Radioactive contamination and (bio)remediation
Radium (Ra) is a radioactive alkaline earth element and forms naturally from the decay of uranium (U) and thorium (Th), elements that are ubiquitous within most rocks, soils, and sediments. Radium contamination associated with anthropogenic activities such as hydraulic fracturing, uranium mining, and nuclear waste disposal poses significant public and ecological health risks. While the occurrence of Ra in groundwater is concerning for public health and safety reasons, Ra is also a powerful tracer for calculating groundwater discharge and pollutant loading to coastal water. In my doctoral thesis, I investigated processes controlling Ra mobility in groundwater that are important for developing remediation strategies and improving our understanding of Ra tracer applications. Some highlights of this work is listed below:
I studied the role of bio-mineralization on Ra uptake from aqueous systems by cyanobacteria using NanoSIMS. The research demonstrated for the first time that Ra could be biomineralized intracellularly in cyanobacteria and thus could be designed as a cost-effective and efficient bio-remediation strategy for the removal of Ra in the environment.
Through a series of batch leaching experiments combined with analytical geochemical and radiochemical characterization, I demonstrated that Ra mobility was enhanced under low pH and anoxic conditions during hydraulic fracturing and thus implying that maintaining alkaline pH conditions in situ may reduce the radioactivity of fracking wastewater. The findings from this work elucidated novel strategies to develop in-situ retardation of Ra and other metalloids in the subsurface system.