Date of Award
Doctor of Philosophy (PhD)
Environmental Engineering and Earth Science
Brian A Powell
The fields of radioecology and environmental radiation protection encompass a multitude of interdisciplinary specialties relating to the use, transport, and effects associated with radioactive substances in the environment, which often must inform each other in an integrated and iterative manner. As these fields have begun to consider a more holistic approach to environmental radiation protection, there is not only a need to evaluate fate and transport of radionuclides in the environment, but also a need to consider the dose and impacts to non-human biota residing in contaminated (or potentially contaminated) areas. Thus, the overall objective of this work was to demonstrate an explicit, integrated, and holistic approach to environmental radiation protection in a soil-plant-hydrologic system. This was accomplished through a series of radionuclide transport studies and non-human biota dosimetric model development. The focused objective of the transport studies was to examine and quantify the influence of an indigenous grass species, Andropogon virginicus (broomsedge), on the mobility of a broad suite of radionuclides (technetium, cesium, neptunium, and uranium) in the vadose zone of Savannah River Site (SRS) soil. Specific experiments sought to elucidate and quantify key influential factors associated with individual system components; batch experiments probed impacts of root exudates on sorption, and hydroponic plant experiments investigated tissue uptake and translocation potential, accounting for the influence of plant growth stage. These experiments were then combined into an integrated system utilizing laboratory-scale vegetated and unvegetated soil columns allowing radionuclide uptake, transport, and soil profile distributions to be evaluated in a controlled, but more environmentally realistic system. Concurrently, the main objective of the dosimetric modeling portion of this work was to develop and compare several increasingly realistic, organism-specific computational dosimetric models for A. virginicus and to apply plant uptake data (from hydroponic uptake experiments) to determine organism dose rates as an example of application. In addition to the individual studies informing each other, this work also has the potential to influence and inform future work on this system or in the wider radioecology community. For example, both the transport studies and the dosimetric models may be useful for tiered environmental risk assessment evaluations and the most anatomically realistic, higher fidelity dosimetric models have the potential to be utilized in organism-specific dose-effect studies.
Montgomery, Dawn Angel, "An Integrative Approach Concerning Radiological Protection of the Environment: Plant Influence on Biogeochemistry and Transport, Plant Uptake, and Non-Human Biota Dosimetry for Select Radionuclides" (2020). All Dissertations. 2709.