P1.14 trajectory analysis of pollutant gases in NOAA flask samples and HFC–134A as a potential leak indicator

Thursday, 12 November 2009
Markeata Lee, OAR, Detroit, MI

This project has two distinct objectives: (1) The first task was to analyze pollutant data from NOAA flask samples collected at the 8 tall tower CO2 monitoring sites using the HYSPLIT trajectory model. Modeled trajectories can aid in determining sources of pollutant gases and whether emissions are changing over time. The focus of this work was on hydro fluorocarbons (HFCs), which are used in air conditioners and refrigerators. HFCs generally serve as markers of urban influence on the sampled air. After performing a trajectory analysis for the LEF Park Falls, Wisconsin tall tower site, it was found that high concentrations of HFCs were originating south of the site and the low concentrations were deriving from the north.

(2) The second goal was to evaluate whether HFC134 (1,1,2,2 –tetrafluoroethane) is a suitable a tracer for detecting leaks in the NOAA flask sampling equipment that is used at the tall tower sites. HFC134 was deliberately leaked it into the building where sampling equipment is housed at the Boulder Atmospheric Observatory tower site. HFC134 is not commonly present at detectable levels in ambient air but artificial enhancements should be easily detectable by the gas chromatography/ mass spectrometry (GC-MS) analysis system that is routinely used to measure the flask samples. It was found that a 1% leak would be detectable using the HFC 134 as the leak indicator.

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