up to 300 - 500 oC). In some cases, it is possible to use a certain amount of gas heat for drying and heating the raw material, the finished product and/or for heating the process water used in the processing; the use of heat from gases to produce steam and other parameters for the necessary heating of the blast furnace. All of this opens up the possibility of achieving very high end results for energy plants. However, as a rule, the exhaust gases are characterized by fairly high concentrations of fine solid particles (fine removals), which must be effectively removed in the separator because in most cases they prevent the efficient use of heat from the exhaust gases. Thus, efficient separation of fine removal is crucial for heat recovery of exhaust gases, especially for high-performance units. The ways to intensify the separation processes in industrial waste were investigated and made practical conclusions. Based on known literature data and results of own experiments, some questions of separation of fine removal are considered. The basics of the separation mechanism are formulated, which are reduced to elucidating the causes and patterns of movement of small particles to the separating surface across the main stream. The mechanisms of separation of small particles due to turbulent diffusion are analyzed in detail, the possibility of realization of the mechanism of separation on the basis of thermophoresis is estimated. The initial parameters and criteria that characterise the particle separation process have been established. A formula for assessing the particle separation rate is derived and the effect of the specified criteria on this value is analyzed. The analysis of the above dat a resulted in practical conclusions on ways to intensify the separation processes under industrial conditions.

Characterization of sub-pollen particles in size-resolved atmospheric aerosol using chemical tracers.

Pollen grains may contain allergens that exacerbate allergic respiratory diseases like asthma and rhinitis. In the presence of water, pollen grains (10–100 μm) can rupture to produce sub-pollen particles (SPP) with diameters <2.5 μm, which in comparison to intact pollen grains, have longer atmospheric lifetimes and greater penetration to the lower lung. The current study examines SPP, fungal spores, and bacteria in size-resolved atmospheric particulate matter (PM) using chemical and biological tracers. During springtime tree pollen season in Iowa City, Iowa, fine particle (PM2.5) concentrations of fructose (a pollen chemical tracer) increased on rainy sampling periods, especially during severe thunderstorms, and peaked when a tornado struck nearby. Submicron fluorescent particles, measured by single-particle fluorescence spectroscopy, were also enhanced during rain events, particularly thunderstorms in agreement with the chemical tracer measurements. PM2.5 sucrose (a pollen chemical tracer) concentrations were higher in early spring when nighttime temperatures were closer to freezing, while fructose concentrations were higher in late spring with warmer temperatures, consistent with chemical tracers being sensitive to seasonal temperature influences. The first co-located measurements of fructose and Bet v 1 (birch pollen allergen), indicated that SPP ranged in diameter from <0.25 to 2.5 μm during rainy sampling periods and that allergens and carbohydrates exhibited distinct size distributions. Meanwhile, mannitol (a fungal spore tracer) peaked on warm, dry days following rain and was primarily in supermicron particles (>1.0 μm), which is consistent with intact fungal spore diameters (1–30 μm). Bacterial endotoxins in PM also increased during extreme weather events, primarily in supermicron particles. While the concentrations of fructose, mannitol, and endotoxin all increased in PM2.5 μm during thunderstorms, the greatest relative increase in concentration was observed for fructose. Together, these observations suggest that SPP containing starch granules and allergens (Bet v 1) were released during rainy sampling periods. This study advances the use of chemical tracers to track SPP and other bioaerosols in the atmosphere, by providing new insight to their size distribution and response to extreme weather conditions.

