| Abstract [eng] |
Air quality indicators are analyzed in the Master's thesis, and their assessment was carried out focusing on the concentration of six polycyclic aromatic hydrocarbons (PAH) (benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, dibenzo(a,h)anthracene, indene(1,2,3-c,d)pyrene). Monitoring, evaluation and regulation of PAH concentrations are very important, due to the carcinogenicity of these compounds to living organisms and the negative impact on the environment. During the study, the trends of six PAH concentrations were analyzed in the period 2007–2023, at six Lithuanian air quality stations. PAH concentration data were analyzed using descriptive statistics, regression analysis, correlation analysis methods. After evaluating the distribution of PAH concentrations in time and space, it was found that the concentrations of the studied compounds are related – the strongest statistically significant correlation was found between benzo(b)fluoranthene and benzo(k)fluoranthene. The weakest correlations were found between dibenzo(a,h)anthracene and other studied PAH. Such a difference may be due to various pollution sources and differences in physical properties. The strongest correlation was found between the PAH concentrations measured in Šiauliai air quality station and Klaipėda Center air quality station (0.887). The weakest relationship was between Panevėžys and Klaipėda Center stations (0.639). PAH concentrations determined in Kaunas Petrašiūnai station were higher than in Šiauliai station due to the peculiarities of the terrain. Seasonal variation of PAH concentrations was observed in all the studied air quality stations – in the cold season, the increase in concentration was due to the heating of settlements and the increase in the intensity of transport. The Mann-Kendall test revealed a weakly significant decrease in individual PAH concentrations. At Vilnius Žirmūnai station, the reduction of benzo(a)pyrene, benzo(a)anthracene and indene(1,2,3-c,d)pyrene concentrations were statistically insignificant (p > 0.05). PAH concentrations vary depending on meteorological conditions – as temperature decreases, concentrations increase, as relative humidity increases, PAH concentrations increase. The nonlinear effect of temperature on pollutant concentrations was greater than that of humidity. After assessing the compliance of PAH concentrations with the EU Directive 2004/107/EC, it was found that from 2019 the concentrations do not exceed the set annual limit of 1 ng/m3. These results show that the air quality in Lithuania is slowly improving, but it is necessary to continue creating regional pollution management plans, reduce the usage of normal petrol and diesel vehicles, and implementing international control measures. |
