FEST: 'A Nano-Scale Perspective on a Novel Pathway for the Preservation of Hydrothermal Iron-Sulfide Colloids'

Friday Earth Sciences Talk by Dr Lotta Ternieten (Marie Curie fellow in Earth Sciences)

Hydrothermal vent systems represent significant yet poorly quantified sources of (bioessential) trace metals, such as iron (Fe), to the global ocean. Constraining their biogeochemical impact requires understanding the early transformation processes that convert dissolved ferrous Fe(II) into insoluble, less bioavailable ferric phases, prone to rapid settling.

This seminar presents results from the joint Royal NIOZ and Utrecht University I-NANO project, which investigates the early transformation mechanisms of hydrothermal iron from the Rainbow hydrothermal vent field along the Mid-Atlantic Ridge. To analyze nanoparticle aggregates, a direct sampling approach was employed in which plume fluids were plunge-frozen, preserving dissolved compounds and nanocolloids through vitrification. An array of microscopic and spectroscopic techniques, combined with machine learning, enabled detailed characterization of the Fe nanocolloids and their early (trans)formation pathways.

The findings provide new insights into the transport and persistence of vent-derived iron phases, emphasizing the role of coatings in protecting nanoscale iron sulfides and challenging the previously proposed significance of organic matter complexation.

With the FEST, we intend to bring the departments of Earth Sciences and Physical Geography together. The aim is to present (mostly) Utrecht-based Earth Sciences in an accessible way, primarily in order to stay familiar with each other’s work across disciplines. Simultaneously, this provides an excellent platform to help (in particular MSc.) students in their orientation on possible graduation specialisations and future careers.