The scanning mobility particle spectrometer (SMPS) is the most commonly used instrument for measuring ultrafine aerosol size distributions. SMPS systems include an aerosol charger, a differential mobility analyzer (DM...
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The scanning mobility particle spectrometer (SMPS) is the most commonly used instrument for measuring ultrafine aerosol size distributions. SMPS systems include an aerosol charger, a differential mobility analyzer (DMA), and an aerosol detector. Due to their high sensitivity and high signal-to-noise ratio, condensation particle counters (CPCs) have been widely used as detectors in SMPS systems. This talk will discuss recent studies on bipolar charging of aerosol particles, DMA performance characterization, and the development of a new CPC. Six different neutralizers including the newly commercialized TSI soft X-ray neutralizer were evaluated. These results provide guidelines for neutralizer selection to bring aerosols to a stationary charge state. Five different DMAs were tested for sub-2nm particle classification. Results are presented in a form that is useful for DMA data inversion. A new CPC using diethylene glycol rather than butanol was developed and evaluated for 1nm particle detection. The implications of these results in electrical mobility measurement will be discussed.
The Community Multiscale Air quality modeling system was used to study the distribution of air pollutants during an air pollution process during May 19th to 20th, 2010. The meteorological environment and the impact of...
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The Community Multiscale Air quality modeling system was used to study the distribution of air pollutants during an air pollution process during May 19th to 20th, 2010. The meteorological environment and the impact of the major emission sources on the concentration of NO2, SO2, PM10 , as well as the components in PM2.5, were simulated. And the comparison of observation and simulation indicated that the modeling system could well simulate the variations of pollutants in *** study showed that the pollution appeared under the typical weather condition with small south-western wind speed and low plenary boundary layer. Under the meteorological condition, the concentration of PM10, sulfate and nitrate in PM2.5 increased significantly. The results by the process analysis method and sensitivity experiment showed that the area emission source was the key factor that induced the particulate matter pollution in the urban area, which accumulated in the planetary boundary layer and caused the formation of high concentration at the surface.
Long-range transport of Asian dust is one of the major environmental concerns of Taiwan during the winter monsoon season when northeasterly winds prevail following passages of cold fronts. Based on hourly measurements...
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Long-range transport of Asian dust is one of the major environmental concerns of Taiwan during the winter monsoon season when northeasterly winds prevail following passages of cold fronts. Based on hourly measurements of Taiwan Environmental Protection Administration (TEPA) air quality monitoring stations, a super heavy dust event has been identified. The dramatically elevated concentration of PM10, along with the strong northeasterly on March 21, 2010 was observed in Taiwan. At Shihlin station, its PM10 concentration peaks more than 1700μgm-3 and most stations their hourly concentrations greater than 1000 μgm-3 and sustain more than 10 hrs in the northern Taiwan. We have found that this case has significantly different spatial distributions of PM10 concentration and transport speed between eastern and western of Taiwan. It is estimated that peak concentration ranging from factor of 2～5 between western and eastern of Taiwan. Moreover, the variation of the peak concentration between northern tip and southern tip is more than factor of ten within about 400 km distance. Numerical results from Weather Research Forecast (WRF) and WRF-chem models suggest that the geographical structure of Central Mountain Range in Taiwan and coastal mountain ranges in southeastern China also play important roles for the discrepancies in spatial distributions of PM10 concentration in Taiwan.
A total of 33 precipitation samples have been collected from individual precipitation events at the bird island ,a scenic zone of Qinghai Lake Monitoring (36°32′～37°15′N, 99°36′～100°16′E;3200...
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A total of 33 precipitation samples have been collected from individual precipitation events at the bird island ,a scenic zone of Qinghai Lake Monitoring (36°32′～37°15′N, 99°36′～100°16′E;3200 m a.s.l) located in the northwest of Tibetan Plateau from June 2010 to August 2010. All samples were analyzed for major cations ( NH4+,Na+,K+,Ca2+ and Mg2+ ) and anions (F-,Cl-,NO3- and SO42-), conductivity, pH and DOC (Dissolved Organic Carbon). The pH value of precipitation ranged from 6.05 to 8.19 with a volume average value of 7.13. The high pH is due to large inputs of crustal aerosols in the atmosphere, which contain a large fraction of carbonate. Ca2+ is the dominant cation in precipitation with a VWM of 125.08 μeqL-1 (1.62-664.21μeqL-1), accounting for 27% of the total cations in precipitation. HCO3- is the predominant anion with a VWM of 125.09 μeqL-1, accounting for 26% of the total anions. Precipitation DOC value ranged from 0.553897 to 10.8449 with a average value of 1.5516 mg·L-1. Correlation and Enrichment factor analysis(EF)indicate that crustal aerosols from combustion emissions of residents and continental dust , which are the major sources for these ions. The high concentrations of alkaline ions(mainly Ca2+)in atmosphere have played an important role in neutralizing the acidity of rainwater.
