Professor: Louis Derry
Project Description: Aluminum is an important mineral component, and has complex hydration and speciation in aqueous solution. Consequently, its behavior in the environment is not as well understood as one might expect. Aluminum is also monoisotopic, and so lacks an isotope ratio that could be used as a tracer for the environmental behavior of Al. Following on work we have done using germanium-silicon ratios as a “pseudo-isotope” tracer for Si, we have begun work on gallium-aluminum ratios. Ga and Al have many chemical and mineralogical similarities but differ in ionic radius, hydrolysis and ligand stability, among other properties. Preliminary work suggests that Ga/Al can be an effective tracer of sources and reaction mechanisms for aluminum transport. Challenges include low Ga abundances in water, but this can be addressed using high resolution ICP-MS analysis. The project will carry out experimental mineral-water reactions and analyze the products, as well as natural waters for Ga and Al. The student will have a chance to design and carry out experiments, calibrate and operate the ICP-MS, and model the results. Gallium is also classified as a Critical Material by the DOE (there are Ga-arsenide chips in your cell phone), and its environmental chemistry is interesting in its own right. Gallium is produced as a by-product of Al mining in most cases, but he processes that control Ga enrichment to economic levels are not fully understood.