Award: OCE-1851106

In this project, we studied the properties of hydrothermal plumes over ten to twenty kilometers, or approximately six to twelve miles, from the source of hydrothermal venting. Our goal was to understand the materials that escape from the near vent area to the broader ocean. Before we get into our findings, let me describe hydrothermal vents and plumes. Deep-sea hydrothermal venting occurs in a variety of ocean floor settings around the world. We could go into much detail here, but the main ingredients for hydrothermal venting are seawater and a fractured or porous seafloor. Hydrothermal fluids are produced through the interaction of seawater and rocks or sediments as seawater circulates through the subseafloor. Hydrothermal fluids are chemically distinct from the original seawater and when they are emitted back to the deep ocean, they mix with seawater to form hydrothermal plumes. Seafloor sites of hydrothermal venting are places where extreme conditions meet. Hot (or warm) vent fluids meet cold seawater; this is an example of a physical difference between vent fluids and seawater. Vent fluids with no dissolved oxygen meet oxygenated seawater; this is an example of a chemical difference between vent fluids and seawater. The physical and chemical contrasts between vent fluids and seawater create conditions ripe for life, starting with microorganisms and building to vibrant and visually stunning vent ecosystems. But the importance of deep-sea hydrothermal venting extends beyond the near vent area to the broader ocean.

This project was focused on measuring the vent-derived materials that can travel on ocean currents away from the vent. We conducted an oceanographic expedition on the research vessel (RV) Atlantis with the autonomous underwater vehicle (AUV) Sentry. The scientists at sea used sensors and real-time physical modeling to choose where to collect water samples in the hydrothermal plume at increasing travel distances from venting. Particles in the water samples were separated from water by filtration in two modes, directly in the water using AUV Sentry and after water was returned to the ship laboratories. Our University of Minnesota team characterized the particles for size, shape, and the chemistry of iron using a variety of electron and X-ray microscopy techniques. We learned that the hydrothermal plume particles that are transported away from the vent are clusters of iron-bearing nanoparticles. Nanoparticles their name from the nanometer unit of length. A nanometer is one-billionth of a meter and a nanoparticle is a solid that is smaller than one-hundred nanometers in size. These clusters of nanoparticles resemble hydrothermal plume particles from other locations with different vent fluid chemistry in the deep-sea. It was surprising to learn that hydrothermal plumes from very different sources can generate the same transported particle signal. Despite the wonderous variety of seafloor settings and hydrothermal vent fluid properties, it might be that the type of hydrothermal plume particles that can stay suspended in seawater are quite specific.  

Last Modified: 10/13/2025
Modified by: Brandy M Toner