An experimcnt was carried out in Six controlled ・ environment chambers to study the effects of elevated CO20n CH . , and N20 emissions from submerged rice soi1 . In three chambers , CO2 concentration was maintained at 350 μ mol mo1 −1 ( arnbient CO2 ) , while in another three , CO2 was controlled at 650 μ mol mo 工 一 1 ( elevated CO2) throughout a rice growing season from May 15 to September 25 , 2002 .At the heading stage of rice ,200 %o δ 13 C − CO2 was fed to all chambers for three days , the

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... δ i3C value of emitted CH , and disso 星 ved CH . , ill flooding water and soil solution were measured by an IRMS befOre and after し he feeding . The results showed that the increase in CH , emission by elevated COz was significant afLer the flowering stage of ricc , regardless of the transport pathways , either plant mediated or ebullition ・ diffusion . The emitted CH4 by ebullition − diffusion accounted for l5 − 20 % of total emission ill both alnbient arld elevated CO2 condltions . N20 was emitted only first 3 weeks after rice transplanting and fertilization 、 There was no difFerence in N20 emissiQn between ambient and elevated COz . Injected N fertilizer h1 5 cm below soil surface did not bring N20 emission at booting stage . The dissolved CH4 and N20 in fioeding water alld soil solution also shown same trerld with CH4