The Magnitude and Drivers of Sediment Methane Production in Streams across Europe

河流系统（溪流和河流）最近被认为是全球大气CH4的重要来源。因此，许多研究测量了沉积物-水界面或水-空气界面的气态CH4通量。然而，由于潜在的气态甲烷通量的各种途径与沸腾事件的随机性质相结合，导致平均通量估计存在很大的不确定性。评估甲烷的潜在产生和氧化速率，即侧重于控制CH4产生和损失的过程，与通量测量相比，可能是一种替代方法。然而，这些过程的驱动因素及其在河流中的空间变异性尚未完全了解。本项目的总体目标是首次在河段尺度和大陆尺度两个空间尺度上估算水系沉积物潜在甲烷产量和氧化速率（PMP和PMO）及其驱动因子的空间变异性。为了实现这一目标，拟议的项目采用了目前正在进行的全欧洲项目的框架：EuroRun（评估欧洲流水的二氧化碳通量）。EuroRun由16个团队组成，分布在11个欧洲国家的不同地方。每个euroorun团队将在欧洲的一条河流中采集沉积物样本，并将它们送到科布伦茨-朗道大学，在那里，该项目的主要研究者将测量PMP和PMO以及各自样本的沉积物特征（沉积物碳氮含量的有机物质量，粒度分布）。拟议项目的成功实施将大大提高目前对河流中CH4生产的认识。此外，在大陆尺度上对PMP和PMO的潜在驱动因素的研究可以为基于过程的模型提供重要的参数，从而预测河流生态系统中CH4的产生和排放动态。

Fluvial systems (streams and rivers) have been recently recognized as a globally significant source of atmospheric CH4. Hence, many studies measure gaseous CH4 fluxes at the sediment-water interface or at the water-air interface. However, the combination of various pathways of potential gaseous methane fluxes to the atmosphere with the stochastic nature of ebullition events lead to large uncertainties in averaged flux estimates. Assessing the potential production and oxidation rates of methane, i.e. focusing on the processes that control CH4 production and loss, may represent an alternative approach compared to flux measurements. However, the driving factors of these processes and their spatial variability in streams are not yet fully understood. The overall goal of this proposed project is, according to our knowledge for the first time, to estimate the spatial variability of potential methane production and oxidation rates (PMP and PMO) and their driving factors in stream sediments at two spatial scales: the stream reach scale and the continental scale. In order to archive this goal, the proposed project uses the framework of a currently ongoing European wide project: EuroRun (Assessing CO2 fluxes from European running waters). EuroRun consists of 16 teams all located at different places in 11 European countries. Each EuroRun team will samples sediment samples in one stream across Europe and send them to the University of Koblenz-Landau, where the principle investigator of the project will measure PMP and PMO as well as sediment characteristics of the respective samples (organic matter quality as sediment carbon to nitrogen content, grain size distribution). A successful execution of the proposed project will strongly enhance the current understanding of CH4 production in streams. Furthermore, the investigation of potential drivers of PMP and PMO at continental scale may provide important parameters which can be implemented in a process-based model, predicting CH4 production and consequently emission dynamics in stream ecosystems.