末次冰消期以来湖北神农架大九湖泥炭湿地产甲烷生物地球化学过程对气候环境变化的响应

泥炭是大气甲烷最重要的源头之一，也是陆地碳循环的主要参与者。泥炭中甲烷主要由古菌产生。产甲烷古菌群落结构、丰度和代谢过程的改变，势必会影响甲烷生成过程，从而对气候变化、陆地碳循环过程产生影响。当前，在百-千年时间尺度上影响泥炭产甲烷古菌活动的气候因素尚不清晰。查明水热条件变化对泥炭产甲烷过程的作用和影响是了解地质历史时期泥炭在碳循环和气候变化中所扮演角色的关键点之一。本项目将利用湖北神农架大九湖泥炭地天然的水位、氧化还原和pH梯度，构建基于微生物GDGTs等醚类化合物的古水文指标体系。将泥炭brGDGTs温度指标和新古水文指标应用到大九湖泥炭沉积柱中，重建末次冰消期以来长江中游古温度和古水文条件的变化。在此基础上，通过泥炭中产甲烷古菌特征性的醚类化合物组成、含量及单体碳同位素来恢复末次冰消期以来该泥炭地不同类群产甲烷古菌的活动，探讨不同水热条件对泥炭产甲烷古菌类群、丰度及代谢过程的影响。

Peatland is a major source of atmospheric methane and also a major player in the terrestrial carbon cycle. Methane in the peatland is primarily produced by methanogenic archaea. Changes in the community structure, abundance and metabolic pathway of methanogen would significantly affect the methanogenesis and in turn the climatic change and terrestrial carbon cycling. Recently, the climatic factors that impact on the methanogenic activity in peatlands on centennial-to-millennial timesacle are still unclear. Investigating the influence of thermal and hydrological changes on the methanogenesis in peatlands is a key to understanding the role of peatlands in the past carbon cycling and climate change. In this project, we will take advantage of the water table, redox and pH gradient occurring in the Dajiuhu peatland of Shennongjia, Hubei. We will try to develop new proxies for paleohydrological reconstruction. These proxies, together with the brGDGT-based temperature proxies, will be applied to a sediment core from the Dajiuhu peatland to reconstruct the variation of paleotemperature and paleohydrological conditions over the last deglaciation. On the basis of the climatic evolution, the activities of different methanogenic archaeal groups will be reconstructed using the diagnostic ether lipids for methanogens and their carbon isotopes, in an effort to explore the response of methanogenic archaeal abundance, community and metabolic pathways to the different thermal and hydrological association.