中文摘要：

通过田间试验研究了持续淹水稻田冬季休闲期和水稻生长期CH4排放通量及其稳定性碳同位组成的时间变化。结果表明：CH4排放在冬季休闲期从4月份呈逐渐上升趋势，至6月份出现排放峰，为CH46．4mgm^-2h^-1；水稻移栽后则迅速增加，于7月和8月出现两个排放峰，分别为CH423．1mgm^-2h^-1和CH429．8mg^-2h^-1此后急剧下降，末期稻田排水落干期间出现一个排放峰。冬季休闲期CH4排放总量为CH43．3gm^-2，占全年排放总量的8．9％。稻田排放的δ^13C在冬季休闲期后期逐渐从-51‰上升至-44‰，然后下降至-56‰。水稻移栽后，δ^13C值从-62‰迅速降至一68％0，然后慢慢上升至-60‰，并在较长一段时间内保持不变，后期再次富集δ^13C末期排水落干对排放δ^13C影响显著。排放δ^13C在水稻生长期较冬季休闲期低得多，原因在于冬季休闲期的CH4氧化率很高（60％-90％），而水稻生长期的CH4氧化率相对较低（10％-80％）。全观测期内，CH4排放通量的季节变化均与土壤温度显著正相关（P〈0．01），与土壤Eh显著负相关（P〈0．01），与δ^13C呈显著负相关（P〈0．05）。

英文摘要：

Investigations were carried out of CH4 emission and its δ^13C values from a rice field under continuous flooding throughout the fallow and following rice seasons. Results show that in the fallow season CH4 flux rose from April and reached a peak value, about 6.4 mg m- 2 h-1, in June. After rice transplanting, CH4 flux increased quickly at the beginning of the rice season and two peaks occurred in July and August, reaching 23.1 and 29.8 mg m-2 h-1, respective- ly, which was followed by a rapid decrease. Then another peak appeared during the final drainage before rice harvest. The total CH4 emission in the fallow season amounted to 3.3 g m - 2, accounting for 8.9% of the annual total emission. On the other hand, 813 CH4 （emitted）increased gradually from -51%r to -44‰, and then dropped back to -56‰ in the late fallow season. After rice transplanting,δ^13C value decreased from -62‰ to -68‰firstly and then increased swiftly to -60%o, which afterwards remained unchanged for a relatively long time. Late in the season, emitted CH4 became ^13C enriched again. The impact of the final drainage on δ^13CH4 （emitted） was remarkable. Theδ^13C value of emitted CH4 was heavier in the fallow season than in the rice season, because the fraction of CH4 oxidized was higher in the fallow season （60% - 90% ） than during the following rice season （10%- 80% ）. Within the whole observation period, the temporal variation of CH4 flux was positively related to soil temperature （p 〈0. 01 ） , but negatively related to soil Eh （p 〈0.01 ） and to δ^13C value （p 〈0.05） as well.