Size Distributions and Elemental Compositions of Particulate Matter on Clear,Hazy and Foggy days in Beijing,China

Total suspended particulates （TSP） samples were collected using low pressure impactors （Andersen Series 20-800, USA） on typical clear, hazy and foggy days in Beijing in order to investigate the characteristics of size distributions and elemental compositions of particulate matter （PM） in different weather conditions. The concentrations of sixteen elements, including Na, Mg, Al, K, Ca, Mn, Fe, Ni, Cu, Zn, As, Se, Cd, Ba, T1 and Pb were detected using inductively coupled plasma mass spectrometry （ICP-MS）. The results showed that Ca, A1, Fe, Mg and Ba on foggy days were 2.0 2.6 times higher than on clear days, and 2.3-2.9 times higher than on hazy days. Concentrations of Cu, Zn, As, Se and Pb on foggy days were 163.5, 1186.7, 65.9, 32.0 and 708.2 ng m-3, respectively, in fine particles, and 68.1, 289.5, 19.8, 1.6 and 103.8 ng m-3, respectively, in coarse particles. This was 1.0~8.4 times higher and 1.4-7.4 times higher than on clear and hazy days, respectively. It is then shown that Mg, A1, Fe, Ca and Ba were mainly associated with coarse particles, peaking at 4.7~5.8 μm; that Cd, Se, Zn, As, T1 and Pb were most dominant in fine particles, peaking at 0.43-1.1 μm; and that Na, K, Ni, Cu and Mn had a multi-mode distribution, with peaks at 0.43-1.1 μm and 4.7-5.8 μm. The enrichment factors indicated that coal combustion along with vehicle and industry emissions may be the main sources of pollution elements.

The grain-size distribution of the suspended particulate matter in the Huanghe Estuary and its adjacent sea area in winter

The grain-size of suspended particulate matter （SPM） in the Huanghe Estuary and its adjacent sea area was investigated with an in situ laser particle size analyzer （LISST-100） in November 2006.The spatial distribution of the grain-size parameters was very complicated.The results show that （1） the mean particle size of SPM ranged from 3.00Φ to 6.41Φ,with an average value of 4.66Φ;（2） the frequency distribution patterns of the SPM grain-size showed three different types,which were mono-mode,dual-mode and tri-mode,respectively;（3） C-M chart suggested that the transportation-processes of the SPM not only included suspended mode,but also the bed load transportation mode.The bed load transportation mode mainly occurred at the bottom layer.The characteristics and space distribution of SPM grain-size might be mainly controlled by sediment discharge of the Huanghe River,hydrodynamics condition,surface sediment types,and biological process within the study area.

Threshold friction velocity influenced by soil particle size within the Columbia Plateau, northwestern United States

Wind erosion is a geomorphic process in arid and semi-arid areas and has substantial implications for regional climate and desertification.In the Columbia Plateau of northwestern United States,the emissions from fine particles of loessial soils often contribute to the exceedance of inhalable particulate matter(PM)with an aerodynamic diameter of 10μm or less(PM10)according to the air quality standards.However,little is known about the threshold friction velocity(TFV)for particles of different sizes that comprise these soils.In this study,soil samples of two representative soil types(Warden sandy loam and Ritzville silt loam)collected from the Columbia Plateau were sieved to seven particle size fractions,and an experiment was then conducted to determine the relationship between TFV and particle size fraction.The results revealed that soil particle size significantly affected the initiation of soil movement and TFV;TFV ranged 0.304-0.844 and 0.249-0.739 m/s for different particle size fractions of Ritzville silt loam and Warden sandy loam,respectively.PM10 and total suspended particulates(TSP)emissions from a bed of 63-90μm soil particles were markedly higher for Warden sandy loam than for Ritzville silt loam.Together with the lower TFV of Warden sandy loam,dust emissions from fine particles(<100μm in diameter)of Warden sandy loam thus may be a main contributor to dust in the region's atmosphere,since the PM10 emissions from the soil erosion surfaces and its ensuing suspension within the atmosphere constitute an essential process of soil erosion in the Columbia Plateau.Developing and implementing strategic land management practices on sandy loam soils is therefore necessary to control dust emissions in the Columbia Plateau.

