Berner Impactor Research Articles

Airborne Pollen, Allergens, and Proteins: A Comparative Study of Three Sampling Methods

Nowadays, there is a wide range of different methods available for the monitoring of pollen and allergens, but their relative efficiency is sometimes unclear, as conventional pollen monitoring does not thoroughly describe pollen allergenicity. This study aims to evaluate airborne pollen, allergen, and protein levels, associating them with meteorological and chemical parameters. The sampling was performed in Bologna (Italy) during the grass flowering period, with three different devices: a Cyclone sampler (CS), a Dicothomous sampler (DS), and a Berner impactor (BI). Total proteins were extracted from aerosol samples, and grass allergens Phl p 1 and Phl p 5 were quantified by ELISA. Airborne Poaceae pollen concentrations were also evaluated, using a Hirst-type trap. Proteins and allergens collected by CS resulted about ten times higher than those collected by the other two instruments, possibly due to their different cut-offs, while DS and BI results appeared consistent only for the total proteins collected in the fine fraction (1.3 vs. 1.6 μg/m3). Airborne proteins correlated neither with Poaceae pollen nor with its aeroallergens, while aeroallergens correlated with pollen only in the coarse particulate, indicating the presence of pollen-independent aeroallergens in the fine particulate, promoted by high wind speed.

Source apportionment and impact of long-range transport on carbonaceous aerosol particles in central Germany during HCCT-2010

Abstract. The identification of different sources of the carbonaceous aerosol (organics and black carbon) was investigated at a mountain forest site located in central Germany from September to October 2010 to characterize incoming air masses during the Hill Cap Cloud Thuringia 2010 (HCCT-2010) experiment. The near-PM1 chemical composition, as measured by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), was dominated by organic aerosol (OA; 41 %) followed by sulfate (19 %) and nitrate (18 %). Source apportionment of the OA fraction was performed using the multilinear engine (ME-2) approach, resulting in the identification of the following five factors: hydrocarbon-like OA (HOA; 3 % of OA mass), biomass burning OA (BBOA; 13 %), semi-volatile-like OA (SV-OOA; 19 %), and two oxygenated OA (OOA) factors. The more oxidized OOA (MO-OOA, 28 %) was interpreted as being influenced by aged, polluted continental air masses, whereas the less oxidized OOA (LO-OOA, 37 %) was found to be more linked to aged biogenic sources. Equivalent black carbon (eBC), measured by a multi-angle absorption photometer (MAAP) represented 10 % of the total particulate matter (PM). The eBC was clearly associated with HOA, BBOA, and MO-OOA factors (all together R2=0.83). Therefore, eBC's contribution to each factor was achieved using a multi-linear regression model. More than half of the eBC (52 %) was associated with long-range transport (i.e., MO-OOA), whereas liquid fuel eBC (35 %) and biomass burning eBC (13 %) were associated with local emissions, leading to a complete apportionment of the carbonaceous aerosol. The separation between local and transported eBC was well supported by the mass size distribution of elemental carbon (EC) from Berner impactor samples. Air masses with the strongest marine influence, based on back trajectory analysis, corresponded with a low particle mass concentration (6.4–7.5 µg m−3) and organic fraction (≈30 %). However, they also had the largest contribution of primary OA (HOA ≈ 4 % and BBOA 15 %–20 %), which was associated with local emissions. Continental air masses had the highest mass concentration (11.4–12.6 µg m−3), and a larger fraction of oxygenated OA (≈45 %) indicated highly processed OA. The present results emphasize the key role played by long-range transport processes not only in the OA fraction but also in the eBC mass concentration and the importance of improving our knowledge on the identification of eBC sources.

Seasonal variability of carbon in humic-like matter of ambient size-segregated water soluble organic aerosols from urban background environment