Carbonaceous aerosol and inorganic ions of PM2.5 in Yangon and Mandalay of Myanmar: Seasonal and spatial variations in composition and sources

To characterize the seasonal and spatial patterns of the concentration, composition and sources of the atmospheric fine particles in Myanmar, 72 p.m.2.5 samples were collected during 2016 and 2017 at two urban sites in Yangon and Mandalay, representative coastal and inland cities in Myanmar, with the concentrations of organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and the water-soluble ions being measured. Significantly higher average concentration of PM2.5 was found in Mandalay (147 μg m−3) during the sampling periods than that in Yangon (77 μg m−3). High contribution of organic matter (averaged at 48% and 37% by mass in winter and summer) and low contribution of secondary ions (<15% except that in summer Yangon) were found in both Yangon and Mandalay. Higher contribution of mineral dust to PM2.5 was found in Mandalay compared to Yangon. Meanwhile, higher average concentrations of SO42− and NH4+ in Yangon indicated a higher contribution from coal usage in Yangon. Correlation analysis and the compositional change during the rainfall event (2017/4/14–16 in Yangon) indicated that NO3− was mainly associated with Ca2+, and the high temperature and low humidity during the dry season in Myanmar inhibited the formation of NH4NO3. Regional transport of pollutants should be the important cause of the different seasonal variations for the measured species in Yangon and Mandalay besides the seasonal differences in emission sources. Positive matrix factorization (PMF) analysis showed that vehicle emissions, biomass burning, mineral dust, secondary formation and sea salt were the main sources of PM2.5 in Myanmar.

Source and Chemistry of Hydroxymethanesulfonate (HMS) in Fairbanks, Alaska.

Fairbanks, Alaska, is a subarctic city with fine particle (PM2.5) concentrations that exceed air quality regulations in winter due to weak dispersion caused by strong atmospheric inversions, local emissions, and the unique chemistry occurring under the cold and dark conditions. Here, we report on observations from the winters of 2020 and 2021, motivated by our pilot study that showed exceptionally high concentrations of fine particle hydroxymethanesulfonate (HMS) or related sulfur(IV) species (e.g., sulfite and bisulfite). We deployed online particle-into-liquid sampler–ion chromatography (PILS-IC) in conjunction with a suite of instruments to determine HMS precursors (HCHO, SO2) and aerosol composition in general, with the goal to characterize the sources and sinks of HMS in wintertime Fairbanks. PM2.5 HMS comprised a significant fraction of PM2.5 sulfur (26–41%) and overall PM2.5 mass concentration of 2.8–6.8% during pollution episodes, substantially higher than what has been observed in other regions, likely due to the exceptionally low temperatures. HMS peaked in January, with lower concentrations in December and February, resulting from changes in precursors and meteorological conditions. Strong correlations with inorganic sulfate and organic mass during pollution events suggest that HMS is linked to processes responsible for poor air quality episodes. These findings demonstrate unique aspects of air pollution formation in cold and humid atmospheres.

Analysis of ways to reduce potential health risk from ultrafine and fine particles emitted from 3D printers in the makerspace.

Due to the growing maker culture, maker spaces using multiple fused deposition modeling (FDM)-3D printers have spread around the world. However, the 3D printing process is known to cause the release of ultrafine and fine particles, which may have adverse health effects on occupants. Therefore, this experiment-based study was conducted on FDM-3D printers placed in an actual makerspace by the following three scenarios: the number of operating FDM-3D printers, ventilation, and measurement location to compare the concentrations of ultrafine and fine particles. In addition, the deposited dose in alveolar region for ultrafine and fine particles was predicted using a respiratory deposition model to analyze the potential health risk on occupants. As a result, the scenario-based comparison revealed that if the number of operating 3D printers is reduced by less than half, the potential health risk can be decreased by 34.1%, proper ventilation can reduce potential health risk by 55.5%, and working away from the 3D printer can also reduce potential health risk by up to 27.5%. This study analyzed the potential health risk of multiple FDM-3D printers on users in an actual makerspace, and proposed various improvement measures to reduce the potential health risk of ultrafine and fine particles.