Distribution and chemical speciation of arsenic in different sized atmospheric particulate matters

The distribution and chemical speciation of arsenic(As)in different sized atmospheric particulate matters(PMs),including total suspended particles(TSP),PM_(10),and PM_(2.5),collected from Baoding,China were analyzed.The average total mass concentrations of As in TSP,PM_(10),and PM_(2.5)were 31.5,35.3,and 54.1μg/g,respectively,with an order of PM_(2.5)>PM_(10)>TSP,revealing that As is prone to accumulate on fine particles.Due to the divergent toxicities of different As species,speciation analysis of As in PMs is further conducted.Most of previous studies mainly focused on inorganic arsenite(iAs^(Ⅲ)),inorganic arsenate(iAs^(Ⅴ)),monomethylarsonate(MMA),and dimethylarsinate(DMA)in PMs,while the identification and sensitive quantification of trimethylarsine oxide(TMAO)were rarely reported.In this study,a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs.An anion exchange column was used to separate MMA,DMA and iAs^(Ⅴ),while a cation exchange column to separate TMAO and iAs^(Ⅲ).Results showed that iAs^(Ⅴ) was the dominate component in all the samples,corresponding to a portion of 79.2%±9.3%of the total extractable species,while iAs^(Ⅲ),TMAO and DMA made up the remaining 21%.Our study demonstrated that iAs^(Ⅲ) accounted for about 14.4%±11.4%of the total extracted species,with an average concentration of 1.7±1.6 ng/m^(3).It is worth noting that TMAO was widely present in the samples(84 out of 97 samples),which supported the assumption that TMAO was ubiquitous in atmospheric particles.

Influence of different weather events on concentrations of particulate matter with different sizes in Lanzhou,China

The formation and development of weather events has a great impact on the diffusion, accumulation and transport of air pollutants, and causes great changes in the particulate pollution level. It is very important to study their influence on particulate pollution. Lanzhou is one of the most particulate-polluted cities in China and even in the world. Particulate matter （PM） including TSP, PM〉10, PMzs-10, PM2.5 and PM1.0 concentrations were simultaneously measured during 2005-2007 in Lanzhou to evaluate the influence of three kinds of weather events - dost, precipitation and cold front - on the concentrations of PM with different sizes and detect the temporal evolution. The main results are as follows： （1） the PM pollution in Lanzhou during dust events was very heavy and the rate of increase in the concentration of PM2.5-10 was the highest of the five kinds of particles. During dust-storm events, the highest peaks of the concentrations of fine particles （PM2.5 and PM1.0） occurred 3 hr later than those of coarse particles （PM〉10 and PM/.5-10）. （2） The major effect of precipitation events on PM is wet scavenging. The scavenging rates of particles were closely associated with the kinds of precipitation events. The scavenging rates of TSP, PM〉10 and PMa.5-10 by convective precipitation were several times as high as those caused by frontal precipitation for the same precipitation amount, the reason being the different formation mechanism and precipitation characteristics of the two kinds of precipitation. Moreover, there exists a limiting value for the scavenging rates of particles by precipitation. （3） The major effect of cold-front events on particles is clearance. However, during cold-front passages, the PM concentrations could sometimes rise first and decrease afterwards, which is the critical difference in the influence of cold fronts on the concentrations of particulate pollutants vs. gaseous pollutants.

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter （PM） and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry （ICP-MS）. The results indicated that the average concentration of PM, chromium （Cr）, arsenic （As）, cadmium （Cd） and lead （Pb） in PM was 177.3 ± 33.2 μg/m^3, 37.3 ± 8.8 ng/m^3, 17.3 ± 8.1 ng/m^3, 4.8 ± 3.1 ng/m^3 and 141.6 ± 49.1 ng/m^3, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1-2.1 μm, followed by 9-10 μm. The size distribution of As, cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1-2.1 μm and 9-10 μm ranges while for Cr, only a single-mode at 4.7-5.8 μm was observed. PM （64.7%, As （72.5%）, cd （72.2%） and Pb （75.8%） were associated with the fine mode below 2.1 μm, respectively, while Cr （46.6%） was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.

