New Understanding of Role of Colloids in Contaminant Transport at Hanford

Summary

Scientists at Washington State University (WSU) have published a research paper describing new results about the stability of natural colloids from the DOE Hanford Reservation. They found that these colloids do form stable suspensions that gradually aggregate into particles that settle out of suspension in the electrolyte solutions. They conclude that due to the very long travel times of water through the Hanford vadose zone most colloids will aggregate and be removed from the water column before reaching groundwater levels. Colloidal particles are a major concern at several DOE sites as they may facilitate transport of radionuclides that have been released into the subsurface environment at these sites. Significant transport could occur if the colloidal particles that contain radionuclides were to form colloid suspensions that are stable for a long enough period of time that water flowing through the area could move the suspension into an aquifer. The research team, led by Dr Markus Flury of the Center for Multiphase Environmental Research at WSU, studied the behavior of Hanford colloids in electrolyte solutions representative of the composition of waters in the Hanford vadose (unsaturated) zone. The research is funded by the Environmental Remediation Sciences Division of the Biological and Environmental Research program.