水稻田土壤甲烷厌氧氧化在整个甲烷氧化中的贡献率

对黄松土水田土壤中>0.02mm的颗粒和<0.02mm的颗粒按不同比例组合成的土壤、不同绝对含水量的黄松土水田土壤、不同温育时段的水田土壤和长期定位不同施肥的水稻田土壤中的甲烷好氧氧化和厌氧氧化的速率的检测结果进行比较,结果相当一致,不仅证实了水稻田土壤甲烷厌氧氧化过程的存在,而且表明水田土壤中的甲烷厌氧氧化活性远较甲烷好氧氧化活性要低,如以两者的氧化活性作为对甲烷氧化的贡献来计,则甲烷厌氧氧化的贡献率一般都在整个甲烷氧化的10%以下.但在水田土壤被水淹没的情形下,由于土壤厌氧条件的形成和甲烷扩散受阻,甲烷厌氧氧化的速率明显超过好氧氧化的速率,甲烷厌氧氧化在整个甲烷氧化中的贡献率可到达30%以上.长期施肥对于水稻田土壤的甲烷好氧氧化活性和甲烷排放通量影响显著,而对甲烷的厌氧氧化活性有影响但未达到显著水平.长期施肥处理的土壤中甲烷好氧氧化活性在(9.072～41.088)×10^-6mol·(d·g)^-1之间,而甲烷厌氧氧化活性仅在(0.325～0.671)×10^-6mol·(d·g)^-1之间,仅及甲烷好氧氧化活性的1.31%～4.43%,占整个甲烷氧化的1.3%～4.14%.

Contribution of Anaerobic Oxidation of Methane to Whole Methane Oxidation

The contribution of anaerobic methane oxidation to the whole methane oxidation is investigated by monitoring the activities of anaerobic and aerobic oxidation of methane in paddy soils composed mechanically of <0.02mm and >0.02mm soil granules, contained different water contents, and long-term fertilized organic manure or inorganic nitrogen, phosphorus and potassium fertilizers. The results obtained from various treated soils are relatively identical, which shows that most of the activities of anaerobic methane oxidation is obviously lower than those of aerobic methane oxidation. The contribution of anaerobic methane oxidation was generally lower than 10% of total methane oxidation in paddy soils with different treatments, however, higher than 30% in the soils emerged in water as the soils became anaerobic and methane diffused difficultly into soil, leading to lower activity of aerobic methane oxidation. The long-term fertilization has a significant effect on the activity of aerobic methane oxidation in paddy soil, with the |t|>t_0.05,p<0.05, but a slightly one with (|t|0.05), leading to the obvious influence on the emission flux of methane. The contribution rates of anaerobic methane oxidation were lower from 1.31% to 4.14% in the whole methane oxidation.