Mississippi River Flood of 2008: Flood-Pulsed Experiments of Coastal Ecosystem Dynamics

这个SGER项目将研究河流洪水脉冲如何控制路易斯安那州沿海湿地盆地的淡水停留时间，以及这种控制如何调节氮(N)的生物地球化学处理。中心假设是，河流洪水的脉冲事件将通过大幅度减少整个湿地流域的水停留时间来减少湿地的N保留和去除（通过反硝化）。反过来，这将导致墨西哥湾的氮负荷增加，在那里，人为的氮负荷长期以来被认为与沿海缺氧和墨西哥湾北部死亡区有关。它将利用2008年的密西西比河洪水，这将是近一个世纪以来路易斯安那州沿海湿地最大的淡水脉冲之一。本研究将使用有管理的河流改道进入研究流域，以检查淡水输入与氮保留之间的关系。这项研究将为生态系统管理者提供关键的水质信息，他们管理着像密西西比河三角洲和佛罗里达大沼泽地这样有价值的大型湿地系统。一个管理目标是防止过量的氮到达沿海海洋，那里有许多经济上重要的渔场，过量的氮会导致有毒的藻华、溶解氧低和大量鱼类死亡。这个实验还将提供重要的数据，说明沿海湿地对非常大的淡水脉冲的反应如何。

This SGER project will examine how river flood pulsing controls freshwater residence time in coastal wetland basins of Louisiana, and how this control regulates biogeochemical processing of nitrogen (N). The central hypothesis is that the pulsed event of river floods will decrease N retention and removal by wetlands (via denitrification) by drastically decreasing water residence times in entire wetland basins. This, in turn, will lead to increased N loading to the Gulf of Mexico, where anthropogenic N loading has long been implicated in coastal hypoxia and the Northern Gulf Dead Zone. It will take advantage of The Mississippi River flood of 2008, which will be one of the largest pulses of freshwater for wetlands in coastal Louisiana in almost a century. This study will use managed river diversions into the study basins to examine this relationship between freshwater inputs and nitrogen retention.This research will provide ecosystem managers, who manage valuable, large wetland systems like the Mississippi River Delta and the Florida Everglades, with critical water quality information. One management goal is to prevent excess N from reaching the coastal ocean where many economically important fisheries are located and where excess N causes toxic algal blooms, low dissolved oxygen, and massive fish kills. This experiment will also provide important data on how well coastal wetlands respond to very large pulses of freshwater.