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，在区域碳循环中发挥着关键作用，并可能受到气候变化的显着影响。这些湿地的温室气体释放率可能会随着变暖而增加，并抵消其固碳能力。通过研究湿地沉积物在空间和时间上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，将向广大受众展示湿地的价值。决定小型内陆水域二氧化碳和甲烷排放的生物地球化学活动的驱动因素很少受到限制，但这些水体中的过程在理解气候变化方面发挥着巨大的作用。人们知之甚少的一个过程是化学反应在介导小湖泊和湿地二氧化碳和甲烷形成中的作用，特别是沉积物-水界面 (SWI) 活性氧 (ROS) 的非生物产生。该项目的假设是，还原的可溶性和颗粒形式的铁、硫和碳与痕量氧在 SWI 发生反应形成 ROS，这是对小型内陆水体中微生物活动和碳循环的一种未被充分重视但至关重要的控制。通过结合北达科他州草原坑洼地区的现场工作、受控实验室实验和中生态系统研究，这项工作将 1) 确定 SWI ROS 生成的地球化学驱动因素，2) 确定 SWI 孔隙水化学和 ROS 相关的时空模式，3) 跟踪通过 ROS-DOM 反应产生的特定不稳定碳底物的生成，这些碳底物影响小湖泊和湿地沉积物中碳矿化和甲烷产生的速率。结合原位伏安法测量、溶解和颗粒有机物、铁和硫物质的详细表征以及微生物组学分析，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非生物活性氧驱动的沉积物-水界面反应如何导致末端电子受体的周转和不稳定微生物底物的产生。需要建立对这些过程的基线了解，以预测不同气候情景下二氧化碳和甲烷通量的变化。收集的数据将有助于了解如何通过非生物/生物耦合途径维持生物地球化学循环，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，例如氮，这在城市湿地地区可能特别重要。社会效益将提高对影响气候变化以及受气候变化影响的过程的了解。为了让尽可能广泛的受众了解该地区的重要性，摄影师将在实地采样旅行中记录景观及其生态功能。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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.