Health Risk Factors of Emissions from Internal Combustion Engine Vehicles: An Up-to-Date Status of the Problem

Introduction: Motor transport with internal combustion engines powered by diesel fuel and gasoline is one of the main sources of ambient air pollution since its emissions pose an urgent medical and environmental challenge. The objective of the study was to identify priority pollutants from emissions of motor vehicles powered by internal combustion engines based on the results of a systematic review in order to substantiate the main preventive strategy to mitigate the associated public health adverse effects. Methods: We did keyword search for relevant publications in several electronic databases, such as the Russian Science Citation Index, CyberLeninka, Scopus, and WoS. Research papers published in 2000–2021 were selected for the analysis. Out of 103 topical full-text publications, 59 works met the criteria for inclusion in the systematic review. Results: We observed that atmospheric emissions of internal combustion engines represent a complex agglomeration of gases, vapors, and particulate matter. The chemicals present in the emissions impair the oxygen transport function by inhibiting cellular respiration, cause irritation of mucous membranes, have mutagenic and carcinogenic effects, contribute to the occurrence of acid rains and to global warming. The biological effect of airborne particles largely depends on their size. It has been established that an increase in the number of airborne particles with an aerodynamic diameter less than 10 μm is associated with the risk of endothelial inflammation, thrombosis, increased cell permeability, and DNA methylation. It has been also demonstrated that a 5 µg/m3 increment in ambient concentrations of fine particles (&lt; 2.5 μm) causes a 7 % increase in the mortality rate. At the same time, PM2.5 exposure-related risks of excess deaths from cardiovascular diseases are twice as high as those posed by exposure to PM10. Conclusions: Diesel and gasoline engine exhausts are a significant risk factor for human health. An effective preventive strategy should be aimed at replacing heavy hydrocarbon motor fuels by compressed gas using hydrogen cells and electric motors.

Industrial emissions effect into atmospheric air quality: mathematical modeling.

This paper presents the results of modeling the distribution process of industrial emission components at specified distances from the emission source along the normal. The model uses a system of differential diffusion equations to compute the concentration profiles of aerosols, industrial gases, and fine particles in the atmosphere. In order to investigate the regularity of the emitter propagation into the atmosphere, a theory of impurity dispersion was developed. The model is constrained by the effect of particle interactions. The partial derivative equations are presented to calculate the concentrations of aerosols and fine particles under the turbulent airflow in the atmosphere, dispersion of inert impurities, and distribution of chemically active compounds. The adequacy of the mathematical model for a series of theoretical calculations was checked by contrasting the data of the atmospheric air monitoring for the cities of Almaty, Ust-Kamenogorsk, Pavlodar, Atyrau, Krasnodar, Chelyabinsk, Beijing, and Shanghai. Air monitoring data included PM10, SO2, and NO2 levels. The mathematical model solutions for the relative values of the emitter concentration in the direction along the normal of the pollution source at the surface were obtained. Graphical interpretation of the calculation results over the 0…200m distance for time intervals ranging from 3 to 600min was provided. According to the multiple factor cluster analysis, the critical values of SO2 concentrations in Atyrau exceeded MPC in 26.2% of cases. The level of NO2 for Shanghai was 15.6%, and those for PM10 concentrations in Almaty and Atyrau amounted to 16.4%. A comparison of theoretical values and results obtained from official sources showed arithmetic mean of 49.4mg/m3 and maximum value of 823.0mg/m3. Standard deviation comprised 48.9mg/m3. Results were considered statistically significant at p≤0.005. The mathematical model developed in this study can be used to predict the status of atmospheric air.

Evaluation of Mass Concentration and Size Distribution of Fine Particles (PM2.5) in Bien Hoa City, Dong Nai Province

Air pollution is one of the most concerning environmental issues, in which fine inhalable particles (PM2.5, with diameters that are generally 2.5 micrometers and smaller) concentration plays a key part. Bien Hoa city contains and locates close to several large industrial zones that might create sources of PM2.5 polluting the local air quality. This study monitors and evaluates PM2.5 concentration trends in Bien Hoa airport of Dong Nai province. PM samples are analyzed by Scanning Electron Microscopy (SEM) to recognize the surface pattern and size distributions are analyzed by ImageJ software. Ten samples of PM2.5 were obtained from sampling collected in October 2021. The results show that 24-h PM2.5 mass concentrations were from 15.2 µg/m3 - 50.4 µg/m3 with an average of 28.2 µg/m3; median of 24.1 µg/m3; and standard deviation of 12.2 µg/m3. The values are lower than the Vietnam National Technical Regulation on Ambient Air Quality (QCVN 05:2013/BTNMT) but far higher than the recommended values of the World Health Organization (WHO). SEM and image results indicate the distributions of the particles of 2.0 - 2.5 µm are minor, where the majority are particles with aerodynamic diameter ≤ 1.0 µm.&#x0D; Keywords: Air pollution; Fine particulate matters; PM2.5; Size distribution, Bien Hoa, Dong Nai.

