Jan Hovorka

Chemical and phase composition of particles produced by laser ablation of silicate glass and zircon—implications for elemental fractionation during ICP-MS analysis

The chemical and phase compositions of particles produced by laser ablation (266 nm Nd:YAG) of silicate NIST glasses and zircon were studied by SIMS and HR-TEM techniques. The data suggest that the formation of phases of different mineralogy and/or chemical composition from the original sample at the ablation site can result in elemental fractionation (non-stoichiometric sampling) in material delivered to the ICP-MS for quantitative analysis. Evidence of the element fractionation is preserved in chemically zoned ejecta deposited around the ablation pit. The chemical composition and mineralogy of particles varies with particle size so that the efficiency of transport of particles also plays a role in elemental fractionation. During the first 250 pulses in a typical ablation experiment using a 266 nm laser, particle sizes are mainly <2.5 μm; thereafter they decrease to <0.3 μm. Pb and U are fractionated significantly during the ablation of both silicate glass and zircon. During the ablation of glass, both micron-sized, melt-derived, spherical particles, and nm-sized, condensate-derived particle clusters, are produced; the very smallest particles (<0.04 μm) have anomalously high Pb/U ratios. For zircon, both larger (0.2–0.5 μm) spherical particles and agglomerates of smaller (∼0.005 μm) particles produced by ablation are mixtures of amorphous and crystalline materials, probably zircon, baddeleyite (ZrO2) and SiO2. Evidence for thermal decomposition of zircon to baddeleyite and SiO2 is preserved in the wall of the ablation pit, and may lead to the commonly observed increase in Pb/U recorded during laser ablation ICP-MS analysis. It follows that a matrix-matched external calibration is essential for achieving highly precise and accurate laser (266 nm wavelength) ablation ICP-MS analysis of Pb and U in silicate samples.

Association of size-resolved number concentrations of particulate matter with cardiovascular and respiratory hospital admissions and mortality in Prague, Czech Republic

We analyzed the association of particle number and PM2.5 concentrations with mortality and cardiorespiratory hospital admissions in Prague. Number concentrations of submicron particles in the range of 15–487 nm were measured continuously at a central site in 2006. The particle number concentrations were integrated into four groups with count median diameters of 31 (NC31), 128 (NC128), and 346 nm (NC346). The total number concentration of submicron particles 15–487 nm (NCtot) was also constructed. The studied health outcomes were the daily hospital admissions due to cardiovascular and respiratory diseases and daily cardiovascular and respiratory mortality and the total mortality. The Poisson regression was used for data analysis. The strongest association was found for the accumulation mode particles (NC346) (RR 1.164, 95% CI: 1.052–1.287 for cardiovascular and 1.334, 95% CI: 1.126–1.579 for respiratory admissions for a 7-day moving average for 1000 particles per 1 cm3 increase). Reasonable association between both the cardiovascular and respiratory admissions and NC346 was also found for lag 0, lag 1, lag 2 (not for respiratory admissions), and the 4-day moving average. For NC128 and NCtot, the association was also significant for both cardiovascular and respiratory admissions at lag 0, lag 1, and lag 2 (not for respiratory admissions) for the 4-day and 7-day moving average. The association between the PM2.5 and daily cardiovascular hospital admissions was significant at 2-day lag and for a 4-day average. Positive association with respiratory admissions was significant only for a 7-day average. No association was found between the studied air pollution variables and daily mortality.

