O(3), NO(2), SO(2), CO and PM(10) concentrations, simultaneously determined for the first time in Belgrade urban area in the autumnal period of 2005, are presented. The obtained results display similar behaviour of SO(2), NO(2), CO, PM(10) opposite from that of O(3). The weekend effect was also investigated showing diminution of average daily concentrations of SO(2), NO(2), PM(10) and CO for 72, 40, 37 and 42% respectively, and increase of the average daily concentration of O(3) for 56%. Influence of meteorological conditions on observed concentration levels was studied, too. The observed influence of wind speed on the O(3) nightly concentration levels was analyzed pointing to the phenomena of O(3) transport during episodic measurements. To make an identification of possible pollution sources and analyse the influence of meteorological parameters on pollution levels, air back trajectories for high level concentrations episodes were calculated and analysed. A multivariate receptor modelling (Principal Component Analysis, Cluster Analysis) has been applied to a set of data in order to determine the contribution of different sources. It was found that the main principal components, extracted from the air pollution data, were related to gasoline combustion, oil combustion and ozone transport.

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Polycyclic aromatic hydrocarbons (PAHs) were analysed in 39 soil samples (0-10 cm upper layer) collected in Belgrade, the capital of Serbia. The sampling sites were randomly selected from urban, urban/recreational and rural areas; the samples were collected in April and December 2003 and July and October 2004. The sum of the 16 PAHs corresponding to the recreational zone (298 microg/kg) was close to the urban zone (375 microg/kg). Mean soil SigmaPAH concentration from rural areas was 18 microg/kg dry weight. Comparing to values observed in the urbanized locations around the world, the overall levels of PAHs in this study are low. The PAH ratios obtained pointed to a domination of pyrogenically formed PAHs in the examined soils. The dominant PAHs in soil samples in urban zones were fluoranthene, benz[a]anthracene, phenanthrene and pyrene, mostly emitted from noncatalyst vehicles which are still in use in Serbia. The total carcinogenic potency for each sampling site was calculated. Regardless of the used carcinogenic activity factors, carcinogenic potency of 7 sites were 3-9 times higher than the reference ones indicating the increased carcinogenic burden of soils from these sites.

The results of an analysis of the total suspended particles (TSP), total solvent organic extracts (TSOE), and polycyclic aromatic hydrocarbons (PAHs) in aerosol samples collected from the atmosphere of Herceg Novi from 17th June to 15th September in 1998 and 1999 are presented. The TSP and TSOE concentrations were determined by the standard gravimetric method, whereas the PAHs from the organic part of the aerosol were analyzed by the GC-MS method. The difference found in the TSP and TSOE contents between the two consecutive years (before and after the bombing of Yugoslavia) was attributed to changes in the intensity and origin of emissions from dominant sources, specific to the summer period of this region. The content and nature of the PAHs identified in the samples of 1998 and 1999 were also different, indicating the significance of traffic as the source of PAHs, which was of significantly lower intensity in 1999 (immediately after the war) due to the lower influx of tourists. Factor analysis showed that the PAH distribution at the measuring site in 1999 was largely determined by meteorological parameters, mainly by the average daily temperature and wind direction. In 1998, the dominant impact on the PAH distribution was attributed to traffic, both local and from a wider region, without an explicit impact of meteorological parameters. .

The genus Ptilostemon comprises 23 species. Ptilostemon gnaphaloides (Cirillo) Sojak (syn. Cirsium gnaphaloides) (Asteraceae) is an endemic species growing in southeast Europe-Greece and Italy. The composition of the essential oil of P. gnaphaloides has previously not been investigated. Chemical constituents of the aerial parts or roots of some species of the genus Ptilostemon were reported elsewhere [1][2][3][4][5][6].Plant material was collected during the flowering season in May 2006 in Porto Rafti, 30 km east of Athens, Greece. A voucher specimen (BEOU PTG052006) was deposited in the Herbarium of the Botanical Garden "Jevremovac," Faculty of Biology, University of Belgrade.From fresh leaves and flowers (50 g) crude essential oil was obtained by 2 h-distillation-extraction in a LickensNickerson apparatus. The volatiles were collected in CH 2 Cl 2 .Gas chromatographic analysis was performed using an HP 5890 series II gas chromatograph equipped with a flame ionization detector (FID) and a split/splitless injector. The separation was achieved using an HP-5 (5% diphenyl and 95% dimethylpolysiloxane) fused silica capillary column, 30 m × 0.25 mm i.d., 0.25 μm film thickness. GC oven temperature was programmed from 50°C (6 min) to 285°C at a rate of 4.3°C/min. Hydrogen was used as carrier gas; flow rate: 1.6 mL/min at 45°C. Injector temperature: 250°C; detector temperature: 280°C. Injection mode: splitless. The injection volume was 1.0 μL.Gas chromatographic-mass spectrometric (GC/MS) analysis was performed using an Agilent 6890 gas chromatograph coupled to an Agilent 5973 Network mass selective detector (MSD), in the positive ion electron impact (EI) mode. The separation was achieved using an Agilent 19091S-433 HP-5MS fused silica capillary column, 30 m × 0.25 mm i.d., 0.25 μm film thickness. GC oven temperature was programmed from 60°C to 285°C at a rate of 4.3°C/min. Helium was used as carrier gas; inlet pressure was 25 kPa; linear velocity: 1 mL/min at 210°C. Injector temperature: 250°C. Injection mode: splitless. MS scan conditions: source temperature, 200°C; interface temperature, 250°C; EI 70 eV; mass scan range, 40-350 amu. Identification of the components was based on retention indices and comparison of the mass spectra with those from the library (Wiley and NIST databases). Percentage (relative) of the identified compounds was computed from GC peak area.Twenty-two compounds representing 93.32% of the essential oil were characterized as listed in Table 1. δ-Cadinene (25.72%) and β-caryophyllene (15.61%) were the main components.