博斯腾湖人工和天然芦苇湿地土壤CO2、CH4和N2O排放通量

摘要

为研究干旱区淡水湖泊人工、天然芦苇湿地土壤温室气体源汇强度及其影响因素,采用静态箱-气相色谱法,于2015年1月-12月对博斯腾湖人工和天然芦苇湿地土壤CO2、CH4和N2O通量进行全年观测.结果表明,人工芦苇湿地土壤CO2、CH4和N2O排放通量变化范同分别为:10.1-588.4mg m-2h-1、2.9-82.4μg m-2 h-1和1.32-29.7μg m-2h-1,天然芦苇湿地土壤CO2、CH4和N2O排放通量变化范围分别为10.3-469.6rng m-2h-1、3.1-64.8μg m-2 h-1和1.9-14.3μg m-2 h-1.人工和天然芦苇湿地夏季土壤CO2排放通量均明显高于其他季节,而土壤CH4和N2O排放通量较大值多集中在春末夏初.全年观测期间,人工芦苇湿地土壤CO2、CH4和N2O排放通量高于天然芦苇湿地(P＞0.05);温度是影响人工、天然芦苇湿地土壤CO2和N2O排放通量的关键因素,近地面温度和5cm土壤温度与CO2和N2O排放通量呈现极显著的正相关关系(P＜0.01).土壤CH4排放通量是温度和水分二者共同影响的,由近地表温度、5cm土壤温度和土壤含水量共同拟合的方程可以分别解释人工、天然芦苇湿地土壤CH4排放通量的71％、74.5％;土壤有机碳、pH、盐分、NH4+-N、NO3--N也是人工、天然芦苇湿地土壤CO2、CH4和N2O排放通量的影响因素;人工和天然芦苇湿地土壤均是CO2、CH4和N2O的“源”.基于100年尺度,由3种温室气体计算全球增温潜势得出,人工芦苇湿地全球增温潜势大于天然芦苇湿地(15150.18kg/hm2＞ 12484.21 kg/hm2).%CO2,CH4,and N2O,have strong warming potentials and are considered to be the primary greenhouse gases in the atmosphere.Global warming caused by the increasing concentrations of atmospheric CO2,CH4,and N2O is one of the hotspots in global change field.Greenhouse gas (GHG) fluxes in reed wetlands are critical in evaluating the source/sink strength of GHG in arid area.We studied the dynamics of soil CO2,CH4,and N2O fluxes using static chamber-based on gas chromatography in two reed wetlands of the freshwater Bosten Lake,located in an arid area of Northwestern China.During a full year of monitoring,environmental variables (including soil moisture,soil temperature,air temperature,pH and salinity) were measured to determine the effects of abiotic factors on soil CO2,CH4,and N2O fluxes in artificial and natural reed wetlands.SPSS 19.0 for Windows was used to analyze the relationships between environmental factors and soil CO2,CH4,and N2O fluxes.The results showed that soil CO2,CH4,and N2O fluxes in the artificial reed wetland were 10.1-588.4mg m-2 h-1,1.32-29.7μg m-2 h-1 and 3.1-64.8μg m-2 h-1,respectively,which was comparable with the values from the natural reed wetland.Higher soil CO2 emissions occurred in summer,whereas CH4 and N2O emissions mainly occurred in late spring and early summer.Temperature was the main factor controlling soil CO2 and N2O fluxes in both reed wetlands (P ＜ 0.01).Soil CH4 emission flux was affected by both temperature and moisture.According to regression analysis,the combination of near-surface temperature,top 5cm soil temperature,and soil water content could explain 71％ and 74.5％ of soil CH4 flux in artificial and natural reed wetlands,respectively.Soil organic carbon,pH,salinity,NH4+-N,and NO3--N are also influencing factors of CO2,CH4,and N2O fluxes in artificial and natural reed wetlands.However,the differences in CO2,CH4,and N2O emissions from soils of artificial and natural reed wetlands were caused by differences in soil organic carbon,soluble nitrogen,and biomass.Based on the centennial scale,the soils of artificial and natural reed wetland were " sources" of GHG,and the global warming potential from artificial reed wetland was higher than that from natural reed wetland.