My research is on the natural biogeochemical cycles of trace elements in the environment and the perturbation of those cycles by anthropogenic processes. Many of my studies investigate aquatic toxicology in freshwater and estuarine and marine ecosystems. Others address the toxicology of trace elements in ecosystems and humans.
The primary focus of my research is on the biogeochemical cycle of lead in preindustrial and contemporary environments. This includes studies of lead cycles in the world’s oceans, Mediterranean Sea, Great Lakes, European Alps, and Antartic. Those studies involve analyses of lead concentrations and stable isotopic compositions in aerosols, water, sediments, and organisms. The concentration measurements are used to quantify the magnitude of anthropogenic perturbations, and the isotopic composition measurements are used to identify natural and anthropogenic sources.
I am also involved with research on the biogeochemical cycling of other trace elements in aquatic systems. This research is focused on the cycling of heavy metals and rare earth elements in the San Francisco Bay estuarine system and the northeast Pacific coastal zone. Again, this involves analyses of elemental concentrations and isotopic compositions in aerosols, water, sediments, and organisms. Complementary studies of sublethal toxicities are being conducted concurrently.