Arctic haze has attracted considerable scientific interest for decades. However, limited studies have focused on the molecular composition of atmospheric particulate matter that contributes to Arctic haze. Our study collected atmospheric particles at Alert in the Canadian high Arctic from mid-February to early May 2000. Over 100 organic species were identified in the solvent-extractable fraction by gas chromatography-mass spectrometry, which were grouped by their functional groups. Plasticizer-derived phthalates were the most abundant, followed by polyacids, sugars, sugar alcohols, biogenic SOA tracers, and fossil fuel combustion tracers. During the dark winter, major contributors to Arctic aerosols include plastic emissions, biomass burning, secondary oxidation products, and fossil fuel combustion products. In the light spring, phthalates (58-76% of the identified organics) dominated, followed by microbial and marine sources and secondary oxidation products. By employing a tracer-based method, we discovered that naphthalene and sesquiterpene oxidation products were the major contributors to SOC, and these contributions were much higher in the winter than in the spring. However, monoterpene and isoprene oxidation products peaked in light spring. Our results confirm that organic aerosols in the Arctic atmosphere are dominated by anthropogenic sources, which consist of both long-range-transported particles and combustion-emitted organics, as well as aged anthropogenic secondary organic aerosols. Despite decreasing anthropogenic pollution being replaced by natural emissions, plastic-derived pollution, represented by phthalates, increased significantly in the high Arctic atmosphere after the polar sunrise.
Keywords: arctic haze; biomass burning; levoglucosan; phthalates; secondary organic aerosol.