摘要
1998年 6月 1日、7月 2日、8月 3日和 9月 1日用静态箱_气相色谱法对内蒙古锡林河流域草甸草原CH4和N2 O排放通量的昼夜观测表明 ,天然草原是N2 O的源、CH4的汇 ,其排放和吸收具有明显的昼夜变化规律。 4次昼夜观测的结果还表明 ,草甸草原排放N2 O和吸收CH4的能力具有强烈的季节变化规律。方差分析表明 ,不同季节N2 O排放通量差异显著 (F =6 .35 9,p <0 .0 0 4 ) ,日均通量变化范围为 0 .2 82～ 2 .134μgN2 O N·m-2 ·h-1;而CH44次测定的日均吸收通量分别为 (- 5 2 .19± 19.6 7)、(- 2 7.2 0± 10 .5 7)、(- 12 6 .0 5± 9.32 )和 (- 16 .4 5± 1.31) μgCH4_C·m-2 ·h-1,从整个生长季看表现为“高_低_高_低”的特点。锡林河流域选择 9∶0 0～ 13∶0 0作为采样日起始采样时间 。
Temperate and tropical oxic soils usually exhibit low levels of atmospheric CH 4 oxidation, which are estimated to consume about 10% of the atmospheric CH 4. It has been reported that the semi_arid grasslands represent a significant global sink for CH 4 and a source of atmospheric N 2O. However, the spatial and temporal variability of methane is usually very high which may result in the uncertainty of the ecosystem’s function in the exchange of greenhouse between ecosystem and atmosphere. In order to help define the possible range of emission of N 2O and CH 4 from temperate grassland of Inner Mongolia, diurnal variation in fluxes of methane and nitrous oxide in meadow steppe in the Xilin River basin were investigated with static_chamber and GC methods on June 1, July 2, August 3 and September 1 of 1998. Suitable sampling time was also discussed with the data of diurnal variation investigation. The native meadow steppe can act as a source of atmospheric N 2O but a sink of CH 4 in which the fluxes of the two greenhouse gases had obvious diurnal variation. ANOVA results showed that there was significant difference for the fluxes of N 2O in the four months(F=6.359, p<0.004), ranging between 0.282-2.134 μg N 2O_N·m -2·h -1. These background emission rates were typically similar to those in other temperate grasslands. The diurnal mean uptake rates of methane were (-52.19±19.67), (-27.20±10.57), (-126.05±9.32) and (-16.45±1.31) μg CH 4 C·m -2·h -1 for the four months respectively, which has a trend of “high_low_high_low” from the end of May through the beginning of September. The methane uptake rates were similar to those in the Colorado short_grass steppe, averaging 31.2 μg CH 4_C·m -2·h -1, compared with varieties of temperate ecosystems. It was proved that selecting 9∶00-13∶00 as sampling time for each sampling day is suitable in Xilin River basin according to the diurnal variation measurement.
出处
《植物生态学报》
CAS
CSCD
北大核心
2003年第6期792-796,共5页
Chinese Journal of Plant Ecology
基金
中国科学院知识创新工程重要方向项目 (KSCX2_1_0 7)
国家自然科学重大基金项目 ( 4 9790 0 2 0 )
关键词
N20
日变化
草甸草原
锡林河流域
内蒙古
CH4
N 2O, CH 4, Diurnal variation, Meadow steppe, Xilin River basin, Inner Mongolia
