Atmospheric measurements of selected nonmethane hydrocarbons and halocarbons from August 1, 1993 to July 31, 1994, in a suburban location: 'A year in Irvine'.

摘要

During period from August 1, 1993 to July 31, 1994, flask samples were collected daily at noontime in Mason Park, Irvine, California, in an effort to better understand the composition and fate of selected halocarbons and nonmethane hydrocarbons, NMHCs, in the suburban atmosphere. The samples were pre-concentrated on a stainless steel loop packed with glass beads, then separated with split capillary column gas chromatography, and quantified by flame ionization and electron capture detectors. The quantified gases were trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113), trichloromethane (chloroform), 1,1,1-trichloroethane (methyl chloroform), tetrachloromethane (carbon tetrachloride), trichloroethene, and tetrachloroethene (perchloroethene), ethane, ethene, ethyne (acetylene), propane, propene, n-butane, methyl propane (isobutane), 1-butene, trans-2-butene, methyl propene (isobutene), 1,3-butadiene, n-pentane, 2-methyl butane (isopentane), cyclopentane, 2-methyl-1,3-butadiene (isoprene), n-hexane, benzene, and methyl benzene (toluene).; Meteorology and emissions controlled the amount of air that the emitted gases were diluted into, and thereby their ambient concentrations.; Concentrations of CCl{dollar}sb4{dollar} and CFC-11 were very consistent throughout the year, showing these gases to have the smallest local emissions. Methyl chloroform and tetrachloroethene had the greatest halocarbon emissions.; Even in the cleanest samples had enhanced NMHCs over reported measurements from remote Pacific Coastline areas. The distribution of NMHC species showed large light duty vehicle exhaust emissions. Linear correlations with NMHCs to ethyne using slopes and coefficients of determination showed high correlations of many NMHCs with ethyne. Local emission compositions compared with much of the 1987 South Coast Air Quality Study data. Correlation coefficients for NMHCs revealed at least two sources, fossil fuel combustion being the dominant source, and a weaker source of smaller chain alkanes.; Two unique events occurred that greatly affected the measurements. The Laguna fires on October 27, 1993 and the Northridge Earthquake on January 16, 1994, had enhanced NMHC and halocarbon mixing ratios and both events coincided with stagnation episodes.; The NMHC impact on ozone formation using the Carter Maximum Incremental Reactivity scale was studied and showed ethene and propene to have had the strongest effect on the formation of ozone within the LA Basin.; The NMHC impact on ozone formation using the Carter Maximum Incremental Reactivity scale is calculated. The ethene and propene have the strongest effect on the formation of ozone within the LA Basin.