KC Donnelly awardee Jill Riddell conducts research at the University of Arizona

Ph.D. student Jill Riddell joined researchers at the University of Arizona Superfund Research Project Center (UA SRP) as a KC Donnelly extern to collect and analyze data to characterize the interaction of engineered microspheres at the water-soil particle interface. Riddell’s research at West Virginia University and her work with PROTECT Project 4 “focuses on evaluating polystyrene microspheres (small, hollow, sphere-shaped particles) as tracers in karst aquifers,” according to Northeastern University’s highlight article on Riddell.

At the Catalina Mountains Critical Zone Observatory, Riddell released fluorescing microspheres into controlled soil samples as an organic pollutant mimetic to monitor mobilization and sequestration through the environment at the micro-scale in an effort to improve models of contaminant flux in karst aquifers. The 1µm diameter polystyrene microspheres were used uncoated and carboxylated as a tracer of contaminant flow in representative dolomitic and calcic soils found in karst terrains.

Quantitative x-ray diffraction (Q-XRD) data, collected for analytical refinement of the mineralogical and amorphous content of the soils, was combined with surface sensitive infrared spectrographic techniques (ATR-FTIR, DRIFT, transmission FTIR) to probe the soil-sphere interaction and elucidate mechanisms of carboxylated (and non-treated) sphere adhesion on aquifer surface sites. Additionally, scanning electron micrographs (SEM) with energy dispersive spectroscopy (EDS) elemental maps were collected to image the microspheres at soil surfaces.

Welcoming Jill Riddell as a KC Donnelly extern allowed UA SRP to share expertise in analytical techniques for the characterization of pollutant-particle surface interactions, while Riddell introduced us to new and novel approaches to contaminant exposure modeling.