Dissertation Research: Phosphorus Cycling in Shallow Freshwater Ecosystems

磷是所有生物所必需的营养，但在工业化肥和其他产品中的使用使其在许多农业和城市流域中的出现增加到污染水平。过量的磷往往会导致淡水生态系统的富营养化。富营养化在美国仍然是一个普遍存在的问题，可能会影响水生生态系统，如有毒浮游植物大量繁殖、水体透明度降低、植物群落变化和鱼类死亡。由于沉积物积累磷的能力，湿地通常被管理来储存磷并防止进入下游生态系统。湿地沉积物结合磷的能力各不相同，有时湿地可能成为磷的来源，而不是汇。磷与沉积物结合和释放的方式在深水湖泊中得到了广泛的研究，但在浅水湿地中的研究较少。浅层湿地与湖泊的不同之处在于，它们经常干涸并重新泛滥，而且倾向于拥有含有更多有机物(分解植物材料)的沉积物。本研究探讨了水位波动对不同性质湿地沉积物中磷的结合和释放的影响，其结果不仅有助于理解沉积物如何通过磷的释放来控制淡水生态系统中的植物生长，而且将直接应用于许多淡水生态系统的管理。这项研究的结果将为如何最好地管理湿地以促进沉积物中磷的积累并防止其释放到下游生态系统提供洞察力。除了研究本身的管理意义外，研究人员还将通过开发旨在教授湿地和湿地沉积物的定义、生态学和功能作用的K-12课程来教育普通公众。课程计划将通过与密歇根州西南部劳顿社区学校的教师合作制定，并将教授给那里的学生，直接评估学生的学习情况。对学生从课程计划中学习的评估将有助于完善课程计划，以便在教育文献中发表。最后，作为该项目的一部分，对生态学感兴趣的本科生将有机会进行独立的研究体验。

Phosphorus is a nutrient required by all living things, but its use in industrial fertilizers and other products has increased its occurrence to polluting levels in many agricultural and urban watersheds. Excess phosphorus often causes eutrophication in freshwater ecosystems. Eutrophication remains a pervasive problem in the U.S. and can impact aquatic ecosystems as blooms of toxic phytoplankton, reduced water clarity, changes in plant communities, and fish kills. Due to the ability of the sediments to accumulate phosphorus, wetlands are often managed to store phosphorus and prevent entry into downstream ecosystems. The ability of wetland sediments to bind phosphorus varies, and at times wetlands can become sources of, rather than sinks for, phosphorus. The ways in which phosphorus binds to and is released from sediments has been studied extensively in deep lakes, but less so in shallow wetlands. Shallow wetlands differ from lakes in that they often dry and re-flood and tend to have sediments with more organic matter (decomposing plant material). This study investigates how water level fluctuations influence phosphorus binding and release in wetland sediments of varying characteristics.The findings of this research will not only inform understanding of how sediment controls plant growth in freshwater ecosystems through P release, but will have direct applications to management of many freshwater ecosystems. The findings of this research will provide insight into how best to manage wetlands to promote phosphorus accumulation in sediments and prevent its release to downstream ecosystems. In addition to management implications of the research itself, researchers will educate the general public through development of K-12 curricula aimed at teaching the definition, ecology, and functional roles of wetlands and wetland sediment. Lesson plans will be developed through a partnership with teachers at Lawton Community Schools in Southwest Michigan, and will be taught to students there with direct assessment of student learning. Assessments of student learning from lesson plans will aide in refining lesson plans for publication in education literature. Finally, undergraduate students interested in ecology will be given opportunities to conduct independent research experiences as part of this project.