PM2.5的研究现状及健康效应

大气细颗粒物PM2.5是大气气溶胶的一部分,由于其粒径小以及可为毒性物质提供载体,对环境和人体健康产生很大的影响。文章总结了国内外有关细颗粒物PM2.5的研究现状,主要围绕PM2.5的物理化学特征、来源解析、健康效应、及其对能见度的影响等方面进行论述,并对其研究动向进行了展望。     

广州市大气细颗粒物及微量元素的分析

在广州市区采集大气细颗粒物PM2．5样品,对PM2．5及其中12种微量元素进行分析。研究结果显示采样期间广州市大气PM25的平均浓度为113．3μg／m3,远远超过了美国EPA制定的PM25日均浓度限值（35μg／m3）。与国内外其它大城市相比,PM2．5中微量元素的浓度处于较高水平,其中重金属元素Cd、Pb、Zn、Cu、As、Ni、M0、Mn、Cr和Co的富集因子EF远远大于1,主要来源于人为污染·     

我国大气细颗粒物中水溶性离子的研究进展

当前我国大部分城市仍然存在严重的大气细颗粒物(PM2.5)污染问题.而水溶性离子作为PM2.5的主要成分之一,会从气候、环境和人体健康等方面影响人类的生存和发展.本文以细颗粒物水溶性离子中的SNA(Sulfate-Nitrate-Ammonium)为重点,从SNA的测定方法、质量浓度的时空分布特征、其形成过程中的影响因...     

细颗粒物PM2.5研究进展

PM2.5由于其较小的粒径、巨大的比表面积、较大的危害性等特点受到世界各国的广泛关注.本文总结了国内外有关细颗粒物PM2.5的研究现状,主要围绕细颗粒物PM2.5的化学物质组成与分析方法、毒性效应、来源解析等方面进行了论述,并对其研究动向进行了展望.     

PM_(2.5)检测方法及研究进展

大气细颗粒物(PM2.5)的污染对于人类和生态环境的影响巨大,因此关于PM2.5检测技术的研究非常重要。本文概述了PM2.5的检测方法,评价了当前典型的PM2.5检测技术优点与不足,并对PM2.5检测技术今后研究方向进行分析并提出了展望。     

环保水性胶成为制鞋行业胶粘剂主流

日前，在国务院常务会议中通过了发布新修订的《环境空气质量标准》，这一措施的出台意味着防治大气污染成为国家政府重点部署的工作。此前频频光顾各大城市的灰霾天气，令人们对其影响感到担忧，直径不到人头发丝粗细1／20的细颗粒物（PM25），不仅可以危害到人类的身体健康，也对交通治安产生一定的威胁，因此大众对于将PM2．5纳入检测的呼声日盛。据了解，新标准增加了细颗粒物（PM2．5）和臭氧8小时浓度限值监测指标，填补了我国在这一方面的空白。     

乌鲁木齐采暖期4种颗粒物质量浓度比对研究

本研究以乌鲁木齐工业区、交通区、生活区、风景对照区4个典型区域为研究对象,采集了采暖期大气颗粒物TSP、PM10、PM5、PM2.5,并对其进行质量浓度分析。结果表明:在采暖期大气中TSP的浓度范围为87.94—325.61ug/m3;在采暖期大气中PM10的浓度范围为76.69—299.21ug/m3;在采暖期大气中PM5的浓度范围为79.68—294.95ug/m3;在采暖期大气中PM2.5的浓度范围为71.80—213.30ug/m3。总体来看,乌鲁木齐采暖期TSP、PM10、PM5、PM2.5的浓度存在一定的差异性,各组分浓度分布为工业区交通区生活区风景对照区,这可能与采样区受污染程度有关。     

