The results of a recent NSF-funded U.S. GEOTRACES research expedition were published in the latest issue of Nature. In this study, lead author and NOAA/PMEL and University of Washington/JISAO scientist Joseph Resing and colleagues unequivocally demonstrate the importance of submarine hot springs (hydrothermal vents) as a source of iron to the ocean interior. Iron is a trace nutrient that is critical to primary production in the ocean. Until recently, the scientific community thought that iron from hydrothermal vents was quickly removed from seawater near the hot springs, however during the expedition they measured hydrothermal iron more than 4,000 km (roughly the distance across the U.S.) from its source. Observations from the study were placed within a global ocean model, and the results suggest that the iron reaches the surface of the Southern Ocean where it supports phytoplankton growth and the transfer of carbon dioxide from the atmosphere to the deep ocean.