Mass Concentrations Of Coarse Particles Research Articles

Size Distributions of Water-Soluble Inorganic Ions in Atmospheric Aerosols During the Meiyu Period in the Yangtze River Delta, China

In order to investigate the chemical composition distributions and pollution characteristics of Total water-soluble inorganic ions (TWSII) in the rain period (Meiyu) in the East Asian summer monsoon season, including the impact of Meiyu on air pollution in the Yangtze River Delta, East China, the gaseous pollutant concentrations, the 9 sizes segregated particles, and water-soluble inorganic ions of aerosols were measured on the north shore of Taihu Lake from June 4 to July 5, 2016. Results show that the mass concentrations of atmospheric particulate matters (PM2.5 and PM10) and main gaseous pollutants (SO2, NO2, CO, and O3) decrease during the Meiyu period, with the largest decline in PM10 and the smallest in CO. TWSII in atmospheric particles are mainly concentrated in fine particles during the Meiyu period. The values of ρ (TWSII) for PM1.1, PM1.1–2.1, and PM2.1–10 before the Meiyu onset are generally greater than those during the Meiyu period. During the first pollution process, the ρ(TWSII) for PM1.1 and PM1.1–2.1 first increase to the peak values, and then decrease during the moderate rainfall period, when the ρ(TWSII) in PM2.1–10 increase to its maximum before the Meiyu onset. The mass concentrations for anions, cations, and total ions at different particle-size sections all exhibit bimodal distributions before and after the Meiyu onset. The mass concentration peaks at a particle size of 1.1–2.1 μm for fine particles, while at 5.8–9.0 μm (before the Meiyu onset) and 9.0–10.0 μm (during the Meiyu period) for coarse particles, respectively. The peak particle size for mass concentration of coarse particles moves toward larger sizes during the Meiyu period. The mass concentrations of SO42− at different particle-size sections show a bimodal distribution before the Meiyu onset and a multi-modal distribution during the Meiyu period. The mass concentrations of NO3− at different particle-size sections show a bimodal distribution before the Meiyu onset and a unimodal distribution during the Meiyu period. The mass concentrations of NH4+ at different particle-size sections present a bimodal distribution before and after the Meiyu onset, with the particle-size for peak concentrations distributing in 1.1–2.1 and 5.8–9.0 μm before the Meiyu onset, and 9.0–10.0 μm during the Meiyu period. The mean value of nitrogen oxidation ratio (NOR) is higher before the Meiyu onset than after, indicating that the secondary conversion of NO2 before the Meiyu onset is enhanced. The sulfur oxidation ratio (SOR) values are greater than NOR values, but the concentrations of NO2 in the same period during the Meiyu period are higher than those of SO2, which indicates that the secondary conversion of SO2 during the Meiyu period on the north bank of Taihu Lake is stronger than that of NO2. During the whole observation, the contribution of stationary sources mainly contributed to the atmospheric particulate matters during the Meiyu period. The contributions of vehicle exhaust and coal combustion to fine particles are more obviously affected by the changes in meteorological conditions during the Meiyu period, and the vehicle emissions contribute more to PM1.1–2.1 than to PM1.1.

Characteristic time for the scavenging of fine particles due to coagulation with coarse particles

This article suggests an approximate analytical solution for the characteristic time for the mass removal of fine particles due to coagulation scavenging by coarse particles. The characteristic scavenging time is expressed as a function of the mass concentration of coarse particles as well as the mass median diameters (MMDs) and geometric standard deviations of fine and coarse particles. The log-normal method of moments was used to take into account the polydispersity effects. The particle number concentration of coarse particles was found to be the most important factor determining the coagulation-scavenging rate. Sensitivity analyses were conducted to quantify the effects of the particle size distribution parameters. The characteristic scavenging times for three specific cases, urban aerosols, Asian dust particles, and indoor aerosols, are discussed based on the derived solution.

Characterization of particulate matter and its extinction ability during different seasons and weather conditions in Sinkiang, China: two case studies.

