HR: 1330h
AN: A52A-0772    [PDF]
TI: Stable hydrogen isotope ratios in atmospheric formaldehyde: methods and preliminary measurements
AU: * Rice, A L
EM: arice@ocean.washington.edu
AF: Joint Institute for the Study of the Atmosphere and the Oceans, Box 354235 University of Washington, Seattle, WA 98195-4235 United States
AU: Quay, P D
EM: pdquay@u.washington.edu
AF: School of Oceanography, Box 355351 University of Washington, Seattle, WA 98195-5351 United States
AU: Gammon, R H
EM: gammon@u.washington.edu
AF: School of Oceanography, Box 355351 University of Washington, Seattle, WA 98195-5351 United States
AB: Formaldehyde (HCHO) is an integral component in the chemistry of urban, rural, and remote atmospheres. Photolysis and its reactions with the hydroxyl and nitrate radicals leads to the generation of hydroperoxyl radical and subsequently the hydroxyl radical and ozone. It is produced both as an intermediate in hydrocarbon oxidation and emitted by primary sources including biomass burning, fossil fuel combustion, and manufacturing processes. Products of its oxidation include carbon monoxide (CO), carbon dioxide, and molecular hydrogen (H$_{2}$). Studying the stable isotopic composition of gaseous HCHO can help clarify the origins of HCHO and provide budgetary constraints for photoxidation products H$_{2}$ and CO. Isotopic studies to date have been few and limited to the $^{13}$C/$^{12}$C ratio in HCHO. Measurements of the D/H ratio in HCHO, in particular, will help constrain the photochemical source to the H$_{2}$ budget, which is currently thought to be roughly 30-50% of the total H$_{2}$ source. The development of an analytical method for the measurement of the D/H ratio in atmospheric HCHO is presented along with details of isotope calibration and sample collection. The technique utilizes a multistep preconcentration technique and online continuous flow gas chromatography isotope ratio mass spectrometry which provides the resolution and sensitivity necessary for analysis. Preliminary measurements are presented.
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
DE: 1610 Atmosphere (0315, 0325)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting