| 摘 要： | CH_4 emission rates have been measured continuously for the early rice of 1988 and late rices of 1987and 1988 during entire growing seasons in a rice paddy field in Hangzhou,Zhejiang Province,China,byusing an automatic sampling and analyzing system.During most parts of the seasons CH_4 emission ratesshowed strong diurnal variations.Bi-mode patterns with the highest value in the afternoon and a secondpeak at mid-night were generally found for the early rice,while the highest values were almost always foundin the night for the late rice.Bi-mode patterns with a second peak in the afternoon were also found duringthe reproductive phase of the late rice plants.These diurnal variations may be explained by the diurnalvariations of the soil temperature and the activity of rice plants.Strong seasonal variations with one peakin the tillering stage and two during the reproductive phase of rice plants were observed for all the threegrowing seasons.The seasonal variations may be explained by the activity of rice plants,availability oforganic substrates in the soil,and the activity of soil bacteria related to soil temperatures,Fertilizationdid not show significant effects on the total seasonal CH_4 emissions but slightly changed the pattern ofthe seasonal variations of the CH_4 emission rates.Averaged over the measuring periods and 8 spots,CH_4emission rates of 7.8 mg m~(-2) h~(-1) for the early rice and 28.6 mg m~(-2) h~(-1) for the late rice were obtained.Based on these measured data,the total global emission of CH_4 from rice paddies is estimated to be about 90Tg/yr ranging from 70 to 110,accounting for 20% of the total source of CH_4.
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