四平市雾霾大气颗粒物的理化性质和来源分析

本研究于2014年11月22日-12月19日对四平市大气颗粒物PM2.5、PM10和气体污染物进行采样监测,对大气颗粒物中重金属离子(Cu、Mn、Pb、Zn和Ni)和水溶性阴离子(F~-、Cl~-、NO~-_2和NO~-_3)的质量浓度和成分进行分析,并且讨论了雾霾天气发生时大气污染物的可能来源。     

大气颗粒物PM2.5化学组分分析方法概述

大气细颗粒物PM2.5中化学组分的分析方法做了简要的介绍,PM2.5的化学组分主要包括水溶性离子、无机元素、有机碳和元素碳,并分析了各种方法的优缺点,以便于在研究中选取更简单有效的方法,并展望了PM2.5中组分的研究前景.     

某核电厂施工期大气TSP、PM_(10)污染水平及相关性研究

为研究核电项目建设工程施工期大气颗粒物污染特征,分别于2012年5月和11月采集TSP,PM10样品,用重量法分析其质量浓度,并对其相关性进行分析。结果表明,用环境空气质量标准(GB 3095-2012)来衡量,监测周期内大气颗粒物TSP,PM10的日均浓度均符合标准;TSP=1.0308 PM10+0.0361,相关性较好。     

某工业园区大气PM_(2.5)中重金属污染特征

为了解玉溪市某工业园区大气PM_(2.5)中重金属污染特征,于2017年3月至2018年3月在玉溪市某工业园区采集PM_(2.5)样品共70个。利用微波消解,ICP-MS方法检测Cr、As、Cd、Pb四种重金属的质量浓度并分析其污染特征。结果表明,玉溪市某工业园区大气PM_(2.5)日均质量浓度在10μg·m~(-3)～75μg·m~(-3),而PM_(2.5)中四种重金属的浓度范围在0.003～0.377μg·m~(-3),并且浓度由高到低依次为PbAsCr Cd,其中As超过国家质量指标限值。因此,应对玉溪市废气排放采取一定控制措施。     

细颗粒物凝并技术机理的研究进展

凝并技术是提高烟气中细颗粒物(PM2.5)去除效率的关键技术之一。凝并机理的研究有利于加深对细颗粒物凝并过程的理解,最大限度地提高PM2.5的凝聚速度,使PM2.5在较短的时间内团聚成大颗粒。本工作对电凝并、化学凝并和声凝并3种凝并效果显著的凝并技术机理进行概述,分别介绍了电凝并机理的核心电凝并系数方程,不同化学添加剂对颗粒的作用机制,同向运动、流体力学和声致湍流作用下的声凝并机理的发展现状。阐述了现有研究的不足,并提出在后续凝并机理的研究中,可利用高速显微摄像技术实时观测颗粒的凝并过程,对已有凝并机理进行验证及修正。同时还需考虑实际烟气成分对颗粒凝并的影响,进一步完善颗粒的凝并机理。     

One– and Three–Hour PM2.5 Characterization,Speciation, and Source Apportionment Using Continuous and Integrated Samplers

Ammonium nitrate and semivolatile organic compounds (SVOC) are significant components of fine particles in many urban atmospheres. These components, however, are not properly measured by current EPA accepted methods, such as the R&P TEOM monitor, due to loss of semivolatile material (SVM) from particles in the heated environment of the filter during sampling. The accurate determination of semivolatile material is important due to the possible effects of these species on human health, visibility, and global climate change. The concentration and composition of fine particulate material were determined using a combination of continuous and integrated samplers at the Brigham Young University–EPA Environmental Monitoring for Public Access and Community Tracking (BYU–EPA EMPACT) monitoring site in Salt Lake City, Utah over a six–day sampling period (30 January to 4 February) during the winter of 2001. Continuous samples were collected using a RAMS (total PM_2.5 mass), a TEOM monitor (nonvolatile PM_2.5 mass), an Aethalometer (elemental carbon), a TSI CPC (particle count), and a Nephelometer (light scattering by particles, b_sp). Fine particle composition and mass were determined on a three–hour basis using the PC–BOSS diffusion denuder sampler. Total PM_2.5 mass–determined with the RAMS agreed with constructed mass determined from the chemical composition measured in collocated PC–BOSS–integrated samples. Results from this study indicate that semivolatile material (ammonium nitrate and semivolatile organic compounds) is a significant component of fine particle mass. Semivolatile organic compounds were the major contributor to light scattering during the six–day sampling period. Semivolatile nitrate, but not organic material, was suggested to be hygroscopic by the nephelometric data. The majority of the SVM observed appeared to be secondary material formed from photochemical reactions of the organic and NO_x emissions from mobile sources and wood smoke combustion.     

