The task of the presented work was the investigation of urban immission concentrations and profiles of polycyclic aromatic hydrocarbons (PAH) and their oxidized derivatives (O-PAH). The substantial factors that influence the urban immission concentrations and profiles of PAH and O-PAH are types and strengths of sources and the meteorological conditions. In order to evaluate the different influences, sampling campaigns were carried out at three different locations (heavy traffic, urban background and outskirts). The seasonal influences were investigated by sampling in summer and winter (domestic heating period). Samples were collected with a 12 channel low volume sampler. Parallel to 24h samples, sampling was conducted with a relatively high time resolution of 160 minutes (160min samples). The particles were collected on quartz fibre filters. Gaseous analytes were collected in adsorption units filled with XAD-2. During sampling, the collected PAH and O-PAH can react with ozone and other oxidants. PAH can be oxidatively decomposed; O-PAH can be decomposed and / or formed from appropriate precursor PAH. These reactions during sampling lead to wrong assessments of the immission concentrations and their adverse health effects. Therefore a MnO2 coated denuder was used during sampling in order to eliminate ozone. In order to evaluate the kind and extent of the sampling artefacts, the 24h samplings were carried out in parallel with and without ozone denuder. 20 PAH and 11 O-PAH were analysed by GC-HRMS after Soxhlet extraction and clean-up using silica gel liquid chromatography. The validation of the method was conducted by comparison of the results from the 24h samples with the results of the parallel collected nine 160min samples. It was shown that the sampling artefacts with a MnO2-ozone-denuder were very small for the low volatility (> 95% in the particle phase) PAH and O-PAH. The investigation of the parallel 24h samples with and without the denuder showed that reactive low volatile PAH and O-PAH were subject to decomposition reactions and/or formation reactions during sampling without the denuder. A highly significant correlation between the ozone concentration and the underestimation ratios of benz[a]pyrene (BaP) was observed in samples without denuder. With an average ozone concentration of about 70 µg/m3, the loss of BaP during sampling without denuder is approx. 20%. By using the MnO2-ozone-denuder during sampling, significant artefacts can occur with analytes, which have substantial gas phase portions or gaseous precursors. The cause of these differences is the reactions of gaseous components with excited oxygen atoms in the MnO2-ozone-denuder. Therefore only the low volatility PAH and O PAH are included in the discussions about the influences of meteorological parameters on their immission concentrations, about their profiles and about the identification and quantification of their sources. Apart from the changes in emission situations, meteorological parameters have substantial influences on the immission concentrations of PAH and O-PAH and their diurnal variations. The dilution conditions, in particular the vertical air exchange, were unfavourable during sampling in winter. Together with the changes in emission situations, they led to the higher (about 10 to 20 times) immission concentrations of PAH and O-PAH in winter. In summer, the maximum concentrations of PAH and O-PAH were found in the period between 4:00 and 6:40 o'clock and between 20:00 and 22:40 o'clock. In contrast, a broad concentration maximum was observed in the evening and night hours in winter. Wind direction, wind velocity and vertical air exchange have clear influences on the diurnal variations of the immission concentrations of PAH and O-PAH. The meteorological parameters also have large influences on the concentration quotients. The relationship of the concentrations of benzo[ghi]perylene (BghiP) and benz[e]pyrene (BeP) was used frequently in other investigations for the identification and partly for the quantification of the traffic contribution to the immission. The presented work shows that the concentration quotient (BghiP/BeP) was clearly affected by meteorological parameters. With the concentration quotient (BghiP/BeP) alone, one cannot therefore judge the absolute traffic contribution to the immission. Significant differences of the profiles of PAH and O-PAH were determined in the different sampling campaigns. BghiP and coronene (COR) showed increased portions in the 24h samples in summer at the sampling location with heavy traffic compared with the other two sampling locations: urban background and outskirts. The analysis of the 160min samples showed that benz[a]anthracene (BaA), BghiP and COR had increased portions in emissions from local traffic in summer. In winter, BaA, chrysene (CHR), BaP, benz[b]+[j]fluoranthene (BbF), benz[k]fluoranthene (BkF), indeno[1,2,3-cd]pyrene (IND) and 7H-benzo[de]anthracen-7-one (BdA-O) originated predominantly from domestic heating. The evaluation of the PMF (Positive Matrix Factorization) analyses resulted in the most plausible results in the case of three factors: factor 1 (local traffic), factor 2 (long-distance transport) and factor 3 (urban background). The diurnal variations of the source contributions supplied further information: The portions of factor 1 (local traffic) in the immissions of PAH and O-PAH were higher during daytime hours than during night hours. In addition, the "rush hours" early in the morning and late in the afternoon were clearly identified in both summer and winter. The portions of factor 2 (long-distance transport) in the immissions of PAH and O-PAH during daytime hours in summer were lower than those in winter, in particular for the more reactive PAH (e.g. BaP). In summer, the portions of factor 3 (urban background) in the immissions of PAH and O-PAH was stable. In contrast, they were clearly higher during the night hours than during daytime hours in winter. The average portions of factor 1 (local traffic) in the immissions of PAH and O-PAH were higher in summer than in winter, while the portions of factor 2 (long-distance transport) showed the opposite pattern. While O-PAH originated predominantly (> 40%) from factor 2 (long-distance transport), the predominant part (approx. 60%) of the BaP immission originated from factor 3 (urban background).
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The task of the presented work was the investigation of urban immission concentrations and profiles of polycyclic aromatic hydrocarbons (PAH) and their oxidized derivatives (O-PAH). The substantial factors that influence the urban immission concentrations and profiles of PAH and O-PAH are types and strengths of sources and the meteorological conditions. In order to evaluate the different influences, sampling campaigns were carried out at three different locations (heavy traffic, urban background...
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