Superfund Research Program
Mobility and Fate of Asbestos Particles
Project Summary (2014-2020)
Minimizing the threat that asbestos disposal sites present to surrounding communities requires containment and preventing offsite migration is of paramount importance. Because asbestos fibers are most hazardous when inhaled, research has focused on airborne transport. However, there is now ample empirical evidence that aqueous transport – in groundwater and rivers – is a significant pathway for spreading of asbestos, and such transport has threatened drinking water supplies in some areas. Because asbestos particles have a large specific surface area, surface charge effects are strong and presumably influence their mobility and interaction with the environment. In particular, asbestos fibers rarely exist in isolation but rather form aggregates. However, little is known regarding the mechanisms controlling aggregate formation. In addition, the unusually large aspect ratio of asbestos is expected to exert a strong control on the migration and trapping of particles in groundwater transport through soil; however no studies have examined aqueous transport in the laboratory.
Douglas Jerolmack, Ph.D., and his research team hypothesize that aggregate size exerts the primary control on the rate of trapping of asbestos particles in soil, and that such trapping, or“straining”, may reverse under changing water chemistry. To test these hypotheses, the researchers will focus on three Specific Aims:
- Elucidating the physico-chemical processes controlling asbestos aggregate formation and mobility.
- Determining mobility and straining of asbestos in groundwater, through laboratory experiments and theory.
- Identifying the extent of groundwater transport, and the size distribution of aggregates, for asbestos particles at the Ambler Superfund site; and make recommendations for containment of asbestos to limit aqueous transport.
The researchers’ key innovations are to:
- Probe the dynamics of asbestos at the fiber scale using real-time electron-microscopy observations;
- Perform innovative soil column experiments that allow them to image the internal granular pore structure; and
- Apply experimentally-validated theories to field observations at a Superfund site to make scientifically-informed recommendations for improving containment strategies of asbestos.
The researchers believe that the ongoing research will directly inform policy for asbestos containment at Superfund and Brownfields sites, while bringing immediate benefit to the community surrounding the Ambler asbestos piles.