Characteristics and fate behavior of environmentally persistent free radicals in atmospheric particulate matter

Background,aim,and scope Environmentally persistent free radicals(EPFRs)have received significant attention due to their longer lifetime and stable existence in various environments.The strong environmental migration ability of particulate matter allows EPFRs to migrate over long-distance transport,thereby impacting the quality of the local atmospheric environment.Additionally,EPFRs can also adhere to atmospheric particles and interact with typical gaseous pollutants to affect atmospheric chemical reactions.EPFRs can produce some reactive organic species,promoting oxidative stress in the human body,damaging biological macromolecules and ultimately affecting the organism health.EPFRs are considered as a novel type of pollutant that affects human health.Despite their significance,there are few literatures available on the characteristics and fate behaviors of EPFRs up to date.Therefore,supplemental reviews are crucial for providing comprehensive understanding of EPFRs.Materials and methods This review summarizes the characteristics of EPFRs in particulate matter,outlines the generation mechanism and influencing factors of EPFRs,and the impacts of EPFRs on environmental quality and organism health.Results The content of EPFRs in particulate matter ranges from 1017 to 1020 spins∙g−1.Due to the strong mobility of atmospheric particulate matter,the long-term exposure to high levels of EPFRs may aggravate the impact of particulate matter on human health.The interaction between EPFRs and typical gaseous pollutants can alter their fate and influence atmospheric chemical reactions.EPFRs are mainly produced by transition metal elements and substituted aromatic hydrocarbons through electron transfer.Additionally,the chemical bond rupture of organic substances through heat treatment or ultraviolet radiation can also produce EPFRs,and heterogeneous reactions are capable producing them as well.The production of EPFRs is not only influenced by transition metal elements and precursors,but also by various environmental factors such as oxygen,temperature,light radiation,and relative humidity.Discussion EPFRs in atmospheric particulates matters are usually rich in fine particulates with obvious seasonal and regional variations.They can easily enter the human respiratory tract and lungs with inhalable particulates,thereby increasing the risk of exposure.Additionally,EPFRs in atmospheric particulates can interact with some typical gaseous pollutants,impacting the life and fate of EPFRs in the atmosphere,and alter atmospheric chemical reactions.Traditionally,EPFRs are generated by transition metal elements and substituted aromatic hydrocarbons undergoing electron transfer in the post-flame and cool-zone regions of combustion systems and other thermal processes to remove HCl,H_(2)O or CO groups,ultimately produce semiquinones,phenoxyls,and cyclopentadienyls.Recent studies have indicated that EPFRs can also be generated under the conditions of without transition metal elemental.Organics can also produce EPFRs through chemical bond rupture during heat treatment or light radiation conditions,as well as through some heterogeneous reactions and photochemical secondary generation of EPFRs.The presence or absence of oxygen has different effects on the type and yield of EPFRs.The concentration,type,and crystal type of transition metal elements will affect the type,content,and atmospheric lifetime of EPFRs.It is generally believed that the impact of transition metal element types on EPFRs is related to the oxidation-reduction potential.The combustion temperature or heat treatment process significantly affects the type and amount of EPFRs.Factors such as precursor loading content,pH conditions,light radiation and relative humidity also influence the generation of EPFRs.EPFRs can interact with pollutants in the environment during their migration and transformation process in environmental medium.This process accelerates the degradation of pollutants and plays a crucial role in the migration and transformation of organic pollutants in environmental media.The reaction process of EPFRs may lead to the production of reactive oxygen species(ROS)such as∙OH,which can induce oxidative stress,inflammation and immune response to biological lung cells and tissues,leading to chronic respiratory and cardiopulmonary dysfunction,cardiovascular damage and neurotoxic effects,ultimately impacting the health of organisms.Conclusions The interaction mechanism between EPFRs in particulate matter and gaseous pollutants remains unclear.Furthermore,research on the generation mechanism of EPFRs without the participation of transition metals is not comprehensive,and the detection of EPFRs is limited to simple qualitative categories and lack accurate qualitative analysis.Recommendations and perspectives Further research should be conducted on the generation mechanism,measurement techniques,migration pathways,and transformation process of EPFRs.It is also important to explore the interaction between EPFRs in atmospheric particulate matter and typical gaseous pollutants.

