Differences in lipid and organic salt constituents of aerosols from eastern and western mediterranean coastal cities

Aliphatic and polycyclic aromatic hydrocarbons and carboxylic acid salts have been determined in aerosols collected in two urban locations from the eastern and western Mediterranean, Heraclion and Barcelona, respectively. The samples analysed in both cities exhibit a similar composition, with predominant anthropogenic inputs related with vehicular traffic and coal combustion in the hydrocarbon fractions and marine biogenic inputs in the fatty acid salts. In terms of anthropogenic hydrocarbons, the major differences between the aerosols collected in the two cities concern the significant higher concentrations in Barcelona and the higher relative content of uncombusted fossil fuel compounds in Heraclion. In terms of fatty acid salts, the Heraclion samples contain a large proportion of ω-oxo- and a, ω-dicarboxylic acids and a lack of unsaturated fatty acids, whereas these latter are important constituents in Barcelona samples, which in turn contain ω-oxo- and a, ω-dicarboxylic acids in low concentrations. These differences support the photochemically mediated precursor/end product association that has been proposed for these two types of carboxylic acids.