Metabolism of Nitrogen in the Amazon River plume and Western Tropical North Atlantic (MeNARP)

河口至关重要地控制着有多少来自河流的外来营养物质到达开阔的海洋，以及有多少二氧化碳可以被隔离在河流的羽流中。亚马逊河为海洋贡献了全球近五分之一的河流淡水，并由世界上最大的流域提供水源。最近，流入热带大西洋和加勒比海的水和营养物质与这些地区马尾藻的大规模繁殖有关。然而，外来营养物对沿羽流产生的作用仍不清楚。不一致的证据表明，所有或没有营养物质到达开阔的海洋。光有效性和无机和有机氮化合物似乎控制着光养和异养生物的产生-这里总结为营养官能团（TFGs）。从最近的研究来看，沿羽流可以确定三种不同的栖息地；河口、中盐区和大洋区。MeNARP项目希望确定和量化无机和有机氮化合物的代谢及其在形成tfg中的作用。在经过批准的流星巡航期间，将通过标准CTD铸件、微观结构剖面仪、流速计和漂流浮标的测量组合来研究羽流结构和混合。这些数据和卫星图像将确定将进行额外采样和实验的生境类型。只测量基本变量的过程站提供水文背景，在生物地球化学站将收集许多稳定同位素数据的样本，在四个长期实验站也将测量许多微生物率。最终目标是生成沿羽流栖息地的基于数据的特征，以便通过与项目伙伴密切合作开发的生物地球化学模型改进对碳固存和氮输出的估计。

Estuaries critically control how much of allochthonous nutrients from rivers reach the open ocean and how much carbon dioxide can be sequestered in the river plume. The Amazon River contributes nearly one fifth of the global riverine freshwater input to the ocean and is fed by the largest drainage basin in the world. The outflow of water and nutrients into the tropical Atlantic and Caribbean Sea has recently been linked to massive blooms of Sargassum in these areas. However, the role of allochthonous nutrients for the production along the plume is still unclear. Discordant lines of evidence suggest that all or none of the nutrients reach the open ocean. Light availability and inorganic and organic nitrogen compounds seem to control the production of photo- and heterotrophs - here summarized as trophic functional groups (TFGs). From recent studies it is possible to identify three different habitats along the plume; the estuary, the mesohaline and oceanic region. The MeNARP project wants to identify and quantify the metabolism of inorganic and organic nitrogen compounds and their role in shaping the TFGs. During an approved Meteor cruise the plume structure and mixing will be studied by a combination of measurements with standard CTD casts, microstructure profiler, current meters and drifter buoy. These data and satellite images will identify the habitat types where additional sampling and experiments will be carried out. Process stations where only basic variables will be measured deliver the hydrographic context, at biogeochemical stations samples for numerous stable isotope data will be gathered and at four long-term experimental stations numerous microbial rates will also be measured. The ultimate goal is to generate a data based characterization of the habitats along the plume to improve estimations of carbon sequestration and N export by means of a biogeochemical model developed in close cooperation with partners of the project.