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We present a study characterizing aerosol particles resulting from a skyscraper blasting. High PM 10 mass concentrations with a maximum of 844.9 μg m -3 were present for a short time period of approximately 15 minutes. They result in a day mean of 32.6 μg m -3 compared to a 27.6 μg m -3 background not exceeding the 50 μg m -3 EU maximum permissive value. The increase in particle number concentration was less pronounced with a maximum concentration of 6.9 ⋅ 10 4 cm -3 compared to the local background value of 1.8 ⋅ 10 4 cm -3 . The size-resolved number concentration shows a single mode of ultrafine particles at approximately 93 nm. The spatial distribution of deposited dust was investigated with Bergerhoff glass collection vessels, showing a decrease with distance. In the deposited dust samples the concentrations of twelve metals was determined, non of them exceeded the regional background concentrations significantly. The chemical composition of individual particles emitted by the demolition was studied by Scanning Electron Microscopy. They were mainly concrete and steel particles, with 60% calcium carbonates, 19% calcium sulfates, 19% silicates and 2% steel. In energy-dispersive X-Ray Spectroscopy, no fibers like asbestos were observed. Using a broad spectrum of instruments and methods, we obtain comprehensive characterization of the particles emitted by the demolition. [ABSTRACT FROM AUTHOR]

Continuous measurements of suspended sediment mass concentration (SSC) and particle size distribution (PSD) in surface waters and hydraulic schemes are of prime importance for the investigation and management of many fine-sediment related processes. In this paper, the performance of selected techniques and instruments for continuous SSC measurements is discussed based on results of a field study and a recent literature-review paper. SSCs measured with Laser In Situ-Scattering and Transmissometry (LISST) or vibrating tube densimetry were confirmed to be not or less biased by temporary PSD variations than SSCs obtained from turbidimeters or a single-frequency acoustic attenuation method. Vibrating tube densimetry allowed measurements of higher SSCs (e.g. 10 g/l) compared to the other investigated instruments. For the conversion of the instruments’ outputs to SSC, i.e. calibration, and for validation, gravimetric analysis of bottle samples is recommended as reference. [ABSTRACT FROM AUTHOR]

The total count number concentration of particles from 10 to 1000 nm, particle size distribution, and PM 2.5 (aerodynamic diameter ≤ 2.5 μm) mass concentration were measured on a parking apron next to the runway at Tianjin International Airport in China. The data were collected 250, 270, 300, 350, and 400 m from the runway. Wind direction and wind speed played important roles in determining the characteristics of the atmospheric particles. An inverted U-shaped relationship was observed between the measured particle number concentration and wind speed, with an average peak concentration of 2.2 × 10 5 particles/cm 3 at wind speeds of approximately 4–5 m/s. The atmospheric particle number concentration was affected mainly by aircraft takeoffs and landings, and the PM 2.5 mass concentration was affected mainly by the relative humidity (RH) of the atmosphere. Ultrafine particles (UFPs, diameter < 100 nm), with the highest number concentration at a particle size of approximately 16 nm, dominated the measured particle size distributions. The calculated particle emission index values for aircraft takeoff and landing were nearly the same, with mean values of 7.5 × 10 15 particles/(kg fuel) and 7.6 × 10 15 particles/(kg fuel), respectively. The particle emission rate for one aircraft during takeoff is two orders of magnitude higher than for all gasoline-powered passenger vehicles in Tianjin combined. The particle number concentrations remained much higher than the background concentrations even beyond 400 m from the runway. [ABSTRACT FROM AUTHOR]