Source apportionment and health risk assessment for potentially toxic elements in size-fractionated road dust in Busan Metropolitan City, Korea

Potentially toxic elements' (PTEs; V, Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Pb, and Hg) pollution level was investigated in size-fractionated road dust in Busan Metropolitan City. Health risks to humans (adult and children) were also evaluated in fine particle fraction (< 63μm) of road dust. PTE concentrations in the fine particles (< 63μm) were ranked as follows (unit: mg/kg): Zn (2511) > Cu (559) > Cr (531) > Pb (385) > Ni (139) > V (83.8) > Sb (31.6) > Co (21.6) > As (17.2) > Cd (4.1) > Hg (0.38). The PTE concentrations in fine particles (< 63μm) were significantly higher than those in coarse particles except for V, Co, and As. The mean PTE loadings of fine particle fraction (< 63μm; 233mg/m2) in road dust were up to 4.5 times higher than other particle fractions. Igeo values of Sb were higher than 5 except for > 1000-μm fraction, indicating extremely polluted status. PCA results and elemental ratios indicated that most of the PTEs in road dust were derived from non-exhaust traffic-related sources such as brake pads and tires. Cr, Pb, and Sb had higher HI values than other metals for both adults and children. Sampling sites of heavy traffic and industrial areas showed that the carcinogenic risk exceeded the maximum threshold level (10 - 4). Especially in children, the mean carcinogenic risk (ingestion pathway) of As (6.8 × 10 - 4) Cd (2.0 × 10 - 4), and Ni (4.1 × 10 - 4) exceeded the maximum threshold level, indicating that continuous exposure to road dust may pose a high cancer risk to children. Therefore, continuous monitoring and management of these metals are needed to protect human health and the urban environment.

Innate and Adaptive Immunity in Workers of the Main Occupations Exposed to Fine Particulate Matter in Potassium Chloride Production

Background: Workplace air pollution with fine particulate matter in industrial premises contributes to imbalance of nonspecific and specific immunity factors, increasing the risk of developing premorbid conditions in workers. Objective: To study the features of phagocytic activity and subpopulation T-lymphocytes composition in workers engaged in the potassium chloride production. Material and methods: The study was conducted in 2019–2022 within the Research Program of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing on hygiene problems, Clause 2.2.18 “Development of approaches to early diagnosis of production-related diseases using genomic and postgenomic analysis technologies in workers associated with harmful factors of working conditions”, R&amp;D No. 121081900044-4. The observation group consisted of 54 workers of the main occupations exposed, inter alia, to fine respirable particulate matter in potassium chloride production. The comparison group included 67 individuals having no occupational exposure to industrial hazards. We evaluated the phagocytic activity of peripheral blood leukocytes and determined the level of CD25+ and CD95+ differentiation cluster expression on T-lymphocytes by flow cytometry. Results: We measured high airborne concentrations of fine particles at workplaces of mill, centrifuge and filter operators, granulation and drying workers that were 6.6 and 7 times higher than those of PM2.5 and PM10 in the working environment of the administrative staff, respectively. We also observed that the ability of neutrophils to absorb and digest foreign particles was 20 % lower in the workers of the observation group (p = 0.047), while the proportions of CD25+ and CD95+ lymphocytes in them were 30 % and 60 % lower than those in the comparison group, respectively (p = 0.001–0.046). Conclusion: We established the effect of fine particulate matter as a priority workplace air pollutant on innate and adaptive immunity in workers of the main occupations in the potassium chloride production facility. Parameters of innate (phagocytic number) and adaptive (CD25+ and CD95+ lymphocytes) immunity are recommended for use in early diagnosis of immune dysfunction and the development of occupational diseases in workers with inhalation exposure to fine particles.