Long-term measurements of carbon in HUmic-LIke Substances (HULIS-C) of ambient size-segregated water soluble organic aerosols were performed using a ten-stage low-pressure Berner impactor from December 2014 to November 2015 at an urban background environment in Ljubljana, Slovenia. The mass size distribution patterns of measured species (PM - particulate matter, WSOC - water-soluble organic carbon and HULIS-C) for all seasons were generally tri-modal (primarily accumulation mode) but with significant seasonal variability. HULIS-C was found to have similar distributions as WSOC, with nearly the same mass median aerodynamic diameters (MMADs), except for winter when the HULIS-C size distribution was bimodal. In autumn and winter, the dominant accumulation mode with MMAD at ca. 0.65 μm contributed 83 and 97% to the total HULIS-C concentration, respectively. HULIS-C accounted for a large fraction of WSOC, averaging more than 50% in autumn and 40% in winter. Alternatively, during warmer periods the contributions of ultrafine (27% in summer) and coarse mode (27% in spring) were also substantial. Based on mass size distribution characteristics, HULIS-C was found to be of various sources. In colder seasons, wood burning was confirmed as the most important HULIS source; secondary formation in atmospheric liquid water also contributed significantly, as revealed by the MMADs of the accumulation mode shifting to larger sizes. The distinct difference between the spring and summer ratios of HULIS-C/WSOC in fine particles (ca. 50% in spring, but only 10% in summer) indicated different sources and chemical composition of WSOC in summer (e.g., SOA formation from biogenic volatile organic compounds (BVOCs) via photochemistry). The enlarged amount of HULIS-C in the ultrafine mode in summer suggests that the important contribution was most likely from new particle formation during higher emissions of BVOC due to the vicinity of a mixed deciduous forest; the higher contribution of HULIS-C in the coarse mode demonstrated that beside soil erosion other sources, such as pollen and plant fragments, could also be responsible.

Regional air quality in Leipzig, Germany: detailed source apportionment of size-resolved aerosol particles and comparison with the year 2000.

A detailed source apportionment of size-resolved aerosol particles in the area of Leipzig, Germany, was performed. Sampling took place at four sites (traffic, traffic/residential, urban background, regional background) in parallel during summer 2013 and the winters 2013/14/15. Twenty-one samples were taken per season with a 5-stage Berner impactor and analysed for particulate mass, inorganic ions, organic and elemental carbon, water-soluble organic carbon, trace metals, and a wide range of organic species. The compositional data were used to estimate source contributions to particulate matter (PM) in quasi-ultrafine (up to 140 nm), accumulation mode, and coarse size ranges using Positive Matrix Factorisation (PMF) receptor modelling. Traffic (exhaust and general traffic emissions), coal combustion, biomass combustion, photochemistry, general secondary formation, cooking, fungal spores, urban dust, fresh sea/road salt, and aged sea salt were all found to contribute to different extents to observed PM concentrations. PMF derived estimates agreed reasonably with estimates from established macrotracer approaches. Quasi-ultrafine PM originated mainly from traffic (20-50%) and photochemistry (30-50%) in summer, while it was dominated by solid fuel (mainly biomass) combustion in winter (50-70%). Tentatively identified cooking aerosol contributed up to 36% on average at the residential site. For accumulation mode particles, two secondary sources typically contributed 40-90% to particle mass. In winter, biomass and coal combustion contributions were up to ca. 25% and 45%, respectively. Main sources of coarse particles were diverse and included nearly all PMF-resolved ones depending on season and air mass origin. For PM10, traffic (typically 20-40% at kerbside sites), secondary formation (30-60%), biomass combustion (10-15% in winter), and coal combustion (30-40% in winter with eastern air mass inflow) were the main quantified sources. At the residential site, contributions from biomass combustion derived up to 60% from local emissions. Coal combustion as a significant source was only present during eastern air mass inflow and showed very similar concentrations at all sites, indicating the importance of trans-boundary air pollution transport in the study area. Overall, nearly half of the PM10 mass was attributed to urban sources by a simple subtractive approach with highest reduction potentials of up to 80% for local (urban) mitigation measures in ultrafine and coarse particles. Local increments of elemental carbon have decreased by about 50% as compared to the year 2000, corroborating results from a former study on the positive effects of a low emission zone, implemented in Leipzig in 2011.

