NONMETHANE HYDROCARBON MEASUREMENTS DURING THE TROPOSPHERIC OH PHOTOCHEMISTRY EXPERIMENT

In the rural troposphere, the nonmethane hydrocarbon compounds (NMHCs) play a significant role in establishing the absolute, as well as, the relative concentration of the odd-hydrogen radicals. In order to prov ide data which could be used to estimate OH reactive loss rates with h ydrocarbons directly, and to broaden our understanding of the producti on of biogenic NMHCs in and the transport of anthropogenic NMHCs into the Colorado mountains, in situ hydrocarbon measurements were made dur ing the Tropospheric OH Photochemistry Experiment in the fall of 1993. NMHC measurements were made using an automated gas chromatographic sy stem that was capable of quantifying alkanes C-3 (propane) through C-1 0 (decane), alkenes C-4 (butene) through C-10 (decene), light alcohols from C-1 (methanol) through C-5 (pentanol), light ketones from C-3 (a cetone) through C-5 (pentanone), aromatics from C-6 (benzene) through C-9 (trimethylbenzenes), C-10 monoterpenes, and acetaldehyde. During p eriods of influx of urban air masses, the NMHCs appeared to be the dom inant sink for OH radicals.