Category Archives: Research

Dr. Martin Dangelmayr (post-doc) and Cullen Meurer (former master’s student) published a cutting-edge technical article titled, Desorption and co-dissolution of uranium-bearing solids during alkalinity enhanced flushing of contaminated sediments, in the journal Groundwater Monitoring and Remediation.  The results of this research showed that alkalinity enhanced flushing of uranium could be employed as a viable remediation scheme if calcite precipitation could be minimized in a field application.

A new research article titled, Single-Well Push–Pull Tracer Test Analyses to Determine Aquifer Reactive Transport Parameters at a Former Uranium Mill Site (Grand Junction, Colorado), was recently published in the scientific journal Minerals.  This research used PHREEQC (geochemistry), PHT-USG (flow and transport), and PEST (calibration) to understand the importance of cation exchange, sorption, and gypsum dissolution on the fate and transport of uranium at a former mill tailings site.

Figure 9. Model fit for uranium in all PPT wells, with and without gypsum addition for wells 0120 and 0121. Phases are: (1) traced river water injection, (2) untraced river water injection (chase), (3) drift phase, and (4) pumping phase. Posted values are the GC_s uranium sorption parameter values (moles/kg-water) for the upper and lower sensitivity testing (gray dashed curve) and the calibrated value from Table 4 (solid blue curve). GC_s values in bold italics indicate the authors’ picks for the best final values.

A field tracer study was just published in the Journal of Contaminant Hydrology, titled, “Elucidating mobilization mechanisms of uranium during recharge of river water to contaminated groundwater“.  This publication was based on the master’s thesis of Kendyl Hoss (link to the Hoss thesis HERE).  This publication demonstrated that solid-phase uranium, in equilibrium with aqueous-phase uranium, may not be readily mobilized when recharged with uranium-free water, i.e., concentration-dependent uranium desorption and/or dissolution may be a very slow process; this has implications on the time it may take for uranium to flush from a contaminated site.

Pre-test isoconcentration profile map of uranium (mg/kg) on aquifer sediments (5% nitric acid leached) above and below baseflow water table (≈ 4.5 ft bgs, ≈ 1.4 m bgs) along A to A’ transect (Fig. 4), bgs = below ground surface, distance from A to A’ is 20 ft (6.1 m), depth is 13 ft (4.0 m).

The Paradis Lab was awarded $350,000 by the NSF to research the biogeochemical mechanisms that are likely responsible for enhanced flushing of uranium during oxygen- and carbonate-rich well injections.  Details of this award can be found at the NSF Awards website at this LINK.  This research is in collaboration with Dr. Majumder at UW-Madison who also received an NSF award (LINK).

UW-Milwaukee assistant professor Charlie Paradis is studying how that road salt impacts waterways in our area. “We suspect that there’s a subsurface component that is storing road salt over the summer months,” he explains. LINK TO FULL STORY