Dissertation Research: Ecosystem Metabolism and Nitrate Retention in Headwater Streams: Influence of the Hyporheic Zone

文摘99-02324 Dahm/FellowsDDIG：生态系统新陈代谢和水源中硝酸盐的滞留：低水区的影响人类通过输入氮素(如化肥、废水和内燃机排放中的氮素)改变全球氮循环是一个关键的全球环境问题。这些输入的一个明显表现是美国地表水和地下水中硝酸盐浓度的增加，这是一种潜在的污染物。了解源头溪流中的营养动态是理解河流将如何响应增加的人为硝酸盐输入的关键部分。潜流带(地表水和地下水的混合区)最近被认为是河流生态系统的重要组成部分，特别是在源头河流。通过代谢活动，生活在低渗出区的微生物可以暂时或永久地保留硝酸盐，并阻止其向下游移动。本研究量化了3条水源河流中潜水带对硝酸盐滞留的贡献，并研究了这种滞留与生态系统新陈代谢速率之间的关系。

Abstract99-02324Dahm / FellowsDDIG: Ecosystem metabolism and nitrate retention in headwater streams: Influence of the hyporheic zoneHuman alteration of the global nitrogen cycle through inputs of nitrogen such as those in fertilizer, wastewater, and combustion engine emissions is a critical global environmental problem. A clear manifestation of these inputs is increased concentrations of nitrate, a potential pollutant, in surface and groundwater throughout the U.S. Understanding nutrient dynamics in headwater streams is an essential part of understanding how rivers will respond to increased anthropogenic inputs of nitrate. The hyporheic zone (the region of mixing between surface water and groundwater) has recently been recognized as an important component of stream ecosystems, especially in headwater streams. Through their metabolic activities, microorganisms which live in the hyporheic zone can temporarily or permanently retain nitrate and prevent it from traveling downstream. This research quantifies the contribution of the hyporheic zone to nitrate retention in 3 headwater streams and investigates the relationship between this retention and rates of ecosystem metabolism.