I study the biogeochemical cycling of metals that are critical in emerging energy technologies but whose environmental behavior and impacts remain largely unknown. I am interested in metal transport and speciation in natural ecosystems, and its intersection with contaminant fate & transport, industrial ecology, and human health.
As more and more elements in the periodic table are found to be useful in applications from electronics to renewable energy, use of these elements is scaled up rapidly, often before their environmental behavior and health impacts are understood. Examples include indium (used in consumer electronics, LEDs, and photovoltaic cells), gallium (LEDs and photovoltaic cells), germanium (semiconductors and photovoltaic cells), and tellurium (photovoltaic cells). It will be critical over the next 20-30 years to learn more about the natural cycling of these metals, how they are released from industrial processes, how humans have altered their natural concentrations, and whether these altered concentrations are likely to have an adverse impact on environmental and human health.
My past research has shown that industrial flows of indium to the environment indeed overwhelm natural flows, despite the recent introduction of indium to industrial use. We also find that presently, and likely for the near future, the dominant industrial releases of indium are from mining, smelting, and coal burning, rather than the semiconductor and electronics industries. My research methods include analyzing present-day and historical samples (air filters, peat and sediment cores, mine tailings, freshwater samples) using a variety of trace-metal measurement techniques (including inductively-coupled plasma mass spectrometry, graphite-furnace atomic absorption spectrophotometry, and neutron-activation analysis).
My current research focuses on the cycling of indium, gallium, germanium, and tellurium in an abandoned lead/zinc mining site in northeastern Oklahoma, now being remediated as a Superfund site. In, Ga, Ge, and Te are found as byproducts of lead and zinc sulfides, and there is evidence that they are at elevated concentrations at the field site. My work addresses hypotheses about how mining processes have affected the cycling of these metals, routes of human exposure to these metals from mining activity, and how these exposures affect human blood levels and health.