Source apportionment of size resolved particulate matter at a European air pollution hot spot

Positive Matrix Factorization-PMF was applied to hourly resolved elemental composition of fine (PM0.15-1.15) and coarse (PM1.15-10) aerosol particles to apportion their sources in the airshed of residential district, Ostrava-Radvanice and Bartovice in winter 2012. Multiple-site measurement by PM2.5 monitors complements the source apportionment. As there were no statistical significant differences amongst the monitors, the source apportionment derived for the central site data is expected to apply to whole residential district. The apportioned sources of the fine aerosol particles were coal combustion (58.6%), sinter production-hot phase (22.9%), traffic (15%), raw iron production (3.5%), and desulfurization slag processing (<0.5%) whilst road dust (47.3%), sinter production-cold phase (27.7%), coal combustion (16.8%), and raw iron production (8.2%) were resolved being sources of the coarse aerosol particles. The shape and elemental composition of size-segregated aerosol airborne-sampled by an airship aloft presumed air pollution sources helped to interpret the PMF solution.

Ultrafine particles are not major carriers of carcinogenic PAHs and their genotoxicity in size-segregated aerosols.

Some studies suggest that genotoxic effects of combustion-related aerosols are induced by carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) and their derivatives, which are part of the organic fraction of the particulate matter (PM) in ambient air. The proportion of the organic fraction in PM is known to vary with particle size. The ultrafine fraction is hypothesized to be the most important carrier of c-PAHs, since it possesses the highest specific surface area of PM. To test this hypothesis, the distribution of c-PAHs in organic extracts (EOMs) was compared for four size fractions of ambient-air aerosols: coarse (1<dae<10μm), upper (0.5<dae<1μm), and lower (0.17<dae<0.5μm) accumulation aerosol particles and ultrafine particles (dae<0.17). High-volume aerosol samples were collected consecutively in four localities that differed in the level of environmental pollution. The genotoxicity of EOMs was measured by analysis of DNA adducts induced in an a cellular assay consisting of calf thymus DNA with/without rat liver microsomal S9 fraction coupled with (32)P-postlabelling. The upper accumulation fraction was the major size fraction in all four localities, forming 37-46% of the total PM mass. Per m(3) of sampled air, this fraction also bound the largest amount of c-PAHs. Correspondingly, the upper accumulation fraction induced the highest DNA-adduct levels. Per PM mass itself, the lower accumulation fraction is seen to be the most efficient in binding DNA-reactive organic compounds. Interestingly, the results suggest that the fraction of ultrafine particles of various ambient-air samples is neither a major carrier of c-PAHs, nor a major inducer of their genotoxicity, which is an important finding that is relevant to the toxicity and health effects of ultrafine particles, which are so extensively discussed these days.

An acellular assay to assess the genotoxicity of complex mixtures of organic pollutants bound on size segregated aerosol. Part I: DNA adducts.

An acellular assay consisting of calf thymus DNA with/without rat liver microsomal S9 fraction was used to study the genotoxicity of complex mixtures of organic air pollutants bound to size segregated aerosols by means of DNA adduct analysis. We compared the genotoxicity of the organic extracts (EOMs) from three size fractions of aerosol ranging from 0.17μm to 10μm that were collected by high volume cascade impactors in four localities of the Czech Republic differing in the extent of the environmental pollution: (1) small village in proximity of a strip mine, (2) highway, (3) city center of Prague and (4) background station. The total DNA adduct levels induced by 100μg/ml of EOMs were analyzed by (32)P-postlabelling analysis with a nuclease P1 method for adduct enrichment. The main finding of the study was most of the observed genotoxicity was connected with a fine particulate matter fraction (<1μm). The concentrations of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) in EOMs indicate that fine fractions (0.5-1μm) bound the highest amount of c-PAHs in all aerosol sampling sites, which might be related to the higher specific surface of this fraction as compared with a course fraction (1-10μm) and higher mass as compared with a condensational fraction (0.17-0.5μm). As for aerosol mass, both fine and condensational fractions are effective carriers of c-PAHs. Similarly, the DNA adduct levels per m(3) of air were highest for the fine fraction, while the condensational fraction (strip mine site and city center) revealed the highest DNA adduct levels in cases where aerosol mass is taken into consideration. A strong correlation was found between the c-PAHs and DNA adduct levels induced by EOMs in all the localities and for various size fractions (R(2)=0.98, p<0.001). It may be concluded that the analysis of total DNA adducts induced in an acellular assay with/without metabolic activation represents a relatively simple method to assess the genotoxic potential of various complex mixtures.