Total Reflection X-ray Fluorescence Analysis of Airborne Silver Nanoparticles from Fabrics

Ag nanoparticles (NPs) are usually applied to consumer products because of their antimicrobial properties, which are desired in fabrics for sportswear as well as cloth used for cleaning. Hazards to human health from airborne Ag NPs may occur when the NPs are inhaled. NPs are comparable in size to macromolecules and viruses and able to penetrate deep into the lungs, e.g., the alveoli, where they may cause damage to cells and tissue due to their large surface area. In this study, aerosols released form fabrics treated with Ag NPs were collected using a low pressure Berner impactor and analyzed with total reflection X-ray fluorescence (TXRF). We found that the Ag NPs are released primarily in the form of larger particles, mainly 0.13-2 μm, probably attached to fiber material. Using an electron micro probe, single particles could be identified. The detection of backscattered electrons suggests small spots on the particle consist of a heavier element, which most likely is Ag, although the signal in energy-dispersive X-ray spectroscopy (EDX) was below the lower limit of detection (LOD). To achieve LODs necessary for Ag determination, Ar peaks were eliminated by a nitrogen atmosphere provided by the "Picofox-box". This enables linear calibration and quantification of Ag. The LOD was calculated at 0.2 ng (2.0 ppb). Following the TXRF and scanning electron microscopy (SEM)/EDX analysis, the aerosol samples were dissolved in nitric acid and analyzed with ICPMS to successfully confirm the results obtained by the TXRF measurements.

Determination of phosphorus and other elements in atmospheric aerosols using synchrotron total‐reflection X‐ray fluorescence

In this study, P and other low Z elements were determined in aerosol particulates from ambient air using synchrotron radiation‐induced total‐reflection X‐ray fluorescence analysis.Atmospheric transport of nutrients such as P or Si to the oceans is a key factor to marine plankton growth. Concentration of these elements in marine air masses is generally low (P < 10 ng/m3). Therefore, analytical procedures enabling for low detection limits are of interest. Because particle size is strongly correlated to its origin and sedimentation, the aerosols were collected with the aid of a low‐pressure Berner impactor, which separates the aerosol particulates in nine size fractions with the smallest fraction from 15 to 30 nm.To be able to determine low Z elements, measurements were performed under vacuum conditions at the FLUO beamline at the ANKA synchrotron. An excitation energy of 3.5 keV near the P K‐edge but below the Ca K absorption edge was chosen to avoid interferences of the P K‐line with the detector escape artifact of the Ca‐Kα line.The result showed P was present in concentration from 2 to 180 ng/m3. Detection limits were found to be generally 0.2–0.3 ng/m3 for a collecting time of 1 h for the aerosols, which is an improvement to detection limits reported in other studies. Other elements such as S, Cl, and Si were determined as well. Si like P is a nutrient for marine plankton (diatoms). S and Cl play an important role in cloud formation, e.g. polar stratospheric clouds. Copyright © 2013 John Wiley & Sons, Ltd.

Experimental Study on the Testing Environment Improvement of Fire Smoke Detectors

Abstract To simulate the test smoke for fire smoke detectors, the bypass setting of aerosol generator is currently adjusted to the particle size of 0.75 μm according to the standard of EN 54-7 of China. It leads to the single test environment of fire smoke detectors. In this paper, the improvement of aerosol generator is presented. It makes the aerosol flow which has different particle size characteristics can be generated by aerosol generator and be installed several bypass flows according to the principle of aerosol generator. By the way, the particle size distribution and particle size characteristics of aerosol flow can be obtained after measuring the quality of aerosol flow which is collected under different bypass flows by Berner Impactor. So the different type of test smoke for fire smoke detectors can be obtained by aerosol generator. And then, the distribution characteristics of aerosol flow can be obtained in testing tubes (EN54-5/7c) of fire smoke detectors. Finally, the improved test environment of fire smoke detectors has realized the diversification of test environment. And the reliability of the test results has improved through this study.

A detailed aerosol particle plume analysis

Aerosol particle dynamics were observed in the summertime marine boundary layer 10 km offshore of the northeast American coast. Particle dynamics were observed using a scanning mobility particle sizer for observation of the number‐based size distribution, and a quadrupole aerosol mass spectrometer (Q‐AMS) for quantification of the mass‐based size distributions and bulk particle mass loadings of nonrefractory components. Analysis was supported by meteorological data, extensive trace gas data, and aerosol Berner impactor data. No new particle formation with clearly identifiable growth of ultrafine particles was identified. One event exhibited a clear banana‐shaped evolution of the number‐based size distribution. However, the conditions were nonstationary in various aspects. In some phases of the event, particle growth mechanisms could not be confirmed despite an increase of the geometric mean of the number‐based size distribution. Air mass changes and dilution of boundary layer air are possible causes for the observed dynamics. The observation of particle number‐based size distributions did not provide sufficient proof for the occurrence of a growth event. Continental organics were the predominant species driving particle dynamics. The contribution of industrial sulfate also was important. The mass size distributions of the Q‐AMS and the impactor agreed reasonably well for the species analyzed. Overall, we conclude that a detailed analysis of aerosol plume dynamics and temporal evolution, including both meteorology and chemistry, reveals much more detail about the aerosol evolution that could be deduced from the number size distribution alone.