Spatial and Temporal Variation of Particulate Matter (PM10 and PM2.5) and Its Health Effects during the Haze Event in Malaysia

This study aims to assess and compare levels of particulate matter(PM10 and PM2.5)in urban and industrial areas in Malaysia during haze episodes,which typically occur in the south west monsoon season.The high concentrations of atmospheric particles are mainly due to pollution from neighbouring countries.Daily PM concentrations were analysed for urban and industrial areas including Alor Setar,Tasek,Shah Alam,Klang,Bandaraya Melaka,Larkin,Balok Baru,and Kuala Terengganu in 2018 and 2019.The analysis employed spatiotemporal to examine how PM levels were distributed.The data summary revealed that PM levels in all study areas were right-skewed,indicating the occurrence of high particulate events.Significant peaks in PM concentrations during haze events were consistently observed between June and October,encompassing the south west monsoon and inter-monsoon periods.The study on acute respiratory illnesses primarily focused on Selangor.Analysis revealed that Klang had the highest mean number of inpatient cases for acute exacerbation of bronchial asthma(AEBA)and acute exacerbation of chronic obstructive pulmonary disease(AECOPD)with values of 260.500 and 185.170,respectively.Similarly,for outpatient cases of AEBA and AECOPD,Klang had the highest average values of 41.67 and 14.00,respectively.Shah Alam and Sungai Buloh did not show a significant increase in cases during periods of biomass burning.The statistical analysis concluded that higher concentrations of PM were associated with increased hospital admissions,particularly from June to September,as shown in the bar diagram.Haze episodes were associated with more healthcare utilization due to haze-related respiratory illnesses,seen in higher inpatient and outpatient visits(p<0.05).However,seasonal variability had minimal impact on healthcare utilization.These findings offer a comprehensive assessment of PM levels during historic haze episodes,providing valuable insights for authorities to develop policies and guidelines for effective monitoring and mitigation of the negative impacts of haze events.

Fate of Particulate Matter from Cruise-Ship Emissions in Glacier Bay during the 2008 Tourist Season

Simulations from the Weather Research and Forecasting Model, inline coupled with chemistry, were used to examine the fate of particulate matter with diameter of 10 μm or less (PM10) in Glacier Bay, Alaska during the 2008 tourist season. The simulations demonstrated that mesoscale and synoptic scale weather systems affect the residence time of PM10, the magnitude of concentrations, and its transport in and out of Glacier Bay. Strong inversions exceeding 2 K (100 m)-1 cause notable trapping of pollutants from cruise-ship emissions, increasing PM10 concentrations up to 43% compared to days with cruise-ship visits without the presence of an inversion. Inversions occurred locally in Glacier Bay on 42% of the 124-day tourist season with an average lifetime of 9 h. Pollutants occasionally originated from outside the National Park when southerly winds advected pollutants from ship traffic in Icy Strait. Occasionally, orographically forced lifting over the Fairweather Mountains transported pollutants from the Gulf of Alaska into Glacier Bay. While hourly (daily) PM10 concentrations reached ~44 μg·m-3 (22 μg·m-3) in some areas of Glacier Bay, overall seasonal average PM10 concentrations were below 2 μg·m-3. Despite up to two cruise-ship visits per day, Glacier Bay still has pristine air quality. Surface and upper air meteorological state variables were evaluated through an extensive network of surface and radiosonde observations, which demonstrated that the model was able to capture the meteorological conditions well.

Response of fine particulate matter to reductions in anthropogenic emissions in Beijing during the 2014 Asia–Pacific Economic Cooperation summit

The nested-grid capability of the global chemical transport model GEOS-Chem, with a horizontal resolution of 1/4°× 5/16° （latitude x longitude）, was used to identify the chemical species whose reductions made the largest contributions to decreases in PM2.s concentrations （fine particulate matter, diameter 〈 2.5μm, defined in this study as the sum of sulfate, nitrate, ammonium, black carbon, and organic carbon aerosols） in Beijing during the 2014 Asia-Pacific Economic Cooperation （APEC） summit. A number of numerical experiments were carried out for the period 15 October-29 November 2014. The model reproduced the observed daily variations of concentrations of PM2.s and gas-phase species （carbon monoxide, nitrogen dioxide, and sulfur dioxide）. Simulated PM2.s concentrations decreased by 55.9%-58.5% during the APEC period, compared to other periods in October and November 2014, which agreed closely with measurements. Sensitivity results showed that emissions control measures regarding nitrogen oxides and organic carbon over North China led to the largest reductions in PM2.s concentrations in Beijing during the APEC summit, which led to overall reductions in the PM2.5 concentration of Beijing by 5.7% and 4.6%, respectively. The control of ammonia emissions was found to be able to greatly reduce PM2.5 concentrations in the whole of North China during the APEC meeting.