Air pollution and inhalation exposure to particulate matter of different sizes in rural households using improved stoves in central China

Household air pollution is considered to be among the top environmental risks in China.To examine the performance of improved stoves for reduction of indoor particulate matter（PM） emission and exposure in rural households, individual inhalation exposure to size-resolved PM was investigated using personal portable samplers carried by residents using wood gasifier stoves or improved coal stoves in a rural county in Central China.Concentrations of PM with different sizes in stationary indoor and outdoor air were also monitored at paired sites. The stationary concentrations of size-resolved PM in indoor air were greater than those in outdoor air, especially finer particles PM0.25. The daily averaged exposure concentrations of PM0.25, PM1.0, PM2.5 and total suspended particle for all the surveyed residents were 74.4 ± 41.1, 159.3 ± 74.3, 176.7 ± 78.1 and 217.9 ± 78.1 μg/m3,respectively. Even using the improved stoves, the individual exposure to indoor PM far exceeded the air quality guideline by WHO at 25 μg/m3. Submicron particles PM1.0 were the dominant PM fraction for personal exposure and indoor and outdoor air. Personal exposure exhibited a closer correlation with indoor PM concentrations than that for outdoor concentrations. Both inhalation exposure and indoor air PM concentrations in the rural households with gasifier firewood stoves were evidently lower than the reported results using traditional firewood stoves. However, local governments in the studied rural areas should exercise caution when widely and hastily promoting gasifier firewood stoves in place of improved coal stoves, due to the higher PM levels in indoor and outdoor air and personal inhaled exposure.

Size Distributions of Atmospheric Aerosol Compositions in Saitama, Japan

A survey of atmospheric aerosols in a suburban area near Tokyo, Japanwas conducted using an Andersen sampler. Significant amounts of Na+and Cl- collected were considered to be derived from sea salt. The difference between the Na+/Cl-ratio in the area and that in sea salt indicated a considerable loss of Cl-. This is assumed to be caused by the formation of NaNO3, which is one of the main nitrate species present. Most of the sulfate in the sample was found to be (NH4)2SO4 in the form of fine particles, which is different from the sulfate derived from sea salt and soil. The size distributions of K and Mg are also discussed in relation to particular sources.

The impact of particle size on the cumulative process of street dust migration

Street dust is a carrier of various pollutants widely distributed in the urban road environment, and has obvious particle size effect on environmental pollution. In this paper, the effects of particle size distribution on dust accumulation, heavy metal pollution and cleaning conditions are mainly discussed. Based on the particle size effect of street dust, the future research and control of non-point source pollution are given a breakthrough.

南海北部内孤立波影响海域悬浮颗粒物特征变化研究

悬浮颗粒物在“源-汇”沉积体系中扮演着关键角色,而南海常见的动力现象—内孤立波,则被证实是影响悬浮颗粒物分布和沉积过程的重要因素。该项研究于2022年9月在吕宋海峡至东沙群岛海域开展,采用LISST-deep与CTD设备进行同步观测,以研究悬浮颗粒物的粒径及体积浓度分布。通过调查期内的卫星遥感数据,划定了内孤立波的影响范围,并结合海床基观测内孤立波影响悬浮颗粒物分布过程,从动力学的角度揭示了内孤立波对悬浮颗粒物在输运过程中特征变化的影响。研究发现:(1)在内孤立波的振幅深度区间(6~79 m)内,以较小粒径的悬浮颗粒物(15~25μm)分布为主,且越接近内孤立波的波谷深度,出现较小粒径悬浮颗粒物的频率越高。(2)悬浮颗粒物分布由内孤立波波峰线中心区域扩散到两侧,在中心为体积浓度低值区(≤91μL/L),而波峰线两侧区域与内孤立波传播路径远端区域为体积浓度高值区(≥500μL/L)。此外,研究进一步揭示了内孤立波通过改造作用使聚集状态的悬浮颗粒物被分解为粒径较小、组成单一的颗粒,通过控制作用改变悬浮颗粒物在波峰线不同位置、传播路径和振幅深度上的体积浓度分布,为理解南海源-汇沉积体系提供了重要的理论依据。