Particulate matter source apportionment in a village situated in industrial region of Central Europe

The bilinear receptor model positive matrix factorization (PMF) was used to apportion particulate matter with an aerodynamic diameter of 1–10 μm (PM1–10) sources in a village, Březno, situated in an industrial region of northern Bohemia in Central Europe. The receptor model analyzed the data sets of 90- and 60-min integrations of PM1–10 mass concentrations and elemental composition for 27 elements. The 14-day sampling campaigns were conducted in the village in summer 2008 and winter 2010. Also, to ensure seasonal and regional representativeness of the data sets recorded in the village, the spatial-temporal variability of the 24-hr PM10 and PM1–10 within 2008–2010 in winter and summer across the multiple sites was evaluated. There were statistically significant interseasonal differences of the 24-hr PM data, but not intrasummer or intrawinter differences of the 24-hr PM1–10 data across the multiple sites. PMF resolved seven sources of PM1–10. They were high-temperature coal combustion; combustion in local heating boilers; marine aerosol; mineral dust; primary biological/wood burning; road dust, car brakes; and gypsum. The main summer factors were assigned to mineral dust (38.2%) and primary biological/wood burning (33.1%). In winter, combustion factors dominated (80%) contribution to PM1–10. The conditional probability function (CPF) helped to identified local sources of PM1–10. The source of marine aerosol from the North Sea and English Channel was indicated by the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT). Implications: This is the first application of PMF to highly time/size resolved PM data in Czech Republic. The coarse aerosol fraction, PM1–10, was chosen with regard to industrial character of the region, sampling site near the coal strip mine and coal power stations. Contrary to expectation, source apportionment did not show dominance of emissions from the coal strip mine. The results will enable local authorities and state bodies responsible for air quality assessment to focus on sources most responsible for air pollution in this industrial region. Supplemental Materials: Supplemental materials are available for this paper. Go to the publishers online edition of the Journal of the Air & Waste Management Association for (1) details of measurement campaigns; (2) CPF for each of the sources contributing to PM1–10; (3) factors contribution to PM1–10 resolved by PMF; (4) diurnal pattern of road dust, car brake factor in summer and winter; (5) trajectories during the marine aerosol episode in winter 2010; and (6) temporal temperature, concentration, and wind speed relationships during the summer 2008 campaign and winter 2010 campaign.

Effect of Indoor and Outdoor Sources on Particulate Matter Concentration in a Naturally Ventilated Flat (URBAN-AEROSOL Project - Prague)

Indoor and outdoor characteristics of particulate matter (PM) were studied in a naturally ventilated flat. Twenty-four-hour concentrations of indoor PM1, PM2.5 and PM10 and outdoor PM2.5 were measured. In winter all indoor concentrations of PM fractions were highly correlated (r 0.97 to 0.98). High correlation was also found between ambient PM10 and outdoor PM2.5 (r 0.99). In summer, the correlations between all PM fractions were lower. Human activity had a stronger effect on indoor PM concentrations in winter than in summer but only when the outdoor levels were low. During the second winter campaign higher outdoor concentrations were able to mask indoor sources. The presence of people corresponded to elevated levels of coarse particle fractions, cooking was associated with higher levels of fine particles. In summer with windows open, indoor PM values were not associated with human activity. A significant negative association was registered between wind speed and indoor PM.