Toward Cleaner Transport Alternatives: Reduction in Exposure to Air Pollutants in a Mass Public Transport.

Commuters are often exposed to higher concentrations of air pollutants due to its proximity to mobile sources. Despite recent trends in urban transport toward zero- and low-tailpipe emission alternatives, the assessments of the impact of these transformations on commuter exposure are limited by the low frequency of such studies. In this work, we use a unique data set of personal exposure concentration measurements collected over the span of 5 years to analyze changes due to the introduction of a new fleet for Bogotá's Bus Rapid Transit System. In that system, over a thousand Euro-II and -III diesel-powered buses were replaced with Euro-VI compressed natural gas and filter-equipped Euro-V diesel buses. We measured personal exposure concentrations of equivalent black carbon (eBC), fine particulate (PM2.5), and ultra fine particles (UFP) during and after the retirement of old buses and the introduction of new ones. Observations collected prior to the fleet renewal were used as baseline and later compared to data collected over two follow-up campaigns in 2019 and 2020. Significant reductions in the concentration of PM2.5 and eBC were observed during the 2019 campaign, with a 48% decrease for mean in-bus eBC (89.9 to 46.4 μg m-3) and PM2.5 (180.7 to 95.4 μg m-3) concentrations. Further reductions were observed during the 2020 follow-up, when the fleet renovation was completed, with mean in-bus eBC decreasing to 17.7 μg m-3 and PM2.5 to 42.3 μg m-3. These observations imply nearly a 5-fold reduction in eBC exposure and a 4-fold decrease in PM2.5. There was a much smaller reduction of in-bus UFP concentration between 2019 and 2020, indicating a persistent presence of high particle number concentrations in the near-road environment despite the fleet renovation process. In-bus UFP concentrations ranged between 65 000 and 104 500 cm-3 during the follow-up campaigns. The results in this work illustrate the immediate benefits of reducing personal exposure through the adoption of vehicles with more stringent emission standards.

Методика оценки концентрации мелкодисперсных частиц PM10 при работе центробежных фрикционных роликов

One of the solutions to increase the storage capacity and speed of handling palletized goods in warehouses is the use of gravity pallet racking. As elements of the safe operation of such conveyors, centrifugal friction rollers are widely used, which ensure the speed of the pallet within the limits that do not exceed the permissible values. During the operation of centrifugal friction rollers, wear products — brake dust, which have an adverse effect on the human body, may enter the atmosphere. Therefore, an urgent task is to study the operation of friction-type brake rollers from the point of view of the environmental assessment of the released brake dust. The paper assesses the concentration of fine particles with dimensions from 10 micrometers to 2.5 micrometers during the operation of centrifugal friction rollers in gravity pallet racks, and proposes a method for estimating their concentration in the warehouse working area. The coefficient of environmental friendliness of the design of the brake roller of the friction type has been introduced, which is one of the factors determining the maximum number of braking, and takes values from 0 to 1.0 for various designs of the friction roller — closed type, ventilated and open type. The results of an experimental study of materials for friction pairs of brake rollers show that the maximum amount of braking is provided at a pressure on the friction lining of 0.1 MPa, which corresponds to a pallet weight of 1000 kg. An example of using the methodology for estimating the concentration of particles in the working area for a warehouse consisting of one block of gravity racks for pallets 1200x800x1500 mm (length x width x height), weighing 1000 kg, with a total number of 546 pallet places is considered. Analysis of the results showed that the maximum number of pallet braking at which the maximum permissible concentration of particles with a dimension of 10 micrometers to 2.5 micrometers is reached and the maximum turnover of the warehouse can serve as a comprehensive assessment of its environmental friendliness.

