CALCULATED VOLATILIZATION RATES OF FUEL OXYGENATE COMPOUNDS AND OTHERGASOLINE-RELATED COMPOUNDS FROM RIVERS AND STREAMS

Large amounts of the ''fuel-oxygenate'' compound methyl-tert-butyl eth er (MTBE) are currently being used in gasoline to reduce carbon monoxi de and ozone in urban air and to boost fuel octane. Because MTBE can b e transported to surface waters in various ways, established theory wa s used to calculate half-lives for MTBE volatilizing from flowing surf ace waters. Similar calculations were made for benzene as a representa tive of the ''BTEX'' group of compounds (benzene, toluene, ethyl benze ne, and the xylenes), and for tert-butyl alcohol (TBA). The calculatio ns were made as a function of the mean flow velocity u (m/day), the me an flow depth h (m), the ambient temperature, and the wind speed. In d eep, slow-moving flows, MTBE volatilizes at rates which are similar to those for the BTEX compounds. In shallow, fast-moving flows, MTBE vol atilizes more slowly than benzene, though in such flows both MTBE and benzene volatilize quickly enough that these differences may often not have much practical significance. TEA was found to be essentially non volatile from water.