DISSERTATION RESEARCH: The nexus of observation and modeling of methane emissions from inland water bodies

气候和湿地之间的相互影响目前还没有得到很好的理解。虽然湿地植物从大气中消耗二氧化碳，但湿地也产生甲烷，这是一种影响全球气候的强大温室气体。甲烷的产生及其在湿地土壤中的运动是由许多同时发生的过程引起的。生活在没有氧气的湿地土壤中的微生物可以产生甲烷。甲烷比空气轻，可以通过土壤进入大气。然而，在通过土壤的运输过程中，如果当地的化学物质有利于这一过程，特殊的细菌可以消耗甲烷。此外，植物可以促进甲烷从土壤到大气的运动。该项目将研究甲烷通过湿地植被的输送，并改进该过程的数学模型。这将通过开发新的测量技术来实现，这种技术可以更准确地预测通过湿地植物输送的甲烷量。这项工作的结果将提高我们对湿地如何在甲烷气体释放方面发挥作用的总体理解，甲烷气体是气候模拟中重要的一种强效温室气体。在常见的甲烷从土壤到大气的途径中，植物运输可能是最复杂和最不为人所知的。此外，湿地通常由土地覆盖类型的紧密镶嵌组成。然而，目前很少有模型考虑湿地内植物异质性对总甲烷通量的影响。植物通过它们的根通气系统、通气组织以及木质部和气孔来移动甲烷。据推测，溶解在植物根区孔隙水中的甲烷在蒸腾过程中被植物动员起来。然而，气孔传导甲烷的作用尚不清楚，现代甲烷排放模型几乎总是忽略了气孔传导甲烷的作用。在这个项目中，研究人员将设计和部署新的室来量化湿地植物介导的甲烷通量，并使用这些数据来参数化该过程的一般模型。部署腔室的研究地点将是老妇溪国家河口研究保护区。这些活动是综合测量活动的一部分，包括测量通过水柱的扩散通量的传统静态室，提供土壤中甲烷浓度概况的孔隙水透析窥视器，以及涡流协方差塔，它将提供进入大气的甲烷通量的现场水平测量。植物流体动力学模型、FETCH2和湿地甲烷模型将耦合模拟通过植物排放的甲烷。

The impacts of climate and wetlands on each other are currently not well understood. While wetland plants consume carbon dioxide from the atmosphere, wetlands also produce methane, a powerful greenhouse gas that influences the global climate. Methane production and its movement within the soils of wetlands results from many simultaneous processes. Microorganisms living in wetland soils where there is no oxygen can produce methane. Methane, being lighter than air, works its way through the soil and can escape into the atmosphere. However, during transport through soils, specialized bacteria can consume methane if the local chemistry is favorable to that process. Additionally, plants can facilitate the movement of methane from soils to the atmosphere. This project will study the transport of methane through wetland vegetation and improve mathematical models of that process. This will be accomplished by developing new measurement techniques that can more accurately predict how much methane is transported through wetland plants. Results from this work will improve our general understanding of how wetlands function with respect to release of methane gas, a potent greenhouse gas important in climate modeling.Plant transport is perhaps the most complex and least understood of the common methane pathways from the soil to the atmosphere. Moreover, wetlands are frequently comprised of a tight mosaic of land cover types. However, few models currently account for the effects of plant heterogeneity within the wetland on the total methane flux. Plants move methane both through their root aeration system, aerenchymous tissue, and through their xylem and stomata. It has been hypothesized that methane dissolved into the pore water at the plant root zone is mobilized by the plant as it transpires. However, the role of stomatally conducted methane is not clear and is almost always ignored by modern methane emission models. In this project, researchers will design and deploy novel chambers to quantify plant-mediated fluxes of methane from wetlands and use those data to parameterize a general model of the process. The study site for chamber deployment will be the Old Woman Creek National Estuary Research Reserve. These activities are part of a comprehensive measurement campaign involving traditional static chambers to measure diffusive fluxes through the water column, pore-water dialysis peepers, which provide a profile of methane concentrations in the soil, and an eddy-covariance tower, which will provide site level measurements of methane flux into the atmosphere. The plant hydrodynamics model, FETCH2, and a wetland methane model will be coupled to simulate the methane emitted through plants.