The Sinkiang Uygur Autonomous Region is located in western China and the centre of the Asian-European continent, which frequently suffers from sandstorm disasters and haze weathers. A 1-year measurement campaign in two selected points in Shihezi and Urumqi of Sinkiang was conducted to characterise the effects of particle matters and factors on particle extinction under different weather conditions. Results showed that the average concentration of PM1-2.5 was 19.83, 9.230, 28.93 and 122.4μg/m3 in Shihezi and 67.25, 16.80, 59.19 and 324.0μg/m3 in Urumqi for spring, summer, autumn and winter, respectively. PM5-10 concentrations can reach up to 500.0 and 160.0μg/m3 during polluted weather conditions in Shihezi and Urumqi, respectively. PM5-10 also accounted for the largest fraction in Shihezi and Urumqi for all types of weather, reaching up to 40.0% under dusty weather conditions. PM1-2.5 significantly increased during winter possibly due to the increased demand for heating compared with non-heating periods. PM0.5-1 is possibly produced from motor vehicle exhaust. Particle size is concluded to be the dominant factor for particle extinction capability under fine weather based on calculations of aerosol optical properties. The refractive index for a particle with a diameter of 100μm (3.10-3.11i) is substantially larger than that with a diameter of 0.5000μm (1.600-0.07000i), but the extinction capability of the latter is 1.30 times that of the former. Comparatively, when the mass concentration of coarse particles is over 17.0 times that of the fine particles, and then mass concentration becomes the dominant factor. Therefore, visibility is negatively correlated to particle mass variations during dust storms and hazy days but not for fine days.

Particle Mass Concentrations and Number Size Distributions in 40 Homes in Germany: Indoor-to-Outdoor Relationships, Diurnal and Seasonal Variation

Few studies investigated residential particle concentration levels with a full picture of aerosol particles from 10 nm to 10 µm size range with size-resolved information, and none was performed in central Europe in the long-term in multiple homes. To capture representative diurnal and seasonal patterns of exposure to particles, and investigate the driving factors to their variations, measurements were performed in 40 homes for around two weeks each in Leipzig and Berlin, Germany. These over 500 days’ measurements combined PM10 and PM2.5 mass concentrations, particle number concentration and size distribution (PNC and PNSD, 10–800 nm), CO2 concentration, and residential activities diary into a unique dataset. Natural ventilation was dominated, the mean ventilation rate calculated from CO2 measurements was 0.2 h–1 and 3.7 h–1 with closed and opened windows, respectively. The main findings of this study showed that, the residents in German homes were exposed to a significantly higher mass concentration of coarse particles than outdoors, thus indoor exposure to coarse particles cannot be described by outdoors. The median indoor PNC diurnal cycles were generally lower than outdoors (median I/O ratio 0.69). However, indoor exposure to particles was different in the cold and warm season. In the warm season, due to longer opening window periods, indoor sources’ contribution was weakened, which also resulted in the indoor PNC and PNSD being very similar to the outdoors. In the cold season, indoor sources caused strong peaks of indoor PNC that exceeded outdoors, along with the relatively low penetration factor - 0.5 for all size ranges, and indoor particle losses, which was particularly effective in reducing the ultrafine PNC, resulting in a different particle exposure load than outdoors. This study provides a detailed understanding of residential particle exposure in multiple homes, facilitating future studies to assess health effects in residential environments.

Trace elements in fine and coarse particles emitted from coal-fired power plants with different air pollution control systems

Emissions from coal-fired power plants (CFPP) are one of the major sources of air pollutants in the industrial sector. We characterized the metal element mass concentration in fine and coarse particles from CFPP using sub-bituminous coal. We sampled stack emissions from six CFPP units equipped with different emission control technologies. The power plants were located in Jepara Regency (using electrostatic precipitator (ESP) alone or in combination, as ESP-flue gas desulfurization, FGD) and in Rembang Regency (using ESP alone). We measured PM2.5 and PM10 particle emissions using the US EPA 201 A method and further subjected the particles to laboratory analysis for trace metal elements using inductively coupled plasma-mass spectrometry (ICPMS). The CFPP emissions showed that the mass concentration of coarse particles was higher than that of fine particles. Based on metal element analysis only, the total mass in fine particles was higher than that in the coarse particles. With respect to the metal elements detected, the major elements, minor elements, and trace elements, on average, represented 7%, 15%, and 77%, respectively. In this study, we identified new trace elements associated with coal combustion, namely Na, Be, and Sn. The emission factor in fine particles is not significant for different air pollution control The element marker of coal fired-power plant should consider installed air pollution control.

