HR: 0800h
AN: A11C-0616    [Abstracts]
TI: Decrease events of atmospheric carbonyl sulfide and methyl chloride observed at Hateruma Island in spring
AU: * Yokouchi, Y
EM: yokouchi@nies.go.jp
AF: National Insitute for Environmental Studies, 16-2, Onogawa, Tsukuba, 305-8506, Japan
AU: Saito, T
EM: saito.takuya@nies.go.jp
AF: National Insitute for Environmental Studies, 16-2, Onogawa, Tsukuba, 305-8506, Japan
AU: Mukai, H
EM: lnmukaih@nies.go.jp
AF: National Insitute for Environmental Studies, 16-2, Onogawa, Tsukuba, 305-8506, Japan
AB: Carbonyl sulfide (COS) and methyl chloride (CH₃Cl) are the most abundant sulfur-containing organic gas, and the most abundant chlorine-containing organic gas, respectively, and their sources and sinks are not fully understood. We have conducted high frequency measurements of these two compounds along with twenty more VOCs using an automated preconcentration/GC-MS at Hateruma Island(lat. 24.1°N, long. 123.8°E). The observation showed occasional decrease of their baseline concentrations (up to -200 ppt for COS and -60 ppt for CH₃Cl) in spring, as well as occasional short-term enhancements over hours to days. The latter enhancements were also observed for other anthropogenic gases such as HFCs and HCFCs, and are considered to be caused by surrounding East Asian sources. On the other hand, the baseline drops were obvious only for COS and CH₃Cl, being related to the airmass trajectory from high altitude inland China. Considering that spring is the "kosa" (yellow dust originating mainly from Gobi Desert and Takla Makan Desert) season, a possible cause for the decrease might be adsorptive loss of COS and CH₃Cl to the dust during the long range transport.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0365 Troposphere: composition and chemistry
DE: 1610 Atmosphere (0315, 0325)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting