Iron from deep-sea vents travels across oceans to fuel marine life

Iron from deep-sea vents travels across oceans to fuel marine life
by Robert Schreiber
Berlin, Germany (SPX) Oct 21, 2025

Most of the iron released by hydrothermal vents rapidly reacts with oxygen and sulfur, forming solid minerals that settle on the seafloor. Yet a small fraction defies this fate, remaining dissolved for long periods-bound to organic molecules or aided by microbial activity-and travels thousands of kilometers across the ocean.

This paradox, explored in a new synthesis study from MARUM - Center for Marine Environmental Sciences at the University of Bremen, reveals how hydrothermal systems quietly sustain ocean life far from their source. "Although much of the iron emitted with the hot fluids reacts immediately with oxygen and sulfur compounds and precipitates as minerals, a small fraction remains dissolved for surprisingly long periods - bound to tiny organic molecules or influenced by microbes - and can thus be transported far beyond the vent sites," explains lead author Dr. Solveig I. Buhring, a geomicrobiologist at MARUM.

Drawing on the MARHYS hydrothermal vent database, the researchers modeled the solubility of iron minerals to show how temperature, plume chemistry, and microbial mediation control long-distance transport. These results highlight hydrothermal plumes as global delivery systems for bioavailable iron-an essential nutrient that shapes ocean productivity and influences the carbon cycle.

The work brings together twelve scientists from leading German marine research institutions including GEOMAR, the Alfred Wegener Institute (AWI), and the Institute for Chemistry and Biology of the Marine Environment (ICBM) at the University of Oldenburg. Co-lead author Dr. Charlotte Kleint of MARUM notes, "Our results show how closely physical, chemical, and biological processes at the seafloor are intertwined - exactly what lies at the heart of the Cluster of Excellence. Studies like this help us understand how the ocean floor functions as an active link within the Earth system."

By merging geochemical, microbiological, and modeling approaches, the team presents a unified framework for understanding how hydrothermal vents contribute to global nutrient cycling-and how the ocean floor's hidden chemistry sustains ecosystems across vast marine distances.

Research Report:Iron's irony: speciation, complexation and microbial processing of Fe in hydrothermal plumes