Characterization of Particulate Matter from Power Plant Stack Emissions in Southern Zimbabwe

The study investigated the effects of four major particulate matter (PM) components namely sulphur, pulsar ash, carbon residue and ammonium components on the physical damage of sugarcane. A cyclone ambient kit tetra detector was used to quantify the components of the particulate matter at 2, 4, 6 and 8 km both in the windward and leeward sides of the power plant. This was done during the oncrop and offcrop season over a period of sixteen weeks. Eight sampling points were selected in an area of 2500 m2. Plant leaves were visually assessed for physical damage and the percentage of damage was noted. The results of the study were analyzed using SPSS version 16 and General Linear model-multivariate analysis to determine variation between the different means of components. Results showed that all PM components were only detected in the leeward side throughout the oncrop season and in the first two weeks of the offcrop. Ash and carbon deposition decreased with increasing distance. Ammonium components and sulphur were deposited only at 6 and 8 km. The percentage damage of the sugar cane was observed in the leeward side during the oncrop season. The physical damage caused by carbon and ash was observed in the 2 and 4 km distances whereas that caused by ammonium components and sulphur was observed in the 6 and 8 km distances.

Emission Factors of Particulate Matter Emitted from Co-Firing of Thai Lignite and Agricultural Residues in Fixed Bed Combustor

Emission factors （EFs） of particulate matter （PM） derived from mono and co-firing of Thai lignite and agricultural residues have been investigated. Two sampling methods for PM, total filtration （TF） and electrical low-pressure impactor （ELPI）, were used together. The study is focused on the influence of fuel mass fraction, and of secondary air to total air; SA：TA on EFs of PM. The results have shown that EFs of PM in mass-basis given by TF method are 8.9, 5.3 and 8.1 mg/kgfuel, while 3.3, 2.7 and 3.3 mg/kgfuel when using ELPI, for firing at constant SA：TA （30%） of lignite, rice husk and bagasse, respectively. For co-firing with 30%SA of coal/rice husk, higher EFs of PM is observed. They are 7.17 and 10.9 mg/kgfuel （TF） for 40 and 70% rice husk share, respectively, or 4.18 and 5.19 mg/kgfuel （ELPI）. However, lower PM emission; 1-3.3 mg/kgruel （TF） or 0.72-2.83 mg/kgfuel （ELPI） are obtained during co-firing of coal/rice husk with lower degree of air staging （i.e. 0-10% SA：TA）. For the influence of oxygenation state, increasing of SA： TA leads to a low formation of ultrafine particles （Dp 〈 0.1 μm）. Apart from PM, major gases （CO, NO, SO2） will be documented in this paper.

Human Health Risks from Exposure to Heavy Metals of Suspended Particulate Matter around the Tongon Gold Mine, Côte d’Ivoire

The Tongon mine, the largest gold mine in C?te d’Ivoire, has been in operation since April 2010. However, to our knowledge to date, no study has been conducted on metallic contamination in suspended particulate matter (PM10 and PM2.5) where there is a lack of information on the carcinogenic and non-carcinogenic risk to human health associated with the exposure of populations in the Tongon area to these pollutants. The general objective of this study is to evaluate the level of contamination of PM10;PM2.5 by heavy metals and their impact on the health of populations exposed to these pollutants in the Tongon gold mine area. The sampling and measurement of suspended particulate matter (PM10 and PM2.5) were done using a MiniVol TAS passive air sampler. Heavy metal concentrations were determined by inductively coupled plasma mass spectroscopy (Nex ION 2000 ICP-MS, USA). The results indicate that the average concentrations of suspended particles (PM2.5 and PM10) obtained are all above the recommended exposure limits. In addition, among the heavy metals contained in the suspended particles, the concentrations of arsenic and nickel are high and all above the standard limit values. The assessment of the health risks related to the inhalation of PM10 particles reveals that their inhalation over a long period could cause a carcinogenic risk.

