Mineral-fluid interactions underpin element cycles and have governed the removal of CO2 from the atmosphere over geologic timescales. Various CO2 removal strategies rely on these same natural geochemical processes to securely store atmospheric CO2 and contribute to greenhouse gas emission reduction goals. These CO2 removal strategies require constraint on reaction rates capacity, and CO2 storage security, as well as potential co-benefits and risks. We experimentally investigate the geochemical mechanisms by which CO2 can be captured and stored using Ca- and Mg-rich rock and waste materials. Our work demonstrates that Mg-carbonate minerals can securely store CO2 at Earth’s surface conditions, despite complex formation pathways, and can also remove potentially hazardous metals from solution. However, the distribution and availability of water, as well as the initial chemical composition of the solids strongly govern the fate of CO2 during mineral-fluid interaction. At present, we aim to better constrain the capacity of geochemical CO2 removal and how its efficiency may evolve in response to climate change.

Hydrothermal alteration describes a process that progressively, and additively, modifies the chemical and physical properties of rock by fluid-rock interactions. At active volcanoes, mixtures of magmatic and meteoric fluids circulate within the rocks forming the volcano and, as a result, hydrothermal alteration can be pervasive. Because the properties of volcanic rocks, such as their strength or their permeability, play a role in dictating the hazard potential of a volcano, then it follows that hydrothermal alteration progressively modifies the hazard potential of a volcano. However, not only does subsurface hydrothermal alteration proceed largely imperceptibly, leading to unpredictable hydrothermal explosions and mass wasting events, but we also do not fully understand the timescales required for hydrothermal alteration, nor its influence of rock properties. As a result, and despite its potential importance, hydrothermal alteration is not routinely monitored at active volcanoes, and often does not feature in routine volcanic hazard assessments. In this seminar, I will outline recent, multidisciplinary advancements in our understanding of hydrothermal alteration, and its influence on volcanic hazards. I will also outline plans for future work on this topic, in the framework of the recently-funded ERC SYNERGY grant "ROTTnROCK".