Particle characterization at the Cape Verde atmospheric observatory during the 2007 RHaMBLe intensive

Abstract. The chemical characterization of filter high volume (HV) and Berner impactor (BI) samples PM during RHaMBLe (Reactive Halogens in the Marine Boundary Layer) 2007 shows that the Cape Verde aerosol particles are mainly composed of sea salt, mineral dust and associated water. Minor components are nss-salts, OC and EC. The influence from the African continent on the aerosol constitution was generally small but air masses which came from south-western Europe crossing the Canary Islands transported dust to the sampling site together with other loadings. The mean mass concentration was determined for PM10 to 17 μg/m3 from impactor samples and to 24.2 μg/m3 from HV filter samples. Non sea salt (nss) components of PM were found in the submicron fractions and nitrate in the coarse mode fraction. Bromide was found in all samples with much depleted concentrations in the range 1–8 ng/m3 compared to fresh sea salt aerosol indicating intense atmospheric halogen chemistry. Loss of bromide by ozone reaction during long sampling time is supposed and resulted totally in 82±12% in coarse mode impactor samples and in filter samples in 88±6% bromide deficits. A chloride deficit was determined to 8% and 1% for the coarse mode particles (3.5–10 μm; 1.2–3.5 μm) and to 21% for filter samples. During 14 May with high mineral dust loads also the maximum of OC (1.71μg/m3) and EC (1.25 μg/m3) was measured. The minimum of TC (0.25 μg/m3) was detected during the period 25 to 27 May when pure marine air masses arrived. The concentrations of carbonaceous material decrease with increasing particle size from 60% for the ultra fine particles to 2.5% in coarse mode PM. Total iron (dust vs. non-dust: 0.53 vs. 0.06 μg m3), calcium (0.22 vs. 0.03 μg m3) and potassium (0.33 vs. 0.02 μg m3) were found as good indicators for dust periods because of their heavily increased concentration in the 1.2 to 3.5 μm fraction as compared to their concentration during the non-dust periods. For the organic constituents, oxalate (78–151 ng/m3) and methanesulfonic acid (MSA, 25–100 ng/m3) are the major compounds identified. A good correlation between nss-sulphate and MSA was found for the majority of days indicating active DMS chemistry and low anthropogenic influences.

Quantification of organic acids in particulate matter by coupling of thermally assisted hydrolysis and methylation with thermodesorption-gas chromatography–mass spectrometry

A quantitative method for the determination of organic acids in atmospheric particles is developed. The method couples a derivatisation step (thermally assisted hydrolysis and methylation) and a Curie point pyrolyser as a thermal desorption technique and gas chromatography–mass spectrometry (CPP-GC–MS). Among the reagents tested (tetramethylammonium hydroxide (TMAH), tetramethylammonium acetate (TMAAc) and phenyltrimethylammonium hydroxide (TMPAH)), the best performance was found using TMAAc as a derivatisation reagent for the reaction time of 4 s at 510 °C as heating temperature. Calibration was performed for a series of fatty acids (FA), dicarboxylic acids (DCA) and terpenoic acids (TA) under these conditions. Coefficients of determination ( R 2) were between 0.94 and 0.98. Limits of detection (LOD) were in the nanogram-range between 0.1 and 3.6 ng. The method is applied on atmospheric particle samples to obtain the quantification reproducibility and quantification limits. Reproducibility was determined in terms of relative standard deviations (RSD) for ambient aerosol samples collected by a high-volume-sampler (HVS, RSD = 6–45%, n = 10) and a Berner impactor (BI, RSD = 5–34%, n = 10). Based on 24 h sampling time the developed method enables quantification of all three classes of acids for both sampling techniques. Calibration data and presented volume concentrations are compared with literature data. A comparison with an off-line methylation-GC–MS using BF 3 as a derivatisation reagent and capillary electrophoresis coupled mass spectrometry (CE-MS) showed a good agreement. Minimal sample preparation is the main advantage of the developed method. Depending on the sensitivity requirements the present method can be a fast and simple alternative to GC–MS techniques with conventional sample preparation steps for semi-volatile organic acids.

