Abstract: A four-year survey (1999-2002) was conducted of the atmosphere CO₂ concentration above the Inner Mongolia grassland and its variations during the grass growing season. The result shows that the grass growing season witnessed significant changes of both CO₂ concentration at large,and CO₂ concentration above the grassland surface in vertical gradient,within a day and one day from another, The 4-year daily mean CO₂ concentration in the atmosphere averaged 361.6 μL/L;and the annual variation fluctuated around 13.5 μL/L. The daily CO₂ concentration above the grassland could be diagrammed in the shape of a saddle,oscillating between 27-37 μL/L,with some particular days reaching as high as 80 μL/L. During the grass growing season,the Iarther the vertical distance away from the ground surface,the thinner the atmosphere CO₂ concentration becomes,with a decreasing rate of 0.94 μL/L per meter.

Key words: Inner-Mongolia grassland, CO₂ concentration, CO₂ gradient, diurnal variation

摘要： 1999~2002年对内蒙古草原生长季节近地面层大气中的CO₂浓度及其变化进行观测研究。结果表明:CO₂浓度及CO₂在近地层的浓度梯度在生长季节均有明显的日变化和逐日变化;观测期间,大气中CO₂浓度四年平均日均值为361.6 μL/L,其年变化幅度约为13.5 μL/L;草原上空CO₂的日变化通常呈马鞍型,平均日变化幅度为27~37 μL/L,个别日期可达80 μL/L;生长季节草原上空近地大气层中CO₂浓度随着高度的增加而递减,平均递减率为0.94 (μL/L)/m。

关键词: 草原学, 内蒙古草原, CO₂浓度, CO₂梯度, 日变化