南京大气颗粒物化学组分的粒径分布和来源解析

大气颗粒物中化学组分的粒径分布与其来源、形成过程、环境及健康效应密切相关。而过去对不同季节颗粒物的粒径分布特征,以及不同来源对粗、细颗粒物的贡献的研究相对较少。于2022年12月(冬季)和2023年8月(夏季)在南京采集了大气分粒径颗粒物样品,分析了粗颗粒物(PM_(2.1-10))和细颗粒物(PM_(2.1))中碳质组分和主要水溶性无机离子的粒径分布和季节变化,运用正定矩阵因子分解模型(Positive Matrix Factorization,PMF)进行PM_(2.1-10)和PM_(2.1)的源解析。结果表明,在粒径分布特征上,冬夏两季有机碳(OC)、元素碳(EC)、水溶性有机碳(WSOC)的平均浓度呈双峰型分布。SO_(4)^(2-)和NO_(3)^(-)的季节平均浓度均为双峰型分布。NH_(4)^(+)主要分布在细颗粒物中,季节平均浓度呈单峰型分布,冬夏季均在0.43-0.65μm出现峰值。在季节变化上,颗粒物中除Na^(+)和SO_(4)^(2-)外的主要化学组分浓度均在冬季高于夏季。冬夏两季Ca^(2+)、Mg^(2+)主要集中在粗颗粒物中。根据PMF模型解析结果,南京大气颗粒物主要有4类来源贡献,即交通源、二次生成、生物质燃烧和扬尘源。PM_(2.1)主要来自二次生成和生物质燃烧源,冬夏季分别贡献了65.7%和61.0%,其中冬季生物质燃烧和二次硝酸盐的贡献占主导地位,而夏季主要来自二次硫酸盐的贡献。冬季PM_(2.1-10)主要来自交通源(41.8%),夏季则主要来自生物质燃烧和硝酸盐的二次生成贡献(43.9%)。研究探讨了大气颗粒物的化学组分的粒径分布特征、季节差异及来源,可为制定有针对性的大气污染防控措施提供科学依据。

降雨强度对不同海拔侧柏叶片滞纳大气颗粒物量的影响

降雨可以有效清除植物叶片滞纳的大气颗粒物,但降雨强度对不同海拔植物叶面滞尘量的影响研究较缺乏。以九龙山不同海拔侧柏人工林为研究对象,采用传统方法测定不同强度降雨前后植物叶片滞纳大气颗粒物的量,进而研究降水强度对不同海拔侧柏叶片滞纳水溶/非水溶性颗粒物的影响。研究结果表明,中雨(17.5 mm)对不同海拔侧柏叶片滞纳颗粒物的去除效果强于小雨(3.2 mm);中雨后,侧柏叶片滞纳颗粒物的阈值为(0.4248±0.0104)g·m^(-2),且与海拔、降雨前叶面滞纳颗粒物的量无关;小雨后,不同海拔侧柏叶面非水溶性颗粒物存在明显的小粒径聚集为大粒径现象;在低、中海拔地区,中雨主要影响侧柏叶面大粒径颗粒物的量,而高海拔地区主要影响小粒径颗粒物的量;降雨对非水溶性大粒径颗粒物的影响大于水溶性颗粒物;小雨会增加不同海拔侧柏叶片大粒径水溶/非水溶性颗粒物的百分比,中雨会使低、高海拔侧柏叶片大粒径水溶性颗粒物和高海拔大粒径非水溶性颗粒物的百分比增加,而其他海拔侧柏叶片大粒径水溶/非水溶性颗粒物的百分比下降。

