Volatile organic compound measurements in the California Mexico border region during SCOS97

Measurements of volatile organic compounds ŽVOC. were carried out in the California Mexico border region during the Southern California Ozone Study in the summer of 1997 ŽSCOS97.. Integrated 3-h samples were collected in Rosarito Žsouth of Tijuana, Mexico. and in Mexicali during intensive operational periods ŽIOP., twice per IOP day. VOC were collected using stainless-steel 6-l canisters; carbonyl compounds were collected using 2,4-dinitrophenylhydrazine ŽDNPH. impregnated C18 SepPak cartridges. The canister samples were analyzed for speciated volatile hydrocarbons ŽC2 C12., CO, CO2, CH4, methyl t-butyl ether ŽMTBE., and halogenated hydrocarbons. DNPHimpregnated cartridges were analyzed for 14 C1 C7 carbonyl compounds. The concentrations of all species were higher at Mexicali than in Rosarito. A good correlation between total non-methane hydrocarbons ŽTNMHC., CO, and other pollutants associated with motor vehicle emissions observed for Mexicali indicates that the main source of TNMHC at this site is vehicular traffic.