Benthic Iron Fluxes and Cycling in the Amundsen Sea

阿蒙森海靠近融化速度最快的南极冰川，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，它们的生长也从大气中去除二氧化碳。在这个地区，浮游植物的生长是由营养铁滋养的，而营养铁在海水中只以低浓度存在。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，铁的沉积物来源从未在这里直接研究过。这个项目通过分析来自阿蒙森海的沉积物，并调查沉积物中的铁是否能促进浮游生物的生长，填补了这一空白。这些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个充满活力、脆弱的地区的影响。这个项目也强调对公众的包容和开放。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向公众传播他们的结果。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。推动这项研究的主要问题是：1)底栖铁是否对南极沿海的初级生产力有益？ 2)南极沿海底栖铁释放与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的铁含量和形态，并计算铁在沉积物-水界面上的通量。这些结果将与沉积物特征（如有机碳含量、活性铁含量、与冰川源的接近程度）进行比较，以确定底栖动物铁释放的控制因素。这项研究与“加速Thwaites生态系统对南大洋的影响”（ARTEMIS）项目的科学目标相吻合，并对其进行了扩展，通过该项目收集了现场样本。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发现将为本项目的结论提供信息，从而深入了解底栖铁对整个系统的影响。该项目为水柱和沉积物生物地球化学的联合研究提供了一个独特的机会，这将对海洋生物地球化学界具有重要价值，并将为未来极地海洋学及其他领域的沉积物-海洋研究提供信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.