【摘要】 澎溪河流域是三峡水库典型支流,对水库区域碳循环及区域化学风化的影响非常重要。2016年5月—2017年2月对澎溪河流域水-气界面CO₂与CH₄通量特征进行监测与分析,采用顶空平衡法结合模型估算法计算表层水体CO₂与CH₄的分压以及水-气界面的交换通量,并运用spearman相关分析法分析了二氧化碳和甲烷的分压和排放通量与其他环境变量之间的相关性。研究发现:澎溪河是温室气体排放"源",表层水体p（CO₂）平均值为（1807.635±315.605）μatm（1μatm=0.101325 Pa,下同）,表层水体p（CH₄）平均值为（218.7725±127.9425）μatm;CO₂扩散通量平均值为（32.53±3.86） mmol?m^-2?d^-1,水-气界面CH₄扩散通量平均值为（0.208±0.143） mmol?m^-2?d^-1,通量与分压趋势基本保持一致。通过与世界上典型河流温室气体扩散通量对比,得出澎溪河流域CO₂通量释放量为中等水平,而CH₄扩散通量较小,且CH₄通量与p（CH₄）、水温、pH值显著正相关,而水-气界面CO₂扩散通量与p（CO₂）显著正相关,与DO、pH值、叶绿素a（Chl-a）显著负相关。更多还原

【Abstract】 Background, aim, and scope The reservoir has always been a source of water and electricity providing energy and convenience for human beings. However, due to the huge water storage capacity, complex dam operation and maintenance process, the reservoir has become the main carrier of carbon cycle in the ecological environment, which emits loads of greenhouse gas to atmosphere. As one of the world’s major dams, the Three Gorges Dam transports many carbon compounds to nature. And this phenomenon has arose the worldwide scholars’ attention. However, there is no uniform method to monitor the absorption and emission of greenhouse gas from reservoirtillnow.AsthetypicaltributaryoftheThreeGorgesReservoir,PengxiRiverplaysasignificantroleincarboncycleandchemicalefflorescenceweatheringinreservoirregion.Consequently,thispaperseekstoestablisha method for quantifying gas emissions and to analyze how greenhouse gases change over the course of a year.Moreover, it is also requested what is the major attributer for emission of greenhouse gas. This paper supervises andanalysisthefluxesofCO₂ and methane in water-gas interface in Pengxi River from May 2016 to February2017. Materials and methods In reference of previous literature, this study adopted the combination of Headspace balance method and model estimation to obtain the partial pressures of carbon dioxide and methane in surface water and exchange fluxes of CO₂ and methane. Additionally, this paper also used field measuring instruments to measure the physical and chemical variables so as to analyze the effects of these factors on greenhouse gas release.ThecorrelationbetweenthepartialpressuresandfluxesofCO₂ and methane and environment variables were analysed by means of the spearman correlation index based on SPSS software. Results Through researching,it was achieved that Pengxi River was the source of greenhouse gas emission. The average value of p（CO₂） in surfaceofwaterswasanalysedtobe（1807.635±315.605）μatm（1μatm=0.101325Pa,thesamebelow）inPengxiRiver, while that of p（CH₄）was（218.7725±127.9425）μatm;andtheaveragevalueforCO₂ flux in water-gas interface was（32.53 ± 3.86） mmol ? m^-2?d^-1, CH₄fluxaveragevaluewas（0.208±0.143）mmol?m^-2?d^-1, the trend ofthepartialpressureandfluxalmostremainedthesame.Moreover,intermsofphysicalandchemicalfactors,water temperature, dissolved oxygen（DO） and pH are proved to be generally higher in summer. Discussion In comparison with other similar study in literature, it can be concluded that the diffusive of CO₂ was higher in mainstream than that in tributary. The CO₂fluxinthePengxiRiverbasinwasmoderate,higherthanthefluxinsomesmallreservoirbutsmallerthanthatinlargelakesandrivers.AndthedataforCO₂ in this paper are much similar with previous study in Pengxi River. With respect to methane, the amount of methane released from tropical waters is greater. The amount of methane released from Pengxi River located in subtropical zone is not only much smaller than that in tropical waters, but also less than that from other rivers in subtropical zone as well as rivers in temperatezone.Moreover,therewasasignificantpositivecorrelationbetweenCH₄flux,p（CH₄）, water temperature,and pH, while the CO₂diffusionfluxatthewater-airinterfacewassignificantlypositivelycorrelatedwithp（CO₂）andnegativelycorrelatedwithDO,pH,andChl-a.Otherenvironmentalfactorsshowedvagueeffectsonthefluxes.ConclusionsComparedwiththediffusivefluxesofgreenhousegasesintypicalriversintheworld,thestudyfoundthat the release of CO₂fluxinthePengxiRiverbasinwasmoderate,whilethediffusionfluxofCH₄ was small. DO,p H, Chl-a and water temperature have apparent impact on the release of greenhouse gas. Furthermore, the emission of greenhouse gas is greater when water carry larger capacity of that gas. Recommendations and perspectives This researchmethodscanbeappliedtootherreservoirsandextensiveanalysisoftheeffectsofotherinfluencingfactorson greenhouse gas emissions such as nitrogen compounds. In addition, the conclusions which have been achieved give evidence for controlling greenhouse gas emissions in future study.更多还原