东北全新世泥炭微生物类脂物记录:季风变化及其对甲烷生物地球化学过程的影响

陆地微生物过程控制着温室气体释放，关系到气候变化长期响应等科学问题，成为预测未来气候及大气组成方面的瓶颈。受控于东亚季风的我国东北泥炭地在气候变化与碳循环中占有重要地位，是解决上述科学问题的最佳突破口。本项目应用分子有机地球化学方法高分辨率地建立植物叶腊单体氢同位素（δD）季风降水指标，定量研究微生物类脂物及其藿类碳同位素组成与特征，评价降水、植被、氧化还原条件及微生物过程之间的联系，发展高分辨率、长序列的甲烷生物地球化学分子记录。着力探索产甲烷与甲烷氧化过程，示踪泥炭地全新世甲烷生物地球化学循环，深入揭示东亚季风变化对现代与全新世甲烷生物地球化学过程的影响，并将其置入微生物与气候变化关系的框架中，探索全新世甲烷生物地球化学过程如何响应季风变化。本项目将是率先应用这些国际前沿方法研究东北泥炭生物地球化学过程，从根本上了解微生物对气候变化的响应，深化甲烷生物地球化学与季风气候的机制研究。

It is crucial to understand terrestrial microbial processes because they governgreenhouse gas emissions; unfortunately, the long-term microbial responses to climate change remain unclear, causing uncertainty in predictions for how they will impact future climate and atmospheric composition. The peatland from the Northeast China, controlled by the East Asian Monsoon system, has been major players in climate change and carbon cycling, such that these deposits represent a truly novel potential to address the above scientific issues. This proposed research will expand the Northeast China dataset of peat-forming plant δ D values, a key hydrological indicator; quantify and isotopically characterise microbial biomarkers and especially those derived from organisms involved with methane cycling; evaluate the link between precipitation, vegetation, redox conditions and microbially mediated processes and especially methanogenesis. These records will be developed using cutting edge approaches exploiting gas chromatography (GC), GC-mass spectrometry, high performance liquid chromatography-mass spectrometry, GC-isotope ratio mass spectrometry (IRMS) and GC-thermal conversion-IRMS. This dataset seeks to understand methanogenic and methanotrophic processes and will be used to develop higher resolution and longer-term CH4 biogeochemical records over the Holocene and to better understand the impact of the East Asian monsoon change on modern and ancient CH4 biogeochemistry, to ultimately embed them in the framework of known and hypothesised relationships between microorganisms and climate change， and to explore how CH4 biogeochemical processes will respond to monsoon climate change and whether this will act as a positive, negative or netutral feedback on monsoon climate change. This work will be one of the very first applications of these novel methodologies to the study of past changes in peat biogeochemistry in Northeast China. It will validate and expand on the Chinese investigations and contribute to a better mechanistic understanding of the microbial response to climate change and its impact on CH4 biogeochemistry.