Size‐ and time‐resolved chemical particle characterization during CAREBeijing‐2006: Different pollution regimes and diurnal profiles

Beijing, the capital of China, faces severe air pollution problems, resulting from a steep economic growth during the past decades. To better characterize the processes leading to the frequently observed high concentrations of air pollutants on a regional scale, the international field campaign “Campaigns of Air Quality Research in Beijing and Surrounding Region 2006” (CAREBeijing‐2006) was conducted in summer 2006. In this contribution, we present chemical data of size‐resolved particles, obtained by a five‐stage Berner impactor during 3 weeks at both an urban and suburban site in the area of Beijing, China. The samples were analyzed for inorganic ions (Cl−, SO42−, NO3−, NH4+, K+, Ca2+, Na+, and Mg2+), carbon sum parameters (OC, EC, and WSOC), and a variety of organic compounds such as dicarboxylic acids, alkanes, PAHs, and, for the first time in China, nitrooxy‐organosulfates. On average, the observed PM10 (where PM is particulate matter) mass concentrations were 133 μg m−3 and 112 μg m−3 at the urban and suburban site, respectively. A high influence of meteorology on the PM pollution was observed and is discussed. The highest concentrations of both PM mass and particle constituents were observed when sampled air masses originated south of Beijing and moved over the area with low wind speeds. During such periods, a strong increase of daytime concentrations of the secondary ions sulfate, nitrate, ammonium, and also some dicarboxylic acids could be observed. A strong diurnal variation of particle sulfate concentration with increasing values from morning to afternoon was observed during an intensive period, which could be attributed to regional production. Similar observations were made for oxalic acid. Generally, water‐soluble organic carbon concentrations were enhanced by a factor of 2 in fine particles during the studied period of intense photochemistry. Elemental carbon, alkanes, and PAHs showed clear nighttime concentration maxima obviously due to enhanced emissions and a relatively low mixing volume during night. For the newly studied compound group of nitrooxy‐organosulfates, qualitative data can be presented indicating an influence of nighttime chemistry and/or anthropogenic activities on their concentrations. The investigation of an intense nucleation and particle growth event revealed that the youngest particles largely consist of ammonium sulfate and primary carbonaceous material, with a possible contribution of secondary organic compounds.

Characterization of atmospheric aerosols using Synchroton radiation total reflection X-ray fluorescence and Fe K-edge total reflection X-ray fluorescence-X-ray absorption near-edge structure

In this study a new procedure using Synchrotron total reflection X-ray fluorescence (SR-TXRF) to characterize elemental amounts in atmospheric aerosols down to particle sizes of 0.015 um is presented. The procedure was thoroughly evaluated regarding bounce off effects and blank values. Additionally the potential of total reflection X-ray fluorescence–X-ray absorption near edge structure (SR-TXRF-XANES) for speciation of FeII/III down to amounts of 34 pg in aerosols which were collected for 1 h is shown. The aerosols were collected in the city of Hamburg with a low pressure Berner impactor on Si carriers covered with silicone over time periods of 60 and 20 min each. The particles were collected in four and ten size fractions of 10.0–8.0 μm, 8.0–2.0 μm, 2.0–0.13 μm 0.13–0.015 μm (aerodynamic particle size) and 15–30 nm, 30–60 nm, 60–130 nm, 130–250 nm, 250–500 nm, 0.5–1 μm, 1–2 μm, 2–4 μm, 4–8 μm, 8–16 μm. Prior to the sampling “bounce off” effects on Silicone and Vaseline coated Si carriers were studied with total reflection X-ray fluorescence. According to the results silicone coated carriers were chosen for the analysis. Additionally, blank levels originating from the sampling device and the calibration procedure were studied. Blank levels of Fe corresponded to 1–10% of Fe in the aerosol samples. Blank levels stemming from the internal standard were found to be negligible. The results from the Synchroton radiation total reflection X-ray fluorescence analysis of the aerosols showed that 20 min of sampling time gave still enough sample material for elemental determination of most elements. For the determination of the oxidation state of Fe in the aerosols different Fe salts were prepared as a reference from suspensions in isopropanol. The results from the Fe K-edge Synchroton radiation total reflection X-ray fluorescence-X-ray absorption near-edge structure analysis of the aerosol samples showed that mainly Fe(III) was present in all particle size fractions.