Correlation analyses between downward longwave radiation particulate matters, aerosol optical depth, and metrological variables under non-dusty and cloudless conditions

This study used downward longwave (LW) radiation measurements, air temperature (T), particulate matter (PM) concentrations of fine (PM 2.5) and coarse (PM10) particles, aerosol optical depth (AOD), wind speed (WS), and precipitable water vapor (PWV) data from Riyadh, an arid site in central Saudi Arabia, between 2014 and 2019 to characterize their variations and investigate the influence of these variables on the measured downward LW radiation under non-dusty, clear sky conditions. The LW radiation and air temperature, it was found, attain their maximum in summer and minimum in winter. Conversely, the PM mean concentrations and AOD showed their maximum in spring and minimum in winter. PWV features an increasing trend during spring, summer, and fall, whereas it features a decreasing trend during the winter. The monthly variation of WS shows low monthly values during fall and winter and considerably higher monthly mean variation during spring and summer. Apart from wind speed, which does not affect the LW radiation, correlation analyses demonstrated that the LW correlates positively with the remainder of the considered variables. The strength and degree of association between the LW radiation and these variables differ from one variable to another, with air temperature having the strongest correlation (correlation coefficient = 0.98) with the LW radiation, followed by the AOD (correlation coefficient = 0.69), with a correlation coefficient of 0.36 with the PWV. Similarly, the relationships between the LW radiation and both PM10 and PM2.5 had the same correlation coefficient of 0.32. The effect of the meteorological variables (mainly air temperature, relative humidity, and wind speed) on the PM concentrations was investigated using the regression analyses. The results showed a significant positive relationship with air temperature and wind speed and a negative relationship with RH.

Shipborne Observations of Chemical Characterization and Light Extinction of Aerosol Along the Yangtze River, China

The study of air quality over the Yangtze River is important for the pollution of urban agglomeration along the longest river in China. A comprehensive 15-day shipborne observation was conducted in the Yangtze River of the Jiangsu section in the summer of 2019. Through online observation and offline chemistry analysis of aerosol and gaseous pollutants, the result showed that the air pollution over the Yangtze River was more severe than that in surrounding cities. Sulfate, nitrate, and ammonium (SNA) dominated the water-soluble inorganic species and accounted for 35.0% ± 7.3% of the fine particle concentration (PM2.5) along the Yangtze River. The high concentration of sulfate in the droplet mode (0.56–1.0 μm) was due to the formation of sulfate through in-cloud processes under high sulfur dioxide (SO2) concentration by ship emission and high relative humidity along the river. The strong correlation between the measured mass absorption efficiency value by carbon analyzer and that simulated based on the assumption of core–shell suggested that the core–shell mode was the main composition form of aerosol in the Yangtze River. The scattering effect was the main part of the aerosol light extinction, and the scattering coefficient of 0.4- to 1.1-μm particles accounted for 85.0% of the total extinction coefficient. Positive matrix factorization model was applied for the source apportionment of particle size segment of main extinction contribution (0.4–2.1 μm), and the result showed that secondary nitrate, ship emission, coal combustion, fugitive dust, and biomass burning were the main sources of aerosols in the Yangtze River. After source reanalysis, the result indicated that the contribution of secondary nitrate from nitrogen oxide (NOx) by ship emission and coal combustion should not be ignored.

