Calcium carbonates (CaCO3) are a group of minerals with a major impact on Earth's climate, as their formation and dissolution regulate the ocean's capacity to take up CO2 from the atmosphere. While each type of CaCO3 has a reactivity that depends on its structure, composition, and environment, experimental and modelling work generally simplifies CaCO3 as one homogeneous phase. Neglecting the variability in CaCO3 reactivity is especially problematic in coastal systems, which are intimately coupled with the atmosphere, contain a multitude of CaCO3 phases, and where environmental conditions shift rapidly.
In REACT, I will introduce and test the concept of a reactive continuum of CaCO3, inspired by models of organic matter degradation. Combining expertise in CaCO3 dynamics, sediment biogeochemistry, and modelling, I will (1) describe the reactive continuum of CaCO3 in a complex mixture of phases through mechanistic laboratory experiments using a novel multi-tracer tool to track the order and rate of dissolution, (2) identify signs of the reactive continuum of CaCO3 in natural sediment environments by combining a thorough geochemical characterization of the sediment with detailed analysis of extracted CaCO3 particles, and (3) determine the effect of human activities on CaCO3 dissolution in coastal sediments by creating a numerical model describing the reactive continuum of CaCO3 and using it to simulate anthropogenic disturbances.
REACT will advance our understanding of CaCO3 dynamics, which will be crucial when assessing the seafloor's response to climate change. The project will produce knowledge to support United Nations and European Union sustainability goals, and will provide new research tools for mechanistic studies of CaCO3 dissolution and incorporation into Earth system models. Leading this project will add key skills to my scientific and academic toolbox and prepare me for a career as an innovative, independent and excellence- oriented researcher.
