中国稻田CH_4排放量估算研究综述

LITERATURE REVIEW ON ESTIMATION OF METHANE EMISSION FROM PADDY FIELDS IN CHINA

稻田是大气CH4的重要排放源,对中国稻田CH4排放量做出准确估算是中国CH4研究的主要目的之一。估算稻田CH4排放的方法主要有四种:根据田间测定结果或特定的排放系数和该值代表的稻田面积外推计算;将水稻的净初级生产力(NPP)的折算系数与模型相结合进行估算;根据新投入到土壤的有机碳量或原有土壤有机质碳折算;机理模型计算。其次,还有模型与GIS技术、其他方法相结合估算。稻田CH4排放在空间和时间尺度上的变异性是估算结果不确定性的主要驱动因素。统计分析显示中国稻田CH4排放量为8.4(7.2～9.5)Tga-1。

Paddy fields are an important source of atmospheric methane. One of the objectives in methane researches is to estimate exactly the amount of methane emission from paddy fields. Currently there are mainly four methods ： 1 ） extrapolation based on field measurements or specific emission coefficient and the acreage of paddy fields the value represents; reckoning by combining conversion coefficient of rice net primary production with models; conversion based on amount of organic carbon newly applied into the soil or the intrinsic soil organic carbon; and calculation by modeling. Besides, there are some other methods, like combining modeling with GIS technique or others. Spatial and temporal variation of methane emission from paddy fields are the primary factors leading to uncertainty of estimation. Statistic analysis shows that the amount methane emission emitted from the paddy fields in China is estimated at 8.4（7.2 -9.5）Tg a^-1