土壤利用管理对土壤甲烷氧化的影响

The Effect of Land Use on Methane Oxidation in Aerobic Soils

甲烷(CH4)是重要的温室气体之一,对全球变暖的贡献值约为20%,仅次于CO2。近年来大气中CH4含量的迅速增加,主要是由于CH4的产生和消耗不平衡。好气性土壤是大气CH4重要的汇之一,虽然其氧化的绝对量较小,但土壤若丧失对CH4的氧化能力,大气中CH4的浓度会以目前增长速率的1.5倍的速度增加。农业生产活动对土壤的理化性质有着极为强烈的影响,因而显著地影响土壤对大气CH4的氧化能力。大量的研究表明森林土壤对CH4的氧化速率要比草地和耕地高得多,其主要原因是森林在开垦耕作后,改变了土壤的物理化学性质和土壤中的微生物区系的结构和组成,从而使土壤对CH4的氧化能力发生了改变。作物生长本身对通气性好的土壤CH4的氧化并没有什么影响,但是在种植过程中,如不同农药的使用、土壤pH值的改变、不同的耕种方式等对土壤CH4氧化能力产生一定的影响。

Methane is a radiatively active trace gas with a high absorption potential for infrared radiation, making it the second most important greenhouse gas after carbon dioxide and it accounts for 20% of the global warming. Methane concentration in the atmosphere increases rapidly due to the unbalance of methane sources and sinks. Aerobic soils play an important role in bacterial CH_4 oxidation, which can contribute approximately 30 Tg(1 Tg=1.010^(12)?g) per year or to 6% of the total CH_4 destroyed. The absence of the soil sink would cause the atmospheric concentration of CH_4 to increase at about 1.5 times the current rate. Agricultural activities sharply impact soil properties thus influence soil methane oxidation. Changes in land use, especially cultivation of formerly undisturbed soils, strongly lowered the capacity of soils to act as sinks for atmospheric CH_4. An important factor is the disturbance of the original soil structure by regular cultivation, which may reduce the probability of the biological, chemical and physical parameters that define the ecological niche for methanotrophic bacteria occurring. In well-aerated arable soils plant growth itself is not primarily responsible for observed effects on CH_4 oxidation, but secondary factors like differential pesticide treatment, changes in pH, or cultivation effects are more likely involved.