Dissertation Research: Extracellular enzyme activity in large rivers and its relationship to dissolved organic matter quality and inorganic nutrient uptake

河流为人类社会和环境提供基本的生态系统服务，从供水和净化到生态旅游。成功的环境政策和有效的淡水资源管理需要对河流中发生的生物地球化学过程有详细和机械的了解。然而，对大河生物地球化学的认识还远远不够，对大河生态过程的研究更是少之又少。溶解有机物是溪流和河流的基本成分。溶解有机物除了是微生物的营养来源外，还会影响酸度、透光性以及氧气和痕量金属的浓度。该项目的目标是填补关于大型河流中溶解有机物的生物地球化学，以及溶解有机物与微生物过程之间的相互作用的知识空白，如养分吸收和胞外酶活性。这项研究将在美国西部和中西部的七条大河中进行。这一博士论文改进项目将有助于更好地了解美国的大河生态和河流管理。研究结果将在国际科学会议上公布，并在同行评议的期刊文章中发表。一名本科生将担任该项目的研究助理，这样做将获得宝贵的经验和培训。PI和共同PI都将把这个项目作为他们在研究生和本科生水平教授的课程的示范或案例研究。最后，联合PI将在印第安纳大学女性科学大会上展示这项研究的结果，作为吸引对研究感兴趣但不确定是否从事科学事业的本科生女性的一种手段。

Rivers provide fundamental ecosystem services to human societies and the environment, from delivery and purification of water supplies to eco-tourism. Successful environmental policies and effective management of freshwater resources require detailed and mechanistic knowledge of the biogeochemical processes occurring in rivers. However, understanding of the biogeochemistry of large rivers is far from complete, and there is a paucity of research on ecological processes in large rivers. Dissolved organic matter is a fundamental component of streams and rivers. In addition to being a source of nutrients for microorganisms, dissolved organic matter can influence acidity, light penetration and the concentration of oxygen and trace metals. The goal of this project is to fill knowledge gaps regarding the biogeochemistry of dissolved organic matter in large rivers, and the interactions between dissolved organic matter and microbial processes such as nutrient uptake and extracellular enzyme activity. The research will be conducted in seven large rivers in the western and midwestern United States. This doctoral dissertation improvement project will contribute to a better understanding of large river ecology and river management in the U.S. The results will be presented at an international scientific meeting and published in peer-reviewed journal articles. An undergraduate student will work as a research assistant on the project and by doing so will gain valuable experience and training. Both the PI and co-PI will use the project as a demonstration or case study in the courses they teach at the graduate and undergraduate levels. Lastly, the co-PI will present results from this study at the Indiana University Women in Science Conference as a means of engaging undergraduate women who are interested in research but unsure about pursuing a career in science.