Measurement Report: Polycyclic aromatic hydrocarbons (PAHs) and their alkylated (RPAHs), nitrated (NPAHs) and oxygenated (OPAHs) derivatives in the global marine atmosphere: occurrence, spatial variations, and source apportionment

Abstract. Ambient polycyclic aromatic hydrocarbons (PAHs) and their derivatives have severe adverse impacts on organism health and ecosystem safety. However, their global distributions, sources, and fate in marine aerosols remain poorly understood. To fill the knowledge gap, high-volume air samples were collected along a transect from China to Antarctica and analyzed for particulate PAHs and derivatives. The highest PAH concentrations in marine aerosols were observed in the Western Pacific (WP: 447±228 pg/m³), followed by the East China Sea (ECS: 195 pg/m³), Antarctic Ocean (AO: 111±91 pg/m³), East Australian Sea (EAS: 104±88 pg/m³), and the lowest in the Bismarck Sea (BS: 17±12 pg/m³). Unexpectedly, PAH concentrations in the AO were even higher than those in the EAS and BS. This could be attributed to the relatively low anthropogenic PAH emissions from Australia and Papua New Guinea, whereas AO is often affected by emissions from engine combustion and biomass burning. In contrast to the distribution of PAHs, OPAH levels in the EAS were much higher than those in the AO. It was assumed that OPAHs mainly originated from the secondary formation of parent PAHs through reactions with O₃ and OH radicals, both of which are more prevalent in EAS. Several source apportionment models suggested that PAHs and their derivatives in marine aerosols are dominated by three sources: coal burning and engine combustion emissions (56 %), wood and biomass burning (30 %), and secondary formation (14 %). Specifically, marine aerosols in ECS and WP were significantly affected by coal burning and engine combustion, while those in BS and EAS were mainly influenced by wildfire and coal combustion. AO was primarily dominated by biomass burning and local shipping emissions.