Dust emission from crushing of hard rock aggregates

Dust constitutes one of the major environmental concerns near many aggregate quarries, with crushing often being the most significant source. In this study, dust emissions and dispersion measurements were conducted under real operating conditions at six aggregate quarries in southern Finland. Five of them represent granitic rocks and one a limestone quarry.Dust concentrations during crushing were measured at varying distances with time intervals of five seconds. The variation in dust concentration was high within all the measured distances, ranging from 10 to 200 m.Crushing produces mainly coarse (TSP and PM10) dust particles, which settle near the dust source. The mass concentration of coarse particles in this investigation varied from few tens of μg/m3 to over 6.5 × 103 μg/m3 downwind from the crusher.The mass concentration of fine particles (PM2.5 and PM1) ranged between ten μg/m3 and few hundreds of μg/m3 downwind from the crusher. The fine particles originated mainly from machinery used in the quarries and remote sources, such as nearby traffic.In quarries operating with secondary crushing, the background concentrations were achieved approximately from a 350 m distance for coarse particles. Local dust sources, such as hauling, impacted the results inside the quarry. Crushing produced more dust compared to comparable studies for drilling. The dust concentrations at the limestone quarry were approximately 50% of concentrations measured at quarries with granitic rocks.

Seasonal dynamics of coarse atmospheric particulate matter between 2.5 μm and 80 μm in Beijing and the impact of 2008 Olympic Games

Beijing is well known as a megacity facing severe atmospheric pollution problems. One very important kind of pollution is the high amount of particles in Beijing's atmosphere. Numerous studies investigated the dynamics of fine particles smaller 10 μm. Less information is available on the coarse particle fraction larger 10 μm, although geogenic dusts, which often are composed by those coarser particles, frequently affect the air quality in Beijing. Therefore, systematic sampling and analysis of size fractionated particulate matter between 2.5 and 80 μm was performed in Beijing from April 2005 till October 2009. Atmospheric particles were collected in the North-West of Beijing using a cost-effective passive sampling method called Sigma-2. Altogether, 200 weeks could be analysed and assessed. Concentrations and size distribution of atmospheric coarse particles were determined by automated microscopic single particle analysis. Seasonal variability of the total mass of different size fractions was identified as follows: spring > winter > autumn > summer. High concentrations of transparent mineral particles indicate the activity of geogenic sources in spring and winter time, due to asian dust events and resuspension of soil from local bare land during dry and windy periods. The percentage of opaque particle components differs seasonally with relatively high values in winter, confirming combustion of fossil fuels for heating purposes as a predominant pollution source in this season. The influence of meteorological conditions on concentrations and size distribution of atmospheric particulate matter between 2.5 and 80 μm is demonstrated for the whole sampling period. Lowest pollution by coarse aerosols occurred during the period of the 2008 Olympic Summer Games. A general trend of decreasing total coarse particle mass concentrations was observed. Due to frequently observed high total coarse particle mass concentrations of several 100 μg·m−³ it is strongly recommended to enhance research and observation regarding these air pollutants to gain a better understanding of their dynamics, health effects, well being impacts on Beijing inhabitants and the effectiveness of mitigation measures.

