Water Level Fluctuations and Internal Eutrophication in Lakes and Wetlands

水生沉积物中磷的释放对调节藻类和水生植物的生长至关重要。由于磷作为一种限制性养分的关键作用，沉积物中磷的释放被称为内部富营养化。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，并且由于硫酸盐的中等浓度而加速，硫酸盐是许多地区正在增加的一种污染物。然而有趣的是，如果沉积物定期干燥，硫酸盐的作用可以被逆转。本研究旨在了解沉积物P释放的生物地球化学，重点关注其如何受到水位稳定与波动的影响。沉积物P释放、沉积物中铁和硫的形式以及周期性干燥的作用之间的新联系将被探索，重点是由堰调节的湖泊系统。本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：它可以引起富营养化，阻碍恢复工作，并延迟营养负荷减少后的恢复。水位的变化是由无数的人类活动造成的，包括蓄水、水井、农田排水、取水和气候变化。重要的是要了解这些水位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.