沖縄辺戸岬で採取したエアロゾル中の低分子ジカルボン酸類の分布と季節変化

• クンワル バガワティ

  北海道大学

• 河村 公隆

  北海道大学

書誌事項

タイトル別名

• Chemical composition and seasonal variation of low molecular weight dicarboxylic acids and related compounds in the marine aerosols from Cape Hedo, Okinawa Island, Japan

抄録

Water-soluble organic compounds including dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls are important components of atmospheric aerosols. They have strong impacts on radiative forcing of climate, human health effects, pollution transport, and visibility degradation. Total dicarboxylic acids account for ˃10% of the total particulate carbon in the remote marine atmosphere. The main purpose of this study is to obtain the atmospheric situation in Okinawa, which is located on the outflow region of Asian countries including China, in order to better understand the origin and transformation of diacids and related compounds in their transport process.Marine aerosol samples were collected in 2009 October to 2010 October at Cape Hedo station of National Institute of Environmental Studies, Okinawa (128.28° E, 26.87° N), an outflow region of Chinese aerosols, using high-volume air sampler and pre-combusted quartz fiber filters for 7 days at a flow rate of 60 m3 h-1. The filters were extracted with Milli Q water (10 mL X 3). The extracts were passed through a glass column (Pasteur pipette) packed with quartz wool to remove particles and then concentrated near dryness using a rotary evaporator under a vacuum and were derivatized with 14% BF3 in n-butanol at 100°C for one hour. The derived dibutyl esters and dibutoxy acetals were extracted with n-hexane. The hexane layer was concentrated to ~50 μL using a rotary evaporator, transferred to small vial (1.5 mL), dried to almost dryness by N2 blow down, and dissolved in known volume of n-hexane and the samples were analysed using gas chromatography and GC/MS.Homologous series of n-diacids (C2-C12), branched diacids, unsaturated diacids, and multifunctional diacids were detected as well as ω-oxoacids (C2-C9), glyoxal and methyl glyoxal. Oxalic acid was found as the dominant species in all four seasons followed by malonic, glyoxylic and succinic acids. The highest concentrations of diacids were found in spring (ave. 88± 28 ng m^-3) followed by winter season (72± 33 ng m^-3). The lowest diacids concentrations were found in summer (30± 30 ng m^-3). Ketoacids also followed similar trend, highest in spring (8± 4 ng m^-3) followed by winter (7± 2 ng m^-3). In contrast the highest concentrations of total α-dicarbonyls were found in winter (4± 2 ng m^-3).This study reported the chemical compositions and seasonal distributions of water-soluble organic aerosols over Okinawa, suggesting an influence of long-range transport of air masses from different region in each season. Higher concentrations of diacids and related compounds in spring followed by winter suggest that the airflow from Asian continent with biogenic emission in spring and anthropogenic emissions in winter. The lower concentrations were found in summer probably due to significant contribution of clean marine air masses. Interestingly, phthalic acid/azelaic acid (Ph/C9) ratios were also found to be higher in winter (ave. 4.8) followed by autumn (1.7) and spring (1.2) and lowest in summer (0.5), indicating the highest contribution of anthropogenic sources in winter.

収録刊行物

• 日本地球化学会年会要旨集

  日本地球化学会年会要旨集 58 (0), 109-109, 2011

  一般社団法人日本地球化学会

キーワード

• ジカルボン酸
• ケト酸
• ジカルボニル
• 長距離輸送
• 沖縄

詳細情報

• CRID: 1390001205732746496
• NII論文ID: 130005054118
• DOI: 10.14862/geochemproc.58.0.109.0
• データソース種別:
  • JaLC
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可