Characterization of Particulate Matter, Ions and OC/EC in a Museum in Shanghai, China

The size-fractionated particle number concentrations were monitored continuously in the different exhibition halls of an enclosed museum, in Shanghai. Particles in different size bins were collected to investigate the main chemical compositions. Results indicated that the mass concentrations of coarse particles, fine particles and ultrafine particles were in the range of 20.50–24.38 μg/m3, 23.39–24.08 μg/m3 and 16.02–17.48 μg/m3, respectively. In addition, the activities of cleaning and walking can greatly elevate the number concentration of coarse particles by a factor of about 8–172 times. The decay rates of size-fractionated particle increased with the enlarging particle diameter, ranging from 2 × 10–5 to 8 × 10–4 s–1. The mass concentration of SO42–, NO3–, NH4+ peaked within the particle size range of 0.32–0.56 μm. The ratios of [NO3–]/[SO42–] on the National Day and working day were 0.08 and 0.12, respectively. Comparatively, the peak concentrations of Na+, Cl–, K+, Mg2+ and Ca2+ occurred in the various size ranges. Total organic acids distributed uniformly, the acetate ion mass concentration was 1.238 μg/m3, which was higher than both formate ion and oxalate ion concentrations. The concentrations of OC and EC showed similar trends on both the National Day and working day, and greater OC/EC ratios were found in the particles within the size range less than 0.1 μm and larger than 1 μm.

Variations in Particle Concentrations and Indoor Air Parameters in Classrooms in the Heating and Summer Seasons

Abstract Simultaneous measurements of the indoor and outdoor particle mass (PM) and particle number (PN) concentrations as well as the air temperature, relative humidity (RH), and CO2 concentrations have been conducted in 6 occupied (L) and unoccupied (V) classrooms in 3 secondary schools in Lublin, Poland, in the heating (H) and summer (S) seasons. The schools were located in residential areas where the majority of private houses are heated by means of coal-burning stoves. The ratios of the average particle concentrations in occupied and unoccupied classrooms (L/V) were higher during the heating season measurements. The ratios of the average particle concentrations during the measurements in the heating and summer seasons (H/S) were higher in occupied classrooms. In both seasons the average PM and PN concentrations amounted to 239 μg/m3 and 7.4×103/cm3 in the occupied classrooms, and to 76 μg/m3 and 5.4×103/cm3 in the unoccupied classrooms, respectively. The particle exposures experienced by students were higher in the monitored classrooms than outdoors and were on average about 50% higher in the heating than in the summer season. A positive correlation between mass concentrations of coarse particles and indoor air temperature, RH and CO2 concentrations in both seasons was observed. The concentrations of fine particles were negatively correlated with the indoor air parameters in the heating season, and positively correlated in the summer season.

The impact of wind on particle mass concentrations in four european urban areas

The impacts of wind conditions to fine and coarse particle mass concentrations at four European urban centers, by multivariate regression analysis of particle measurements against categorized wind (direction and speed) conditions were estimated. Statistically significant associations (both positive and negative) were observed for all urban areas. Both fine and coarse particle mass concentrations were decreased for moderate and strong winds (speed > 2.2 m s-1) in Athens and Helsinki. Weak winds had a positive influence on particle mass, accounting for up to 40% of fine particles in Athens. For the three coastal urban areas (Amsterdam, Athens and Helsinki), positive correlations were observed for sectors encompassing ports and areas with intense marine traffic. For Birmingham, the association of both particle fractions with the eastern sector indicated the influence of emissions from central UK and continental Europe. The method described here may be used to screen the orientation of sources near receptor sites.

Fine and coarse particle mass concentrations and emission rates in the workplace of a detergent industry

Aerosol mass concentration (PM10, PM2.5) measurements were conducted in the workplace of a detergent industry for two time periods during July 2005 and January 2006, using two portable real-time photometric monitors. The results showed increased mass concentrations both for PM10 and PM2.5 particles during the detergent production periods. The differences in the concentrations of the PM10 and PM2.5 particles were used to determine the corresponding mass concentrations of coarse particles and these values were then used to evaluate the diurnal variation both for fine and coarse particles. An indoor mass balance model was applied to estimate the aerosol mass emission rates, as well as the particle loss rates due to all removal processes. A good agreement was obtained between the model predictions and the measurements. The indoor model can be used in conjunction with experimental measurements for the evaluation of aerosol mass concentrations in industrial sites.

