Hydrogel-Encapsulated Soil: A New Tool to Measure Contaminant-Soil Interactions in the Subsurface


Measuring the transformation of contaminants such as radionuclides and heavy metals in the subsurface over time remains an important but difficult challenge. A team of scientists from Oak Ridge National Laboratory (ORNL) has developed a novel and powerful approach for encapsulating soils and sediments in polyacrylamide hydrogels called PELCAPs. The PELCAPs can be placed in the subsurface for extended periods of time, readily retrieved, and non-destructively assayed to observe and measure many water-solid contaminant interactions under natural groundwater flow conditions. The team showed that when PELCAPs were placed in a subsurface environment with uranium contaminated groundwater, uranium was adsorbed by the soils in the PELCAPs. The PELCAPs could be resampled over several years, the transformation of uranium-contaminated soil could be readily determined, and the hydrogel remained inert and fully functional. Finally, many different soils (limestone, Portland cement paste, activated charcoal and other materials) could be encapsulated for extended periods of time in the hydrogel. PELCAPs represent an important new tool for measuring contaminant-soil interactions in the subsurface.


Spalding, B., S.C. Brooks and D.B. Watson. 2010. “Hydrogel-Encapsulated Soil: A Tool to measure Contaminant Attenuation In Situ.” Environmental Science & Technology 44(8):3-47-3051.