Permalink : http://hdl.handle.net/2115/45164

海洋生物生産の活発な時期における海洋大気エアロゾル中の有機物組成と生物起源の寄与を明らかにすることを目的として, 外洋域における有機炭素および有機態窒素の質量粒径分布測定を行った. 本稿では, その結果について解説する. 夏季の西部北太平洋での有機エアロゾルの放出源として海洋生物の影響が大きく, その組成は有機態窒素に富むことが明らかになった. 安定炭素同位体比の分析から, 本研究海域でのエアロゾル全炭素に占める海洋生物起源の割合は46-72%と見積もられた.
Size-segregated aerosol samples were collected over the western North Pacific in the summer of 2008 for the measurements of organic nitrogen (ON) and organic carbon (OC). ON and OC showed bimodal size distributions and their concentrations showed positive correlation with those of biogenic tracers, methanesulfonic acid and azelaic acid. We found that average ON and OC concentrations were twice greater in aerosols obtained in the oceanic region with higher biological productivity than with lower biological productivity. The average ON/OC ratios are higher (0.49±0.11) in more biologically influenced aerosols than those (0.35±0.10) in less biologically influenced aerosols. Stable carbon isotopic analysis indicates that marine-derived carbon accounted for ～46-72% of total carbon in more biologically influenced aerosols. These results provide evidence that organic aerosols in this region are enriched in ON that is linked to oceanic biological activity and the subsequent emissions to the atmosphere.