This paper describes the use of a unique valve switching system that allowed for high temporal resolution indoor and outdoor data to be collected concurrently from online C-ToF-AMS, SMPS and OC/EC, and offline BLPI measurements. The results reveal near real-time dynamic aerosol behaviour along a migration path from an outdoor to indoor environment. An outdoor reduction in NR-PM 1 mass concentration occurred daily from AM (06:00–12:00) to PM (12:00–18:00). SO 4 (26%–37%) [AM/PM] increased proportionally during afternoons at the expense of NO 3 (18%–7%). The influences of mixing height, temperature and solar radiation were considered against the mean mass concentration loss for each species. Losses were then calculated according to species via a basic input/output model. NO 3 lost the most mass during afternoon periods, which we attribute to the accelerated dissociation of NH 4 NO 3 through increasing temperature and decreasing relative humidity. Indoor/outdoor (I/O) ratios varied from 0.46 for <40 nm to 0.65 for >100 nm. These ratios were calculated using average SMPS PNC measurements over the full campaign and corroborated using a novel technique of calculating I/O penetration ratios through the indoor migration of particles during a new particle formation event. This ratio was then used to observe changes in indoor composition relative to those outdoors. Indoor sampling was carried out in an undisturbed room with no known sources. Indoor concentrations were found to be proportional to those outdoors, with organic matter [2.7 μg/m 3 ] and SO 4 [1.7 μg/m 3 ] being the most prominent species. These results are indicative of fairly rapid aerosol penetration, a source-free indoor environment and small afternoon I/O temperature gradients. Fine fraction NO 3 was observed indoors in both real-time AMS PM 1 and off-line BLPI measurements. Greater mass concentration losses were observed from filter measurements, highlighting an important time dependency factor when investigating semi-volatiles. Coarse mode NO 3 was observed by impactor measurements, ascribing value to observing the full particle mass size distribution for understanding aerosol origin. [ABSTRACT FROM AUTHOR]

The TSI-3321 APS was used to measure concentration of atmospheric particulates in Ranjiaba region of Yubei District in Chongqing City during March 21-29, 2014, and the temporal variations in the hourly average mass and number concentration and median particle diameter of PM10 and PM2.5 as well as their correlation with relative humidity were analyzed. The results showed that the three indicators of PM10 and PM2.5 except for the mass concentration correlated with relative humidity, of which the correlation between the mass median particle diameter and relative humidity was the best. The correlation coefficient Ft between the mass median particle diameter of PM10 (PM2.5) and relative humidity was up to 0.943 (0.832). Therefore, relative humidity and pressure are key impact factors of indicators of particles. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultra-fine particles (UFPs, d ≤ 100 nm) and submicron particles (PM1, d ≤ 1 μm) in an east Asian urban area, which are hypothesized to be affected by the interchange of summer and winter monsoons. An observation experiment was conducted at TARO (Taipei Aerosol and Radiation Observatory), an urban aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The measurements included the mass concentration and chemical composition of UFPs and PM1, as well as the particle number concentration (PNC) and the particle number size distribution (PSD) with size range of 4-736 nm. The results indicated that the mass concentration of PM1 was elevated during cold seasons with a peak level of 18.5 μgm-3 in spring, whereas the highest concentration of UFPs was measured in summertime with a mean of 1.64 μgm-3. Moreover, chemical analysis revealed that the UFPs and PM1 were characterized by distinct composition; UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents of PM1. The seasonal median of total PNCs ranged from 13.9×10³ cm-3 in autumn to 19.4×103 cm-3 in spring. Median concentrations for respective size distribution modes peaked in different seasons. The nucleationmode PNC (N4-25) peaked at 11.6×10³ cm-3 in winter, whereas the Aitken-mode (N25-100) and accumulation-mode (N100-736) PNC exhibited summer maxima at 6.0×10³ and 3.1×10³ cm-3, respectively. The change in PSD during summertime was attributed to the enhancement in the photochemical production of condensable organic matter that, in turn, contributed to the growth of aerosol particles in the atmosphere. In addition, clear photochemical production of particles was observed, mostly in the summer season, which was characterized by average particle growth and formation rates of 4.0×1.1 nm h-1 and 1.4×0.8 cm-3 s-1, respectively. The prevalence of new particle formation (NPF) in summer was suggested as a result of seasonally enhanced photochemical oxidation of SO2 that contributed to the production of H2SO4, and a low level of PM10 (d ≤ 10 μm) that served as the condensation sink. Regarding the sources of aerosol particles, correlation analysis of the PNCs against NOx revealed that the local vehicular exhaust was the dominant contributor of the UFPs throughout the year. Conversely, the Asian pollution outbreaks had significant influence in the PNC of accumulation-mode particles during the seasons of winter monsoons. The results of this study implied the significance of secondary organic aerosols in the seasonal variations of UFPs and the influences of continental pollution outbreaks in the downwind areas of Asian outflows. [ABSTRACT FROM AUTHOR]

