RedoxFlux: Biogeochemical fluxes and transformations at pelagic redoxclines in lakes

氧化还原跃层是好氧水体和缺氧水体之间的界面，它将两种截然不同的生境分开，或者说连接起来，是许多湖泊中生物地球化学转化的热点。在氧化还原跃层的深处，发生例如硫、铁和锰的强烈循环。这种循环涉及化学和微生物反应，相应的转化率主要受以下因素控制：（i）溶解和颗粒物质的垂直运输，（ii）反应和沉淀溶解动力学，以及（iii）光的可用性。在这个项目中，我们将获得这些过程的相互作用的过程为基础的理解。垂直通量和地球化学周转率将估计在三个不同的湖泊，代表三个对比鲜明的水体减少化学物种，光，垂直混合的可用性方面的实地实验。将在为两个研究地点设立的实验室围隔实验中研究潜在的化学和微生物反应的详细动力学。在一种创新的方法中，中型生态系统将独立地模拟密度分层、所有相关成分的垂直通量和垂直混合。从实验室和现场实验的结果将结合到一个基于过程的数值模型，允许我们的结果转移到不同的水生系统和不断变化的环境条件。

The interface between oxic and anoxic water bodies, the redoxcline, separates, or rather connects two very contrasting habitats and is a hotspot of biogeochemical transformations in many lakes. At the depth of the redoxcline, intense cycling of, e.g. sulfur, iron and manganese, occurs. This cycling involves chemical as well as microbial reactions and the corresponding transformation rates are mainly controlled by (i) vertical transport of dissolved and particulate substances, (ii) reaction and precipitation-dissolution kinetics, and (iii) by the availability of light. In this project we will gain a process-based understanding of the interplay of these processes. Vertical fluxes and biogeochemical turnover rates will be estimated in field experiments at three different lakes, representing three contrasting water bodies in terms of the availability of reduced chemical species, light, and vertical mixing. The detailed kinetics of the underlying chemical and microbial reactions will be studied in laboratory mesocosm experiments, set up for two of the study sites. In an innovative approach, the mesocosms will independently mimic density stratification, vertical fluxes of all relevant constituents and vertical mixing. Results from laboratory and field experiments will be combined into a process-based numerical model, allowing for a transfer of our results to different aquatic systems and to changing environmental conditions.