三江平原泥炭沼泽湿地N2O排放通量及影响因子

运用静态暗箱-气相色谱法观测了三江平原毛苔草泥炭沼泽湿地植物生长季N2O排放通量,并分析了其关键影响因子.结果表明:生长季N2O排放通量季节变化动态明显,最大值出现在7月上旬;平均排放通量为76.77μg/(m2·h),高于潜育沼泽湿地20~60μg/(m2·h), 2002~2005].N2O排放通量与土壤温度存在极显著指数关系(P<0.01),且随土壤深度(土壤10cm以下)的增加相关关系逐渐减弱;与水位呈极显著负相关关系(P<0.01);另外,植被是影响N2O排放的主要生物因子,有植被参与的N2O排放是无植被的1.7倍.总之,水位和土壤温度是控制泥炭沼泽N2O排放呈明显季节变化的主要因素,而土壤水文物理特性的差异是引起泥炭沼泽N2O排放高于潜育沼泽的主要原因.经初步估算,三江平原泥炭沼泽每年植物生长季N2O排放总量约为72.9Mg,表明泥炭沼泽湿地在生长季是重要的N2O潜在排放源.

N2O emissions and its controlling factors from the peatlands in the Sanjiang Plain

The seasonal N2O emissions and the key controlling factors during the growing season were monitored in the Carex lasiocarpa peatland of the Sanjiang Plain. Through the closed chamber-GC method, clearly seasonal variation of N2O fluxes was found, with the maximum value in early July. The mean flux of N2O in the growing season was 76.77μg/(m2·h), being higher than that of the gley swamp 20~60μg/(m2·h), 2002~2005]. The N2O fluxes showed exponential relationship correlated with the soil temperature (P<0.01) and the correlation gradually weaken when the soil depth was below 10cm. Meanwhile, vegetation was another factor that affects N2O emissions. The N2O flux emitted from soil with vegetation was 1.7 times higher than that without vegetation. The water table and soil temperature were the main factors that controlled the seasonal N2O emissions from peatland. Higher N2O flux in peatland than the gley swamp was caused by the difference of the hydrological and physical properties. Additionally, in the growing season, the total N2O emission in the herb peatland was about 72.9Mg/a, indicating that the peatland in the Sanjiang Plain was a large N2O potential source.