The Army has persistent issues with lead (Pb) migration onto public lands from intensively used training ranges. Here, the adaptation of a new, in situ jarosite formation technology will be explored for mitigating the mobility and bioavailability of these chemicals in soils on Department of Defense (DoD) training ranges. The objectives of this project are: (i) to determine the effectiveness of this new technology to immobilize forms of colloidal and adsorbed Pb existing in impacted DoD soils, and (ii) to lay the groundwork for field demonstration of this technology by optimizing the reaction and soil reconditioning parameters using up-scaled treatability studies.

The main technical challenge of this study involves whether the jarosite immobilization technology is effective against both the sorbed and particulate species of Pb expected to predominate on DoD training ranges. There are three main tasks for this project.

• Task 1: Soils will be collected from DoD training ranges and chemical speciation of its Pb contaminants will be determined.
• Task 2: The effectiveness and optimization of the technology will be determined in transforming the different sorbed and particulate Pb species into jarosite-mineral derivatives using small reactor systems (analogous to a field-implemented system).
• Task 3: The effectiveness of a post-treatment approach to restore soil functionality for revegetation and restoration of the site will be determined.

Reactor Setup for Optimizing the Reaction Parameters and Upscaling the Jarosite Technology

Successful completion of this project will provide DoD with an effective technology for immobilizing Pb in soils. Results from this project will provide evidence confirming Pb transformation based on differences in soil speciation as well as soil types. The approach employed will provide optimized parameters for scaling up the technology as well as parameters for restoring their post-treatment functionality. Overall, the scientific contribution of this work may potentially expand the range of applications from purely "adsorbed" forms of Pb particulates, which is expected to be an important fraction of chemicals on DoD training sites. (Anticipated Project Completion - 2024)

Karna, R.R., M.R. Noerpel, C. Nelson, B. Elek, K. Herbin-Davis, G. Diamond, K. Bradham, D. J. Thomas, and K.G. Scheckel. 2021. Bioavailable Soil Pb Minimized by In Situ Transformation to Plumbojarosite. Proceedings of the National Academy of Sciences, 118(3):e2020315117. doi.org/10.1073/PNAS.202031517.

Sowers, T.D., S.E. Bone, M.R. Noerpel, M.D. Blackmon, R.R. Karna, K.G. Scheckel, and K.D. Bradham. 2021. Plumbojarosite Remediation of Soil Affects Lead Speciation and Elemental Interactions in Soil and in Mice Tissues. Environmental Science and Technology, 55(23):15950-15960. doi.org/10.1021/acs.est.1c06067.