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不同干扰强度下三江平原湿地土壤温室气体排放对冻融作用的响应
李富
佳木斯大学
摘要:
为了评估季节性冻融作用对不同干扰强度湿地温室气体产生机制的影响,采用静态箱/气相色谱法,原位观测三江平原洪河国家自然保护区内未受干扰的常年积水的小叶章湿地(Undisturbed Deyeuxia Angustifolia Wetland, UDAW)、保护区外受人类活动干扰导致湿地含水量减少的季节性积水的小叶章湿地(Disturbed Deyeuxia Angustifolia Wetland, DDAW)以及由小叶章湿地开垦10年以上的水稻田(Rice Paddy, RP)温室气体排放通量,分析季节性冻融作用对3种湿地温室气体排放的影响特征。结果表明 :3种湿地冻融期都有CO2和CH4排放,且在春季冻融初期CO2和CH4均出现短期的高排放现象,随着冻融温度 升高,温室气体排放速率均逐渐增加。其中,CO2排放速率表现为UDAW?DDAW>RP,CH4排放速率却表现为DDAW?RP?UDAW;DDAW的CH4排放速率与冻融温度的相关性最高(P<0.01, R2=0.6475),UDAW中的相关性最低(P<0.01, R2=0.4247)。相关性分析显示,DDAW和RP土壤中CO2与CH4的释放速率均呈正相关(P均<0.01,R2分别为0.7491、0.5744),而UDAW土壤中CO2与CH4的释放速率表现为弱相关(P<0.05,R2=0.3038),可见冻融温度会影响CO2和CH4的释放速率。季节性冻融作用影响了3种湿地土壤N2O的释放速率,秋季冻融期UDAW和DDAW表现为N2O的汇,而在春季冻融期3种湿地均为N2O的源,表明不同干扰湿地N2O的释放速率对冻融作用的响应不同,但均随土壤温度的升高其排放通量不断增加。研究显示,三江平原的冻融作用降低了湿地温室气体排放,干扰强度越大,冻融作用影响越小,且秋季冻融作用大于春季 。
关键词:  冻融作用  三江平原  不同类型湿地  温室气体
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基金项目:佳木斯大学青年基金项目(No. Lq2013-034);“十三五”国家重点研发计划(No. 2016YEC0500405);国家自然科学基金项目(No. 31670489)
Response of Greenhouse Gas Emission to Freeze-thaw with Different Disturbance Intensity of the Sanjiang PlainWetland
李富
Abstract:
This study aims to evaluate the effects of seasonal freezing-thawing on the mechanism for greenhouse gas emission, as well as determine the controlling factors for different interference intensities of the wetlands in Sanjiang Plain, Northeast China. The static chamber technique and gas chromatography were used to observe greenhouse gas fluxes of undisturbed Deyeuxia angustifolia wetlands (UDAW) in the Honghe National Nature Reserve, disturbed D. angustifolia wetland (DDAW) and rice paddy reclaimed by D. angustifolia wetland (RP) outside the Honghe National Nature Reserve in the Sanjiang plain. Results reveal that CO2 and CH4 emissions occurred during the freezing period in the three wetland types. Further, CO2 and CH4 emissions were high during a short period in the early stage of thawing. The greenhouse gas emission rate was positively correlated with temperature in the three wetland types. The CO2 emission rate performance showed UDAW > DDAW > RP. Whereas the CH4 emission rate showed DDAW > RP > UDAW. The CH4 emission rate of DDAW had the highest correlation with temperature (P<0.01, R2=0.6475). Meanwhile, the lowest correlation occurred in UDAW (P<0.01, R2=0.4247). The correlation analysis shows that DDAW and RP were significantly correlated with the release of CO2 and the CH4 rate (P?0.01, R2=0.7491 and R2=0.5744). However, the results for UDAW were weak correlation with the release of CO2 and the CH4 rate (P?0.05, R2=0.3088). This demonstrates that temperature affected the release rate of CO2 and CH4. Further, seasonal freezing-thawing affected the release of N2O in different wetlands. UDAW and DDAW served as sinks of N2O during the freezing period. The three wetland types served as sources of N2O during the thawing period, indicating that the release rate of N2O had different responses to freezing-thawing in the different interference intensity wetland types. However, the emission flux increased with the increase in soil temperature. Results showed that the freezing-thawing effect reduced greenhouse gas emissions in the wetlands: the greater the interference intensity, the less significant the influence of freezing-thawing. The freezing-thawing effect was more marked in Autumn than in Spring.
Key words:  freezing and thawing  Sanjiang Plain  different type of wetland  greenhouse gas