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Cross-Media Transport and Transformation of Carbonaceous Nanomaterials

Linsey C. Marr
Virginia Tech, Blacksburg, VA

Research that accounts for cross-media effects is needed to understand the environmental fate of manufactured nanomaterials. All known studies of manufactured nanomaterials in aquatic systems have used the pure, or "fresh," form of the compounds. However, nanoparticles that are released into the atmosphere undergo transformations (coagulation, coating, and reactions) that will change the particles' size, chemical composition, and surface properties. When these "aged" particles later deposit onto the earth's surface, they may have very different fates in the aquatic and terrestrial environments compared to the "fresh" compounds.

The overall objective of this research is to conduct a cross-media assessment of the transport, transformation, and fate of manufactured nanomaterials in atmospheric, aquatic, and terrestrial environments. A key component of the project is to examine how "fresh" versus atmospherically "aged" nanomaterials behave in aquatic and terrestrial systems. The experiments focus on carbonaceous nanomaterials (CNMs, including fullerenes and endohedral metallofullerenes).

In the first set of experiments, we will determine the rates at which airborne CNMs transform under naturally occurring conditions. In the second set of experiments, we will examine the interactions of both "fresh" and atmospherically "aged" CNMs with water and soil in order to evaluate their environmental transport and reactivity. Specific tasks are to: (1) quantify the rate of reaction of airborne CNMs with ozone; (2) age CNMs in a smog chamber and characterize the processed aerosol; (3) evaluate transport of "fresh" and atmospherically "aged" CNMs in porous media; (4) develop CNM-functionalized atomic force microscope tips; and (5) characterize CNM interactions with soil surfaces in aquatic systems.

The cross-media approach will lead to significant gains in understanding of how manufactured CNMs are transported and transformed in the environment. We will determine how CNMs transform in the atmosphere under naturally occurring conditions and to what extent such transformations affect their transport in aqueous systems. This study will be the first to utilize atomic force microscopy to quantify the adhesive and repulsive forces that exist between CNMs (both "fresh" and "aged") and relevant environmental surfaces. An improved understanding of the environmental effects of manufactured CNMs will help address barriers to adoption of nanotechnology.

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