Net Ecosystem Exchange of the Lower Amazon River - from Land to the Ocean and Atmosphere

河流系统正逐渐被认为是全球碳循环的重要组成部分，因为它们不仅调节和调整其流域的碳动态，而且还调节其海洋接收水域的碳动态。它们的主要作用是从内陆水域向大气排放二氧化碳的巨大来源。如果这种影响是重要的，那么全球陆地二氧化碳汇可能比目前估计的要小。解开水流向下游并进入海洋的过程对于理解淡水生态系统在全球碳循环中的作用至关重要，但对这些通量的机制理解仍然难以捉摸。最近的技术进步使以前不可能的令人兴奋的新工作成为可能。现在可以通过网络生态系统交换有效地检查和理解河流系统。该项目的总体目标是研究控制碳在亚马逊河下游从Óbidos（亚马逊河上最后一个传统测量站）到海洋的运动和过渡的过程。一项雄心勃勃的实地和实验室研究，结合尖端的地球化学和地理空间分析，将探索下游加工对全球相关地球化学通量的影响。这项研究本身将极大地促进人们对热带河流在全球碳循环中更广泛作用的理解，并有可能改变人们对河流输送和反应有机物的看法。在资助机构FAPESP的支持下，与巴西科学界建立独特而广泛的伙伴关系不仅将促进科学，而且将促进美国和巴西学生的重要能力建设。项目团队将解决该地区的社会挑战；随着农业、化石燃料勘探和水力发电需求对亚马逊下游地区的压力越来越大。

River systems are becoming progressively recognized as significant components of the global carbon cycle because they modulate and adjust the carbon dynamics not only of their watersheds but also of their marine receiving waters. Their primary role is as an immense source of outgassing of CO2 from inland waters to the atmosphere. If this effect is important, then the global terrestrial CO2 sink may prove to be smaller than current estimations indicate. Unraveling the processes that occur as water travels downstream and into the ocean is critical to understanding the role of freshwater ecosystems in global C cycling, yet a mechanistic understanding of these fluxes remains elusive. Recent advances in technology allow exciting new work that has not been previously possible. Riverine systems can now be effectively examined and understood through the lenses of Net Ecosystem Exchange. The overall objective of this project is to examine the processes that govern the movement and transitions of carbon through the lower reach of the Amazon River, from Óbidos (the last traditional measuring station on the Amazon), to the ocean. An ambitious field and laboratory study, combining cutting edge geochemical and geospatial analyses, will explore the influence of downstream processing on globally-relevant geochemical fluxes.The research itself will promote significantly greater understanding of the broader role of tropical rivers in the global carbon cycle, with the potential to shift the paradigm of how the transport and reaction of organic matter by rivers is viewed. A unique and extensive partnership with the Brazilian science community, via support from the funding agency FAPESP, will promote not only the science but significant capacity building, of both US and Brazilian students. The project team will address societal challenges in the region; as agriculture, fossil fuel exploration and hydropower demands progressively stress the lower Amazon.