COLLABORATIVE RESEARCH: INVESTIGATING HYDROLOGY-DRIVEN MODELS FOR METHANE CYCLING IN NORTHERN PEATLANDS

项目摘要目前关于泥炭地的碳循环将如何应对气候变暖的不确定性的主要原因是对游离气体(FPG)的生产、储存和排放的不完全理解，这是一种以前被低估的甲烷和二氧化碳排放到大气中的来源。越来越清楚的是，煤层气的生产、储存和排放受到水力强迫以及泥炭的机械特性的调节，即泥炭地的碳循环和水循环密切相关。该项目的重点是实地范围的水文和水文地球物理研究，以进一步调查最近启用的“浅”与“深”泥炭模型对北部泥炭地浮选煤层气的生产、储存和排放的重要性。该项目的具体目标包括：[1]量化泥炭地三个地点中每一个地点甲烷的储存和释放在至少六个月期间随深度的垂直变化，[2]确定驱动深层和浅层天然气释放的水文强迫机制，[3]估计作为地下非均质性的函数的储存和释放的空间差异，以及[4]量化浅层和深层气体对北部泥炭地甲烷排放的相对贡献。这项研究将通过将水文地质学方法与对浮式天然气的生产、储存和排放敏感的新型小室、地球物理和大地测量传感技术结合起来进行。现场地点是Cariou沼泽，这是位于缅因州中部的一个经过充分研究的多单元泥炭地综合体。将开发经验预测模型和简单机制模型，以评估关键强迫机制对FPG排放的相对重要性。还将采用时间序列数据集的时频分析，以更好地了解可能的强迫成分，以调节FPG的生产、储存和释放。这项研究将极大地促进我们对北部泥炭地浮游植物动态的水文控制的理解，对于泥炭地碳动态对气候变化的响应具有重要的意义。北部泥炭地全球覆盖面积超过3.5亿公顷，包含约三分之一的陆地储存碳。这种碳在应对持续气候变暖方面的命运是高度不确定的。泥炭地也是大气甲烷的来源，甲烷是一种导致气候变暖的强有力的温室气体。这项研究将提供必要的基础科学知识，以促进对泥炭地甲烷循环的理解，以及泥炭地水文学如何控制从泥炭地向大气排放甲烷。考虑到气候变暖对环境和经济的影响，这项工作具有直接的社会意义。在这个项目中，露易丝·斯托克斯少数民族参与联盟的本科生将接触到三个机构之间的实践跨学科研究。此外，一个国际研究生社区将在美国地球物理联盟的会议上参加以学生为中心的关于北部泥炭地甲烷循环的会议。Cariou沼泽附近的社区外展将通过使用Orono沼泽木板路的年度导游进行，2009年接待了30,000名游客。

Project AbstractA major contributor to the current uncertainty regarding how carbon cycling in peatlands will respond to climate warming is the incomplete understanding of the production, storage and emission of free phase gas (FPG), a previously under-appreciated source of methane and carbon dioxide emissions to the atmosphere. It is increasingly clear that FPG production, storage and emission are regulated by hydraulic forcing, as well as the mechanical properties of the peat, i.e. that the carbon and water cycles in a peatland are intimately connected. The focus of this project is field-scale hydrological and hydrogeophysical research to further investigate the importance of recently invoked "shallow" versus "deep" peat models for the production, storage and emission of FPG in northern peatlands. Specific objectives of the project include [1] quantifying vertical variations in storage and release of methane with depth over a minimum six month time period at each of three locations within a peatland, [2] determining the hydrological forcing mechanisms that drive releases from both deep and shallow gas, [3] estimating spatial variations in storage and release as a function of subsurface heterogeneity, and [4] quantifying relative contributions of shallow versus deep gas to methane emissions from a northern peatland. This research will be conducted by coupling hydrogeological methods with novel chamber, geophysical and geodetic sensing technologies sensitive to FPG production, storage and emissions. The field site is Caribou Bog, a well-studied multi-unit peatland complex in central Maine. Empirical predictive models and simple mechanistic models will be developed to assess the relative importance of key forcing mechanisms on FPG emissions. Time-frequency analysis of time-series datasets will also be employed to improve understanding of likely forcing components regulating production, storage and release of FPG. This research will significantly advance our understanding of hydrological controls on FPG dynamics in northern peatlands, with important implications for the response of peatland carbon dynamics to climate change.Northern peatlands globally cover more than 350 million ha and contain about one third of the terrestrially stored carbon. The fate of this carbon in response to continued climate warming is highly uncertain. Peatlands are also a source of atmospheric methane, a potent greenhouse gas that contributes to climate warming. This research will provide fundamental scientific knowledge needed to advance the understanding of the cycling of methane in peatlands, and how peatland hydrology controls the emission of methane from peatlands to the atmosphere. The work has direct societal relevance given the concerns about the environmental and economical affects of climate warming. In this project, Lois Stokes Alliance for Minority Participation undergraduate students will be exposed to a hands-on interdisciplinary research among three institutions. Furthermore, an international community of graduate students will participate in a student-focused session on methane cycling in northern peatlands at American Geophysical Union meetings. Community outreach in the vicinity of the Caribou Bog will occur via annual guided tours using the Orono Bog Boardwalk that served +30,000 visitors in 2009.