Influence of density stratification and macrophytes on nutrient dynamics and resuspension in a shallow lagoon

本计画旨在探讨沉水植物与盐度层化对浅水表层沃茨中剪切诱导紊流混合与再悬浮之影响。我们将在一个天然河口进行研究，由于其独特的水生植物生长和盐度分层的年周期，这是一个理想的参考案例。分层，混合和再悬浮控制的积累和再分配的营养物质进出沉积物，因此被认为是管理发生藻华的泻湖。研究目标将分四步实现。(I)首先，我们将研究沉水植物的影响，通过比较研究的溶质和颗粒之间的传输动力学区域覆盖的水生植物和区域没有植物覆盖。(II)其次，我们将确定的物理驱动力，支配在沉积物-水界面的化学条件在盐分层期间。我们还将在冬季和春季进行连续测量，以了解水柱中营养物质的积累。(III)固相和孔隙水的沉积物进行了分析，相对于磷和铁的物种，氧，硫酸盐和pH值。这将提供深入了解如何吸附和释放动力学变化的化学条件下。(IV)最后，（I）和（II）的结果将被用来开发和校准一个数值反应传输模型，可以帮助预测未来的藻华和支持战略河口管理。

The proposed project aims to investigate the influence of submerged macrophytes and haline stratification on shear-induced turbulent mixing and resuspension in shallow surface waters. We will perform the study in a natural estuary which serves as an ideal reference case due to its distinct annual cycle of macrophyte growth and haline stratification. Stratification, mixing and resuspension control the accumulation and redistribution of nutrients into and out of the sediment and are therefore assumed to govern the occurrence of algal blooms in the lagoon. The research goal will be achieved in four steps. (I) First, we will examine the effects of submerged macrophytes through comparative studies of solute and particle transport dynamics between regions covered with macrophytes and regions without plant cover. (II) Secondly, we will identify the physical driving forces which govern the chemical conditions at the sediment-water interface during the period of haline stratification. We will also perform continous measurements during winter and spring in order to understand the accumulation of nutrients in the water column. (III) The solid phase and the porewaters of the sediment are analyzed with respect to phosphorous and iron species, oxygen, sulfate and pH. This will provide insight into how sorption and release dynamics will change under variable chemical conditions. (IV) Finally, the results of (I) and (II) will be used to develop and calibrate a numerical reaction transport model that can help to predict future algal blooms and support strategic estuary management.