The comparison of two severe Hwangsa (Asian dust) cases of spring and winter in Seoul, Korea

This study investigated meteorological, physical, and chemical characteristics of 2 severe Hwangsa (Asian dust, maximum average of PM10 above 1000 μg m−3) observed in Seoul, the capital city of Korea, during 30∼31st May, 2008 (DSS2008) and 25∼26th December, 2009 (DSS2009). DSS2008 and DSS2009 had a same source region and route. However, they have different meteorological conditions. DSS2009 had a shorter travel time from the source region to Korea and shorter duration time in Korea than DSS2008 due to a strong winter Siberian anticyclone. One of DSS2008 sample was affected by not only Asian dust but also a long-range transported haze due to consecutive influx after low pressure passed while DSS2009 sample collected only dust aerosol. For both cases, the mass concentration of coarse particles (PM10-1) increased by 3∼14 times compared to that during non Asian dust period, however, that of fine particles (PM1) increased only in DSS2008. For DSS2008 water-soluble ion balance between anions and cations in fine mode was close to 1:1 while cations were higher than anions in coarse mode. NH4 + and Ca2+ were found to be the main contributing factors for the neutralization. Cl− loss was observed about 60% indicating an active interaction of Na+ with pollutants. Reconstruction of chemical compositions showed relatively high concentrations of secondary pollutants (NH4NO3 and (NH4)2SO4), CaCO3, and Ca(NO3)2 compared to that during non Asian dust period. DSS2009 exhibited the typical characteristics of Asian dust having a high concentration of Ca2+ with higher equivalent concentration of cations than anions in all size bins. Cl− loss was hardly observed. The secondary pollutants were lower than that of non Asian dust cases. The result of reconstruction of ionic components indicated the CaCO3 derived from soil particle, CaSO4, and Ca (NO3)2 were dominant in DSS2009.

Pollution Characteristics of PM2.5 during a Typical Haze Episode in Xiamen, China

In this study, mass concentrations and chemical compositions of fine particles, mass concentrations of coarse particles, light extinction, and meteorological parameters in the atmosphere ofXiamenwere presented and analyzed to study the chemical and optical characteristics of a typical haze episode from Dec 25, 2010 to Jan 1, 2011. The major chemical compositions of PM2.5, such as water soluble inorganic ions (WSIIs), carbonaceous fractions (mainly composed of organic carbon (OC) and elemental carbon (EC)), and elements were determined. The results showed that with the typical haze episode process, the concentrations of PM2.5 mass, WSIIs, OC, EC, and TE first increased and then decreased. The average concentrations of PM2.5 mass in the stages of Before Haze, During Haze, and After Haze were (88.80 ± 19.97), (135.41 ± 36.20), and (96.35 ± 36.26) μg/m3, respectively. The corresponding average concentrations of secondary organic carbon (SOC) were 6.72, 8.18, and 10.39 μg/m3, accounting for 46.5%, 27.0%, and 61.0% of OC, respectively. S42- , NO3-, and NH4+ were three major WSIIs species, accounting for 31.4%, 26.0%, and 12.1% of total WSIIs. The major elements in PM2.5 were S, K, Fe, Zn, Pb, Ti, and Mn, covering 97.9% of the total elements, while the percentage of the other ten elements was only 2.1%. The average value of light extinction coefficients (bext) was 371.0 ±147.1 Mm-1 during the typical haze episode. The average percentage contributions to bext were 39.3% for organic mass, 19.9% for elemental carbon, 16.0% for ammonium sulfate, 13.0% for coarse mass, and 11.8% for ammonium nitrate.

