Environmental Geochemistry

Environmental Applications of Tracer Isotopes
Researchers in our laboratory have applied Sr, Pb and U isotopes to a range of environmental research problems. The primary application is in tracing anthropogenic inputs to natural systems, though the same concepts apply to tracing sources of naturally occurring concentration plumes of these elements. Approximately one half of our environmental samples are done under contract from environmental consulting organizations. We are in the process of seeking certification for determination of lead content in environmental samples.

We have methods for extracting and analyzing lead from a wide variety of substrates, including paint, hydrocarbon fuels, soil, water and blood. We have promising indicators for tracing the sources of lead in paint, gasoline and contaminated soils, and have developed an extensive database of lead isotopic compositions in lead ores worldwide. In one recent project, we analyzed pigments from an abandoned paint factory and its nearby watersheds, in order to determine the extent of contaminated waste dispersal. In other drainages, we have looked at cores of sediments deposited over the past 200 years to document both the isotopic composition and concentration of lead as a function of time. These cores reflect regional as well as local anthropogenic inputs, and show variations that correlate with urbanization and industrialization in the watersheds. In several of these projects, our lead isotopic analyses were supplemented by concentration determinations for a broad array of other trace elements, so that a range of anthropogenic inputs can be correlated with isotopic composition variations.

Other projects have involved analyses of lead, uranium and strontium isotopes as environmental tracers. Analyses of this type can be applied both to establish regional, natural baselines and to demonstrate anthropogenic impacts.