艾比湖湿地季节性冻融土壤温室气体排放规律研究

Greenhouse gas emission from seasonal frozen-thawed soil in Ebinur Lake wetland

利用静态箱–气象色谱法对2015年11月—2016年3月艾比湖湿地季节性冻融期土壤温室气体进行观测.结果表明:季节性冻融期裸地土壤CO2表现为汇、芦苇和柽柳土壤CO2表现为源;芦苇、柽柳和裸地土壤CH4表现为汇,而N2O表现为源;芦苇、柽柳和裸地土壤温室气体最低值均出现在冻结期(11月—次年2月)且为负通量;不同植被类型下土壤CO2在融化期(3月末)出现排放峰值,而土壤CH4和N2O在冻融交替期(3月初)出现排放峰值;在整个观测期,芦苇和柽柳土壤CO2、CH4和N2O排放峰值高于裸地;温度对季节性冻融期土壤CO2和N2O影响显著,均达到显著正相关(P<0.05),土壤温度能解释芦苇、柽柳和裸地土壤CO2通量的77%~88%;土壤质量含水量对土壤CH4和N2O影响均达到显著正相关关系(P<0.05),土壤质量含水量能解释芦苇、柽柳和裸地CH4和N2O通量的25%~46%和41%~69%.表明在干旱区季节性冻融期,温度变化对不同植被类型下土壤CO2影响较大,而在冻融交替期水分变化对CH4和N2O通量影响显著.芦苇、柽柳和裸地土壤呼吸Q10值分别为2.37,2.58和2.33,不同植被类型基于100 a尺度,土壤温室气体全球增温潜势由大到小依次为芦苇(569.67 kg·hm^-2)、柽柳(152.09 kg·hm^-2)、裸地(–861.50 kg·hm^-2).

Static box-meteorological chromatography was used to examine soil greenhouse gas emission in seasonal freezing-thawing period of Ebinur Lake wetland arid areas from November 2015 to March 2016.CO2 of bare soil was found to be the sink,CO2 of reed and tamarisk the source,CH4 of reed,tamarisk and bare soil the sink,N2O the source.The lowest value of greenhouse gas in reed,tamarisk and bare soil was found to appear in the freezing period(November–February)with a negative flux.Under different vegetation types,soil CO2 emission was found to peak in thawing period(late march),while soil CH4 and N2O emissions peak in freezing–thawing alternate period(early march).During the observation period,emission peaks of CO2,CH4 and N2O in soil of reed and tamarisk chinensis were found higher than bare land.Temperature was found to have significant influence on soil CO2 and N2O in seasonal freezing-thawing period,both with significant positive correlation(P<0.05).Soil temperature explained 77%-88%of the CO2 flux of reed,tamarisk and bare soil.The soil moisture content was found significantly positively correlated with soil CH4 and N2O(P<0.05).Soil moisture content explained 25%-46%and 41%-69%of CH4 and N2O fluxes of reed,tamarisk and bare land.Temperature change was found to have a great impact on soil CO2 in different vegetation types,while water change in freezing–thawing alternate period was found to have a significant impact on CH4 and N2O flux in the seasonal freezing-thawing period in arid areas.Respiratory Q10 values of reed,tamarisk and bare soil were found to be 2.37,2.58 and 2.33,respectively.Global warming potential of different vegetation types based on 100-year scale of soil greenhouse gas was found to be:reed(569.67 kg·hm^-2)>tamarisk(152.09 kg·hm^-2)>bare land(–861.50 kg·hm^-2).