Size distribution of chemical elements and their source apportionment in ambient coarse, fine, and ultrafine particles in Shanghai urban summer atmosphere

Ambient coarse particles (diameter 1.8-10 μm), fine particles (diameter 0.1-1.8 μm), and ultrafine particles (diameter < 0.1 μm) in the atmosphere of the city of Shanghai were sampled during the summer of 2008 (from Aug 27 to Sep 08). Microscopic characterization of the particles was investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX). Mass concentrations of Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, and Pb in the size-resolved particles were quantified by using synchrotron radiation X-ray fluorescence (SRXRF). Source apportionment of the chemical elements was analyzed by means of an enrichment factor method. Our results showed that the average mass concentrations of coarse particles, fine particles and ultrafine particles in the summer air were 9.38 2.18, 8.82 3.52, and 2.02 0.41 μg/m3, respectively. The mass percentage of the fine particles accounted for 51.47% in the total mass of PM10, indicating that fine particles are the major component in the Shanghai ambient particles. SEM/EDX results showed that the coarse particles were dominated by minerals, fine particles by soot aggregates and fly ashes, and ultrafine particles by soot particles and unidentified particles. SRXRF results demonstrated that crustal elements were mainly distributed in the coarse particles, while heavy metals were in higher proportions in the fine particles. Source apportionment revealed that Si, K, Ca, Fe, Mn, Rb, and Sr were from crustal sources, and S, Cl, Cu, Zn, As, Se, Br, and Pb from anthropogenic sources. Levels of P, V, Cr, and Ni in particles might be contributed from multi-sources, and need further investigation.

Variation between near-surface and columnar aerosol characteristics during the winter and summer at Delhi in the Indo-Gangetic Basin

Aerosol characteristics were studied over Delhi, a typical urban station in the Ganga basin in Northern India, during two contrasting weather conditions: winter and summer, to explain the changes in columnar and surface aerosol characteristics with the help of ground based measurements and CALIPSO satellite data. The near-surface mean aerosol mass concentrations of PM10 and PM2.5 (±standard deviation) were observed to be ∼200 (±24) and 118 (±33)μgm−3, respectively, during the winter and ∼168 (±31) and 55 (±12)μgm−3, respectively, during the summer. PM2.5 was found to be about two times higher than the PM10 concentration during the winter period. Aerosol mass size distribution showed bi-modal nature during both the periods, with relative dominance of fine-particle mass concentrations during the winter, having low Reff value (0.63±0.05μm) and coarse-particle mass concentrations during the summer, having large Reff value (1.52±0.60μm). The concurrent measurement of columnar aerosol optical depth (AOD) showed high values (>0.60 at 500nm) during both the periods. The Ångström exponent (α) over the station, however, also suggests relatively large contribution of fine-mode particles during the winter (α∼1.02) and coarse-mode dust particles during the summer (α∼0.51). The observed features in the surface and columnar measured aerosol characteristics during two different seasons are explained using the vertical winds coupled with the vertical profile of aerosols.

Characteristics of Water-Soluble Ionic Species in Fine (PM2.5) and Coarse Particulate Matter (PM10–2.5) in Kaohsiung, Southern Taiwan

Eleven ionic species and fine and coarse particle mass concentrations of fine (PM2.5) and coarse (PM10–2.5) particulate matter were investigated in Kaohsiung, southern Taiwan. The PM2.5 and PM10–2.5 particulate concentrations were 49–64 and 34–37 μg∙m-3, respectively. Fifty-five to 64% of the particulate matter less than 10 μm in aerodynamic diameter (PM10) mass was attributed to the PM2.5. PM2.5 concentrations at Daliao (a rural and industrial complex area) were higher than at Tzuoying (an urban and industrial complex area). Ionic species contributed 45–53% and 42–45% of PM2.5 and PM10, respect tively. Potassium ions (K+), sulfate (SO4 2−), and ammonium (NH4 +) were predominant in PM2.5, whereas sodium, calcium, and magnesium ions were foremost in PM10–2.5. Nitrate (NO3 −) existed in both the PM2.5 and PM10–2.5. Chloride (Cl−), NO3 −, and NH4 + concentrations were higher at night than during the day, and they were easily transferred into the gas phase by photochemical reactions and temperature-induced volatilization. The NH4 +/SO4 2− ratios were 2.6 and 2.5 at Daliao and Tzuoying, respectively, which indicated that both sampling sites were rich in NH4 +. Therefore, ammonium nitrate would be present in the area.

