Radiogenic isotope (Hf, Nd, Sr, Pb, Os) and trace element geochemistry, Igneous Petrology, in their broadest sense. Geochemical evolution of the Terrestrial mantle. Mantle plume dynamics, plume-lithosphere interaction, and the origin of Ocean Island volcanism. Water and the fate of volatiles in the mantle. Element fluxes in subduction zones. Elemental exchange between seawater and mantle lithosphere in hydrothermal systems. Hg-isotopes as a tracer of Hg cycling in the environment. Elemental fluxes in salt marshes and coastal environments.