Oxygen dynamics in large reservoirs: A new framework for understanding the formation of metalimnetic oxygen minima

溶解氧（DO）是湖泊和水库水质管理的关键指标。它对这些生态系统的生态系统功能至关重要。过低的浓度（缺氧）限制了水的饮用和其他用途。缺氧的水还会产生其他健康问题。最后，水处理变得昂贵。因此，淡水水体的健康和可持续运作是公众的首要利益。因此，我们建议中德两国顶尖研究机构的科学家在水资源研究领域开展合作，这些研究机构在处理国内外新颖而具有挑战性的环境问题方面享有盛誉。数值模拟工具以及现场实验和测量都将在当前可用设备的最前沿进行操作。通过这次合作，我们期望双方对现有的水问题有一个相互的理解，就现代现场设备和在数值模拟中实施这些数据进行密集的交流，最后对如何在另一个国家将有关水问题和水库管理的新知识付诸实践更加敏感。水是一个核心的健康问题，公众从改善水质中获益。氧对环境压力如有机污染、富营养化或气候变化反应非常敏感。由于生态、生物地球化学和物理过程的复杂相互作用，其动态预测是一项具有挑战性的任务。虽然低浓度DO的动力学已经得到了深入的研究，并且因此可以在许多目的中以足够的精度预测，但金属离子（即温暖的上膜层和寒冷的深层低浓度离子之间的层）中DO的动力学却知之甚少。超磁性氧极小值（MOM）是淡水和海洋系统中已知的一种现象，是由高需氧量和低垂直交换的结合引起的。金属离子内DO需求增加的原因受到猜测，涉及浮游生物呼吸、进口异质物质、浊度结合呼吸或沉积物质分解等替代机制。本提案的目的是在德国和中国的水库（Rappbode水库和Panjiakou水库）实施高分辨率DO监测，并进行现场和实验室实验，以测试有关DO消耗驱动因素的各种假设。野外和实验室实验结果以及高分辨率监测研究通过嵌入一维和三维耦合水动力-生物地球化学湖泊模型的数学过程描述进行概念化。开发的模型工具以基于开源代码的模型框架的形式提供给科学界。

Dissolved oxygen (DO) is a key quantity in water quality management of lakes and reservoirs. It is essential for the ecosystem functioning of these lentic ecosystems. Too low concentrations (anoxia) limit the usability of water for drinking and other purposes. Additional health issues arise from anoxic waters. Last and not least, water treatment becomes expensive. Hence, a healthy and sustainable operation of our freshwater bodies is of prime public interest. Therefore, we propose cooperation between scientists of a leading Chinese and German research institutions involved in water research with a reputation for approaching novel and challenging environmental concerns inside and outside their own countries. Both, numerical simulation tools as well as field experiments & measurements will be operated at the forefront of currently available equipment. From this collaboration, we anticipate a mutual understanding for existing water issues, an intensive exchange about modern field equipment and the implementation of such data in numerical simulations and finally more sensibility of how new knowledge about water issues and reservoir management are put into practice in the other country. Water is a central health issue and the public profits from improved water quality. Oxygen reacts highly sensitive against environmental stressors like organic pollution, eutrophication or climate change. The prediction of its dynamics is a challenging task due to the complex interaction of ecological, biogeochemical, and physical processes. While the dynamics of hypolimnetic DO have been studied intensively and, as a consequence, can be predicted with sufficient accuracy for many purposes, the dynamics of DO in the metalimnion (i.e. the layer between the warm upper epilimnion and the cold, deep hypolimnion) have been understood far less. Metalimnetic oxygen minima (MOM), a phenomenon known from freshwater and marine systems, arise from a combination of high oxygen demand and low vertical exchange. The causal factors of the increased DO demand within the metalimnion are subjected to speculation and involve alternative mechanisms like plankton respiration, imported allochthonous material, turbidity-bound respiration or the breakdown of sedimenting material. The aim of this proposal is the implementation of high-resolution DO-monitoring in German and Chinese Reservoirs (Rappbode Reservoir and Panjiakou Reservoir) together with field and laboratory experiments for testing various hypotheses about the drivers of DO consumption. Results of the field and lab experiments as well as high-resolution monitoring studies are conceptualized by mathematical process descriptions that are embedded in 1D and 3D coupled hydrodynamic-biogeochemical lake models. The developed model tools are provided to the scientific community in model frameworks based on open source codes.