温度对农田N_2O产生与排放的影响

Impacts of Temperature on N 2O Production and Emission.Zheng Xunhua,Wang Minging et al.

以华东太湖地区的水稻－冬麦轮作农田为研究对象，采用基于箱法－气相色谱法的自动连续观测系统，对整个轮作周期的Ｎ２Ｏ排放和温度进行了同步自动连续观测，同时，在实验室开展了一系列的模拟实验，以研究Ｎ２Ｏ产生与排放过程的温度效应．实验研究结果表明，在土壤湿度适宜的一定温度范围内，Ｎ２Ｏ排放通量对温度的依赖性可用指数函数Ｆ＝Ａｅａｔ来描述；轮作周期内显著Ｎ２Ｏ排放发生的频率随温度的变化呈正态分布，６７％的排放量都集中在１５—２５℃温度范围内；在旱地阶段，温度是影响Ｎ２Ｏ排放季节变化的关键因子，而在水田阶段则不然；水田和旱地Ｎ２Ｏ排放具有相同的规律性日变化形式，但后者达到极大值的时间要比前者延迟约３ｈ．

N 2O emission fluxes from a rice wheat rotation ecosystem of the Taihu Region in Southeast China and temperature of air and soil were simultaneously measured with an automated system to understand the effects of temperature on N 2O emission. The principle of this automated system for N 2O emission measurement was based on static chamber techniques and gas chromatography with an electronic capture detector. Additionally,some simulated experiments were also undertaken in laboratory to study temperature impacts on N 2O production. Based on the results from this experimental study,conclusions as following could be drawn. N 2O emission flux from fields with suitable moisture is exponentially correlated to top soil temperature. The occurring frequency of significant N 2O emission in a rice wheat rotation cycle versus top soil temperature is in normal distribution,with 67% of the total N 2O amount emitted within 15—25℃. Temperature is rather a key factor regulating N 2O emisson from wheat fields. However,on significant relationship between temperature and seasonal variation of N 2O emission from rice field was found.Although the diurnal maximum of N 2O emission from rice fields which occurs simultaneously with diurnal temperature peak appears about 3 hours earlier than that from wheat fields,the diurnal variation patterns from both rice and wheat fields are the same.