中文摘要：

采用FACE田间试验,对高CO2浓度影响稻田CH4排放规律进行了观测分析,并利用δ13C技术初步分析了土壤CH4的排放来源。结果显示,植株和土壤的CH4排放速率在高CO2浓度处理大于对照18%以上,其增加幅度为土壤大于植物,CH4排放速率可能受田间水分条件影响较大。与对照比较,高CO2浓度条件下植物和土壤部分CH4累积排放总量增加,且变化幅度随生长期而降低,前期（54d）常规氮处理（NN）高于低氮处理（LN）,后期LN高于NN;但是行间裸土CH4累积排放总量在前期（54d）增加和之后降低的幅度均为NN高于LN。土壤排放CH4δ13C值从移栽到第102d,高CO2浓度处理LN和NN水平下土壤对照（CK）仅分别升高9.0%和8.3%,种水稻则降低8.8%和8.1%;但是在对照CO2浓度条件下土壤对照降低17.2%和112.5%（P=0.047）,种水稻降低40.3%和105.9%（P=0.023）,表明高CO2浓度下有更多C4来源的碳释放,对照CO2浓度条件下有更多C3来源的碳释放。水稻不同生长期与土壤对照比较,种水稻土壤排放CH4δ13C值降低的幅度总和在高CO2浓度条件LN和NN水平下分别为114.8%和72.7%,对照CO2浓度条件下分别为41.9%和72.8%,表明在种有植物的情况下更多当季的碳分解释放,LN水平下高CO2浓度促进来源于当季碳的CH4排放,NN水平下没有发现CO2浓度的影响,可能与作物生物量和它的间接产物（根系分泌物）的影响有关。

英文摘要：

This study was conducted indirectly to analyze the effects of elevated CO2 on CH4 emission from different pools in rice paddy field based on the 13C isotope technique.Results showed that in rice season elevated CO2 increased the CH4 emission from plant and soil in field morn than 18% compared to ambient CO2,with great degree for soil than plant,which was affected maybe by water content changes.Compared with the control the cumulative CH4 emissions were increased from plants and soil under conditions of high CO2 concentrations,and the magnitude of changes lowered with the growing season.Cumulative CH4 emissions increasing magnitude was higher at NN than at LN before earlier stage（54 days）,and higher at LN than at NN in latter growth stage.However,cumulative CH4 emissions from control without plant（CK）in the earlier period（54 days）to increase and in latter stage to decrease were larger at NN than at LN.From transplanting to the 102 days,soil emission CH4 δ13C values were increased only by 9.0% and 8.3% in contro（lCK）at LN and NN levels under high CO2 concentration,decreased by 8.8% and 8.1% in soil with plant,but under the control CO2 concentration it was decreased by 17.2% and 112.5%（P=0.047）in contro（lCK）and by 40.3% and 105.9%（P=0.023）in soil with plant at LN and NN levels,respectively.Results suggested that there are more carbon emissions from C4 source under elevated CO2 concentrations and morn from C3 sources under control CO2 concentration.At different growth stages of rice,compared with the soil control the sum of soil emission CH4 δ13C value reduced under condition with plant growth were 114.8% and 72.7% at LN and NN levels under high CO2 concentration,were 41.9% and 72.8% under control CO2 concentration.Results indicated that there are more new carbon decomposed to release under plants growth and,elevated CO2 concentration promote the CH4 emissions from new carbon sources at LN,which might be related to biomass and its indirect products（root exudates）related to the impact