RAPID: COLLABORATIVE RESEARCH: The 2011 Historic High Flows in the Atchafalaya Basin: How will Hydrologic transport Alter Nutrient Retention (C and N)?

通过森林湿地-特别是在密西西比河下游流域-转移富含营养的水，是减少营养物质向沿海河口输出的一种拟议方法。本研究的主要目的是量化营养保留和碳矿化的河水通过Atchafalaya流域洪水系统（ABFS）输送。通过表征通过流域的渠化部分输送的水，与包括森林沼泽的非渠化溢洪道相比，研究小组希望发现通过溢洪道转移的水中的营养物质去除，这是由于停留时间增加和与洪泛区沉积物的接触增强。将在洪水期间（12周）在整个流域收集样本。将测量水的同位素和保守阴离子，以量化水源并推断水的停留时间。营养物质（磷和氮的物种）将被测量，以量化系统处理和划定的空间差异在ABFS.Although分流是一种建议的方法，以减少营养出口，和相关的缺氧区的范围，在墨西哥湾，非常大规模的分流对营养物质减少的幅度的影响还没有得到很好的理解。目前密西西比河下游的洪水（自1927年以来的最高水平）导致陆军工程兵团自1973年以来首次将莫甘扎溢洪道开放到ABFS。通过ABFS探索营养丰富的密西西比水的命运的机会是前所未有的，并将提供有价值的洞察水文和地球化学的阿查法拉亚河和洪泛区的耦合。这项研究将提供与大规模转移泉水径流水的养分减少的见解。

The diversion of nutrient-rich water through forested wetlands--especially within the Lower Mississippi River Basin--is one proposed approach to reduce nutrient export to coastal estuaries. The primary objective of this research is to quantify nutrient retention and carbon mineralization as river water is transported through the Atchafalaya Basin Floodway System (ABFS). By characterizing water transported via channelized sections of the basin in contrast to the un-channelized spillway including the forested swamps, the research team expects to find enhanced nutrient removal within water diverted through the spillway due to increased residence time and enhanced contact with floodplain sediments. Samples will be collected across the basin over the flood period (12 weeks). Water isotopes and conservative anions will be measured to quantify water sources and infer water residence time. Nutrients (phosphorus and nitrogen species) will be measured to quantify system processing and delineate spatial differences across the ABFS.Although diverting water is a proposed approach to reduce nutrient export, and associated hypoxic zone extent, in the Gulf of Mexico, the effect of very large-scale diversion on the magnitude of nutrient reduction is not well understood. The current flooding in the Lower Mississippi (highest levels since 1927) has resulted in the Army Corps of Engineers opening the Morganza Spillway into the ABFS for the first time since 1973. The opportunity to explore the fate of the nutrient-rich Mississippi water through the ABFS is unprecedented and will provide valuable insight into the coupling of hydrology and biogeochemistry of the Atchafalaya River and Floodplain. This study will provide insights on nutrient reduction associated with large scale diversion of spring runoff water.