内蒙古典型草原土壤N2、N2O、NO和CO2排放的研究

为了进一步了解内蒙古典型草原生长季内主要温室气体氧化亚氮（N2O）、一氧化氮（NO）和二氧化碳（CO2）及反硝化终产物N2的排放，本研究采用氦环境培养--气体同步直接测定法，在不同土壤温度（5°C和20°C）和不同土壤含氧量（10%和20%）条件下，关注不同放牧处理土壤N2、N2O、NO和CO2排放。结果显示，不同放牧处理土壤N2、N2O、NO和CO2排放速率分别为0.3~2.0 μgN/(h?kg)]、0.02~0.4 μgN/(h?kg)]、0.08~0.7 μgN/(h?kg)]和0.01~1.9 mg C/(h?kg)]，N2排放为N2O的8~17倍。由于较大的空间变异性，并未观测到不同放牧处理对土壤N2、N2O、NO和CO2排放的影响。土壤温度升高和湿度增加能促进N2、N2O、NO和CO2的排放，而土壤O2含量对其排放的影响不显著。

Influence of Grazing Effects on Soil N2, N2O, NO and CO2 Emissions

To get better know the emissions of greenhouse gases (nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2)) and the end product of denitrification, dinitrogen (N2) in the typical grassland of Inner Mongolia, a gas-flow-soil-core technique with the helium-environment incubation system was used to measure these emissions from two grazing treatments. Two soil temperature (5oC and 20oC) and two levels of soil oxygen content (10% and 20%) were set for our laboratory expriement. The results showed that emission rates of N2, N2O, NO and CO2 were in the range of 0.3-2.0 μg N/(h?kg)], 0.02-0.4 μg N/(h?kg)], 0.08-0.7 μg N/(h?kg)]) and 0.01-1.9 mg C/(h?kg)], respectively. The N2 emissions were 8-17 times as high as N2O emissions. Due to the higher spatial variability, no significant differences of N2, N2O, NO and CO2 emissions and two grazing treatments were detected. Soil temperature and soil water content had a positive effect on N2, N2O and NO emissions, whereas the soil oxygen content had no effect on their emissions.