Iron’s Irony: Hydrothermal plumes as invisible transport pathways for iron

A new international review by researchers from the MARUM – Center for Marine Environmental Sciences at the University of Bremen and Constructor University highlights how hydrothermal vents on the seafloor shape iron availability and influence the global oceanic element cycles. The review study, titled “Iron’s Irony,” has been published in Communications Earth & Environment. 

The study synthesizes existing research and reinterprets it to explain how iron released from hydrothermal systems can be transported across entire ocean basins. “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 Dr. Solveig I. Bühring, lead author of the study and geomicrobiologist at MARUM.

Beyond compiling the current state of knowledge, the authors contribute new analyses from the MARHYS hydrothermal vent database and model the solubility of iron minerals to illustrate how environmental parameters and plume chemistry affect iron transport. These findings emphasize how hydrothermal plumes act as long-distance supply systems for bioavailable iron – a process with far-reaching consequences for ocean productivity and the global carbon cycle.

Professor Andrea Koschinsky from Constructor University Bremen played a central role in shaping the study’s conceptual framework through a global perspective approach on the hydrothermal iron cycle. She also points out the possibility of applying this knowledge beyond the study of hydrothermal systems: "The understanding of the physical transport and chemical and biological modifications of hydrothermal iron may serve as a model for the future ocean under climate change, with ocean water warming, acidifying and having less oxygen - like in a hydrothermal plume." 

The research was led by Dr. Solveig I. Bühring from MARUM – Center for Marine Environmental Sciences at the University of Bremen – together with her MARUM colleagues Alexander Diehl and Charlotte Kleint, and Professor Koschinsky, who is also affiliated with the Cluster of Excellence “The Ocean Floor – Earth’s Uncharted Interface” based at MARUM. By combining geochemical, microbiological, and modeling perspectives, the team provides an integrated view of how hydrothermal systems are connected to global nutrient cycles – and how substances are dispersed along the invisible pathways of hydrothermal plumes, stimulating ocean productivity even in distant regions.

Original publication:

Bühring, S.I., Böhnke-Brandt, S., Diehl, A. et al. Iron’s irony: speciation, complexation & microbial processing of Fe in hydrothermal plumes | Communications Earth & Environment  6, 821 (2025).