Collaborative Research: Consequences of changing oxygen availability for carbon cycling in freshwater ecosystems

许多湖泊和水库的含氧量在全球范围内正在发生变化。这些变化可能会威胁到湖泊提供的生态系统服务。除了降低饮用水和渔业的质量外，氧气的变化还会改变湖底埋藏的碳量。由于人造水库每年储存的碳比海洋多，这些变化可能会对全球碳循环产生重大影响。氧气变化的幅度以及对水质的影响尚不清楚。该项目将利用一个前所未有的机会，将整个水库从低氧转变为高氧。这项研究包括几个实验，涉及改变氧气水平，并检查对碳循环的影响。这项研究将改善对环境变化将如何影响湖泊碳埋藏的预测。项目成果将帮助管理人员实现改善水库水质的目标。它还将有助于理解管理对湖泊碳埋藏的长期影响。该项目将为本科生的水库生态学课程制作教育工具和教案。项目科学家将与自来水公司和更广泛的研究社区合作，分享知识，以改善政策。最后，研究生和本科生将接受横跨生态学、地球科学和工程学的培训。淡水，尤其是人造水库，接收和处理大量的碳，这些碳可能以二氧化碳和甲烷的形式排放，也可能被埋在沉积物中。氧浓度的日益变化可能对淡水碳循环产生全球影响，因为高氧条件不仅促进最近进入生态系统的新碳的矿化，而且促进多年沉积积累的遗留碳的矿化。这个项目将解决最重要的问题：氧气的变化将如何改变淡水生态系统中的碳处理以及二氧化碳和甲烷的排放？为了回答这些问题，在全生态系统氧气实验中，将利用新的传感器技术在分钟的时间尺度上测量不同氧气和温度条件下的碳矿化和电子受体途径，以量化碳的处理速度。在开源生态系统模型中，将使用对一组水库进行的氧气可获得性梯度的额外采样，以改进对淡水生态系统长期碳埋藏的预测。总而言之，将整个生态系统的氧气操作与建模相结合，将确定动态氧气条件如何改变水生生态系统中的碳循环。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。

The amount of oxygen in many lakes and reservoirs is changing globally. These changes may threaten ecosystem services lakes provide. In addition to degrading drinking water and fisheries, changes in oxygen can change how much carbon is buried in lake bottoms. Since human-made reservoirs store more carbon annually than the ocean, these changes may have a major impact on global carbon cycling. The magnitude of changes in oxygen, and consequences for water quality, are unknown. This project will take advantage of an unprecedented opportunity to switch an entire reservoir from low to high oxygen. The study includes several experiments that involve changing oxygen levels, and examining the impacts on carbon cycling. This research will improve predictions of how environmental changes will affect carbon burial in lakes. The project results will help managers meet goals to improve reservoir water quality. It will also contribute to understanding long-term effects of management on carbon burial in lakes. This project will produce educational tools and lesson plans for undergraduate courses on reservoir ecology. Project scientists will work with water utilities and the broader research community to share knowledge to improve policy. Finally, graduate and undergraduate students will be trained in subjects spanning ecology, geosciences, and engineering. Freshwaters, especially human-made reservoirs, receive and process a vast amount of carbon, which can be emitted as carbon dioxide and methane or buried in sediments. Increasingly variable oxygen concentrations may have global implications for freshwater carbon cycling because high oxygen conditions promote not only the mineralization of new carbon that has recently entered an ecosystem, but also legacy carbon accumulated over years of sedimentation. This project will address the overarching question: How will changes in oxygen alter carbon processing and carbon dioxide and methane emissions in freshwater ecosystems? To answer these questions, carbon mineralization and electron acceptor pathways will be measured with new sensor technology at the time scale of minutes under different oxygen and temperature conditions in whole-ecosystem oxygen experiments to quantify rates of carbon processing. Additional sampling across a suite of reservoirs on a gradient of oxygen availability will be used in open-source ecosystem models to improve predictions of long-term carbon burial in freshwater ecosystems. In sum, integrating whole-ecosystem manipulations of oxygen with modeling will determine how dynamic oxygen conditions alter carbon cycling in aquatic ecosystems.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.