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

目前泥炭地碳循环将如何响应气候变暖的不确定性的主要原因是对自由相气（FPG）的产生、储存和排放的不完全了解，FPG是一种以前未被充分认识的甲烷和二氧化碳排放到大气中的来源。越来越清楚的是，FPG的生产、储存和排放受到水力压力以及泥炭的机械特性的调节，也就是说，泥炭地的碳和水循环密切相关。该项目的重点是现场尺度的水文和水文地球物理研究，以进一步调查最近引用的“浅”与“深”泥炭模型对北部泥炭地FPG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在至少六个月的时间内甲烷随深度的垂直储存和释放变化；[2]确定驱动深层和浅层气体释放的水文强迫机制；[3]估计储存和释放的空间变化作为地下异质性的函数；b[4]量化了北部泥炭地浅层和深层天然气对甲烷排放的相对贡献。这项研究将通过将水文地质方法与对FPG生产、储存和排放敏感的新型腔室、地球物理和大地测量传感技术相结合来进行。研究地点是位于缅因州中部的加勒比沼泽（Caribou Bog），这是一个经过充分研究的多单元泥炭地。将开发经验预测模型和简单的机制模型，以评估关键强迫机制对FPG排放的相对重要性。时间序列数据集的时频分析也将用于提高对调控FPG生产、储存和释放的可能强制成分的理解。该研究将极大地促进我们对北部泥炭地FPG动态的水文控制的理解，对泥炭地碳动态对气候变化的响应具有重要意义。全球北部泥炭地覆盖面积超过3.5亿公顷，约占陆地碳储量的三分之一。随着气候持续变暖，这些碳的命运是高度不确定的。泥炭地也是大气中甲烷的来源，甲烷是一种导致气候变暖的强效温室气体。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，以及泥炭地水文如何控制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，Lois Stokes少数民族参与联盟的本科生将在三个机构中进行动手跨学科研究。此外，在美国地球物理联合会会议上，一个国际研究生团体将参加一个以学生为中心的会议，讨论北部泥炭地的甲烷循环。carcaribou Bog附近的社区外展活动将通过每年一次的导游带领，使用Orono Bog Boardwalk， 2009年接待了超过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.