In a broad sense, I am interested in the application of chemical principles to understand marine processes involving ocean circulation, biogeochemical cycles, and climate. I have an especial interest in surface and interfacial chemistry in the environment. Trace metals have become significant in the minds of ocean researchers whether as micro-nutrients, paleoceanographic proxies, or tracers of modern processes (such as dust deposition or carbon export). A commonality of many metals is their “particle-reactive” nature in the ocean, or the tendency to be removed from solution by adsorption onto particles.
I am studying two such metals, thorium and protactinium in the ocean. 230Th can be used for reconstructing past sedimentary fluxes, a key tool to understand past changes in, for example, phytoplankton productivity. 231Pa and the 231Pa/230Th ratio are more complex but have been used to represent changes in circulation rates or as indicators of the chemical composition of the particles which “scavenge” these metals. While providing intriguing proxies for properties of the past ocean, the present distribution of Th and Pa in the ocean is not well known. Much of my research is focused to gain better observations of Th and Pa in seawater and marine sediments to better understand their chemistry in the modern ocean and to validate their application to the past ocean.