Benthic Iron Fluxes and Cycling in the Amundsen Sea

阿蒙森海靠近南极冰川融化最快的地方，拥有世界上最具生产力的极地生态系统之一。浮游植物是食物链的基础，它们的生长也能清除大气中的二氧化碳。浮游植物在这一地区的生长是由营养铁提供肥沃的，而铁只在低浓度的海水中存在。先前的研究表明，海底沉积物可能为阿蒙森海生态系统提供铁。然而，这里从来没有直接研究过铁的沉积物来源。该项目通过分析阿蒙森海的沉积物并调查沉积物铁是否会促进浮游生物的生长来填补这一空白。这一结果将帮助科学家了解基本的生态系统驱动因素，并预测气候变化对这一充满活力的脆弱地区的影响。该项目还强调包容性和对公众的开放性。研究人员将通过极地影响网络为不同的极地科学家建立一个指导网络，并通过网站CryoConnect.org向公众公布他们的结果。该项目利用已经从阿蒙森海(NBP22-02)收集的样本来研究沉积物铁(Fe)的循环和通量。推动这项研究的广泛问题是：1)底栖铁是否使南极沿海的初级生产力肥沃；2)底栖铁的释放与南极沿海碳循环之间的反馈是什么？为了回答这些问题，研究人员将分析孔隙水中铁的含量和形态，并计算跨越沉积物-水界面的铁的通量。这些结果将与沉积物特征(例如有机碳含量、活性铁含量、靠近冰川来源)进行比较，以确定对海底铁释放的控制。这项研究符合并扩展了“加速对南大洋的生态系统影响”(ARTEMIS)项目的科学目标，通过该项目收集了实地样本。反过来，Artemis关于模拟和观察到的痕量金属动力学、地表水生产力和碳循环的研究结果将为该项目的结论提供依据，使人们能够深入了解底栖铁在整个系统中的影响。这个项目代表了一个独特的机会，将水柱和沉积物生物地球化学结合起来研究，这将对海洋生物地球化学界有很大的价值，并将为极地海洋学和其他地区未来的沉积物-海洋研究提供信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Amundsen Sea, near the fastest melting Antarctic glaciers, hosts one of the most productive polar ecosystems in the world. Phytoplankton serve as the base of the food chain, and their growth also removes carbon dioxide from the atmosphere. Phytoplankton growth is fertilized in this area by nutrient iron, which is only present at low concentrations in seawater. Prior studies have shown the seabed sediments may provide iron to the Amundsen Sea ecosystem. However, sediment sources of iron have never been studied here directly. This project fills this gap by analyzing sediments from the Amundsen Sea and investigating whether sediment iron fertilizes plankton growth. The results will help scientists understand the basic ecosystem drivers and predict the effects of climate change on this vibrant, vulnerable region. This project also emphasizes inclusivity and openness to the public. The researchers will establish a mentoring network for diverse polar scientists through the Polar Impact Network and communicate their results to the public through the website CryoConnect.org. This project leverages samples already collected from the Amundsen Sea (NBP22-02) to investigate sediment iron (Fe) cycling and fluxes. The broad questions driving this research are 1) does benthic Fe fertilize Antarctic coastal primary productivity, and 2) what are the feedbacks between benthic Fe release and carbon cycling in the coastal Antarctic? To answer these questions, the researchers will analyze pore water Fe content and speciation and calculate fluxes of Fe across the sediment-water interface. These results will be compared to sediment characteristics (e.g., organic carbon content, reactive Fe content, proximity to glacial sources) to identify controls on benthic Fe release. This research dovetails with and expands on the science goals of the “Accelerating Thwaites Ecosystem Impacts for the Southern Ocean” (ARTEMIS) project through which the field samples were collected. In turn, the findings of ARTEMIS regarding modeled and observed trace metal dynamics, surface water productivity, and carbon cycling will inform the conclusions of this project, allowing insight into the impact of benthic Fe in the whole system. This project represents a unique opportunity for combined study of the water column and sediment biogeochemistry which will be of great value to the marine biogeochemistry community and will inform future sediment-ocean studies in polar oceanography and beyond.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.