Collaborative Research: New Roles for Reactive Oxygen Species in Mediating Carbon Fluxes at the Terrestrial-Aquatic Interface

美国中北部地区的湿地是重要的生态系统，在区域碳循环中起着关键作用，并可能受到气候变化的巨大影响。这些湿地的温室气体释放速率可能会随着气候变暖而增加，从而抵消它们固碳的能力。通过研究湿地沉积物中随时间和空间变化的化学和微生物过程，预测气候变化对这些关键栖息地的影响将成为可能。通过摄影记录该地区的生态重要性，将向广大观众展示湿地的价值。生物地球化学活动的驱动因素决定了小内陆水域二氧化碳和甲烷的排放，但这些水体的过程在理解气候变化方面发挥着巨大的作用。一个鲜为人知的过程是化学反应在小湖泊和湿地中介导二氧化碳和甲烷形成的作用，特别是在沉积物-水界面（SWI）上活性氧（ROS）的非生物生产。该项目的假设是，在SWI中，铁、硫和碳的还原可溶性和颗粒形式与微量氧形成ROS的反应是对小型内陆水体中微生物活性和碳循环的重要控制，但这一控制尚未得到充分认识。本研究将结合北达科他州草原坑穴区野外工作、对照实验室实验和中尺度研究，1)确定SWI区ROS生成的地球化学驱动因素；2)确定SWI区孔隙水化学与ROS相关的时空格局。3)追踪影响小湖泊和湿地沉积物中碳矿化速率和甲烷生成速率的ROS-DOM反应产生的特定活性碳底物的生成。现场伏安法测量，溶解和颗粒有机物，铁和硫物种的详细表征，以及微生物组学分析的组合将用于了解耦合的生物地球化学过程。这项工作的一个关键组成部分是了解沉积物-水界面上非生物ROS驱动的反应如何导致终端电子受体的周转和不稳定微生物底物的产生。为了预测不同气候情景下二氧化碳和甲烷通量的变化，需要建立对这些过程的基本认识。收集的数据将有助于了解生物地球化学循环如何通过耦合的非生物/生物途径维持，以及这些过程如何影响水生环境中的碳循环。这种方法也适用于其他系统和其他元素的循环，如氮，这在城市湿地地区可能特别重要。社会效益将是增进对影响气候变化和受气候变化影响的过程的了解。为了让尽可能多的人了解该地区的重要性，摄影师将在实地采样旅行中记录该地区的景观及其生态功能。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wetlands in the north central region of the United States are important ecosystems that play critical roles in the regional carbon cycle and are likely to be dramatically affected by climate change. Rates of greenhouse gas release from these wetlands may increase with warming and offset their ability to sequester carbon. By studying the chemical and microbiological processes in wetland sediments over space and time, predictions of the effects of climate change on these critical habitats will be possible. Documentation of the ecological importance of this region via photography will demonstrate the value of wetlands to a broad audience.The drivers of biogeochemical activity that dictate the emissions of carbon dioxide and methane in small, inland waters are poorly constrained, yet processes in these water bodies play an oversized role in understanding climate change. One process that is poorly understood is the role of chemical reactions in mediating carbon dioxide and methane formation in small lakes and wetlands, especially the abiotic production of reactive oxygen species (ROS) at the sediment-water interface (SWI). The hypothesis for this project is that the reaction of reduced soluble and particulate forms of iron, sulfur, and carbon with trace level oxygen to form ROS at the SWI is an under-appreciated, yet critical, control on microbiological activity and the cycling of carbon in small inland water bodies. Using a combination of field work in the prairie pothole region of North Dakota, controlled laboratory experiments, and mesocosm studies, this work will 1) identify the geochemical drivers of ROS generation at the SWI, 2) determine spatiotemporal patterns of linked pore water chemistry and ROS at the SWI, and 3) track the generation of specific labile carbon substrates produced through ROS-DOM reactions that affect rates of carbon mineralization and methane production in small lake and wetland sediments. A combination of in situ voltammetry measurements, detailed characterization of dissolved and particulate organic matter, iron, and sulfur species, and microbial -omics analyses will be used to understand the coupled biogeochemical processes. A key component of this work is understanding how abiotic ROS driven reactions at the sediment-water interface lead to turnover of terminal electron acceptors and generation of labile microbial substrates. Establishing a baseline understanding of these processes is needed to predict changes in carbon dioxide and methane fluxes under different climate scenarios. The collected data will enable understanding of how biogeochemical cycles are maintained through coupled abiotic/biotic pathways, and how these processes impact carbon cycling in aquatic environments. This approach is also applicable to other systems and the cycling of other elements, such as nitrogen, which may be especially important in urban wetland regions. The societal benefit will be improved understanding of processes that influence, and are influenced by, climate change. To reach as broad an audience as possible regarding the importance of this region, a photographer will document the landscape and its ecological function during field sampling trips.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.