| Abstract |
Semi-volatile organic compounds (SVOCs) constitute a significant percentage of the organic aerosol in the atmosphere. A lot of epidemiological studies have shown that these compounds are probably carcinogenic, mutagens, which are able to cause a great number of health effects. Moreover, some of them are able to react with the main oxidants of the atmosphere to form products of increased toxicity. High concentrations of SVOCs have often been reported in the atmosphere of background regions, far away from anthropogenic activity, although their main sources are due to human activity. Three categories of SVOCs, aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), were investigated in this study. Atmospheric sources of SVOCs were studied by frequent sampling (11 samples) for 10 days in the station SMEAR II, a department of Physics University of Helsinki, in a background region (Hyytiälä), which is located in southern Finland. Total concentrations of SVOCs in Hyytiälä atmosphere varied from 29.81 to 186.65 ng m-3 for n-alkanes, from 9.85 to 26.25 ng m-3 for PAHs and from 41.81 to 122.95 pg m-3 for PCBs. Moreover, the isoprenoid hydrocarbons pristane (Pr) and phytane (Ph) and the unresolved mixture of cyclic branched and unsaturated hydrocarbons (UCM) were also quantified in gas/particle phase of aerosol. These compounds have average concentrations of 1.41 ng m-3, 1.86 ng m-3 and 909.5 ng m-3, respectively. More than 90% of the PAHs and the PCBs were detected in gas phase, while n-alkanes where distributed in equal amounts between the two phases. Possible atmospheric sources of SVOCs were determined using concentration diagnostic ratio, also including the study of gas-to-particle partitioning and the calculation of back trajectories (HYbrid Single-Particle Lagrangian Integrated Trajectory) to define the origin of air at the station, during the sampling period. Gas-to-particle partitioning is very important for the environmental fate of SVOCs and their long-range transport. The differences in gas-to-particle partitioning observed for several classes of compounds, might reflect the mode in which the studied group of compounds get into the atmosphere. Generally, it was observed that the gas-to-particle thermodynamic equilibrium was not established, which has been also reported for other background regions. Moreover, the calculation of back trajectories showed the influence of the Hyytiälä atmosphere by the polluted countries of western Europe, but also by urban centres of Finland. Finally, some factors were investigated that probably affect the atmospheric concentrations of SVOCs: environmental temperature, wind speed (WS), relative humidity (RH) etc. However, no significant influence on the SVOCs concentrations in Hyytiälä atmosphere was found.
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Μελέτη της παρουσίας ημιπτητικών οργανικών ρυπαντών στην ατμόσφαιρα δασικής περιοχής στη νότια Φιλανδία
