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

在热带小溪上筑坝，在巴西农业边境地区建造了数十万座人工水库，这是该国悠久的养牛业历史留下的持久遗产。这些水体的低氧条件有利于甲烷的产生，甲烷是一种强大的温室气体，其威力是二氧化碳的25倍。尽管这些水体分布广泛，可以持续数十年，但我们对控制水库甲烷产生的因素，或它们对全球碳收支的集体贡献知之甚少。这一作品奖通过支持新的研究、相关培训和首席研究员的指导机会来解决这一知识差距。接触到尖端的实验室技术将使她能够研究水库产生甲烷的潜在机制，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对全球碳循环进行建模，以及负责监测温室气体源和汇的国家机构。它们在巴西和其他热带地区的水库管理中也有实际应用。最终，结果将提高对哪些途径主导甲烷通量的理解，并有助于确定潜在的管理策略，以减少农业景观中的温室气体排放。通过促进利用该奖项收集的数据与亚马逊东南部十多年的研究数据集的合成，该项目将解决几个关键研究目标。首先，它将通过对稳定同位素(13C，D)的分析，以及沉积物堆积和有机碳在水库中埋藏的动力学，帮助澄清甲烷的生产和消费途径。其次，它将结合放射性碳(14C)和稳定同位素分析，阐明不同有机质来源推动微生物甲烷生产的相对重要性。沉积物中的碳同位素还可以洞察外部有机质来源(即来自森林、牧草或大豆的碳)与内部生产(即受最近营养沉积刺激的藻类或大型植物)之间的相对重要性。最后，这项工作将通过描述大气中生物来源水库排放的同位素指纹并评估它们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，碳同位素可能会提供关于水库是作为全球碳源还是碳汇的重要线索。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.