This event will be held remotely over Zoom.
Title: Ocean CaCO3 Dissolution: its Role in the Global Alkalinity Cycle
Abstract: In this talk I will try to cover an arc of work by my USC group in tight collaboration with Jess Adkins’ Caltech group on calcium carbonate dissolution in sea water. One theme I hope to bring home is the way carbonate dissolution will be changing in an acidifying ocean. I will discuss ongoing research on dissolution that occurs in sandy, shelf sediments but mainly focus on dissolution that occurs in the water column, primarily in the N. Pacific Ocean. Using novel lab-based and field measurements, we’ve examined dissolution kinetics of calcite, aragonite, biogenic forms and modeled their respective contributions to ocean alkalinity budgets. Alas, none of our measurements and models ‘fit’ the data field, so we apply water column ‘inverse’ modeling to try to match the observed. Our results will not surprise you, there is substantial respiration-driven dissolution of carbonate above the thermodynamic saturation horizon. But how we demonstrate this is, hopefully, quite interesting. The final swing of this talk is to present to you a new mechanistic model of what controls carbonate dissolution kinetics