HR: 0800h
AN: A51C-0580    [Abstracts]
TI: Development of a new method for determination of atmospheric halogen atom and halogen oxide concentrations
AU: * Tackett, P J
EM: ptackett@purdue.edu
AF: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, United States
AU: Shepson, P B
EM: pshepson@purdue.edu
AF: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, United States
AU: Shepson, P B
EM: pshepson@purdue.edu
AF: Purdue Climate Change Research Center (PCCRC), 503 Northwestern Avenue, West Lafayette, IN 47907, United States
AB: A flowtube reactor has been developed for the quantitative determination of atmospheric halogen atom concentrations. The technique operates by drawing atmospheric halogen atoms (Cl, Br, I) into a 20-mm diameter quartz flowtube, in which they quickly react with an introduced alkene (trifluoropropene) and NO to produce a halogenated ketone that is detected by gas chromatography with electron capture detection (GC-ECD). This method allows for the "direct" determination of atmospheric halogen atom concentrations, which have so far only been determined by indirect methods, e.g. as inferred from hydrocarbon decay rates. The fluorinated alkene reagent is utilized to increase the final product's ECD sensitivity as well as provide a compound not found in the environment (i.e. very low blanks), leading to greater overall instrument sensitivity. Halogen monoxide radicals (XO), typically only measured spectroscopically, can also be quantitatively determined by conversion to X via reaction with NO at the inlet. The resulting halogen atom and halogen oxide concentration measurements allow for the greater understanding of halogen photochemistry in the lower troposphere. Here we show results from laboratory tests and system calibrations in preparation for upcoming field work aboard the icebreaker CCGS Amundsen in the Canadian Arctic as part of IPY 2007-2008.
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
DE: 0750 Sea ice (4540)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting