Investigating PAH relative reactivity using congener profiles, quinone measurements and back trajectories

Abstract. Vapour and particle-associated concentrations of 15 polycyclic aromatic hydrocarbons (PAH) and 11 PAH quinones have been measured in winter and summer campaigns at the rural site, Weybourne in eastern England. Concentrations of individual PAH are 20–140 times smaller than average concentrations at an English urban site. The concentrations of PAH are greatest in air masses originating from southern England relative to those from Scandinavia and the North Atlantic, while quinone to parent PAH ratios show an inverse behaviour, being highest in the more aged North Atlantic polar air masses. While concentration of 1,2-naphthoquinone decline from summer to winter, those of 1,4-naphthoquinone and anthraquinone increase suggesting a photochemical formation pathway. A comparison of congener concentration profiles measured at Weybourne with those from an urban source area (Birmingham) reveals differential losses at the rural site, especially evident in fluoranthene: pyrene ratios and consistent with the known rates of vapour phase reactions of 3 and 4 ring compounds with hydroxyl radical. The ratios of quinones to their parent PAH at Weybourne are greater than those in the urban source area indicating either more rapid loss processes for PAH, or formation of quinones during advection of the air mass, or probably both.