Homologous series of n-alkanes and fatty acids in the summer atmosphere from the Bering Sea to the western North Pacific

Lipid biomarkers can be used as key tracers for studying organic aerosols. To better understand the effects of anthropogenic and natural sources on Northern Hemisphere organic aerosols over the marine boundary in the context of global warming, we investigated n-alkanes and fatty acids in three years of summer aerosol samples which were collected from the Bering Sea (BS) to the western North Pacific (WNP) atmosphere during the cruise of China Arctic Research Expedition in 2014, 2016 and 2018. Lipid concentrations were the highest in 2018, with the WNP influenced by neighboring Eurasia and the BS influenced by the transport of aerosols from the WNP as well as an increased primary productivity. The sources of n-alkanes and fatty acids were found to be similar, and the qualitative assessment of the characteristic parameters indicated that temporally, n-alkanes were more abundant from higher plant wax in 2016 and 2018 as well as fatty acids in 2018. Furthermore, the quantitative assessment of principal component analysis with multiple linear regression showed that spatially, the WNP and BS were most influenced by terrestrial natural sources (57.8%) and anthropogenic sources (58.8%), respectively, and the contribution of marine emissions to BS was higher. In addition, the evaluation of organic carbon (OC) contribution revealed that lipids from BS contributed more OC and that the contribution of fatty acids to OC was higher than that of n-alkanes. This study provides useful information for further understanding the sources and influencing factors of organic aerosols.