Seminar: Isotopic Study of Environmental Uranium Contamination in the Vicinity of Fernald

Abstract:

Production and testing of nuclear materials and devices inevitably result in dispersal of radioisotopes into the environment.  Environmental samples can potentially serve as archives of these activities, providing information on the nature of the materials, timing of dispersals, and source location.  Our recent work on uranium isotopes (²³⁸U-²³⁶U-²³⁵U-²³⁴U) in tree bark, lichen and pond sediment near the Fernald Feed Materials Production Center (FFMPC) has demonstrated that: 1) Tree bark and lichen preserve a time-averaged signature of airborne U contamination, and directional contamination with distinct signatures (both DU and EU) are recorded; 2) Progressively increasing ²³⁶U/²³⁸U ratios in tree bark from distal to proximal locations allow the source of contamination to be traced to the FFMPC; and 3) Variations in ²³⁵U/²³⁸U and ²³⁶U/²³⁸U with depth in a sediment core (combined with ¹³⁷Cs dating) allow both the timing of releases to the environment, as well as the nature of the material (both DU and EU) to be determined, and are consistent with records of past FFMPC activity.  Recently initiated related studies are aimed at investigating the potential of tree rings as archives of the nature and timing of uranium releases to the environment.

Bio:

Dr. Widom is a Professor at Miami University in the Department of Geology and Environmental Earth Science.  She received a Bachelors degree in Geology at Cornell University and a Ph.D. in Geochemistry at the University of California Santa Cruz.  She was a Postdoctoral Fellow in Isotope Geochemistry at the Carnegie Institution of Washington and the National Institute of Standards and Technology prior to arriving at Miami.  Dr. Widom’s research focuses on problems in the areas of chemical volcanology, environmental geochemistry and nuclear forensics, and involves both field- and laboratory-based studies.  Dr. Widom has extensive experience in high-precision analysis of a wide range of radiogenic isotope systems (Sr, Nd, Hf, Pb, Os, U, Th, and Ra) in diverse geologic and environmental samples including rocks, sediment, tree bark, lichen, and water.  She specializes in isotopic analysis by thermal ionization mass spectrometry, including ultra-low abundance elements and isotopes.

Hosted by Professor Henry Spitz (University of Cincinnati)