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Updated: Jul 12, 2026

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Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films
Published on: November 9, 2015
Hanford-derived plutonium in columbia river sediments.
Summary
Columbia River sediments contain plutonium with isotope ratios indicating both global fallout and a local source. Plutonium-239 from Hanford nuclear reactors significantly contributes to sediment contamination.
Area of Science:
- Environmental Science
- Nuclear Chemistry
- Radiological Assessment
Background:
- Columbia River sediments are a sink for environmental contaminants.
- Plutonium isotopes originate from both global fallout and local nuclear activities.
- Understanding plutonium sources is crucial for environmental remediation and risk assessment.
Purpose of the Study:
- To investigate the sources of plutonium isotopes in Columbia River sediments.
- To quantify the contribution of historical nuclear reactor operations to plutonium contamination.
- To differentiate between global fallout and local sources of plutonium in the riverine environment.
Main Methods:
- Mass spectrometry analysis of plutonium isotopes (Pu-240, Pu-242, Pu-239) in sediment samples.
- Comparison of measured isotopic ratios with known global fallout values.
- Modeling to estimate the contribution of reactor-derived plutonium.
Main Results:
- Plutonium-240 to plutonium-242 ratios align with global fallout patterns.
- Plutonium-240 to plutonium-239 ratios deviate significantly from global fallout, indicating an additional source.
- An estimated 20-25% of plutonium in McNary Reservoir sediments originates from Hanford reactor operations.
Conclusions:
- Columbia River sediments show a mixed plutonium signature from global fallout and Hanford Site reactors.
- Reactor effluent water from Hanford contributed neptunium-239, which decayed to plutonium-239, contaminating sediments.
- Local nuclear activities represent a significant, quantifiable source of plutonium contamination in downstream sediments.
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