Groundwater Nanoparticles in the Far-Field at the Nevada Test Site: Mechanism for Radionuclide Transport
Journal
Environmental Science & Technology
Journal Volume
43
Journal Issue
5
Start Page
1293
End Page
1298
ISSN
0013-936X
1520-5851
Date Issued
2009-02-26
Author(s)
Abstract
Colloid-like nanoparticles in groundwater have been shown to facilitate migration of several radionuclides: 239,240Pu, 137Cs, 152,154,155Eu, and 60Co (1). However, the exact type of nanoparticle and the speciation of the associated radionuclides has remained unknown. We have investigated nanoparticles sampled from the far-field at the Nevada Test Site, Nevada, utilizing advanced electron microscopy techniques, including high-angle annular dark-field scanning TEM (HAADF-STEM). Fissiogenic elements: Cs, rare earth elements (REE), activation elements: Co; and actinides: U and Th, were detected. Cesium is associated with U-forming cesium uranate with a Cs/U atomic ratio of ∼0.12. Light REEs and Th are associated with phosphates, silicates, or apatite. Cobalt occurs as a metallic aggregate, associated with Cr, Fe, Ni, and ± Mo. Uranyl minerals; Na-boltwoodite and oxide hydrates are also present as colloids. Because of these chemical associations with nanoscale particles, in the size range <100 nm, these particles may facilitate transport, and a variety of trace nanoscale phases may be responsible for the migration of fissiogenic and actinide elements in groundwater. To accurately model the transport of these contaminants, predictive transport models should include consideration of nanoparticle-facilitated transport.
Subjects
Colloids
Elements
Motion
Nanoparticles
Nevada
Radioisotopes
Soil
Uranium Compounds
Water Supply
North America
United States
Actinides
Cesium
Chromium
Cobalt
Colloid chemistry
Europium
Groundwater
Hydrates
Hydrogeology
Molybdenum
Nanostructured materials
Phosphate minerals
Plutonium
Radiometry
Silicates
Sodium
Trace elements
Underground reservoirs
Uranium
actinide
cobalt
ground water
nanoparticle
organic carbon
radioisotope
Actinide elements
Atomic ratios
Chemical associations
Facilitated transports
Far fields
Haadf stems
High-angle annular dark fields
Microscopy techniques
Nano-scale
Nano-scale particles
Nevada test sites
Oxide hydrates
Predictive transports
Radionuclide transports
Rare-earth elements
Scanning tem
Size ranges
cesium
groundwater
pollutant transport
radionuclide
rare earth element
speciation (chemistry)
article
nanoanalysis
nuclear waste
transmission electron microscopy
Publisher
American Chemical Society (ACS)
Type
journal article