黄绵土N_2O排放的温度效应及其动力学特征  

The effect of temperature and moisture on N_2O flux kinetics from loessial soil

作　　者：雒新萍[1] 白红英[1] 路莉[1] 李西祥[1] 张清雨[1] 

机构地区：[1]西北大学城市与资源学系,陕西西安710127

出　　处：《生态学报》2009年第3期1226-1233,共8页Acta Ecologica Sinica

基　　金：国家科技基础性工作专项重点资助项目(2007FY110800);陕西省自然科学基金资助项目(2006D02);西北大学科学研究资助项目(Okyqdf123)

摘　　要：以室内试验为手段,以黄绵土为供试土壤,研究了不同水热条件下农田土壤中N2O的排放特征,并借助于化学反应动力学理论对N2O排放的热效应机理进行了探讨。结果表明:在适宜的温度范围内,表现为土壤N2O排放量随温度升高而增大。14.50%水分时,20～25℃温区N2O排放呈现"跃增"现象,即温度效应较强,而18.70%和22%水分时,N2O排放的"跃增区"分别出现在15～20℃温区和25～30℃温区,即水分条件影响着N2O排放的温度效应。土壤N2O累积排放量随时间t的变化均符合修正的Elovich方程y=a+blnt,并应用表观排放速率b从动力学角度验证了N2O排放"跃增"现象的存在。在一定的水分条件下,随着温度的增加,土壤N2O排放出现最大值(此时温度为T0),在T1～T0温区内,随温度升高土壤N2O排放量增加,在T0～T2温区内,随温度升高土壤N2O排放量降低,对于黄土性土壤而言,这一转折点(T0)在30℃左右。7.86%水分时干燥土壤存在吸收NO的现象。A laboratory experiment was conducted to determine the effect of temperature and moisture on N2O flux from a loess-derived agricultural soil. A mechanism explaining the effect of temperature on N2O flux was proposed based on kinetic theory of chemical reactions. Results showed that under normal temperature, N2O flux increased as temperature increased. When soil water content was 14.50% w/w, N2O flux was highest between 20 -25℃. In contrast, N2O flux was highest between 15 -20℃ when soil water content was 18.70% w/w and between 25 -30℃ when soil water content was 22% w/w. Thus, soil water content influenced the effect of temperature on soil N2O flux. Curves showing accumulated N2O flux across time were described by the revised Elovich equation y = a ＋ blnt. The apparent reaction rate b was used to verify the existence of elevated N2O flux under certain temperature conditions from a kinetic view point. Within the same soil moisture treatment, N2O flux was a maximum at T0. Soil N2O flux increased as temperature increased in the area from T1- T0. In contrast, soil N2O flux decreased as temperature rose in the area from T0- T2. In this loess-derived soil, the turning point （ TO ） occurred at approximately 30℃. In addition, we observed that N2O was weakly absorbed when soil water content was 7.86% w/w.

关 键 词：水热因子 土壤N2O排放 动力学方程 表观反应速率 温度效应 

分 类 号：S154[农业科学—土壤学]