【作者】 杨光明；

【导师】 沙丽清；

【作者基本信息】 中国科学院研究生院（西双版纳热带植物园） ， 生态学， 2007， 硕士

【摘要】 随着人们对全球气候变化的日益关注,有关温室气体排放的研究已经成为研究的热点。我国五大稻作区稻田生态系统CH4、CO2和N2O通量已经有大量观测数据,但是热带地区水稻田CH4、CO2和N2O通量还未有观测。本研究采用静态箱(暗箱)-气相色谱法对云南西双版纳热带地区单季稻田CH4、CO2和N2O通量进行了田间原位观测。试验从2005年1月开始到2005年12月结束,包含了水稻生长季节和水稻田休闲期。试验设置了三个处理,即无氮肥对照处理(NN)、低氮施肥处理(LN)和高氮施肥处理(HN),氮肥(尿素和复合肥)水平分别为0 kg N hm-2、150 kg N hm-2和300 kg N hm-2。本研究的主要结果如下:1)水稻生长季节稻田CH4和CO2排放通量有明显的季节变化,而N2O的排放受施肥和晒田影响大,无明显的季节变化规律。2)水稻生长季节稻田CH4和CO2排放通量有明显的日变化规律。CH4排放的日变化有三种类型,即午后单峰型、下午和夜间双峰型以及无规律型。CO2排放的日变化呈午后单峰模式,而N2O排放无明显的日变化规律。3)与无氮肥对照相比,水稻生长季节不同氮肥水平处理对CH4排放通量的影响规律不明显,但是明显促进了CO2和N2O的排放。CH4、CO2和N2O排放通量的变化不能完全由温度变化来解释。CH4、CO2和N2O排放通量与稻田水深均无显著的相关关系。4)水稻生长季节无氮肥对照处理(NN)、低氮施肥处理(LN)和高氮施肥处理(HN)的CH4季节平均排放通量分别为6.69±0.37、7.19±0.43和6.04±0.31 mg m-2 h-1,CO2季节平均排放通量分别为543.28±27.57、680.92±32.26和724.58±32.40 mg m-2 h-1,N2O季节平均排放通量分别为0.04±0.01、0.17±0.03和0.15±0.03 mg m-2 h-1。5)休闲期稻田表现为排放CH4、CO2和N2O,但是无明显的季节排放规律。休闲期稻田CH4、CO2和N2O排放与水稻生长季节的施肥处理无明显的相关性。休闲期稻田CH4和N2O排放通量与土壤湿度有极显著的线性相关关系,而CO2排放通量与土壤湿度和采样时箱内温度都有极显著的指数相关关系。6)休闲期稻田无氮肥对照处理(NN)、低氮施肥处理(LN)和高氮施肥处理(HN)的CH4季节平均排放通量分别为0.51±0.16、0.19±0.03和0.09±0.02 mg m-2 h-1,CO2季节平均排放通量分别为220.56±7.76、195.18±6.99和228.36±7.94 mg m-2 h-1,N2O季节平均排放通量分别为0.04±0.00、0.03±0.01和0.04±0.01 mg m-2 h-1。7)水稻生长季节稻田CH4、CO2和N2O累积排放量分别占全年排放量的83.26-96.37%,48.24-56.90%和32.24-71.07%,可见稻田CH4排放以水稻生长季节贡献较大,而休闲期CO2和N2O排放也不容忽视。更多还原

【Abstract】 The global climate change is becoming a special concern, which leads to the hot discussion of greenhouse gases emission. So far the data about CH4, CO2 and N2O emission are already available in all the five major rice culture regions in China, but there is still no relevant observation in tropical regions of China. By using static opaque chamber and gas chromatography techniques, field experiments were carried out to investigate CH4, CO2 and N2O fluxes from paddy field in Xishuangbanna, Yunnan, Southwest China. The experiment period lasted from January to December in 2005, including the rice growing season and the fallow stage. Three treatments were applied as the control(NN, no nitrogen fertilizer application), low nitrogen fertilizer level (LN, 150 kg N hm-2) and high nitrogen fertilizer level (HN, 300 kg N hm-2). The results were as follows:1) During rice growing season obvious seasonal changes occurred in CH4 and CO2 fluxes. Greatly controlled by water level and fertilization, N2O fluxes showed no marked seasonal variations.2) There were obvious diurnal variations in CH4 and CO2 fluxes. Three types of diurnal variation of CH4 emission were observed, which were afternoon-maximum mode, two-peak mode with maxima occurred both in the afternoon and at night and the irregular mode. The diurnal changes of CO2 fluxes followed afternoon-maximum pattern, while the diurnal changes of N2O fluxes showed no clear regularity.3) Compared with NN treatment, fertilization had no significant effect on CH4 emission, but remarkably promoted CO2 and N2O emissions in rice growing season. The changes of CH4, CO2 and N2O fluxes could not be fully explained by temperature variations. No pronounced correlations were found between water depth and the fluxes of CH4, CO2 and N2O.4) In rice growing season, the calculated seasonal mean CH4 fluxes were 6.69±0.37, 7.19±0.43 and 6.04±0.31 mg m-2 h-1 for treatments NN, LN and HN, respectively, and the corresponding seasonal mean CO2 fluxes were 543.28±27.57, 680.92±32.26 and 724.58±32.40 mg m-2 h-1, respectively, and accordingly the seasonal mean N2O fluxes were 0.04±0.01, 0.17±0.03 and 0.15±0.03 mg m-2 h-1, respectively.5) The paddy feild emitted CH4, CO2 and N2O in fallow season, however, which demonstrated no clear seasonal changes. Nitrogen fertilizer applied to the field in rice growing period showed little effect on the fallow season emissions of CH4, CO2 and N2O. CH4 and N2O fluxes significantly depended on soil moisture, and CO2 fluxes exponentially increased both with the increase of soil moisture and inner chamber temperature.6) During fallow period, the seasonal average CH4 fluxes were 0.51±0.16, 0.19±0.03 and 0.09±0.02 mg m-2 h-1 for treatments NN, LN and HN, respectively,and the seasonal average CO2 fluxes were 220.56±7.76, 195.18±6.99 and 228.36±7.94mg m-2 h-1, respectively, and the seasonal average N2O fluxes were 0.04±0.00, 0.03±0.01 and 0.04±0.01 mg m-2 h-1, respectively.7) The cumulative CH4, CO2 and N2O emissions from paddy field over rice growing season accounted for 83.26-96.37%,48.24-56.90% and 32.24-71.07% of the annual cumulative CH4, CO2 and N2O emissions, separately, which indicated that the CH4 emissions played a vital role in rice growing season and the CO2 and N2O emissions over fallow season could not be neglected.更多还原