OPUS MCS: Developing a mechanistic understanding of methane production from small agricultural reservoirs in the Amazon-Cerrado frontier

在巴西的农业前沿筑坝修建小型热带溪流，形成了数十万个人工水库，这是该国悠久的养牛历史的持久遗产。这些水体中的低氧条件有利于甲烷的产生，这是一种强效温室气体，其威力是二氧化碳的二十五倍。尽管这些水体分布广泛并且可以持续数十年，但我们对控制水库甲烷产生的因素或其对全球碳预算的集体贡献知之甚少。该 OPUS 奖项通过支持首席研究员的新研究、相关培训和指导机会来弥补这一知识差距。接触尖端实验室技术将使她能够研究水库中甲烷产生的机制，并扩大她未来的研究范围。由此产生的数据集将有助于科学家模拟全球碳循环，以及负责监测温室气体源和汇的国家机构。它们还可以实际应用于巴西和其他热带地区的水库管理。最终，结果将加深对哪些途径主导甲烷通量的理解，并帮助确定减少农业景观中温室气体排放的潜在管理策略。通过促进该奖项收集的数据与亚马逊东南部十多年研究数据集的综合，该项目将解决几个关键研究目标。首先，通过稳定同位素（13C、D）分析以及水库中沉积物积累和有机碳埋藏的动态分析，有助于阐明甲烷产生和消耗的途径。其次，它将结合放射性碳（14C）和稳定同位素分析，阐明驱动微生物甲烷产生的不同有机物来源的相对重要性。沉积物中的碳同位素还可以深入了解外部有机物来源（即来自森林、牧草或大豆的碳）与内部生产（即最近养分沉积刺激的藻类或大型植物）的相对重要性。最后，这项工作将通过表征大气中生物库排放的同位素指纹并评估其作为甲烷来源的相对重要性，为全球建模工作提供信息。最终，碳同位素可能提供关于水库是否作为景观中的全球碳源或碳汇的重要线索。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。

Damming small tropical streams has created hundreds of thousands of artificial reservoirs across Brazil’s agricultural frontier, a lasting legacy of the country’s long history of cattle ranching. The low-oxygen conditions in these water bodies favors production of methane – a potent greenhouse gas that is twenty-five times more powerful than carbon dioxide. Although these water bodies are widespread and can persist for decades, we know little about the factors controlling methane production in reservoirs, or their collective contribution to the global carbon budget. This OPUS award addresses that knowledge gap by supporting new research, relevant training, and mentorship opportunities for the principal investigator. Exposure to cutting-edge lab techniques will allow her to examine the mechanisms underlying methane production in reservoirs and expand the scope of her future research. Resulting datasets will be useful for scientists modeling the global carbon cycle, as well as national agencies tasked with monitoring sources and sinks of greenhouse gases. They also have practical applications for the management of reservoirs in Brazil and other tropical regions. Ultimately, results will improve understanding of which pathways dominate methane fluxes and help identify potential management strategies to reduce greenhouse gas emissions in agricultural landscapes.By facilitating the synthesis of data collected with this award with datasets from over a decade of research in the southeastern Amazon, this project will address several key research objectives. First, it will help clarify the pathways of methane production and consumption through analyses of stable isotopes (13C, D) and the dynamics of sediment accumulation and organic carbon burial in reservoirs. Second, it will shed light on the relative importance of different sources of organic matter driving microbial methane production using a combination of radiocarbon (14C) and stable isotope analyses. Carbon isotopes in sediments may also yield insights into the relative importance of external sources of organic matter (i.e. carbon derived from forest, pasture grasses, or soybeans) versus internal production (i.e. algae or macrophytes stimulated by recent nutrient deposition). Lastly, this work will inform global modeling efforts by characterizing the isotopic fingerprint of biogenic reservoir emissions in the atmosphere and evaluating their relative importance as a methane source. Ultimately, carbon isotopes may provide important clues about whether reservoirs act as a global source or sink of carbon in the landscape.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.