オホーツク海南部の春季植物プランクトンブルーム期における大気有機エアロゾルの起源と生成過程

抄録

Marine organic aerosol (OA) affects the local climate through direct aerosol-radiation interactions and by altering the cloud properties. The Sea of Okhotsk is one of the most biologically productive oceans, especially during spring bloom period, which is expected to act as a huge source of OA. However, origin and formation process of OA in that oceanic region are not well understood. Continuous ground-based sampling of submicrometer aerosols was conducted, at a coastal site of the southern Sea of Okhotsk, in Mombetsu from August 2023 to March 2025. During the spring bloom in March and April 2024, submicrometer aerosol was dominated by organic matter (OM) (46±18%), followed by sulfate (30±10%). OM was highly water-soluble and overall analysis by stable carbon isotope ratios and molecular tracers in aerosols suggested that aerosol water-soluble organic carbon (WSOC) was attributable to marine secondary OAs associated with α-pinene and dimethyl sulfide in that oceanic region during the bloom.