Ironing out the role of benthic processes on nutrient cycling in the Gulf of Alaska

北太平洋东北部是一个高营养、低叶绿素的地区，铁的可用性限制了初级生产力。海洋初级生产力是通过海洋生物泵进行碳循环的关键组成部分，生物泵描述了无机碳通过光合作用固定并输出到海洋内部或海底的过程。了解北太平洋等地区对初级生产力的控制对于了解海洋碳循环和全球气候非常重要。海洋边缘沉积物可能是北太平洋铁的重要来源。该项目将研究阿拉斯加湾沉积物中的铁循环，以限制该地区沉积物中铁的来源。项目负责人将创建旨在“将海洋研究带到美国中西部”的教育活动。该项目将资助一名博士后研究员、一名研究生和一名本科生。该小组将使用孔隙水和沉积物地球化学方法对大陆边缘样带内的沉积铁循环进行研究。铁的数量和形态将被确定，以约束控制铁活性再活化的过程，以及铁的沉积来源在未来发生变化的可能性。此外，这项工作将研究有机物和铁循环之间的联系，以了解沉积物中有机物输送的变化如何驱动铁的再动员，以及海底铁-有机物复合物的形成如何增强沉积物中有机物和铁的动员或长期封存。对孔隙水和沉积物的地球化学结果将用遥感技术解释，以研究铁再动员的时空驱动因素。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 northeastern North Pacific Ocean is a high nutrient, low chlorophyll region, where the availability of iron limits primary productivity. Marine primary productivity is a key component of the carbon cycle through the ocean’s biological pump, which describes the processes through which inorganic carbon is fixed by photosynthesis and exported into the ocean’s interior or to the seafloor. Understanding the controls on primary productivity in regions like the North Pacific is important to understanding the marine carbon cycle and global climate. Ocean margin sediments may be an important source of iron in the North Pacific. This project will study iron cycling in sediments in the Gulf of Alaska in order to constrain the source of iron from sediments to the ocean water column in this region. The project leader will create educational activities designed to “bring ocean research to the Midwest US.” The project will support a postdoctoral researcher, a graduate student, and undergraduate students. The team will investigate sedimentary iron cycling within a continental margin transect using a paired porewater and sediment geochemical approach. The quantity and speciation of iron will be determined to constrain the processes controlling active remobilization of iron and the potential for the sedimentary source of iron to change in the future. Additionally, this work will investigate linkages between organic matter and iron cycling to understand how changes in organic matter delivery to the sediments drives remobilization of iron, as well as how the formation of iron-organic matter complexes within the seafloor can enhance either mobilization or long-term sequestration of organic matter and iron within sediments. Paired porewater and sediment geochemical results will be interpreted with remote sensing techniques to investigate spatial and temporal drivers of iron remobilization.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.