Characterization of Indoor and Outdoor Aerosols in a Suburban Area of Prague

The mass, ionic and elemental size distributions of particulate matter (PM) measured indoors and outdoors in an apartment situated in a north–westward suburb of Prague are presented. The PM samples were collected by two Berner type low pressure impactors separating particles into 10 size fractions from 26 nm to 10 μm and were further analyzed by ion chromatography (IC) and proton induced X-ray emission (PIXE). Temperature, pressure and relative humidity were measured both indoors and outdoors parallel to PM sampling. The indoor and outdoor PM dynamics were recorded by two scanning mobility particle sizers (SMPS) and an aerodynamic particle sizer (APS). Finally, the ventilation rate was determined by a radon technique. Ion chromatography showed that the major inorganic components of the fine particle mode are sulfate, nitrate, and ammonium with very low indoor nitrate concentration. Crustal elements (Al, Si, Ca, Ti, Mn, and Fe) were associated with the coarse aerosol mode. The presence of people increased the mass concentration of coarse particles, whereas cooking, smoking, and burning of incense and candles contributed predominantly to the fine particle mode. Smoking and the burning of incense also increased the concentration of potassium, bromine and chlorine content in fine particles.

Springtime soluble particles in a suburban area of Taichung in central Taiwan

Continuous measurements of concentrations of soluble species between fine and coarse particles were made using a RP 2300 sampler to characterize springtime particulate pollutants in Shalu, a suburban area of Taichung, Taiwan. Particulate matter was closely observed from March 4 to April 2, 2006. The characteristics of ambient particulates were investigated during the winter monsoon period, the weak winter monsoon period and the non-winter monsoon period. The wind speed influenced the ratio of the mass concentration of coarse particles to that of fine particles. The ratio was high during the strong winter monsoon because the coarse particles were re-suspended by high wind speed. In contrast, the low ratio was associated with the accumulation of local anthropogenic particles in a stagnant atmosphere in the non-winter monsoon period. The increases in the concentrations of soluble SO 4 2− and NO 3 − species were associated with the long-range transport of pollutants from the Asian Continent and local urban pollution emissions, respectively. Factor analysis was performed on the measurements to determine the variances of the identified sources among the three atmospheric conditions. The deviations from the seawater Cl −/Na + ratio of 1.16 in the coarse particles indicated the notable deficit of chloride. A large amount of air pollutants was transported by airflow during a dust event: the mass concentrations of fine particles and coarse particles in a dust event were 30% and 160% higher than those in a non-dust event, respectively.

Physicochemical Characterization and Origin of the 20 March 2002 Heavy Dust Storm in Beijing

This study characterized the profiles of particles collected during a dust-storm (DS) period in Beijing on 19-21 March 2002, which was one of the heaviest episodes in the previous decade. Several determinations of particle measurements were observed, including total mass concentrations, particle size distributions, dry deposition flux, and chemical ions concentrations. The TSP concentrations reached an extremely high peak value of 12 mg/m3 in DS period, and especially showed a characteristic increase in the size range of coarse particles (> 2.0 μm). The mass concentrations of coarse particles during DS period accounted for 91% of total particles, compared to 61% on non-DS days. The dry deposition mass flux of the dust storm reached 17.5 g/m2-d on 20 March in Beijing. Additionally, the transported pathway of the pollutants was investigated by using backward trajectory analysis. The result of analysis indicated that the high level of dust sand originated from the arid regions of southern Mongolia, passing through central Inner Mongolia, Shanxi Province, and then to Beijing. Concentrations of Cl−, NO3−, and SO42− in TSP were about 10 times higher in DS period than non-DS, probably because of some atmospheric processes enhancing chemical accumulation in the transported aerosols.

Statistical Considerations in the Interpretation of Size-Resolved Particulate Mass Data

ABSTRACT Random measurement error can account for a substantial fraction of the observed variability in coarse particle mass concentrations. This noise decreases the spatial correlation of coarse particle concentrations, tending to obscure any regional coherence in their variation. It also works to obscure associations between coarse particles and the effects to which they contribute. Multiple regressions can misattribute coarse effects to fine particles if the fine measurement is sufficiently more precise.