Evolution of the Methane Cycle in the Siberian Arctic: Insights from Microbiological and Biogeochemical Studies

在拟议的项目范围内，将调查西伯利亚东北部永久冻土环境中甲烷循环的演变。尤其令人感兴趣的是对微生物过程的了解和确定在现在和过去不断变化的气候条件下参与碳分解的主要微生物。为此，将对年龄不超过30万年的永冻土沉积物进行微生物脂标记和核糖体核糖体RNA(定量和定性微生物生物标记)的高分辨率地层分析。该永久冻土岩芯将在2008年春季国际地球科学中心“在埃尔盖京火山口湖进行科学钻探”项目的范围内，从埃尔盖京湖区开采出来。El‘gytgyn湖是一个理想的案例研究，因为该地区自陨石撞击以来就没有冰川。因此，该地区的多年冻土在其发育过程中经历了几个气候阶段，预计气候诱导的沉积序列的化学和物理变化导致微生物群落的变化，从而影响过去的甲烷气体通量。所获得的数据将填补我们在古碳动力学、环境条件变化下微生物群落发展方面的基本知识空白，并将进一步用于了解和预测多年冻土环境中甲烷循环的未来发展。

In the scope of the proposed project the evolution of the methane cycle in permafrost environments of Northeast Siberia will be investigated. Of particular interest is the understanding of microbial processes and the identification of the main microbial players involved in the carbon decomposition under changing climatic conditions in the present and past. For this purpose a combined highresolution stratigraphic analyses of microbial lipid markers and ribosomal RNA (quantitative and qualitative microbial biomarkers) will be applied on permafrost deposits with an age of up to 300,000 years. The permafrost core will be recovered from the El'gygytgyn Lake region in the scope of the ICDP project "Scientific Drilling at El'gygytgyn Crater Lake" in spring 2008. The El'gygytgyn Lake represents an ideal case study because the region was unglaciated since the time of the meteorite impact. Thus, permafrost in this region went through several climatic stages during its development and it is expected that climatically induced chemical and physical changes in the sedimentary sequences results in variations of the microbial communities concomitantly affecting the methane gas fluxes in the past. The acquired data will fill fundamental gaps in our knowledge on the paleo carbon dynamics, the development of microbial communities under changing environmental conditions, and will be further used for the understanding and prediction of the future development of the methane cycle in permafrost environments.