Particulate PAHs and n-alkanes in the air over Southern and Eastern Mediterranean Sea

Abstract

Particulate polycyclic aromatic hydrocarbons, n-alkanes and polar organic compounds were investigated in the marine atmosphere of Southern and Eastern Mediterranean Sea, in the frame of the scientific cruise of Urania ship between 27 July and 11 August 2013. The PM10 fraction of aerosol to which most organic substances are associated, were collected daily; contemporarily, gaseous regulated toxicants (ozone, nitrogen oxides and carbon oxide) and carbonyls were recorded. Samplings were carried out in front of Palermo and Messina, respectively the start and end harbors, and along the cruise, both in movement (transects, N = 14) and at stops (N = 11). Total PAHs ranged from 0.06 ng/m3 up to 1.8 ng/m3, with the maximums observed close to harbors. Unlike total concentrations that were in general comparable, the percent composition of PAHs was distinct for harbors, transects and stops, which allowed to draw insights about the pollution sources impact. Concentrations of n-alkanes (C18–C35) ranging from 6.7 to 43 ng/m3 were quantified. The carbonyls evaluation revealed relatively high concentrations of formaldehyde (∼4–24 μg/m3) and acetone (∼5–35 μg/m3) near harbors, and of acrolein (up to 12 μg/m3) offshore, while benzaldehyde was quite independent of the site type (≈0.5 μg/m3). Nicotine and caffeine were detected, at different extents (0.0–2.2 ng/m3 and 0.01–0.17 ng/m3, respectively), in ca. 70% and 100% of samples. Alkyl phthalates ranged from 2.7 to 67 ng/m3 and showed variable percentages in the samples. Finally, traces of N,N-diethyl-meta-toluene amide (up to 0.4 ng/m3) were found at all sites.