Four years of continuous aerosol number size distribution measurements from the Arctic Climate Observatory in Tiksi, Russia, are analyzed. Tiksi is located in a region where in situ information on aerosol particle properties has not been previously available. Particle size distributions were measured with a differential mobility particle sizer (in the diameter range of 7-500 nm) and with an aerodynamic particle sizer (in the diameter range of 0.5-10 μm). Source region effects on particle modal features and number, and mass concentrations are presented for different seasons. The monthly median total aerosol number concentration in Tiksi ranges from 184 cm-3 in November to 724 cm-3 in July, with a local maximum in March of 481 cm-3. The total mass concentration has a distinct maximum in February-March of 1.72- 2.38 μg m-3 and two minimums in June (0.42 μgm-3) and in September-October (0.36-0.57 μgm-3). These seasonal cycles in number and mass concentrations are related to isolated processes and phenomena such as Arctic haze in early spring, which increases accumulation and coarse-mode numbers, and secondary particle formation in spring and summer, which affects the nucleation and Aitken mode particle concentrations. Secondary particle formation was frequently observed in Tiksi and was shown to be slightly more common in marine, in comparison to continental, air flows. Particle formation rates were the highest in spring, while the particle growth rates peaked in summer. These results suggest two different origins for secondary particles, anthropogenic pollution being the important source in spring and biogenic emissions being significant in summer. The impact of temperature-dependent natural emissions on aerosol and cloud condensation nuclei numbers was significant: the increase in both the particle mass and the CCN (cloud condensation nuclei) number with temperature was found to be higher than in any previous study done over the boreal forest region. In addition to the precursor emissions of biogenic volatile organic compounds, the frequent Siberian forest fires, although far away, are suggested to play a role in Arctic aerosol composition during the warmest months. Five fire events were isolated based on clustering analysis, and the particle mass and cloud condensation nuclei number were shown to be somewhat affected by these events. In addition, during calm and cold months, aerosol concentrations were occasionally increased by local aerosol sources in trapping inversions. These results provide valuable information on interannual cycles and sources of Arctic aerosols. [ABSTRACT FROM AUTHOR]

Real-time mass spectra of the non-refractory species in submicron aerosol particles were recorded in a tropical rainforest in the central Amazon Basin during the wet season from February to March 2008, as a part of the Amazonian Aerosol Characterization Experiment (AMAZE- 08). Organic material accounted on average for more than 80% of the non-refractory submicron particle mass concentrations during the period of measurements. There was insufficient ammonium to neutralize sulfate. In this acidic, isoprene-rich, HO2-dominant environment, positive-matrix factorization of the time series of particle mass spectra identified four statistical factors to account for the 99% of the variance in the signal intensities of the organic constituents. The first factor was identified as associated with regional and local pollution and labeled "HOA" for its hydrocarbon-like characteristics. A second factor was associated with longrange transport and labeled "OOA-1" for its oxygenated characteristics. A third factor, labeled "OOA-2," was implicated as associated with the reactive uptake of isoprene oxidation products, especially of epoxydiols to acidic haze, fog, or cloud droplets. A fourth factor, labeled "OOA-3," was consistent with an association with the fresh production of secondary organic material (SOM) by the mechanism of gasphase oxidation of biogenic volatile organic precursors followed by gas-to-particle conversion of the oxidation products. The suffixes 1, 2, and 3 on the OOA labels signify ordinal ranking with respect to the extent of oxidation represented by the factor. The process of aqueous-phase oxidation of water-soluble products of gas-phase photochemistry might also have been associated to some extent with the OOA-2 factor. The campaign-average factor loadings had a ratio of 1:4 V 1 for OOA-2 VOOA-3, suggesting the comparable importance of particle-phase compared to gas-phase pathways for the production of SOM during the study period. [ABSTRACT FROM AUTHOR]

