MEASUREMENTS OF METHANE CONCENTRATION IN THE AIR AND SURFACE SEAWATER ON BOARD THE ICEBREAKER SHIRASE

元データ 国立極地研究所

概要

Methane concentrations in surface seawater and the lower troposphere were measured on board the icebreaker SHIRASE at almost every 5°latitude between Japan and Antarctica from November 1990 to April 1991. The atmospheric methane concentration measured in November and December 1990 was 1750-1770 ppbv in the mid-northern hemisphere, and decreased rapidly going southward until constant values of about 1670 ppbv were found in the southern hemisphere. A large discontinuity of the methane concentration was observed in the equatorial region due to suppression of interhemispheric air exchange by the Inter-Tropical Convergence Zone. The methane concentrations measured in the mid-southern hemisphere in March and April 1991 was lower by 15 ppbv than those in December 1990,reflecting the seasonal variation of the methane concentration. The methane concentration in surface seawater, which was determined by analyzing air samples equilibrated with oceanic methane, showed 3000-10000ppbv except in the Antarctic region where the concentration was about 2000 ppbv. These values were much higher than the those found in previous studies. Taking account of the fact that carbon dioxide concentrations of the air samples which were measured simultaneously agreed well with those of continuous measurements, such high concentrations cannot be ascribed to failure in sample collection. Therefore, the cause may be attributable to additional methane produced by organic decomposition in sample seawater tubing which was provided on SHIRASE.

著者

張 紀久夫 阪大基:福井工大工
Yamanouchi Takashi National Institute of Polar Research
HAYASHI Masahiko Solar Terrestrial Environment Laboratory, Nagoya University
Takata Morimasa National Institute Of Polar Research
Kawaguchi Sadao Nagaoka National College Of Technology
Hashida Gen National Institute Of Polar Research
Hashida Gen Center For Antarctic Environment Monitoring National Institute Of Polar Research
Shimohara Kimiko Kitami Institute of Technology
Nakazawa Takakiyo Center for Atmospheric and Oceanic Studies, Tohoku University
Nakazawa Takakiyo Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Aoki Shuji Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
SHIMIZU Akira National Institute for Environmental Studies
KAWAGUCHI Sadao National Institute of Polar Research
TANAKA Masayuki Center for Atmospheric and Oceanic Studies, Faculty of Science, Tohoku University
AOKI Shuhji National Institute of Polar Research
Yamanouchi Takashi National Institute For Polar Research
Aoki Shuhji Faculty Of Science Tohoku University
Tanaka Masayuki Center For Atmospheric And Oceanic Studies Faculty Of Science Tohoku University
Satow Kazuhide Nagoya Technical College
Nakazawa Takakiyo Center For Atmospheric And Oceanic Studies Graduate School Of Sci. Tohoku Univ.
Hayashi Masahiko Solar Terrestrial Environment Laboratory Nagoya University
Nakazawa Takakiyo Center For Atmospheric And Oceanic Studies Faculty Of Science
清水 明 Center For Atmospheric And Oceanic Studies Graduate School Of Science Tohoku University
Shinbori K Hokkaido Univ. Sapporo
Nakazawa T Center For Atmospheric And Oceanic Studies Faculty Of Science
Yamada T Geosystems Inc.
Kawaguchi Sadao Nagoya University
Yamanouchi Takashi National Inst. Of Polar Res. And Dep. Of Polar Sci. The Graduate Univ. For Advanced Studies 10-3 Mid
Yamanouchi Takashi National Institute Of Polar Research 10-3 Midoricho Tachikawa Tokyo Japan.
Tanaka Masayuki Department Of Materials Science And Processing Graduate School Of Engineering Osaka University
Shinbori K Nagaoka National College Of Technology
Yamada Tomomi Geosystems Inc.

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