Methane Dynamics of Kettle Holes in a Postglacial Agricultural Landscape –Microbial Ecology and Biogeochemistry (Acronym: MeDKet)

冰川后农业景观中水壶孔的甲烷动力学——微生物生态学和生物地球化学（缩写：MeDKet）

• 批准号: 465808595
• 负责人: Professorin Dr. Claudia Knief, since 4/2023
• 金额: --
• 依托单位: Arbeitsgruppe Molekularbiologie der Rhizosphäre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/465808595?language=en
• 关键词: Methane; Dynamics; Kettle; Holes; Postglacial

Wetlands represent a major natural source of methane, which is the second most abundant greenhouse gas in the atmosphere. Methane fluxes of wetlands are dynamic in space and time and are linked to the activity of methanotrophic (methane consuming) and methanogenic (methane producing) microorganisms. The activity of these microorganisms is controlled by diverse environmental factors, but this is not well understood, because e.g. the quantitative relevance of anaerobic methanotrophs remains largely unclear. The aim of this project is to study the spatiotemporal variation of net methane fluxes and explain it by distribution patterns and activities of methane-cycling microorganisms in dependence on different environmental factors. We will conduct our studies on kettle holes, as these show a high spatio-temporal variability in methane emissions at small scale. Kettle holes occur frequently in postglacial landscapes and are often surrounded by agricultural land. They are considered as methane source, but the mechanisms driving their dynamic surface methane fluxes are not well understood. Soil profile, soil chemistry, water level, redox conditions, nutrient input and vegetation are anticipated as key environmental factors that influence the abundance, activity and community composition of the methane-cycling microorganisms. To understand the regulatory importance of these factors, MeDKet will combine field studies with laboratory experiments, in which different abiotic factors will be modulated under controlled conditions. The spatial variation of methane formation and consumption as well as the composition of methane-associated microorganisms will be assessed in eight kettle holes, while the impact of the most relevant environmental factors will be studied in detail for one kettle hole. High-resolution gas measurements will be combined with methods of microbial ecology using quantitative PCR, amplicon sequencing, mRNA analysis, stable isotope probing and metagenome analysis to identify and quantify methane-cycling microorganisms, describe their dynamics and distribution, and to resolve their physiological traits. As we aim at a holistic understanding regarding the contribution of methane-cycling microorganisms in kettle holes to methane fluxes, we extent our analyses to aboveground plant parts, a habitat of methanotrophs that has been largely neglected so far. We will use a newly developed approach to measure vertical methane profiles in the atmosphere above the kettle hole and evaluate the presence of methanotrophs on aboveground plant parts. In summary, the results of MeDKet will serve as a valuable basis to (a) understand the regulation of methanotrophy and methanogenesis and thus the high variability of net methane fluxes (b) assess thereby the role of anaerobic methane oxidizers and (c) the role of above-ground methane oxidation in agriculturally impacted wetlands of the Northern hemisphere.

湿地是甲烷的主要天然来源，甲烷是大气中含量第二大的温室气体。湿地的甲烷通量在空间和时间上是动态的，并与产甲烷（甲烷消耗）和产甲烷（甲烷产生）微生物的活动有关。这些微生物的活性受到多种环境因素的控制，但这一点尚不清楚，因为厌氧甲烷氧化菌的定量相关性在很大程度上仍不清楚。本项目旨在研究甲烷净通量的时空变化，并通过甲烷循环微生物在不同环境因子下的分布格局和活动来解释净通量的时空变化。我们将对壶洞进行研究，因为壶洞在小尺度上显示出较高的甲烷排放时空变异性。壶洞经常出现在冰川后的景观中，通常被农业用地包围。它们被认为是甲烷源，但驱动其动态地表甲烷通量的机制尚不清楚。预计土壤剖面、土壤化学、水位、氧化还原条件、养分输入和植被是影响甲烷循环微生物丰度、活性和群落组成的关键环境因子。为了了解这些因素的调控重要性，MeDKet将结合现场研究和实验室实验，在受控条件下调节不同的非生物因素。对8个壶孔进行甲烷生成、消耗和甲烷相关微生物组成的空间变化评估，并对1个壶孔进行最相关环境因子的影响研究。高分辨率气体测量将与微生物生态学方法相结合，使用定量PCR，扩增子测序，mRNA分析，稳定同位素探测和宏基因组分析来识别和量化甲烷循环微生物，描述其动态和分布，并解决其生理特性。由于我们的目标是全面了解壶孔中甲烷循环微生物对甲烷通量的贡献，我们将分析范围扩大到地上植物部分，这是迄今为止在很大程度上被忽视的甲烷氧化菌栖息地。我们将使用一种新开发的方法来测量釜孔上方大气中的垂直甲烷剖面，并评估地上植物部分甲烷氧化菌的存在。总而言之，MeDKet的结果将为以下方面提供宝贵的基础：(a)了解甲烷化和产甲烷的调控，从而了解净甲烷通量的高度变异性；(b)从而评估厌氧甲烷氧化剂的作用；(c)北半球受农业影响的湿地中地上甲烷氧化的作用。