An intensive sampling campaign was conducted in the autumn of 2012 to study the size distribution of inorganic ions and ion deposition at an offshore site of Yangtze River Delta region (YRD), China. Particles in <0.43, 0.43-0.65, 0.65-1.1, 1.1-2.1, 2.1-3.3, 3.3-4.7, 4.7-5.8, 5.8-9.0 and 9.0-10.0 µm were collected and analyzed by ion chromatography for NH4+, Na+, Mg2+, K+, Ca2+, F-, Cl-, NO3- and SO42-. The average mass concentrations in the nine particle sizes ranged from 13.1 to 38.7 µ g m-3, accounting for 5.5%-16.8% of the total mass. Concentrations exhibit bi-modal distribution, peaking at 0.65-1.1 µm and 3.3-4.7 µm. PM1.1, PM2.1 and PM2.1-10 account for 41%, 56% and 44% of PM10 implying the dominance of finer particles. Different ions hold different size distribution patterns. The concentrations of NO3-, SO42-, NH4+, K+ and Ca2+ exhibit the highest values when compared to literature values indicating the serious air pollution situation in YRD. A haze-precipitation-fog transition course is captured. The precipitation can decrease all the particles in the nine sizes by 20%-62% and the fog formation process can promote the particles' accumulation, with their mass concentrations increasing by 26%-232% except for those in 5.8-9.0 µm and 9.0-10 µm. Mass percentages of SO42-, NO3- and NH4+ exhibit decreases during precipitation and increases during fog formation course. The anion to cation ratios are lower than 1.0 indicating the anion deficiency and they exhibit significant negative relationship with the particle diameter. The Cl-dep (%) is higher for particles larger than 0.65 µm, increasing from 1.3% to 61% with size added. Sea salt only accounts for 0.12%-2.1% of PM10. The ratios of nss-SO42-/NO3- decrease with increasing particle size, from 1.68 to 0.69, and are well fit as linear form (r = -0.74, p = 0.02). It indicates that stationary sources make more contributions to smaller particles and vehicle emission is more important for larger particles. The dry deposition fluxes for F-, Cl-, NO3- and SO42- are 3.10, 0.59, 22.99 and 17.04 mg/(m²d). They exhibit multi-linear correlation with corresponding ion concentrations and the coefficients are higher for coarse particles. More researches are needed to obtain the distribution, transportation and deposition characteristic of ions at Chinese coastal area. [ABSTRACT FROM AUTHOR]

This paper experimentally investigates the particle concentration distribution and deposition in three-dimensional 90° bends considering three potential influencing factors: inlet mass concentration C m , Reynolds number Re and wall material. Particle penetrations were found to decrease moderately within 11% with the increase of C m under current conditions, but deposition velocity would increase by 1.29–2.87 times. The inlet particle concentration will not affect the outlet concentration distribution and particle penetration for the particles of St=5.15×10−4. For larger particles, however, higher C m , St and Re cause higher concentration near the outer wall of bend outlet, lower concentration near the inner wall and even ‘particle free zone’. For the outlet concentration distribution, apexes and concave points are observed, which may be formed by the rebounding particles. Furthermore, concentration polarization factor is introduced to analyze the outlet nonuniformity. Accordingly, Re is found to be a higher weighting factor compared with C m . Compared to penetration, deposition velocity is more sensitive to wall materials, for example, with an increase factor up to 1.45. Furthermore, a rough estimation method and an empirical model are suggested to establish the correlation among dimensionless outlet concentration, St and ‘particle free zone’. [ABSTRACT FROM AUTHOR]