BRIQUETTES PRODUCTION FROM LIGNOCELLULOSIC WASTE FOR ENERGY PURPOSES AS AN ALTERNATIVE FUEL

The briquetting process was developed seeking to reuse the waste generated both in forestry production and in industrial processes. The compression of lignocellulosic waste concentrates the available energy in terms of volume and facilitates the handling and storage of these materials. The present work aims to verify the influence on the quality of briquettes of different compositions between the residues of coffee grounds, pine sawdust and cambará sawdust by evaluating the physical, chemical and mechanical characteristics of the briquettes generated from the compaction of these waste. For this, several tests were carried out with the briquettes, analyzing the properties of particle size, resistance to diametrical compression, moisture and ash for each composition of the briquette. The briquettes were produced on a 12-tonne hydraulic press. The waste used showed a high concentration of fine particles, with pine sawdust being 50.5% of particles with a diameter of 0.425mm. Coffee beans have moisture content above 50%, positively impacting the ash content and negatively impacting briquetting and tensile strength by diametral compression. In the production of briquettes, material with up to 60% addition of coffee grounds was obtained. The compression tests showed good results for the treatments, highlighting the treatments with a high concentration of pine. It is also concluded that the coffee grounds can be used in the production of briquettes with sawdust, however, it is suggested for future articles, the correction of moisture in the briquettes for better compaction.

Wind Tunnel Studies on the Prevention of Particle Accumulation Onto the Bogie of High-Speed Train

When high-speed train runs in the environment with a large number of airborne particles, these particles may accumulate on the bogie of the train, which will further challenge the normal operation of the bogie and reduce the riding comfort and train safety. In order to prevent particles entering into the bogie area, different protective devices around the bogie are used. However, up to present, the systematical analysis on the protective effects of diverse protective measures against different types of particles are still very limited. In this study, with the widely-used shirt boards and spoilers as protective devices, the airborne particle transport processes around the bogie were simulated in the wind tunnel Lab. Three kinds of typical particles, including artificial snow particle, wheat bran (substitute of snowflake) and sieved soil, were chosen to represent different airborne particles under real conditions. Three evolution indexes, including the relative reduction ratio of artificial snow particles, the relative particle flux reduction ratio of fine wheat bran, and the relative concentration reduction ratio of fine sieve soil particles, were used to assess their protective effects. Results showed that the combination of short-skirt board and straight triangular spoiler (i.e., in A5 case, the straight triangle spoilers installed at the front and rear ends of the train bogie, and the short-skirt boards installed on both sides of the train bogie) was the best protection with the studied three particles. The relative reduction ratio of the average snow mass in this case was 75.59%, the relative reduction ratio of the flux in the level of fine wheat bran exceeded 78%, and the relative reduction ratio of the fine soil particle concentration was more than 96%.

Spatiotemporal estimation of the PM2.5 concentration and human health risks combining the three-dimensional landscape pattern index and machine learning methods to optimize land use regression modeling in Shaanxi, China

PM2.5 pollution endangers human health and urban sustainable development. Land use regression (LUR) is one of the most important methods to reveal the temporal and spatial heterogeneity of PM2.5, and the introduction of characteristic variables of geographical factors and the improvement of model construction methods are important research directions for its optimization. However, the complex non-linear correlation between PM2.5 and influencing indicators is always unrecognized by the traditional regression model. The two-dimensional landscape pattern index is difficult to reflect the real information of the surface, and the research accuracy cannot meet the requirements. As such, a novel integrated three-dimensional landscape pattern index (TDLPI) and machine learning extreme gradient boosting (XGBOOST) improved LUR model (LTX) are developed to estimate the spatiotemporal heterogeneity in the fine particle concentration in Shaanxi, China, and health risks of exposure and inhalation of PM2.5 were explored. The LTX model performed well with R2 = 0.88, RMSE of 8.73 μg/m3 and MAE of 5.85 μg/m3. Our findings suggest that integrated three-dimensional landscape pattern information and XGBOOST approaches can accurately estimate annual and seasonal variations of PM2.5 pollution The Guanzhong Plain and northern Shaanxi always feature high PM2.5 values, which exhibit similar distribution trends to those of the observed PM2.5 pollution. This study demonstrated the outstanding performance of the LTX model, which outperforms most models in past researches. On the whole, LTX approach is reliable and can improve the accuracy of pollutant concentration prediction. The health risks of human exposure to fine particles are relatively high in winter. Central part is a high health risk area, while northern area is low. Our study provides a new method for atmospheric pollutants assessing, which is important for LUR model optimization, high-precision PM2.5 pollution prediction and landscape pattern planning. These results can also contribute to human health exposure risks and future epidemiological studies of air pollution.