长白山天池火山温室气体的释放通量与成因

Quantitative and qualitative study on fluxes and origin of greenhouse gases emitting from volcanic fields has become one of the most effective proxies for monitoring activities of deep-seated magma chamber and forecasting potential future eruptions of active volcanoes, which could also serve as important method for evaluating to what extent greenhouse gases released by volcanoes contribute to the atmosphere. Tianchi volcano, although quiescent at present, is undoubtedly the largest and most dangerous active volcano with potential threat of future eruption in China, as indicated by the magma chamber beneath the Tianchi volcanic cone and intensive hydrothermal activities. This proposal will focus on long-term and continuous study on fluxes, compositions and origin of greenhouse gases released by Tianchi volcano, aiming to quantitatively calculate fluxes of greenhouses at Tianchi volcano and reveal genesis of volcanic degassing. Furthermore, the potential links between activities of deep-seated magma chamber and temporal variations of greenhouse gas fluxes and gas compositions will be investigated, which could provide scientific evidence for effectively evaluating activities of deep-seated magma chamber and quantitatively estimating scale of greenhouse gases emitting from Tianchi volcano.

火山区温室气体释放通量的测量及其成因研究已经成为当今国际火山学界探测深部岩浆囊的活动性和预测火山未来喷发最有效的方法之一，同时也是研究火山区向大气圈释放温室气体规模的重要手段。长白山天池火山的地下深部存在岩浆囊，地表水热活动强烈，是我国最具潜在喷发危险性的巨型休眠火山。本项目拟在天池火山区开展长时间尺度、连续的温室气体释放通量测量、火山气体取样和测试工作，以定量地估算天池火山的温室气体释放规模、揭示温室气体的来源与成因，并探讨温室气体通量与气体成分的变化特征及其与天池火山深部岩浆囊活动性之间的联系，为监测天池火山的活动状态和估算其温室气体释放规模提供科学依据。

项目实施期间，所有研究计划均顺利执行并完成。本项目通过详细的野外调查，对长白山天池火山区地质源温室气体来源进行了分类，并在此基础上对长白山天池火山区温室气体释放通量进行了整体性、连续性和系统性的研究，首次报道了中国玛珥系统地质源CO2释放通量及特征和成因。现有研究表明，长白山天池火山区每年通过土壤微渗漏、温泉逸出气、温泉溶解气、土壤水溶解气和地表水逸散等方式向大气圈释放CO2约3.91 Mt，约占我国典型火山地热区地质碳排放量的15%。基于气体地球化学定性分析与定量模拟结果，提出长白山火山区释放的温室气体与太平洋深俯冲板片之间存在着密切的联系，主要体现在海相灰岩与俯冲有机沉积物等深俯冲物质对火山气体地球化学特征的贡献。研究表明，区内单成因火山区的土壤气释放可能受到天池火山岩浆房的影响，影响程度可能与其和天池火山口的距离有关。同时，活动火山区土壤气释放调查还对火山监测具有一定的参考意义。