Aerosol Proteinaceous Matter in Coastal Okinawa, Japan: Influenceof Long-Range Transport and Photochemical Degradation

The characteristics, sources, and atmosphericoxidation processes of marine aerosol proteinaceous matter(APM), including total proteins and free amino acids (FAAs),were investigated using a set of 1 year total suspended particulate(TSP) samples collected in the coastal area of Okinawa Island in thewestern North Pacific rim. The concentrations of APM at this site(total proteins: 0.16 +/- 0.10 mu gm-3and total FAAs: 9.7 +/- 5.6 ngm-3, annual average) are comparable to those of marine APM. Themajor FAA species of APM are also similar to previously reportedmarine APM with glycine as the dominant species (31%). Based onthe different seasonal trends and weak correlations of total proteinsand FAAs, we found that they were contributed by different sources,especially with the influence of long-range transport from the Asiancontinent of northern China and Mongolia and the oceanic area of the Bohai Sea, Yellow Sea, and East China Sea. Thephotochemical oxidation processes of high-molecular-weight proteins releasing FAAs (especially glycine) were also considered as animportant factor influencing the characteristics of APM at this site. In addition, we propose a degradation process based on thecorrelation with ozone and ultraviolet radiation, emphasizing their roles in the degradation of proteins. Ourfindings help to deepenthe understanding of atmospheric photochemical reaction processes of organic aerosols

Automated summary

This research investigated the characteristics, sources, and atmosphericoxidation processes of marine aerosol proteinaceous matter (APM) in the coastal area of Okinawa Island. The concentrations of APM were comparable to those of marine APM, and different sources, including long-range transport from northern China and Mongolia and oceanic areas, contributed to the total proteins and free amino acids (FAAs). The photochemical oxidation processes of high-molecular-weight proteins releasing FAAs were also found to influence the characteristics of APM.