Synthesis of Spherical β-Silicon Carbide Particles by Ultrasonic Spray Pyrolysis

Fine agglomerate-free spherical β-SiC powder was synthesized from a dispersion of colloidal silica, saccharose, and boric acid, by means of an ultrasonic spray pyrolysis method. Droplets of 2.2 μm were formed with an aerosol generator, operated at 2.5 MHz, and carried into a reaction furnace at 900°C with argon. Spherical X-ray amorphous gel particles of 1.1 μm were obtained. β-SiC particles with a mean diameter of 0.79 μm and spherical shape resulted when the SiC gel precursor particles were heated at 1500°C in argon.     

超细TATB-BTF核-壳型复合粒子的制备

用喷雾干燥法制备了超细TATB-BTF核-壳型复合粒子。通过BTF在TATB表面结晶沉积,达到对超细TATB粒子进行包覆的目的。扫描电镜分析显示粒子表面形态发生了一定变化,表明TATB粒子表面有包覆层,用光电子能谱(XPS)对粒子表面各成分含量进行了分析。对复合粒子的热行为进行了DTA分析。结果表明,核粒大小是影响超细TATB-BTF核-壳型复合粒子包覆效果的主要因素。     

Characterization of Fine Particulate Emissions from Casting Processes

Fine particle (PM_2.5) emission rates and compositions from gray iron metal casting foundry were characterized for No-Bake molds poured at the Research Foundry located at Technikon, LLC (McClellan, CA). For each mold, PM_2.5 was collected for chemical analysis, and particle size distributions were measured by an Electrical Low Pressure Impactor (ELPI) to understand PM emissions during different part of the casting process. Molds prepared with phenolic urethane binders were poured with Class 30 gray cast iron at 1,427–1,480°C. PM_2.5 was collected from the pouring, cooling, and shakeout processes for each mold. Most of the PM_2.5 mass emitted from these processes was composed of carbonaceous compounds, including 37–67% organic carbon (OC) and 17–30% elemental carbon (EC). Oxides of aluminum (Al), silicon (Si), calcium (Ca), and iron (Fe) constituted 8–20% of PM_2.5 mass, and trace elements (e.g., K, Ti, Mn, Cu, Zn, and Pb) contributed 3–6%. Chemical abundances in PM were different between pouring and shakeout for each discrete mold. PM_2.5 mass emissions from pouring were 15–25% of the total from each discrete mold. Ultrafine particles (< 0.1 μm) contributed less than 1% of PM_2.5 mass, but nearly all of the particle numbers. Different mechanisms for pouring and shakeout result in variations in chemical abundances and particle size distributions. The highest PM_2.5 mass and number concentrations were observed when shakeout started. PM_2.5 size distributions in mass concentration during shakeout contained particles in the tail of coarse particles (1.6–2.5 μm) and a vapor condensation mode (0.65–1.6 μm). Flame conditions, vaporization, thermal decomposition of organic materials, and the variability of mold breakup during shakeout affect PM emission rates. A detailed chemical speciation for size-segregated PM samples at different process points needs to be conducted at full-scale foundries to obtain emission factors and source profiles applicable to emission inventories, source receptor modeling, and implementation of emission standards.     