Impact of Urban 3D Morphology on Particulate Matter 2.5(PM2.5) Concentrations:Case Study of Beijing, China

Urban particulate matter 2.5(PM2.5)pollution and public health are closely related,and concerns regarding PM2.5 are widespread.Of the underlying factors,the urban morphology is the most manageable.Therefore,investigations of the impact of urban three-dimensional(3D)morphology on PM2.5 concentration have important scientific significance.In this paper,39 PM2.5 monitoring sites of Beijing in China were selected with PM2.5 automatic monitoring data that were collected in 2013.This data set was used to analyze the impacts of the meteorological condition and public transportation on PM2.5 concentrations.Based on the elimination of the meteorological conditions and public transportation factors,the relationships between urban 3D morphology and PM2.5 concentrations are highlighted.Ten urban 3D morphology indices were established to explore the spatial-temporal correlations between the indices and PM2.5 concentrations and analyze the impact of urban 3D morphology on the PM2.5 concentrations.Results demonstrated that road length density(RLD),road area density(RAD),construction area density(CAD),construction height density(CHD),construction volume density(CVD),construction otherness(CO),and vegetation area density(VAD)have positive impacts on the PM2.5 concentrations,whereas water area density(WAD),water fragmentation(WF),and vegetation fragmentation(VF)(except for the 500 m buffer)have negative impacts on the PM2.5 concentrations.Moreover,the correlations between the morphology indices and PM2.5 concentrations varied with the buffer scale.The findings could lay a foundation for the high-precision spatial-temporal modelling of PM2.5 concentrations and the scientific planning of urban 3D spaces by authorities responsible for controlling PM2.5 concentrations.

Mineralogical characterization of airborne individual particulates in Beijing PM10

This work mainly focuses on the mineralogical study of particulate matter（PM10） in Beijing. Samples were collected on polycarbonate filter from April, 2002 to March, 2003 in Beijing urban area. Scanning electronic microscopy coupled with energy dispersive X-ray（SEM/EDX） was used to investigate individual mineral particles in Beijing PM10. 1454 individual mineral particulates from 48 samples were analysed by SEM/EDX. The results revealed that mineral particulates were complex and heterogeneous. 38 kinds of minerals in PM10 were identified. The clay minerals, of annual average percentage of 30.1%, were the main composition among the identified minerals, and illite/smectite was the main composition in clay minerals, reaching up to 35%. Annual average percentage of quartz, calcite, compound particulates, carbonates were 13.5%, 10.9%, 11.95%, 10.31%, respectively. Annual average percentage less than 10% were gypsum, feldspar, dolomite, and so on. Fluorite, apatite, halite, barite and chloridize zinc（ZnCl2） were firstly identified in Beijing PM10. Sulfurization was found on surface of mineral particles, suggested extensive atmospheric reaction in air during summer.

Short-term exposure to fine particulate matter and hospital admission for stroke:a meta-analysis

Objective Air pollution is an important risk factor for cardiovascular diseases throughout the world.Fine particulate matter(PM)air pollution alone is responsible for over three million deaths each year.Large and growing literature has explored whether short-term exposure to fine particulate matter is associated with stroke,but results from prior studies have been inconsistent.To fill this gap,we assessed the evidence quantitatively from epidemiological time-series studies published worldwide and determined whether short-term exposure to fine particulate matter(<2.5μm or<10μm)diameter[PM2.5 and PM10]was associated with increased risk of hospital admission for stroke(including ischemic and hemorrhagic stroke).

Development of Emission Factors for Quantification of Blasting Dust at Surface

Environmental impact assessment (EIA) and environmental management plan (EMP) is a statutory requirement for execution of new mining projects or for expansion of the operating projects. For this purpose, quantification of blasting dust emission is required. This can be done by developing emission factors for blasting. The concept is similar to that of specific charge in blasting. For mining operations other than blasting, quantification of dust can be done using emis- sion factors. Emission estimation techniques are very limited for blasting. In this study, the emission factors were de- veloped by carrying out a detailed field study at one of the largest opencast coal mines of India in all four seasons. Da- ta on atmospheric and meteorological conditions were generated by installing sodar and automatic weather station at the mine site. Respirable dust samplers were installed for monitoring of the dust emitted during coal or overburden bench blasting. Emission factors for dust concentrations were developed in gram per cubic meter of rock excavated. The developed emission factors were used to estimate dust emissions for adjacent mines due to similarity in mining and meteorological conditions. Seasonal variations in moisture contents in benches, where dust was monitored, indicated the lowest emission factors in monsoon due to high moisture in the bench materials. Similar field studies were also conducted at another coalfield of India for two seasons. It was found that the emission factors are site-specific.

