天池火山口湖温室气体释放的规模与成因

Caldera lakes of active volcanoes must be regarded as high risk systems that are strongly influenced by volcanic activities such as gas emission, hydrothermal water inflow and rising magma. Quantitative and qualitative study on fluxes and origin of greenhouse gases emitting from caldera lakes 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 server as important method for evaluating to what extent greenhouse gases released by volcanoes contribute to the atmosphere. The Tianchi caldera lake is the largest caldera lake in China and the deepest mountain lake in the world. 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 degassing. The exsoluted volcanic gases from the magma chamber can release into the caldera lake, which makes the caldera lake a potential important degassing area for greenhouse gases emission and high risk systems. This proposal will focus on continuous study on fluxes, compositions and origin of greenhouse gases released by Tianchi caldera lake, aiming to quantitatively calculate fluxes of greenhouse at Tianchi caldera lake and reveal genesis of volcanic degassing. Furthermore, the potential links between activities of deep-seated magma chamber and temporal variation 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 caldera lake. Our results would be of significant help both for the study of deep carbon cycles and monitoring of volcanic activities.

火山口湖是连接地球深部岩浆和地表水热系统的纽带。对火山口湖温室气体释放通量的测量及其成因的研究已成为当今国际火山学界进行火山活动性监测的有效方法之一，同时也是研究火山区向大气圈释放温室气体规模、进行深部碳循环研究的重要手段。天池是我国最大的火山口湖，火山地下深部存在岩浆囊，湖中存在持续、大量、形式多样的温室气体释放，是潜在的温室气体释放区，也是受火山活动强烈影响的高风险系统。本项目拟综合气体地球化学和水化学的研究方法，在天池火山口湖开展连续的温室气体释放通量测量，进行气体样品和水样品的取样和测试，定量估算天池火山口湖不同类型温室气体释放规模、研究温室气体的来源与成因、探讨火山口湖深部气体的脱气过程，为深部碳循环研究以及火山活动性监测提供科学依据。