Effects of continuously regenerating diesel particulate filters on regulated emissions and number-size distribution of particles emitted from a diesel engine

The effects of continuously regenerating diesel particulate filter （CRDPF） systems on regulated gaseous emissions, and number-size distribution and mass of particles emanated from a diesel engine have been investigated in this study. Two CRDPF units （CRDPF-1 and CRDPF-2） with different specifications were separately retrofitted to the engine running with European steady-state cycle （ESC）. An electrical low pressure impactor （ELPI） was used for particle number-size distribution measurement and mass estimation. The conversion/reduction rate （RcR） of hydrocarbons （HC） and carbon monoxide （CO） across CRDPF-1 was 83% and 96.3%, respectively. Similarly, the RCR of HC and CO and across CRDPF-2 was 91.8% and 99.1%, respectively. The number concentration of particles and their concentration peaks; nuclei mode, accumulation mode and total particles; and particle mass were highly reduced with the CRDPF units. The nuclei mode particles at downstream of CRDPF-1 and CRDPF-2 decreased by 99.9% to 100% and 97.8% to 99.8% respectively; and the particle mass reduced by 73% to 92.2% and 35.3% to 72.4%, respectively, depending on the engine conditions. In addition, nuclei mode particles increased with the increasing of engine speed due to the heterogeneous nucleation initiated by the higher exhaust temperature, while accumulation mode particles were higher at higher loads due to the decrease in the air-to-fuel ratio （A/F） at higher loads.

Quantifying the characteristics of particulate matters captured by urban plants using an automatic approach

It is widely accepted that urban plant leaves can capture airborne particles. Previous studies on the particle capture capacity of plant leaves have mostly focused on particle mass and/or size distribution. Fewer studies, however, have examined the particle density, and the size and shape characteristics of particles, which may have important implications for evaluating the particle capture efficiency of plants, and identifying the particle sources. In addition, the role of different vegetation types is as yet unclear. Here, we chose three species of different vegetation types, and firstly applied an object-based classification approach to automatically identify the particles from scanning electron microscope（SEM）micrographs. We then quantified the particle capture efficiency, and the major sources of particles were identified. We found（1） Rosa xanthina Lindl（shrub species） had greater retention efficiency than Broussonetia papyrifera（broadleaf species） and Pinus bungeana Zucc.（coniferous species）, in terms of particle number and particle area cover.（2） 97.9% of the identified particles had diameter ≤10 μm, and 67.1% of them had diameter ≤2.5 μm. 89.8% of the particles had smooth boundaries, with 23.4% of them being nearly spherical.（3） 32.4%–74.1% of the particles were generated from bare soil and construction activities, and 15.5%–23.0% were mainly from vehicle exhaust and cooking fumes.

含表面活性剂溶液的雾化特性及对细颗粒物的强化去除效果

喷雾技术在气体净化、粉尘控制、化学合成等领域应用广泛,其中液滴尺寸控制及提高喷雾均匀性是该技术面临的挑战。为此,本文拟利用表面活性剂对水雾的雾化特性进行调控,以提高喷雾均匀性,并进一步探究其对细颗粒物去除的促进作用。本文采用实验研究,首先对三种不同性质表面活性剂(十二烷基苯磺酸钠、十六烷基三甲基溴化铵、吐温80)溶液的雾化特性进行了分析,探究了表面活性剂的种类和浓度对于雾化特性的影响。结果表明,与去离子水相比,表面活性剂的加入可以显著提升喷雾的均匀性,喷雾总体粒径减小,并且非离子型表面活性剂吐温80雾化形成的小液滴数量占比最高。当表面活性剂溶液浓度达到临界胶束浓度(CMC)时,三种类型表面活性剂溶液的液滴数达到峰值,以此作为最佳雾化浓度。此外,通过喷雾去除细颗粒物实验表明,含表面活性剂溶液喷雾可以加快细颗粒物去除速率。