Effect of Varying Temperature and Oxygen on Particulate Matter Formation in Oxy-Biomass Combustion

Offsetting particulate matter emissions has become a critical global aim as there are concerted efforts to deal with environmental and energy poverty challenges.This study consists of investigations of computing emissions of particulate matter from biomass fuels in various atmospheres and temperatures.The laboratory setup included a fixed bed electric reactor and a particulate matter(PM)measuring machine interfaced with the flue gas from the fixed bed reactor combustion chamber.The experiments were conducted at seven different temperatures(600℃-1200℃)and six incremental oxygen concentrations(21%-100%).Five biomass types were studied;A-cornstalk,B-wood,C-wheat straw,D-Rice husk,E-Peanut shell,each pulverized to a size of approximately 75 microns.The study shows that PM emitted during char combustion is consistently higher than that emitted during the de-volatilization.During de-volatilization,increase in temperature leads to linear decrease in PM emission between atmospheres of 21%O_(2)to 50%O_(2),thereafter,between 70%O_(2)to 100%O_(2);increase in temperature leads to a rise in PM emission.The average PM formation from all the five considered biomass is relatively comparable however,with differing atmospheres and temperatures,the fibrous and low-density biomass forms more PM.During char combustion,the study shows that at oxygen levels of 21%,70%,90%and 100%,increase in temperature leads to increased PM emission.The increase in oxygen concentration and temperature increases the rate of combustion hence diminishing the time of combustion.

A Study of the Correlation between the Concentration of Particulate Matter and Green Area Ratio Measured through a Portable Monitoring System: With Particular Focus on the Case of Dalseo-Gu, Daegu Metropolitan City

This study analyzed the relationship between the measured concentration of particulate matter (PM) and green area, which is an important spatial factor affecting urban PM concentration and even more carbon neutral in cities. In order to investigate the effects of green area, the green area ratio (GAR) is used and correlated with particulate matter. As a result of analyzing the correlation between GAR and PM concentration using the measured PM data, it was found that there was a positive correlation between the two variables. Hence, the higher the GAR, the lower the PM concentration. It can be said that the introduction of spatial elements with high GAR scores, such as parks and forests in cities, is effective in reducing PM concentration. In this study, a portable PM monitoring system using a vehicle for PM measurement was also established and operated. As a result, it was found that a PM monitoring system using a light-scattering sensor is an effective PM measurement method that can be used at the local government level. It was also found that a follow-up study is needed in the future to identify the PM mitigation functions of urban green areas according to the detailed characteristics of green areas as well as various environmental factors. This study can be used in air quality improvement activities and efforts as reference data by policy decision makers and in the field of environmental planning associated with the removal of airborne particulate matter pollution in urban areas.

Indoor and Outdoor Particulate Matter Exposure of Rural Interior Alaska Residents

To assess the exposure of residents in rural communities in the Yukon Flats to particulate matter of 2.5 μm or less in diameter (PM2.5), both indoor and outdoor concentration observations were carried out from March to September 2019 in Ft. Yukon, Alaska. Indoor concentrations were measured at 0.61 m (breathing level during sleeping) in homes and at 1.52 m heights (breathing level of standing adult) in homes and office/commercial buildings. Air quality was better at both heights in cabins than frame homes both during times with and without surface-based inversions. In frame houses, concentrations were higher at 0.61 m than 1.52 m, while the opposite is true typically for cabins. Differences between shoulder season and summer indoor concentrations in residences were related to changes in heating, subsistence lifestyle and mosquito repellents. In summer, office and commercial buildings, air quality decreased due to increased indoor emissions related to increased use of equipment and mosquito pics as well as more merchandise. During summer indoor concentrations reached unhealthy for sensitive groups to hazardous conditions for extended times that even exceeded the high outdoor concentrations. Due to nearby wildfires, July mean outdoor concentrations were 55.3 μg·m-3 which exceeds the 24-h US National Ambient Air Quality Standard of 35 μg·m-3. Indoor and outdoor concentrations correlated the strongest with each other for office/commercial buildings, followed by frame houses and cabins. Office/commercial buildings with temperature monitors had one to two orders of magnitude lower concentrations than those without.

