Colloquia – Athena Nghiem

A tale of two redox-sensitive trace elements: from Southeast Asia to Southeast Wisconsin

Athena Nghiem, Assistant Professor
Department of Geoscience
University of Wisconsin-Madison

Trace elements are naturally occurring in low concentrations in the environment. However, some trace elements can have a disproportionate impact on human health due to their presence in groundwater. For example, consumption of groundwater naturally contaminated with the toxic trace element arsenic (As) in groundwater affects millions of people worldwide, especially in South and Southeast Asia. Meanwhile, molybdenum (Mo) has been investigated to a much lesser extent and is essential at low concentrations, but toxic at high concentrations – a local hotspot of which has been previously found in Southeast Wisconsin. Importantly, the mobility in the subsurface of many trace elements, including As and Mo, are governed by redox-sensitive solid-solution partitioning. Understanding speciation of these trace elements, both in the solid-phase and in the aqueous phase, is critical to understanding their mobility in groundwater. Using techniques ranging from traditional lab and field measurements to synchrotron spectroscopy, in this talk, I will present research highlights from our new investigations of trace element mobilization in case studies spanning from Southeast Asia to Southeast Wisconsin.