2009 年 43 巻 4 号 p. 199-211
Volatile organic compounds (VOC) are ubiquitously trace species in the atmosphere and play a variety of roles in the chemistry of atmosphere, including as precursors of photochemical smog formation, carriers of ozone-destroying halogens into the stratosphere, and radiatively active gases that affect on the Earth's climate system. This review summarizes our geochemical studies regarding emission sources, transport processes, and past trend of VOC in the atmosphere. The major results are (1) vertical profiles of non-methane hydrocarbons over east Asia are caused mainly by the mixing of fresh emissions with aged air masses containing reactivity-determined amount of photochemically aged non-methane hydrocarbons, (2) atmospheric concentration of methyl chloride, a naturally occurring ozone-depleting substance, was relatively constant, being similar to the present levels, during the pre-industrial Holocene, and (3) tropical plants produce methyl chloride with a biogenic mechanism and global methyl chloride emission by tropical plants represents 30-50% of the global emissions.
