中文摘要：

CH4氧化是影响CH4排放通量的主要过程之一, 对CH4源汇效应起着重要作用.用实验室培养法对青藏高原多年冻土区沼泽草甸土壤在-10、-5、0、5、10和18 ℃等6个温度条件下1~72 h内CH4氧化速率进行研究. 结果表明： 正温条件下, 各层土壤CH4氧化速率呈现＂U＂型分布特征, 0~20 cm高、20~80 cm低、80~100 cm高;负温条件下, 各土层CH4氧化速率相对较低且无明显差异. -5、0、5、10和18 ℃时的CH4氧化速率分别是-10 ℃时的1.3、26.5、390.5、1 644.7和4 926.4倍, CH4氧化速率与温度之间呈现显著的指数关系. 正温条件下, 各深度平均的CH4氧化速率与时间呈现极显著的线性正相关关系;但CH4氧化速率变化范围存在着差异, 在0、5、10和18 ℃条件下, 各土层平均CH4氧化速率变异率为510%、173%、244%和179%, 0 ℃条件下的CH4氧化速率变异性最大. 在正温条件下, CH4氧化速率与土壤pH值存在负相关关系;冻土冻结时, CH4氧化速率与土壤pH值没有明显的相关性.

英文摘要：

On the Tibetan Plateau, global warming causes more permafrost thawing out. How permafrost degradation impacts on methane emission from wetlands in permafrost regions and thus regulates the feedback effects of wetlands to global warming are mostly unknown. This study was designed to examine soil methane oxidation rate in swamp meadows of permafrost regions on the Tibetan Plateau under various temperature scenarios using an anaerobic incubation technique. The results show that there is significant exponential correlation between methane oxidation rate and incubation temperature. The methane oxidation rate under -5, 0, 5, 10 and 18 ℃ are 1.3, 26.5, 390.5, 1 644.7 and 4 926.4 times of that at -10 ℃. At 0, 5, 10 and 18 ℃, the distribution of methane production rates from various soil layers takes a ＂U＂ shape;it is higher at the depths of 0-20 and 20-80 cm, while the lowest methane oxidation rate presents at the depth between 20 and 80 cm. However, no obvious traits are observed at incubation temperatures of -10 and -5 ℃. The methane oxidation rates are significantly correlated with incubation time at temperatures of 0, 5, 10 and 18 ℃ （n=6, R2=0.91;n=6, R2=0.8;n=6, R2=0.88;n=6, R2=0.81）, but the ranges of the average methane oxidation rates at different depths at all incubation temperatures during the entire 72 hours have obvious difference. The ranges of 0, 5, 10 and 18 ℃ are 0.019-0.097, 0.61-1.06, 4.01-9.78 and 7.4-13.25 ng·g-1·h-1, and the variation rates are 510%, 173%, 244% and 179%. In this study, the methane oxidation rate is not significantly correlated with soil organic carbon contents, but those from different soil layers are significantly correlated with soil pH-value at 0, 5, 10 and 18 ℃. At the same time, the results show that the methane oxidation rates are significantly correlated with grain distribution of soils.