成都平原稻田甲烷排放的实验研究

Methane Emissions from Rice Fields in the Chengdu Plain of China

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:在水稻生医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2.35～33.95％mgm-2h-1之间。4年的平均排放通量为12mgm-2h-1,与四川乐山的7年平均值30mgm-2h-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:在成都平原水稍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。

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.