N. BoontanonS. WatanabeT. OdateN. YoshidaNarin Boontanonนรินทร์ บุญตานนท์Mahidol University. Faculty of Environment and Resource Studies.Japan Science and Technology Agency. 2SORST project.Japan Marine Science and Technology CenterJapan. National Institute of Polar Research.Interdisciplinary Graduate School of Science and Engineering. Department of Environmental Science and Technology.2015-08-152019-12-232015-08-152019-12-232015-08-152010Biogeosciences Discussions. Vol.7, No.5 (2010), 7207-7225.1810-6277 (Print)1810-6285 (Online)https://repository.li.mahidol.ac.th/handle/20.500.14594/48481The distribution of dissolved CH4 in the Southern Ocean at 140 E was measured during the austral summer. Surface CH4 was supersaturated on average, and the calculated mean sea-air flux rate was 0.32 μmolm−2 d−1. The vertical distributions exhibited a CH4 5 maximum at approximately 125 m (ÉCH4, 2.94 nM) below the chlorophyll-rich layer, suggesting a relationship between CH4 production and plankton dynamics in this area. CH4 oxidation and ocean movement characteristics in the deep layer led to the enrichment and fluctuation of 13CCH4 . We estimated the influence of Southern Ocean CH4, a source of isotopically heavy CH4 to the atmosphere, on the global CH4 budget 10 to be approximately 0.19Gg d−1.engMahidol University.MethanecarbonArticle10.5194/bgd-7-7207-2010