【摘要】 室内模拟研究不同水热条件下土壤中N2O的释放特征,有助于阐明N2O释放的水热效应机理。本文通过室内试验研究了西北地区的典型耕种土壤土娄土中N2O在不同水温变化下的释放特征,借助化学反应动力学理论对其释放机理进行了初步的探讨。结果表明:10℃和30℃下,不同含水量的土壤中N2O的浓度变化随着培养时间的延长呈"S"型曲线。可用方程C=1/[A+Bexp(-t)]来描述。随着温度的升高(10℃到30℃),N2O释放的快速期,减速期,稳定期的启动时间明显提前。在较低的土壤湿度范围内(27%至58%wfps),土壤中N2O释放的稳定浓度与土壤湿度呈正相关;田间持水量(58%wfps)时,N2O释放的稳定浓度达到最大;超过田间持水量时,其逐渐变小。当土壤湿度从27%-42%wfps增加时,30℃下土壤中N2O释放的稳定浓度大于10℃下的;当土壤湿度等于或大于田间持水量(58%wfps)时,30℃下土壤中N2O释放的稳定浓度小于10℃下的。低温下(10℃)的风干土壤(8%wfps)存在吸收N2O的现象。不同水热条件下土壤硝化和反硝化过程中N2O释放的表观化学反应速率常数和对应活化能的大小决定了土壤中N2O的释放量及难易程度。更多还原

【Abstract】 Model experiment provides possibilities for the study of N₂O emission from soil under different water and temperature regimes. Effects of water and temperature on the N₂O emission and the preliminary mechanism of the soil N₂O emission were studied in terms of the kinetic theory of chemical reactions in the Lou soil-a typically cultivated soil in arid and semiarid region in the Northwester of China. Results showed: the curve of soil N₂O concentration with incubation time under the different water regime is "S-shaped" and can be described by the equation C=1/[A+Bexp（-t）] when the incubation temperatures are 10℃and 30℃. The startup time of fast-stage, deceleration-stage and stable stage of soil N₂O emission were advanced clearly with the increase of incubation temperature from 10℃to 30℃.The stable concentration of N₂O increased with the increase of soil water contents （from 27 to 58% wfps）, and it became smaller gradually when water content was above the field water capacity. The highest concentration occurred at the field water capacity （58%wfps）. The stable concentration at the 30℃ was higher than that at the 10℃ when the soil moisture varied from 27 to 42%wfps. However, the trend was opposite when water content was above the field water capacity （58%wfps）. Also, the air-dried soil （8%wfps） could absorb N₂O weakly at the lower temperature （10℃）.The apparent rate constant and activation energy of soil nitrification and denitrification process dominated the soil N₂O emission in the different water and temperature regime.更多还原