Investigating the physical and chemical controls on aerobic methane oxidation

该项目将研究控制天然含氧水体中甲烷氧化的变量。甲烷是一种重要的温室气体。人们通常认为，随着气候变暖，海洋有可能向大气释放大量甲烷。然而，目前从海洋表面排放到大气中的甲烷相对较少。当地的研究表明，这些天然水体中甲烷的有氧氧化有助于在甲烷排放之前将其去除。然而，由于两个原因，估计这种移除一直具有挑战性。首先，不同实验室的甲烷氧化测量结果并不总是一致的。其次，不同的国情改变了甲烷的好氧氧化速率。这个项目将解决这些问题。这项工作将有助于确定这一甲烷汇的全球重要性，预测未来甲烷氧化率将如何变化，并建立测量方案，以提高结果的可比性。此外，这个项目将吸引一批本科生。这些学生将学习以这个项目为中心的海洋学研究方法。此外，他们还将学习如何发展自己的科学兴趣、假设和实验计划。然后，这些学生将有机会参加与这项工作相关的研究巡航，在那里他们将制定自己的实验计划。该项目过去的参与者为5篇科学出版物做出了贡献，12名学生进入了竞争激烈的研究生课程。本项目将通过系统的实验室实验和环境测量相结合的方式来完成。将对美国五大湖和美国大西洋边缘的海洋进行调查，以评估好氧甲烷氧化的稳态和非稳态化学动力学。该项目将检验水温和甲烷浓度是控制好氧甲烷氧化的主要变量，溶解氧和营养物浓度等其他变量是次要影响的假设。在这项工作的结论，将建立一个相对简单的模型结合水温和底物浓度(s)来预测甲烷氧化速率。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。

This project will study the variables that control the oxidation of methane in oxygenated natural waters. Methane is an important greenhouse gas. Oceans are often viewed as having the potential to release large amounts of methane to the atmosphere with warming. However, current emissions of methane from the sea surface to the atmosphere are relatively low. Local studies have shown that aerobic oxidation of methane in these natural waters helps to remove methane prior to emission. However, estimating this removal has been challenging for two reasons. First, methane oxidation measurements from different laboratories do not always agree. Second, different national conditions change the rates of aerobic methane oxidation. This project will solve these problems. This work will help determine the global importance of this methane sink, predict how methane oxidation rates will change in the future, and establish measurement protocols for greater comparability of results. Additionally, this project will engage a cohort of undergraduate students. These students will be taught oceanographic research methods centered around this project. Also, they will be coached on how to develop their own scientific interests, hypotheses, and experimental plans. Then, these students will be given the opportunity to join the research cruise associated with this work where they will enact their own experimental plans. Past participants of this program have contributed to 5 scientific publications, and 12 students have gone on to highly competitive graduate programs. This project will be accomplished through a combination of systematic laboratory experiments and environmental measurements. Investigations on the US Great Lakes and at sea along the US Atlantic Margin will be conducted to evaluate the steady-state and non-steady-state chemical kinetics of aerobic methane oxidation. This project will test the hypothesis that water temperature and methane concentration are the dominant variables governing aerobic methane oxidation with other variables of dissolved oxygen and nutrient concentrations contributing secondary influences. At the conclusion of this work, a relatively simple model will be established combining water temperature and substrate concentration(s) to predict rates of methane oxidation.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.