Size distribution of atmospheric particulate ionic species at a coastal site in Portugal

A Berner impactor was used to collect size-differentiated aerosol samples from March to August 2003 in the city of Aveiro, on the Portuguese west coast. The samples were analysed for the main water-soluble ion species. The average concentration of sulphate, nitrate, chloride and ammonium was 6.38, 3.09, 1.67 and 1.27 µg m-3, respectively. The results show that SO4(2-) and NH4+ were consistently present in the fine fraction < 1 µm, which represents, on average, 72 and 89% of their total atmospheric concentrations, respectively. The NO3-particles were concentrated in the coarse size. Chloride presented the characteristic coarse mode for marine aerosols. During some spring/summer events, an ammonium surplus was observed (NH4+/SO4(2-) molar ratios > 2), possibly due to greater availability of ammonia coming from agricultural activities or from the neighbouring chemical industrial complex. During the remaining periods, the aerosol was found to be somewhat acidic and predominantly in the form of ammonium bisulphate (NH4+/SO4(2-) molar ratios = 0.5-1.25). Samples collected under a major or exclusive influence of maritime air masses were essentially constituted by coarse particles with enrichment in sea salt, while for air masses of continental origin the contribution of water-soluble ionic species in the fine mode was more pronounced.

Approaching PM2.5 and PM2.5 − 10 source apportionment by mass balance analysis, principal component analysis and particle size distribution

A chemical characterization was carried out for PM2.5 and PM2.5–10 samples collected in a suburban area and the concentrations of 12 elements were determined in 8 size segregated fractions using a Berner Impactor. Two main objectives were proposed in this work: 1) to test for closure among chemical and gravimetric measurements of PM2.5 and PM2.5–10 and 2) evaluate the performance of Multilinear Regression Analysis (MLRA) and Mass Balance Analysis (MBA) in the determination of source contribution to Particulate Matter (PM) concentrations. The fraction unaccounted for by chemical analysis comprised on average 17% and 34% of gravimetric PM2.5 and PM2.5–10, respectively. The lack of closure in PM2.5 and PM2.5–10 mass (i.e., constituent concentrations not adding up to gravimetrically measured) could partly result from the presence of water associated with particles and errors in the estimation of unmeasured species. MLRA and MBA showed very similar results for the temporal variation of the source contributions. However, quantitatively important discrepancies could be observed, principally due to the lack of mass closure in PM2.5 and PM2.5–10. Both methods indicated that the major PM2.5 aerosol mass contributors included secondary aerosol and vehicle exhaust. In the coarse fraction, marine and mineral aerosol contributions were predominant.

Study on radon and radon progeny in some living rooms

In the first part of this work, the potential alpha energy concentration (PAEC) of radon progeny, the equilibrium factor (F), the activity concentration of 222Rn gas (Co) and the unattached fraction (fp), were determined in 15 living rooms at El-Minia City, Egypt. The activity size distribution of (214)Pb was measured by using a low pressure Berner impactor. Based on the parameters of that distribution the total effective dose through the human lung was evaluated by using a dosimetric model calculation of ICRP. An electrostatic precipitation method was used for the determination of 222Rn gas concentration. The mean activity concentration of 222Rn gas (Co) was found to be 123 +/- 22 Bq m(-3). A mean unattached fraction (fp) of 0.11 +/- 0.02 was obtained at a mean aerosol particle concentration (Z) of (3.0 +/- 0.21) x 10(3) cm(-3). The mean equilibrium factor (F) was determined to be 0.35 +/- 0.03. The mean PAEC was found to be 37 +/- 8.1 Bq m(-3). The activity size distribution of (214)Pb shows mean activity median diameter of 290 nm with mean geometric standard deviation (sigma) of 2.45. At a total deposition fraction of approximately 23% the total effective dose to the lung was determined to be approximately 1.2 mSv. The second part of this paper deals with a study of natural radionuclide contents of samples collected from the building materials of those rooms under investigation given in part one of this paper. Analyses were performed in Marinelli beakers with a gamma multichannel analyser provided with a NaI(Tl) detector. The samples have revealed the presence of the uranium-radium and thorium radioisotopes as well as (40)K. Nine gamma-lines of the natural radioisotopes that correspond to 212Pb, 214Pb, 214Bi, 228Ac, 40K and 208Tl were detected and measured. The activity concentrations of 226Ra, 232Th and 40K were determined with mean specific activities of 65 +/- 22, 35 +/- 12 and 150 +/- 60 Bq kg(-1), respectively. These activities amount to a radium equivalent (Ra(eq)) of 126 Bq kg(-1) and to a mean value of external hazard index of 0.34.

