Thirteen-years of observations on primary sugars and sugar alcohols over remote Chichijima Island in the western North Pacific

In order to understand the atmospheric transport of bioaerosols, we conducted long-term observations of primary sugars and sugar alcohols over remote Chichijima Island in the western North Pacific from 2001 to 2013. Our results showed that concentrations of total sugar compounds for 13 years ranged from 1.2 to 310 ng m−3 (average, 46 ± 49 ng m−3). We found that atmospheric circulations significantly affect the seasonal variations of bioaerosol distributions over the western North Pacific. The primary sugars (glucose and fructose) maximized in summer, possibly due to a decreased transport of Asian aerosols and increased local emission of vegetation products from the vascular plants in Chichijima. We also found higher concentrations of sugar components (arabitol, mannitol and trehalose) in more recent years during summer/autumn, suggesting an enhanced emission of fungal and microbial species over the island. Sucrose peaked in late winter to early spring, indicating a springtime pollen contribution by long-range atmospheric transport, while elevated concentrations of sucrose in early summer could be assumed to be long-range transport of soil dust from Southeast Asia to Chichijima. Positive matrix factorization analyses suggested the locally emitted sugar compounds as well as long-range transported air borne pollen grains, microbes and fungal spores are the major contributors to total sugar compounds in the Chichijima aerosols. Backward air mass trajectories support the atmospheric transport of continental aerosols from the Asian continent during winter/spring over Chichijima.