山柰酚改善细颗粒物PM2.5诱导的老龄大鼠肺损伤的作用和机制研究

目的细颗粒物(PM2.5)被认为与多种呼吸系统问题有关,在老年人群中尤为显著。本研究旨在探索山柰酚是否可以治疗PM2.5诱导的老龄大鼠肺损伤,并探讨其潜在的作用机制。方法30只雄性Wistar大鼠(16个月龄)被随机分为5组:对照组、PM2.5暴露组和PM2.5暴露+山柰酚低剂量、中剂量和高剂量组。PM2.5暴露持续时间2周后,检测各组大鼠的肺功能、肺形态、炎症程度以及Toll样受体4(TLR4)/核因子-κB(NF-κB)信号通路相关蛋白的表达水平。结果与对照组相比,PM2.5暴露导致老龄大鼠发生显著的肺损伤,表现为明显的肺功能受损和组织病理学改变,支气管肺泡灌洗液(BALF)中的炎性因子TNF-α和IL-6浓度增加,血液中炎性细胞比例改变,肺组织中TLR4的表达和核转录因子-κB(NF-κB)磷酸化水平增加。山柰酚的治疗则呈剂量依赖性地改善了PM2.5所致肺功能损伤和组织病理学改变,抑制炎性因子分泌和炎症细胞比例失衡,抑制了TLR4/NF-κB信号通路的激活。结论山柰酚能够对PM2.5暴露引起的老龄大鼠肺损伤产生保护作用,抑制炎症反应和结构损伤,其作用机制可能与抑制TLR4/NF-κB信号通路的激活相关。

典型通航飞机PM与TVOC排放特征及排放因子

选取DA-40D型为典型机型,于2019年12月5日~8日在辽宁省朝阳机场开展飞机在推力功率为13%、37%、52%、73%和100%的5种工况下颗粒物(PM)、黑碳(BC)、总挥发性有机物(TVOC)的测试和分析.结果显示,5种推力功率下PM粒子数浓度在大推力工况中峰值位于0.25和0.3μm处,小推力工况峰值不明显,且PM1/PM10达99%以上.该款发动机排放PM_(2.5)、BC和TVOC排放质量浓度随推力上升均呈现升高的趋势,浓度分别在129.8~1039.4,18.3~291.9和311.6~7343.2μg/m^(3),排放浓度快速增加分别出现在全推力、中/全推力以及中等推力区间.通过逐步回归方法分析发现发动机进气总共压力对于PM_(2.5)和BC浓度影响最大,而TVOC浓度主要受冷却液温度影响.通过构建飞机LTO飞行模型,结合排放强度拟合及飞机性能参数计算,确定PM_(2.5)、BC和TVOC在LTO过程的排放因子分别为25.91,6.98和71.26μg/LTO,爬升阶段污染物排放的贡献占比最大.研究结果为探究通航飞机污染物排放特性和推进机场及周边污染防治提供基础.

可凝结颗粒物排放对北京市PM_(2.5)污染的影响估计

可凝结颗粒物(CPM)是PM_(2.5)的前体物之一.行业研究发现我国燃煤燃气锅炉、冷却塔等存在大量CPM排放,理论上存在致霾可能,但环境污染研究很少将CPM纳入PM_(2.5)排放成因分析中.基于北京市空气质量监测数据的统计分析发现,PM_(2.5)超标时PM_(2.5)/PM10显著上升,二次污染特征明显,且有逐年加剧趋势.而当前被视为主要前体物的SO_(2)和NO_(2)排放量和环境浓度逐年下降,且环境浓度与PM_(2.5)/PM10和PM_(2.5)积累速率无显著相关关系.估算北京市燃气采暖源的CPM排放量对环境空气中PM_(2.5)含量的贡献至少与NOx相当,且PM_(2.5)污染高发的静稳高湿气象极易导致CPM集聚转化,推测当前监测管理中忽视的CPM是影响北京市PM_(2.5)继续削减的原因,建议制定法规对CPM排放予以控制,筛选并推广先进技术,实现水蒸气余热回收和雾霾治理双重效益.