Fine particle coating by a novel rotating fluidized bed coater

Fine particle coating has been conducted by using a novel rotating fluidized bed coater. The coater consists of a plenum chamber and a horizontal porous cylindrical air distributor, which rotates around its axis of symmetry inside the plenum chamber. Cohesive fine cornstarch (mass median diameter of 15 μm), a Geldart Group C powder, was used as core particle and an aqueous solution of hydroxypropylcellulose (HPC-L) was sprayed onto the cornstarch to generate a film coating. Fine particle coating was conducted under various coating levels (wt.% HPC-L) and the particle size distribution of the coated particles, release rate of an aqueous pigment (food blue No. 1), which had been pre-coated onto the initial cornstarch, and the degree of agglomeration were investigated. The relationship between the coating level and the physical properties of the coated particles was analyzed. The results indicated that coating of cohesive fine cornstarch with HPC-L could be achieved, producing a favorable prolonged release property with almost maintaining the individual single particle.     

Effect of zirconia particle size on the properties of alumina-spinel castables

The industrial application of alumina-spinel refractory castables has crucial requirements on the service performance. Thus, the effects of different sized desilicated zirconia particles on the castables microstructure, thermal-mechanical properties and high temperature elastic modulus have been investigated. The zirconia particle sizes were varied from 1000 µm to 2.5 µm (d₅₀). It was observed that the finer (below 88 µm) zirconia particles were beneficial to improve the cold modulus of rupture (CMOR) and the hot modulus of rupture (HMOR), but could not effectively enhance the thermal shock resistance. Fine zirconia particles can homogeneously disperse in the matrix and significantly promote the sintering process. Accompanied with the phase transformation of zirconia, both the high density of matrix cracks and the strong ceramic bonding (between the coarse grains and the matrix) were found in the refractory castables, which was responsible for an increase of CMOR. However, the binding characteristic could also give rise to the high stored elastic energy that was adverse to the thermal shock resistance, and the excessive amount of preexisting matrix cracks could induce more microdamage during the thermal shock. Additionally, it was proposed that the second-phase dispersion reinforcement and the highly ceramics bonding resulted in the superior HMOR when introducing fine ZrO₂ particles.     

Plerosphere and its role in reduction of emitted fine fly ash particles from pulverized coal-fired power plants

Fine particles (PM_2.5) emitted from the stacks of the coal-fired power plants are of environmental concern since they can easily enter the human respiratory track. The detailed study of the fly ash particles using scanning electron microscope/electron dispersive spectrometry (SEM/EDX) show that fine solid spherical particles (microspheres) are contained by the large cenosphere particles (>50 μm) during the combustion process. The resulting macro particles are known as “plerosphere”, which are typically impregnated by the fine microspheres. The coal-fired power plants’ particle control devices such as the electrostatic precipitators (ESP) and baghouse filters tend to capture the large plerospheres, more efficiently. Therefore, the result of this study suggests that the containment of the microspheres by plerospheres during the coal combustion process can effectively reduce the amount of fine particles and associated elements released into atmosphere.     

Submicron ash formation from coal combustion

In recent years, fine particles have been found to be the cause of various harmful effects on health, and many countries have imposed restrictions on emission of these particles. Fine ash particles are formed during coal combustion in power stations and, if not collected in the air pollution control devices, are emitted into the atmosphere. The fine ash particles can remain airborne for long periods and can result in deleterious health effects when inhaled and deposited in the lungs.Previous studies have shown that combustion of coals of different rank can result in differences in the amount and chemistry of the submicron ash particles. This study examines the variability occurring between the submicron ashes formed from coals of similar rank. Five Australian bituminous coals were burned in a laminar flow drop tube furnace in two different oxygen environments to determine the amount and composition of submicron ash formed. The experimental setup is described and the repeatability of the experiments is discussed. The variability in the submicron ash yield as a percentage of the total ash collected and the submicron ash composition are presented and discussed. This paper presents experimental results rather than a detailed discussion on its interpretation. However, the results indicate that the condensation of evaporated species is responsible for the formation of ash particles smaller than 0.3 μm.