重量法测定闽粤藏地区的香品燃烧产生颗粒物的粒径分布特征

燃烧产生粒径小于10μm的颗粒物对人体健康存在威胁,因此对不同地区香品燃烧产生颗粒物的粒径分布研究具有重要性。通过对滤膜、样品质量和采样时间的优化选择,采用重量法建立了香品燃烧后产生颗粒物9个粒径段的采集方法。方法检出限为0.0276mg/m^(3),测定下限为0.1105mg/m^(3),相对标准偏差在2.46%~12.26%之间。通过对闽粤藏三个地区9种香品燃烧产生的颗粒物分析,结果表明:(1)9种香品燃烧产生的颗粒物粒径分布特征较为一致,均呈单峰分布,主要集中在0.65~1.1μm和0.43~0.65μm的范围内;(2)PM_(1.1)/PM_(2.1)>70%,PM_(2.1)/PM_(10)>90%;(3)PM_(1.1)、PM_(2.1)、PM_(10)的排放因子分别为10.597~29.251mg/g、11.741~39.568mg/g、12.439~43.467mg/g。

机动车制动颗粒物测试技术研究综述

非尾气颗粒物排放已超过车辆尾气颗粒物排放,但限制非尾气排放的法规仍不完善。本文综述了机动车制动颗粒物排放的试验方法和粒径分布特征。制动磨损颗粒物的测试方法主要包括销盘法、惯性制动台架法、底盘测功机法和实际道路法。研究发现,受制动摩擦片材质、制动运行特征、制动力、温度、路况和测试工况等多种因素影响,制动颗粒物的粒径分布没有典型的统一特征,具有单峰、双峰和多峰等多种粒径分布形态。

基于粒径分布的机动车尾气颗粒物排放检测方法

常规的机动车尾气颗粒物排放检测方法使用NDIR红外气体传感器采集颗粒物排放信息,易受动态变化尾气浓度影响,导致检测的尾气颗粒物排放浓度与实际排放浓度偏差较高,因此需要基于粒径分布设计一种全新的机动车尾气颗粒物排放检测方法。即计算各微粒的质量浓度,基于粒径分布提取了尾气颗粒物排放特征,再根据经典PID控制算法,构建了Lug Down尾气颗粒物排放检测模型,从而完成了尾气颗粒物排放检测。实验结果表明,设计的尾气颗粒物排放粒径分布检测方法检测的尾气颗粒物排放浓度与实际排放浓度较拟合,证明设计的检测方法的检测效果较好,有一定的应用价值,为提高大气空气质量作出了一定的贡献。

林场不同树种选育对PM_(2.5)大气颗粒物的调控研究

为了降低PM_(2.5)大气颗粒物含量,研究林场不同树种选育对PM_(2.5)大气颗粒物的调控效果。文章采集某区域6种园林植物叶表面空气微粒、叶中元素的组成、含量以及再悬浮速率,并对植物叶片滞尘能力测定方法进行优化,构建空气质量浓度与气象要素关系调控模型。通过检测不同样本叶片蜡质层对颗粒物的截留能力、滞尘粒度分布曲线的变化趋势、以及叶片滞留尘埃的平均颗粒大小,通过拟合计算获取不同树种选育对PM_(2.5)大气颗粒物的调控效果。单叶面积小且叶表粗糙的林场植物可以更好地对PM_(2.5)大气颗粒物进行调控。

Advances in Centrifugal Separators for Particulate Matter Control from Stationary Sources

This paper summarized recent developments in centrifugal separators for particulate matter (PM) emission control. Airborne particulate matter, which is responsible for many health and environmental problems, is generated mostly from combustion processes in stationary sources such as house burners and power plants and other production facilities, except field dust. Reverse flow cyclones are centrifugal separators having been widely used for industrial particulate matter removal. Typical pressure drops of these cyclones for air cleaning are 500 Pa or higher, and were believed to be only able to separate particles larger than 10 μm. An aerodynamic deduster that could separate particles as small as 1μm at a pressure drop of 200 Pa was recently developed. Field evaluation showed that the deduster can be effectively used in reducing particulate matter emission from stationary sources.