Source Impact Determination using Airborne and Ground Measurements of Industrial Plumes

Industrial particulate matter (PM) air pollution exposing nearby residential areas forms several European air pollution hot-spots. One of these hot-spot is the residential district of Ostrava Radvanice-Bartovice with frequent exceedances for PM and benzo[a]pyrene B[a]P, a carcinogenic polycyclic aromatic hydrocarbon (PAH) of MW > 228 amu. Such PAHs are highly bonded to the ultrafine particles (UFPs), the smallest PM size fraction, which deposits most efficiently in the alveolar region of human lungs. Airborne measurements identified UFP point sources in the adjacent metallurgical complex and mapped limited horizontal and vertical dispersion of industrial plumes enriched with UFPs (3.2 × 10(5)cm(-3)). The plumes, episodes of simultaneous peaks of UFPs (1.4 × 10(5)cm(-3)), SO2 (88.2 ppb), and CO (11.3 ppm), were recorded on the ground downwind in the residential district when wind speeds >1 ms(-1). In the plumes, UFPs were mostly 19-44 nm in diameter, enriched with PAHs/B[a]P up to 43.8/3.5 mg·g(-1). Electron microscopy showed that these plume UFPs were mostly agglomerates of spherules of 30-50 nm in diameter. These source impact measurements, that combine airborne and ground-level measurements, are applicable to clearly identify specific industrial air pollution sources and provide information to assess their possible impact to human health in similar hot-spots worldwide.

Tracing Outdoor/Indoor Penetration of PM2.5, PM1.0 by 210Po/210Pb

Alpha activities of 210Po were determined in low-volume, 24-hour samples of 2 particulate matter (PM) size fractions indoors and outdoors in 3 localities in the centre of Prague during the winter periods of 2002-2003. High values of ventilation rates (0.34 0.12h 1) and penetration of outdoor aerosols into the indoor environment, which favours particles smaller than 1 m size, allows the application of a simplified equation of the indoor/outdoor (I/O) relationship. The slope of linear regression of indoors against outdoors for both mass concentrations and alpha activities as well as the I/O penetration factors Cmass, and Calpha, respectively were determined. While the Cmass ranged from 0.46 to 0.64, appropriate Calpha ranged from 0.57 to 0.95 being always greater and reflecting size selective particle penetration through the building envelope. Personal activities indoors had little effect on particle deposition indoors, which is in agreement with the finding that the majority (70%) of PM2.5 indoors is formed by PM1.0. For all 3 localities it was shown that outdoor PM concentrations determined indoor ones while probably the particle removal during infiltration through the building envelope is the most important aerosol loss mechanism.

Impact of Mining Activities on the Air Quality in The Village Nearby a Coal Strip Mine

The objective of the presented study was to estimate a share of atmospheric aerosol emitted by coal strip mine on PM10 or PM1-10, mass concentration of aerosol particles < 10μm or 1-10μm in aerodynamic diameter respectively, in the village situated in proximity to the mine. Parallel measurements were conducted in the mine and village situated in the northern part of the Czech Republic from the 15th to 27th November 2012. Three size fractions, consisting PM10, were sampled by a Davis rotating-drum impactor and analysed for 27 elements by Synchrotron-XRF with time resolution 1 hour. Appropriate hourly PM10 were measured by a Beta attenuation monitor in the village and calculated from 5 minute values by a nephelometer in the mine. Also, 24 hour aerosol samples for five size fractions were sampled by a personal cascade impactor sampler and viewed by scanning electron microscopy - SEM. Meteorological parameters were also recorded. Average contribution of coarse aerosol, PM1-10, to PM10 was 70% (119 +59 μgm-3) in the mine and 20% (12 + 10 μgm-3) in the village. The SEM revealed solely soil particles in the mine samples but bioaerosol, ash and aggregates of ultrafine particles in the village samples. Databases of hourly elemental and mass concentrations from the two localities were analysed by EPA PMF 5.0. There were revealed following sources/average contribution to local PM10: wood burning/34%, resuspended dust/30%, coal combustion/22%, industry/11% and gypsum/3% in the village while resuspended dust/43%, coal combustion/37%, gypsum/16% and mining technologies/4% in the mine. Based on factor chemical profiles, the mine was found to contribute to PM1-10 and PM10 in the village by 6% and 20%, respectively.