| Project/Area Number |
16340175
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geochemistry/Astrochemistry
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| Research Institution | National Institute for Environmental Studies |
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Principal Investigator |
YOKOUCHI Yoko National Institute for Environmental Studies, Environmental Chemistry Division, Independent Senior Research Scientist, 化学環境研究領域, 主任研究官 (20125230)
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| Co-Investigator(Kenkyū-buntansha) |
ARAMOTO Mitsutaka University of the Ryukyus, Tropical Biosphere Research Center, Professor, 熱帯生物圏センター, 教授 (20045115)
SAITO Takuya National Institute for Environmental Studies, Environmental Chemistry Division, NIES Postdoc fellow, 化学環境研究領域, NIESポスドクフェロー (40414370)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥9,600,000 (Direct Cost: ¥9,600,000)
Fiscal Year 2005: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥6,500,000 (Direct Cost: ¥6,500,000)
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| Keywords | methyl chloride / subtropical plants / emission / Iriomote Island / tree fern / 放出量 / 大気 / 熱帯植物 / 症物起源有機化合物 / 放出機構 |
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| Research Abstract |
(1)Screening of methyl chloride emitting plants
In order to find methyl chloride emitting plants, we put one or multiple leaves detached from a plant into a 40 ml-vial, and measured methyl chloride concentration in it after a few days. Two hundred and fourteen species of subtropical plants were collected in Iriomote Island. Thirty-two species among them were found to emit methyl chloride with average emission rate of 0.11〜0.51μg・(g dry wt)^<-1>・hr^<-1>.
(2)Measurements of atmospheric methyl chloride in Iriomote Island
Air samples were collected at 5 sites in August and at 6 sites in February, and were analyzed for methyl chloride. Highest concentration, 2750 ppt, was observed at a forestal site. In the samples collected at coastal sites, 40〜50 ppt difference was found between the upwind sample and the downwind sample, suggesting accumulation of methyl chloride during the transport over the island covered by tropical forests. Based on the wind velocity and assumed mixing height, the emission rate of methyl chloride from the forest was calculated to be 5〜100μg・m^<-2>・h^<-1>, which would correspond to annual total emission of 10〜250 metric ton from the whole island.
(3)Factors affecting methyl chloride emission from plants
Foliar emission rates of methyl chloride from tropical tree ferns were investigated using a bag enclosure method. Cyateha lepifera showed a midday decline in emission rates, whereas Cyathea podophyla showed a midday maximum. However, both of the ferns had a midday minimum in their methyl chloride emission in the experiment using a dynamic mass balance chamber. Increased ambient temperature enhanced methyl chloride emission from Cyathea podophylla, but suppressed the emission from Cyateha lepifera.
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