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

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.