地球環境学堂 大気環境科学Volatile organic compounds (VOCs) emitted from Akamatsu (Pinus densiflora) or Japanese red pine, the predominant conifer species found in Japan, were measured by gas chromatography with flame ionization detection (GC-FID). Eleven chromatographic peaks were obtained and assigned by standard samples except the biggest peak called X1. Based on various considerations, X1 was assigned as the peak of β-phellandrene. The total OH reactivity was also measured by a laser flash pump-probe technique at the same time as the GC analysis. The experiments were performed under a daily cycle simulated by controlling temperature and light intensity. A comparison between the expected OH reactivity calculated from the GC measurements and the measured OH reactivity revealed the existence of undetermined VOCs accounting for about 40% of the total OH reactivity. The unaccounted- for reactivity did not show any positive correlation with predominant monoterpenes detected from Akamatsu.我国の優勢樹種であるアカマツから放出されるVOC濃度をGC-FIDにより測定した。11のピークのうちの未同定であったX1をβ-phellandreneと同定した。VOC測定と同時にレーザー分光法による総OH反応性を測定した。温度および光強度を制御して日サイクルを模擬的に作り出しVOCおよびOH反応性を測定した。個々のVOC測定から導かれる総OH反応性の計算値とレーザーにより実測される値の比較を行った。その結果、４割の未知VOCの存在が明らかとなった。未知VOCは観測されたいずれのモノテルペン類とも相関が低かった。