| Abstract |
Polycyclic Aromatic Hydrocarbons (PAHs) are organic molecules with two or more fused benzene rings characterized by well-recognized toxic and carcinogenic effects. These compounds originate mainly from incomplete combustion processes, are formed during the combustion or pyrolysis of organic matter and despite their impact on human health, extensive measurements of PAHs are clearly missing in the Greek urban areas. In this study, PAHs levels were measured in sixty-eight (68) PM2.5 aerosol fraction samples collected throughout a year(December 2018 – December 2019) at Piraeus, the largest port in Greece and one of the largest ports in the Mediterranean region. PM2.5 samples were analyzed for PAHs according to a specific sample extraction and purification protocol, followed by gas chromatography analysis and mass spectrometry (GC-MS) detection. Finally, the results were processed and the PAHs were quantified using the Internal Standard (IS) method. Thirty-three PAH members were identified and their levels and monthly and seasonal variability were investigated. The concentration of PAHs was significantly higher in winter, especially during intense air pollution events, compared to summer. The average value of the total concentration of 33 PAH members (Σ33 PAH) in winter was 16,13 ng/m3 , while in summer it was 2,51 ng/m3 . In the area of Piraeus, the concentration of PAHs was increased in summer, especially during June and July, a fact which can be attributed to the local activities of the port area. To get a clear picture of the type of sources (local or regional) and to identify possible origins of particles, biparametric diagrams of the correlation of EC and OC concentrations with wind direction and speed are presented. The effect of both direct local sources and those from the wider port area to the west is evident, with greater intensity during the warm season. Further-more, in order to determine the possible sources of the PM2.5 particle fraction, Pearson correlations were conducted between all PAH members and the other measured particulate components in the PM2.5 particle fraction such as Ions, Metals, Elemental and Organic Carbon and also the mass concentrations of PM2.5. This was followed by Pearson correlations with the results of ACSM sampling, which focused on a fraction of PM1 particles (organic aerosol (OA) and particulate ions such as SO42- , NO3- , Cl-- , NH4+ ) and Aethalometer sampling (“Black Carbon” from biomass combustion and fossil fuels), but also with other gaseous pollutants such as NOx. These correlations provide very useful information on the common sources of PAHs with certain chemical constituents that are related to primary combustion emissions. Αfterwards, suitable qualitative (PCA) and quantitative assay (PMF) models are used to obtain a better profile of PM2.5 particulate emission sources. Specifically, medium and high molecular weight PAHs are grouped with data resulting from combustion processes such as biomass combustion and direct road emissions. Moreover, PAHs are compounds known for their mutagenic and carcinogenic effects and some of them are bioaccumulative. The assessment of the excess cancer risk (ECR) during the daily inhalation of PAHs in PM2.5 particles in the port atmosphere is important. Compounds such as BaP, B(b)F, B(k)F, DBA, IPy and BaA were found to contribute the most to the equivalent concentrations of BaP (BaPeq). The estimated risk of lung cancer during lifetime by PAH compounds in the atmosphere of the port of Piraeus is 65,6x10-6 based on WHO and 0,83x10-6 based on CalEPA (OEHHA). To conclude, the levels of PAH concentrations in the port of Piraeus are compared with the levels in Thissio, Athens (2016 - 2018) and those in some coastal areas within Greece, Mediterranean, Europe and China.
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