Combination of biodiesel-ethanol-diesel fuel blend and SCR catalyst assembly to reduce emissions from a heavy-duty diesel engine

In this study, the efforts to reduce NOx and particulate matter （PM） emissions from a diesel engine using both ethanol-selective catalytic reduction （SCR） of NOx over an Ag/Al2O3 catalyst and a biodiesel-ethanol-diesel fuel blend （BE-diesel） on an engine bench test are discussed. Compared with diesel fuel, use of BE-diesel increased PM emissions by 14% due to the increase in the soluble organic fraction （SOF） of PM, but it greatly reduced the Bosch smoke number by 60%-80% according to the results from 13-mode test of European Stationary Cycle （ESC） test. The SCR catalyst was effective in NOx reduction by ethanol, and the NOx conversion was approximately 73%. Total hydrocarbons （THC） and CO emissions increased significantly during the SCR of NOx process. Two diesel oxidation catalyst （DOC） assemblies were used after Ag/Al2O3 converter to remove CO and HC. Different oxidation catalyst showed opposite effect on PM emission. The PM composition analysis revealed that the net effect of oxidation catalyst on total PM was an integrative effect on SOF reduction and sulfate formation of PM. The engine bench test results indicated that the combination of BE-diesel and a SCR catalyst assembly could provide benefits for NOx and PM emissions control even without using diesel particle filters （DPFs）.

Inventory of Atmospheric Pollutant Emissions from Burning of Crop Residues in China Based on Satellite-retrieved Farmland Data

The burning of crop residues emits large quantities of atmospheric aerosols.Published studies have developed inventories of emissions from crop residue burning based on statistical data.In contrast,this study used satellite-retrieved land-cover data(1 km×1 km)as activity data to compile an inventory of atmospheric pollutants emitted from the burning of crop residues in China in 2015.The emissions of PM10,PM2.5,VOCs,NOx,SO2,CO,and NH3 from burning crop straw on nonirrigated farmland in China in 2015 were 610.5,598.4,584.4,230.6,35.4,3329.3,and 36.1 Gg(1 Gg=109 g),respectively;the corresponding emissions from burning paddy rice residues were 234.1,229.7,342.3,57.5,57.5,1122.1,and 21.5 Gg,respectively.The emissions from crop residue burning showed large spatial and temporal variations.The emissions of particulate matter and gaseous pollutants from crop residue burning in nonirrigated farmland were highest in east China,particularly in Shandong,Henan,Anhui,and Sichuan provinces.Emissions from burning paddy rice residue were highest in east and central China,with particularly high levels in Shandong,Jiangsu,Zhejiang,and Hunan provinces.The monthly variations in atmospheric pollutant emissions were similar among different regions,with the highest levels observed in October in north,northeast,northwest,east,and southwest China and in June and July in central and south China.The developed inventory of emissions from crop residue burning is expected to help improve air quality models by providing high-resolution spatial and temporal data.

High Magnetic Property and Toxicity of Particulate Matter Generated during Welding and Cutting Processes

Magnetic particulate matter(PM)has raised increasing concern due to its abundant presence in ambient air and negative health impact.However,there is still a lack of comprehensive understanding of their emission sources and toxicities.We here report the observation of high magnetic property and toxicity of PM generated during typical welding and cutting processes.Magnetite,formed during high-temperature operation with less oxygen pressure,was revealed to be the major magnetic contributor.The averaged saturation magnetization and magnetic susceptibility values of fine PM(PM_(2.5))from welding processes are 1.4−4.2 times greater than those of PM emitted from other unintended emission sources,including iron and steel plants and brake wear,while they are 2.0−5.7 times greater for the cutting processes.Furthermore,PM_(2.5)from welding and cutting processes are nearly 3.5−4.5 times more neurovirulent and 2.1−7.0 times more likely to induce oxidative stress than those from other magnetic sources in the nerve cells lines.Moreover,all of these magnetic PM_(2.5)exhibit greater negative health effects than typical atmospheric PM_(2.5)collected in Shanghai urban regions.These new findings suggest that appropriate occupational protection measures should be implemented for the welding and cutting process to reduce adverse health impacts.