Water Level Fluctuations and Internal Eutrophication in Lakes and Wetlands

水生沉积物中磷的释放对藻类和水生植物的生长起着至关重要的调节作用。沉积物中磷的释放被称为内部富营养化，因为磷作为限制营养物质的关键作用。最近的研究表明，内部富营养化涉及复杂的生物地球化学过程，中等浓度的硫酸盐加速了富营养化，硫酸盐是一种在许多地区不断增加的污染物。然而，有趣的是，如果允许沉积物定期干燥，硫酸盐的影响可以逆转。这项研究试图了解沉积物磷释放的生物地球化学，重点是水位稳定与波动如何影响沉积物磷的释放。本研究将探讨沉积物中磷的释放、沉积物中铁和硫的形态以及周期性干化的作用之间的新联系，重点放在一个由怪石调节的湖泊系统上。这项研究具有更广泛的影响，因为内部富营养化是管理湖泊和湿地的基础：它可能导致富营养化，阻碍修复努力，并在营养负荷减少后延迟恢复。水位制度被无数的人类行动所改变，包括蓄水、增水井、农田排水、取水和气候变化。重要的是要了解水位制度的这些变化如何影响富营养化，从而影响湖泊和湿地提供的生态系统服务和价值。

Release of phosphorus (P) from aquatic sediments is critical in regulating the growth of algae and aquatic plants. Sediment release of P is referred to as internal eutrophication because of the pivotal role of P as a limiting nutrient. Recent research has suggested that internal eutrophication involves complex biogeochemical processes and is accelerated by moderate concentrations of sulfate, a pollutant on the increase in many areas. Yet interestingly, the effects of sulfate can be reversed if sediments are allowed to dry periodically. This research seeks to understand the biogeochemistry of sediment P release, with an emphasis on how it is affected by water level stabilization vs. fluctuation. New linkages between sediment P release, the forms of iron and sulfur in sediments, and the role of periodic desiccation will be explored, focusing on a lake system regulated by a weir.This research has broader impacts because internal eutrophication is fundamental to managing lakes and wetlands: it can cause eutrophication, stymie restoration efforts, and delay recovery after nutrient loading is reduced. Water level regimes are altered by a myriad of human actions including impoundments, augmentation wells, agricultural land drainage, water withdrawals, and climate change. It is important to understand how these changes in water level regimes impact eutrophication, and thus affect ecosystem services and values provided by lakes and wetlands.