隆宝滩沼泽湿地不同区域的甲烷通量特征及影响因素

Characteristics and Influence Factors of CH_4 Flux in Different Areas of Longbaotan Marsh Wetland

高寒湿地是大气中甲烷(CH_4)重要的排放源,气温升高和水位波动会对脆弱的高寒湿地CH_4排放产生影响。为了解高寒湿地不同区域CH_4通量特征以及差异,以位于青藏高原中部的隆宝滩湿地为研究对象,分别在湿地中的湿地区域(WA)、过渡带区域(TA)、平坦地区域(FA),使用便携式温室气体分析仪原位观测CH_4通量的变化,分析和确定高寒湿地CH_4排放的时空异质性及其影响因素。结果表明,WA和TA是CH_4排放源,在生长旺季(7-9月)CH_4通量的日变化特征为单峰型,峰值出现在午后(14:00-15:00),FA表现为CH_4的"汇",其日变化特征较不明显。3个区域的CH_4通量有显著的季节变化差异(P<0.05),WA、TA和FA的CH_4通量峰值分别出现在7月、8月和8月,峰值分别为25.46、25.13、-0.42 nmol?m^(-2)?s^(-1)。测定期间,WA、TA和FA的CH_4通量均值分别为905.75、581.58、-9.02μg?m^(-2)?h^(-1),差异显著(P<0.01),其变异系数分别为63.5%、76.3%、85.9%。Pearson相关分析表明,3个区域的CH_4通量均与土壤温度呈极显著相关(P<0.01),表明土壤温度是CH_4通量的重要影响因素。WA和FA的CH_4通量与土壤湿度呈显著相关(P<0.05),TA的CH_4通量与土壤湿度无显著相关性(P>0.05),但是TA不同土层Q10值均大于WA,表明TA的CH_4通量对土壤温度的变化比WA更敏感。

Alpine wetlands are important sources of atmospheric methane(CH4).Temperature increase and fluctuations in water levels will affect CH4 emissions from fragile alpine wetlands.In order to understand the characteristics and differences of CH4 flux in different areas of alpine wetland,this study takes the Longbaotan wetland in the middle of the Qinghai-Tibet Plateau as a research object,using ultra-portable greenhouse gas analyzer to observe the variations of CH4 flux in wetland area(WA),transition area(TA)and flat area(FA)respectively,analyze and determine the spatial and temporal heterogeneity of CH4 emissions in alpine wetlands and its influencing factors.The results showed that WA and TA were CH4 emission sources.The diurnal variation of CH4 flux was a monopeak curve at WA and TA sites during the growing season(July–September)and the peak appeared in the afternoon(14:00– 15:00),whereas there was no significant diurnal variation at FA.The CH4 fluxes for the three areas had significant seasonal variation(P<0.05),and the CH4 flux peaks at WA,TA,and FA appeared in July,August and August,with peak values of 25.46,25.13,and-0.42 nmol·m^-2·s^-1,respectively.During the measurement period,the mean CH4 fluxes of WA,TA and FA were 905.75,581.58 and-9.02μg·m^-2·h^-1,respectively.The CH4 flux differences between WA,TA and FA were significant(P<0.01),and the coefficients of variation were 63.5%,76.3%and 85.9%,respectively.Pearson correlation analysis showed that the CH4 fluxes at the three areas were significantly correlated with soil temperature(P<0.01),indicating that soil temperature was an important factor affecting CH4 fluxes.The CH4 fluxes of WA and FA were significantly correlated with soil moisture(P<0.05),while the CH4 fluxes of TA had no significant correlation with soil moisture(P>0.05).However,the Q10 values of different soil layers of TA were greater than those of WA,indicating that the CH4 flux of TA was more sensitive to soil temperature than that of WA.