The intimate coupling between iron mineral transformations and biogeochemical cycles

– Peter Kraal, Senior Scientist, NIOZ- Royal Netherlands Institute for Sea Research –

Résumé :

Iron (Fe) minerals play a central role in the mobility and bioavailability of many bioessential and toxic elements, from arsenic to zinc, 
on land and in the sea. A particularly interesting feature in this respect is that the interaction of Fe with other elements can affect 
the mineralogical properties and thereby the environmental fate of Fe minerals. These interactions and their implications are challenging to investigate. 
In this talk, I will focus on the power of X-ray and electron (micro)spectroscopic techniques to investigate interactions of Fe minerals with 
the ubiquitous and biogeochemically important elements phosphorus (P) and silicon (Si). From the laboratory to Dutch tidal flats and 
Atlantic hydrothermal vents, the disruption of iron mineral structure arising from incorporating P and Si will become clear, as well as 
its impact on the stability and long-term transformation pathways of the resulting Fe minerals. Because a geochemical talk that doesn't 
feature the carbon cycle will likely be frowned upon, I will present our latest, perhaps surprising findings regarding the role of iron-carbon 
interactions in hydrothermal systems.