Stable isotope geochemistry and biogeochemistry, interactions among the different spheres of the earth system, and relationships among tectonic, topographic, and climatic processes and conditions. Source and transport of fluids in active orogens and volcanic centers. Geochemical and biogeochemical proxies for climate change in the southern hemisphere on a variety of spatial and temporal scales. Geochemical tracing and quality assessment of water resources. Biogeochemical evaluation of foodweb structure including nutrient and trace element transport paths in exotic ecosystems. Paleotopographic investigation of mountain belts and plateaus.