成都平原稻田甲烷排放的实验研究

根据1996～1999年四个稻季的观测资料,分析了成都平原单季稻甲烷排放的季节变化和年际变化特征.结果表明:在水稻生长季节甲烷排放通量变化很大,在分蘖期和成熟期一般会出现峰值.年际间的通量变化也很大,其年均排放通量的变化范围在2.35～33.95mg m-2 h-1之间.4年的平均排放通量为12 mg m-2 h-1,与四川乐山的7年平均值30mg m-2 h-1相比,存在着明显的地区差异.同时分析讨论了温度、施肥、水稻品种、土壤氧化还原电位(Eh)以及稻田水位等诸多因素对稻田甲烷排放的影响.结果表明:在成都平原水稻生长季节的平均气温对CH4的平均排放通量影响不大;而气温对CH4排放的日变化有相对重要的影响,但气温对甲烷排放日变化的影响与水稻植物体的生长阶段有关;发现了水稻植物体(根、茎、叶)重量对CH4排放的重要作用.讨论了合理使用肥料和施肥量,控制水位和Eh值对稻田CH4的减排作用,提出优化组合诸影响因子,以充分发挥其减排潜力.

Methane Emissions from Rice Fields in the Chengdu Plain of China

According to the measured data of four rice seasons between 1996 and 1999, characteristics of seasonal variation and annual variation of methane emission are analyzed for single-season rice in the Chengdu Plain. The results show a great variation in methane emission during the rice growing season, and the peak values appear during tillering period and fruiting period. A great inter-annual change is also observed and ranged from 2.35 mg m 2 h-1 to 33.95 mg m-2 h-1. The averaged value of CH4 emission for the four years is 12 mg m-2 h-1. Compared with 30 mg m-2 h-1 for the 7-year average of Leshan in Sichuan Province, there is an apparent regional difference. Methane emission from rice field is affected by several factors including temperaturc, ferlilization, rice variely, soil oxidation-reduction potential and water depth of rice field and so on. Results show that the average temperature during rice growing season in the Chengdu Plain has a little influence on annual CH4 emission. However, during the early growing season, the lemperature has a relatively significant influence on daily variation of CH4 emission from rice field. Another finding is that the weights of root, stalk and leaf of rice plant body have a signif-icant influence on CH4 emission. An oplimum combinalion of many effeclive factors is proposed in order to develop its potential of reducing CH4 emission.