温度对土壤氧化大气CH_4的影响

Effect of temperature on atmospheric CH_4 oxidation in soils

讨论了温度对土壤氧化大气CH4的影响及其机理。当温度较低时土壤也具有一定的氧化大气CH4的能力 ,两者具有很高的相关关系 ,但是由于CH4氧化菌对大气CH4具有很强的亲和力以及大气CH4氧化所需活化能较低 ,因此土壤氧化大气CH4对温度的敏感度远低于产CH4,导致温度系数Q10 较小。当大气CH4和O2 扩散进入土壤的速率等于土壤中CH4和O2消耗的速率时 ,大气CH4氧化达到最大值 ,此时的土壤温度就是CH4氧化的最佳温度。如果温度继续升高并大于最佳温度 ,由于CH4氧化菌无法与利用O2 能力更强的硝化细菌和其它微生物竞争利用土壤空气中有限的O2 ,使得土壤中CH4氧化菌的繁殖和活性降低。这一作用机理的提出较好地解释了为什么随着温度升高土壤氧化大气CH4能力呈低高低的态势。

The research progresses in the effects of soil temperature on atmospheric CH 4 oxidation in soils were reviewed in this paper. Atmospheric CH 4 oxidation occurs in soils even if the temperature is very low. The atmospheric CH 4 oxidation rates are highly correlated with soil temperature, but not so closely as those of CH 4 production since methanotrophs have high affinity for CH 4 and low activation energy for CH 4 oxidation. As a result, the temperature effectiveness Q 10 is much smaller than that of CH 4 production. When the rates of CH 4 and O 2 diffusion from the atmosphere into the soil air are equal to those of CH 4 and O 2 consumption in soils, CH 4 oxidation rates in soils reach the maximum values at a given temperature which is called the optimal one. If the temperature continually rises and is higher than the optimal temperature, the reproduction and activity of methanotrophs in soils will gradually decrease because methanotrophs fail to compete with nitrifiers and other microbes for the limited oxygen in soil air. What we have proposed as above has successfully explained why soil temperature influencing the rate of atmospheric CH 4 oxidation shows the trend of increasing at first, then reaching the maximum and at last decreasing with temperature.