Does energy, water and gas transport determine carbon sequestration and methane release in anoxic peatland soils? - Testing a novel hypothesis.

北方泥炭地是全球重要的碳储存和大气甲烷来源。因此，在水文条件变化的情况下，碳在这些环境中的长期命运具有相当大的科学意义。我们对泥炭地碳循环的了解尤其缺乏关于能量、水和气体运输的影响，这些影响可能最终控制碳封存和甲烷释放。我们将使用泥炭土模型系统来解决这一研究空白，在该模型系统中，地球化学条件、水和气体的运输可以得到控制，并且对厌氧泥炭分解和甲烷释放的关键过程的影响进行量化。 初步工作证明，缺乏水的运输可能会导致泥炭分解和甲烷释放的失活。水和气体传输速率的增加对泥炭分解关键过程的定量影响迫切需要解决，并确定物理和化学条件的影响。具体而言，该项目将分析：- 泥炭中二氧化碳和甲烷的积累如何减少甲烷释放和无氧呼吸，以及这种效应是否可归因于自由能的缺乏，-这种产物抑制如何受地球化学和物理因素如温度、土壤酸度和泥炭的化学质量的控制，-酶活性如何响应二氧化碳和甲烷的积累，以及地球化学和物理因素，-溶质运输和沸腾的速率如何以及在多大程度上控制泥炭中的产甲烷分解，- 水在泥炭中的停留时间是否可以用来预测泥炭地中泥炭厌氧分解的速率。除了填补一个重要的知识空白外，该项目为改进生态系统模型提供过程级数据，以了解和预测泥炭地碳循环对水文条件变化的反应。在这方面取得的进展将有助于在今后的研究中更准确地分析气候变化对这一重要类型生态系统的影响。

Northern peatlands represent an important global carbon stock and source of methane to the atmosphere. The long-term fate of carbon in these environments under changed hydrologic conditions is thus of considerable scientific importance. Our knowledge of peatland carbon cycling is especially deficient with respect to the effects of energy-, water-, and gas transport that may ultimately control carbon sequestration and methane release. We will address this research gap using peat soil model systems in which geochemical conditions, water and gas transport can be controlled and the effects on key processes in anaerobic peat decomposition and methane release be quantified. Preliminary work documented that absence of water transport can result in an inactivation of peat decomposition and methane release. The quantitative effects of increased rates of water and gas transport on key processes in peat decomposition urgently need to be addressed and the effect of physical and chemical conditions to be identified. Specifically, the project will analyze:- how accumulation of carbon dioxide and methane in peats diminishes methane release and anaerobic respiration and whether such effects can be attributed to a lack of free energy,- how such product inhibition is controlled by geochemical and physical factors, such as temperature, soil acidity and chemical quality of the peat,- how enzymatic activity responds to accumulation of carbon dioxide and methane, and geochemical and physical factors,- how and to what extent rates of solute transport and ebullition control methanogenic decomposition in peats, - if residence time of water in peats can be used to predict rates of anaerobic peat decomposition in peatlands.Apart from closing an important knowledge gap, the project provides process-level data for the improvement of ecosystem models that aim at understanding and predicting the response of peatland carbon cycling to changing hydrologic conditions. Progress in this direction will allow for a more accurate analysis of climate change impacts on this important type of ecosystem in future studies.