The Tracer Technology Group (TTG) developed the use of
perfluorocarbon tracers (PFTs) as tools for studying long range
atmospheric transport and dispersion in the early 1980s.We are world
leaders in the use of PFTs for solving diverse research and engineering
problems in the atmospheric sciences, the energy production and utility
industries, and building characterization.
The unique capabilities of the TTG are derived from our analytical
expertise, infrastructure, and experience. We have developed PFT
analytical methods that have detection limits at the femtogram level.
We can measure global background levels of PFTS at the parts per
quadrillion levels. Our scientists and technical staff have extensive
experience in designing and executing tracer-based field programs. We
have four highly modified, dedicated gas chromatographic analytical
systems and over 100 automated, programmable field samplers giving us
the ability to make measurements with exceptional temporal and spatial
resolution.
The perfluorocarbon tracer compounds are totally fluorinated cycloalkane
compounds consisting of 4, 5, and six atom carbon rings. Because
the fluorine-carbon bond is strong, these molecules are very stable.
They are not susceptible to oxidation in the atmosphere. The only
important sink for perfluorocarbons is photolysis in the
mesosphere. They are biologically benign and have been considered as
blood substitutes and are used in eye surgery.
PFTs make good tracers because of their physical characteristics and
because they are present in the atmosphere at low levels. Background
concentrations are several parts in 1015 (parts per quadrillion by
volume, ppqv) so the release of small amounts of PFT results in
unambiguous signals. The large numbers of fluorine atoms and the
structure of these molecules cause them to have high electron
affinities.
The TTG has participated in atmospheric transport and dispersion experiments on long range, regional, and local scales over distances from 1.5 to 2000 km. We have developed tracer methods to measure air infiltration in buildings from single family residences to multi-story urban office buildings. These data have been used in studies of energy efficiency and indoor air quality including a major indoor air quality health study sponsored by the Canadian national health department, Health Canada, and building energy efficiency studies conducted by the Canadian National Research Council.
We have measured the effectiveness of air filtration systems designed for hazard mitigation in nuclear power plant control rooms and conducted indoor measurement programs testing hazard mitigation systems at the Pentagon.
We developed PFT methods for testing the integrity of underground systems including hazardous waste containment structures, and developed a PFT based leak detection systems for the Electric Power Research Institute and the Northeast Natural Gas Utilities trade association. These systems are now in use internationally. We have a global network of private contractors that use these techniques to find dielectric fluid leaks in underground transmission cables.
Other applications we have developed include the validation of tower
footprint models for the Ameriflux program, characterization of the
fractured heat exchange volumes created in engineered geothermal
systems, and development and application of methods for monitoring,
verification, and accounting of sequestered CO2 in support of DOE carbon
sequestration research.