Activity size distributions of some naturally occurring radionuclides 7Be, 40K and 212Pb in indoor and outdoor environments

The activity size distributions of natural radionuclides 7Be and 40K were measured outdoor in El-Minia city, Egypt by means of gamma spectroscopy. A low-pressure Berner cascade impactor was used as a sampling device. The activity size distribution of both 7Be and 40K was described by one log-normal distribution, which was represented by the accumulation mode. The activity median aerodynamic diameter (AMAD) of 7Be and 40K was determined to be 530 and 1550 nm with a relative geometric standard deviation ( δ , which was defined as the dispersion of the peak) of 2.4 and 2, respectively. The same sampling device (Berner impactor) and a screen diffusion battery were used to measure the activity size distribution, activity concentration and unattached fraction ( f P) of 212Pb in indoor air of El-Minia City, Egypt. The mean activity median aerodynamic diameter (AMAD) of the accumulation mode for attached 212Pb was determined to be 250 nm with a mean geometric standard deviation ( δ ) of 2.6. The mean value of the specific concentration of 212Pb associated with that mode was determined to be 460±20 mBq m −3. The activity median thermodynamic diameter (AMTD) of unattached 212Pb was determined to be 1.25 nm with δ of 1.4. A mean unattached fraction ( f p) of 0.13±0.02 was obtained at a mean aerosol particle concentration of 1.8×10 3 cm −3. The mean activity concentration of unattached 212Pb was found to be 19±3mBq m −3. It was found that the aerosol concentration played an important role in varying the unattached, attached activity concentration and unattached fraction ( f P).

Field intercomparison of filter pack and impactor sampling for aerosol nitrate, ammonium, and sulphate at coastal and inland sites

An intercomparison has been performed on the coarse (>2.5 μm) and fine fraction (<2.5 μm) mass concentrations of particulate nitrate, ammonium, and sulphate determined simultaneously by filter pack and MOUDI samplers. Five intensive field campaigns have been carried out in summer and winter seasons, both at coastal sites (Mace Head, Ireland, and Tenerife, Spain) and at an inland site (University of Birmingham, West Midlands, UK). Comparison between particle sulphate measurements shows that sulphate measurements are the same with both filter pack and MOUDI, independent of sampling site or season. For both nitrate and ammonium, the MOUDI results are observed to be usually less than those from the filter pack, especially in the case of polluted air masses. During periods when the measured concentration products [NH 3][HNO 3] are low (<0.1 ppbv 2), the ammonium concentrations obtained with the two samplers are matched very well with each other, but for nitrate, the filter pack system provides 15% higher mass concentrations than the MOUDI which are attributable to different inlet efficiencies. During more polluted periods, however, when there are high levels of gaseous ammonia and nitric acid in the atmosphere (with the measured concentration products [NH 3][HNO 3]>0.1 ppbv 2), significantly negative sampling artefacts are observed for both nitrate and ammonium concentrations obtained with the impactor relative to the filter pack. Nevertheless, it is shown that both filter pack and MOUDI are capable of collecting ammonium nitrate from polluted air masses although the absolute efficiency is unknown. From the measurements obtained with the MOUDI in summertime at both coastal and inland sites, it is observed that about 64% of collected particle nitrate is present in the coarse (>2.5 μm) mode; but in wintertime, only about 29% of particle nitrate is found to reside in the coarse particles collected at the inland site. The lower efficiency of the MOUDI for ammonium nitrate relative to the Teflon filter is in marked contrast to the reported higher efficiency of the Berner impactor than the Teflon filter for sampling nitrate from polluted air.

