Grantee Research Project Results
Use of fullerenes as ground water pollution tracers
EPA Grant Number: U914948Title: Use of fullerenes as ground water pollution tracers
Investigators: Callegary, James B.
Institution: University of Arizona
EPA Project Officer: Hahn, Intaek
Project Period: January 1, 1996 through October 29, 1999
Project Amount: $68,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Earth Sciences
Objective:
The objectives of this research project are to: (1) use fullerenes as a tracer to evaluate the likelihood of contaminants reaching aquifers and polluting groundwater; and (2) use the knowledge of contaminant fate and transport processes to aid in developing remediation strategies.
Approach:
One of the standard methods for studying contaminants makes use of tracers that can mimic their behavior. An ideal tracer should be nontoxic, similar in chemical and physical properties to the contaminant being modeled, inexpensive, and easy to monitor. No tracer has been able to match all the criteria. Fullerenes are nonpolar molecules composed of pure carbon. Better known examples include C60 and C70. They dissolve readily in many organic solvents. They can be modified fairly easily by the addition of functional groups to change their reactivity and solubility to match that of the contaminant of interest. At many contaminated sites, there are numerous chemicals belonging to different chemical classes. Some are soluble in water, while others are not. Soluble substances may include some heavy metals and radio isotopes. Insoluble compounds frequently include organics such as trichloroethylene. The insoluble compounds may form a separate layer known as a "non-aqueous phase layer," which can move at different speeds from aqueous solutions.
We expect the fullerenes to fulfill other requirements of an ideal tracer as well. As far as we know, fullerenes are nontoxic. The only current health effect being investigated is inhalation of fullerene particles. This would not apply to using them as a groundwater tracer, because they will be used only in solution and in very small quantities. Fullerenes also have the advantage of being easily separable using high performance liquid chromatography and detectable into the nanomole range using laser desorption-ionization time-of-flight mass spectrometry (LD TOFMS). I am qualified in both of these techniques, which are used in the laboratory. Finally, fullerenes have the advantage that they come in different sizes that are readily distinguishable using LD TOFMS. Thus, different fullerenes could be injected in different places to assess groundwater sources and mixing.
We will measure basic soil and water parameters such as particle size, specific gravity, electrical conductivity, and cation/anion content. This information is necessary for a clear understanding of the behavior of groundwater and the contaminants associated with it. We will coordinate column studies generating breakthrough curves for the fullerenes and their derivatives, and will apply this knowledge to field tracer tests.