Plutonium Associations to Natural Chancellor Water Colloids: Implications for Subsurface Transport

摘要

There have been several studies that highlighted the importance of colloid-facilitated transport of low-solubility, strongly adsorbing radionuclides. Unlike dissolved species, which can readily diffuse into small and dead-end pore spaces or sorb onto the immobile rock and soil grains, colloidal species may experience size and volume exclusion effects during their transport in porous media, rendering them "facilitators" of radionuclides transport. This colloid-facilitated transport was shown by several laboratory and field studies to be the main mechanism underlying the unexpected transport of Pu in the subsurface environment under various conditions 1-3. Colloid-associated Pu transport over a distance of 1.3 km in ～30 years from the Benham nuclear test cavity on Pahute Mesa at the NNSS is one of the most sited examples of Pu colloid facilitated transport.