Suchergebnisse

This thesis presents a comprehensive analysis of the global health impacts of polycyclic aromatic hydrocarbons (PAHs) in ambient air, conducted on the basis of a high-resolution emission inventory, global chemical transport modeling, and probabilistic risk assessment. One of the main strengths of the thesis is the concentration downscaling process, which provides a linkage between emissions and exposure concentrations at a comparatively high resolution. Moreover, by focusing on individual susceptibility, the thesis proposes an instrumental revision of current risk assessment methodology and argues that, if individual susceptibility were not taken into consideration, the overall risk would be underestimated by 55% and the proportion of highly vulnerable populations would be underestimated by more than 90%

In Hungary, the measurement of ambient PM10-bound polycyclic aromatic hydrocarbon (PAH) concentrations is great importance for a number of reasons related to human health, the environment and compliance with European Union legislation. However, the monitoring of PAHs associated with PM2.5 aerosol fraction is still incomplete. Therefore, the main aim of this study was to investigate the concentration levels of PAHs in PM2.5 urban aerosol fraction. PM2.5 and associated PAHs were monitored in November 2014 in an urban site of Győr (Northwest Hungary). The aerosol samples were collected every day for 24-hours over two weeks with a high volume air sampler provided with a PM2.5 cut-off inlet. The levels of 19 PAH compounds associated with PM2.5 aerosol fraction were quantified by a gas chromatographic method. Polluted air quality for PM2.5 (>25 g/m3) was indicated in 50% of the collected samples. The total PAHs concentrations ranged from 2.1 to 37.3 ng/m3 with the mean value of 12.4 ng/m3. Indeno(123-cd)pyrene (IND) and sum of three benzofluoranthene isomers were the most dominant PAH species followed by benzo(ghi)perylene and benzo(a)pyrene (BaP). Using BaP-equivalent approach on the concentration data of carcinogenic PAH species, BaP, and IND contributed the highest carcinogenic exposure equivalent (1.50 and 0.24 ng/m3 on average). A selected number of concentration ratios of specific PAH compounds were calculated to evaluate the possible sources of PAH contamination. The ratios reflected that the major source of PAH compounds in the PM2.5 aerosol fraction of Győr during the study period was fossil fuel combustion from automobiles.

This study evaluated the effect of nitrogen on the biostimulation of microbial load in soil mesocosms contaminated with bunker oil. Urea was used as a nitrogen source, with C/N ratios of 60:1 and 100:10 established to analyze its impact on the biodegradation of polycyclic aromatic hydrocarbons (PAHs). Experiments were conducted in plastic trays containing 2 kg of soil contaminated with 8% bunker oil. Samples were taken on days 15, 30, 60, and 90, and chemical analysis was performed using gas chromatography-mass spectrometry (GC-MS). Results indicated that the treatment with a C/N ratio of 100:10 achieved the highest PAH reduction percentage (99.27%), demonstrating the efficacy of urea biostimulation. This study highlights the importance of optimizing nutrient proportions to enhance biodegradation efficiency in hydrocarbon-contaminated soils. The addition of urea is confirmed as a viable and economical solution for soil remediation, aligning with previous studies emphasizing the crucial role of nitrogen in microbial activity and the degradation of recalcitrant contaminants. In conclusion, incorporating urea as a nitrogen source proved to be an effective strategy for biostimulation and PAH biodegradation in soil mesocosms, offering a sustainable solution to mitigate hydrocarbon contamination.