Phase separation and regrowth of aerosol matter collected after size fractionation in an impactor

Aerosol matter in the size range <2 μm was collected in a Berner impactor and subsequently analysed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectrometry. Owing to the low electron beam energy of 5 keV (occasionally 10 keV), analysis was restricted to elements with atomic numbers ⩽20 (Ca). Sub-micrometer aerosol matter was found to contain mostly S, O, and C as well as some K and Ca. Nitrogen appeared to escape detection, probably due to bombardment-induced sublimation of NO 3 and NH 4. During sampling at low to moderate relative humidity (<60%) the sulphur-rich fraction of the aerosol matter (most likely sulphates) regrew in the form of microcrystals with sizes up to 10 times larger than the mean aerodynamic diameter of the respective impactor stage. By contrast, when sampling during periods in course of which the relative humidity exceeded 70%, the aerosol matter regrew in the form of extended amorphous agglomerates. The aerosol deposits also contained large numbers of carbon nanoparticles, well separated from the regrown sulphate-rich matter. The nanoparticles were similar in size (∼20–40 nm), much smaller than the equivalent aerodynamic diameter of the impacting particles (63 nm–2 μm). Presumably, the carbon nanoparticles constituted the core of larger air-borne particles covered with sulphates (as well as with nitrates and organic carbon). The regrown microcrystals disappeared rapidly under electron bombardment at high current density, an observation that indicates high volatility at elevated temperatures. Aerosol matter collected in the size range between 1 and 2 μm contained large fractions of particles made of O, Si, P, K, and Ca (oxides). These particles were highly resistant to electron bombardment (hard) and showed little or no evidence for agglomeration or regrowth. After removing the soluble (acidic) material from the collected aerosol matter, only carbon nanoparticles and hard coarse particles were left behind. The observation of agglomerated or crystallized “soft” aerosol matter in combination with phase separation of carbon nanoparticles lends further support to the assertion that it is not possible to collect useful quantities of fine and ultrafine aerosol particles with as-suspended morphology. Some implications for health-related research are discussed.

Impact and growth phenomena observed with sub-micrometer atmospheric aerosol particles collected on polished silicon at low coverage

The processes occurring during the initial stages of size-selected sampling of atmospheric aerosol matter were explored by means of high-resolution scanning electron microscopy and energy dispersive X-ray spectrometry. The final four stages of a Berner impactor served to collect particles with aerodynamic diameters between 60 nm and 1 μm on polished silicon substrates at sampling times between 10 s and 16 min. In the single-particle impact regime (fractional coverage below 5%), most of the particles produced circular black tracks, of which 15 to 30% contained cores of carbonaceous nanoparticles. At a fractional coverage above about 10%, initially generated deposits became increasingly active as centres of preferred aerosol collection. As a result, the number of black spots remained almost constant, but the area per spot increased rapidly. At this stage of fractional coverage, structured aerosol matter became visible within large black areas of random shape. The deposits showed clear evidence for the onset of phase separation between carbon nanoparticles and material rich in sulphur, probably a mixture of alkaline and alkaline earth sulphates. After some time of sample storage in air the low-coverage sulphate matter tended to attain a fractal pattern. At a fractional coverage of several hundred per cent, large amorphous or crystalline objects had grown, but 30% or more of the nominal impact area still did not contain any aerosol matter. Moreover, carbon nanoparticles were found to be phase separated from the newly grown, very uniform aerosol material. The observations imply that sub-micrometer aerosol matter collected in impactors has lost memory of the original particle morphology.

Characterization of Solid Emissions from Atmospheric Fluidized-Bed Combustion of Two Czech Lignites

We investigated composition and morphology of solid residues (fine and coarse fly ashes and bottom ash) from atmospheric fluidized-bed combustion (AFBC) of two Czech lignites that are currently used or that will likely be used for generating energy in Czech thermal power plants. The experiments were carried out on an experimental-scale 100 kW AFBC boiler using ash as a material of the bed. Coarse fly ashes were collected by a process cyclone; fine fly ashes were separated by a low-pressure Berner impactor. The elemental composition of fly ashes was examined by using INAA and PIXE and, for some samples, also by using ion chromatography. Morphology of ashes was investigated by SEM. The fine particles were found to be spherical or smooth aggregates; they were formed by alkaline-earth and alkali metal sulfates, substantially enriched by volatile trace elements. The coarse particles, both spherical and irregular in shape, were formed by partially transformed mineral inclusions remaining after burn out of organ...