Continuous measurements of atmospheric ammonia (NH3) were conducted using Ogawa passive samplers from February 2008 to July 2010 at an urban site and from January 2007 to July 2010 at a rural site in Beijing, China. N...
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Continuous measurements of atmospheric ammonia (NH3) were conducted using Ogawa passive samplers from February 2008 to July 2010 at an urban site and from January 2007 to July 2010 at a rural site in Beijing, China. NH4+ in fine particles was also collected at the rural site during 2008-2009. The field comparison between the Ogawa passive samplers and an active analyzer for NH3 conducted at the urban site assures the quality and accuracy of the measurements. The concentrations of NH3 at the urban site ranged from 0.7 to 85.1 ppb, with the annual average of 18.5±13.8 and 23.5±18.0 ppb in 2008 and 2009, respectively. The NH3 concentrations at the rural site were lower than those at urban site, and varied from 0.8 to 42.9 ppb, with the annual average of 4.5±4.6, 6.6±7.0 and 7.1±3.5 ppb in 2007, 2008 and 2009, respectively. The data showed marked seasonal variations at both sites. The results emphasized traffic to be a significant source of NH3 concentrations in winter in urban areas of Beijing. This was illustrated by the strong correlations of NH3 with the traffic related pollutants (NOx and CO) and also by the bimodal diurnal cycle of NH3 concentrations that was synchronized with traffic. Similar patterns were not observed during the summer, suggesting other non-traffic sources became more important. At the rural site, the daily NH4+ concentrations ranged from 0.10 to 36.53 μg/m3, with an average of 7.03 μg/m3 from June 2008 to December 2009. Monthly NH3 were significantly correlated with NH4+ concentrations. Average monthly NH3/NH4+ ratios varied from 0.13 to 2.28, with an average of 0.73. NH4+ in PM2.5 was primarily associated with SO42- at the rural site.
PM10 and size-resolved (9-stage) aerosol samples in the urban air of Xi'an, China were collected during the spring of 2009 including a massive dust storm occurring on April 24th and measured for inorganic ions, wa...
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PM10 and size-resolved (9-stage) aerosol samples in the urban air of Xi'an, China were collected during the spring of 2009 including a massive dust storm occurring on April 24th and measured for inorganic ions, water-soluble organic (WSOC) and inorganic carbon (WSIC), water-soluble organic nitrogen (WSON), EC and OC. Characteristics of chemical compositions and size-distributions of those measured species in the urban samples were investigated and further compared with those simultaneously observed on the mountaintop of Mt. Hua, which is located about 150 km east to the city, to recognize the impact of dust storm on aerosol chemistry of the downwind region. PM10 in Xi'an during the non-dust storm period ranged from 58-420 g m-3 (257±79 g m-3), and sharply increased to a 3-hr maximum of 890 g m-3 (av. 589±273 g m-3) on the dust storm day (April 24th). Mass-closure study results showed that during the non-dust storm period organic matters accounted for 25% of the PM10 particle mass, followed by SO42- (13%), NO3- (10%), water-soluble carbonate (10%), EC (5%), NH4+ (4%), and other ions (7%). In contrast, water-soluble carbonate became the most abundant among the measured species during the dust storm period, accounting for 12% of the PM10 mass, followed by organic matters (11%), SO42- (3%), Ca2+(2%) and NO3- (1.5%). Such a changes in chemical compositions suggests a significant heterogeneous reaction of acidic gases (e.g., H2SO4, HNO3, SO2 and N2O5) with dust to form water-soluble mineral compounds. A bimodal size distribution of particles was observed during the non-dust time with two equivalent peaks in the fine (<2.1 m) and coarse (>2.1 m) ranges, in contrast to a unimodal pattern (i.e., coarse mode) observed on the dusty day. All the measured ions except NH4+ significant shifted toward larger particles during the dust storm time. Similar size-distribution patterns of particles were found on the mountaintop of Mt. Hua, which are bimodal during the non-dust period and
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