RESUMEN
We use recent aircraft measurements of a comprehensive suite of anthropogenic halocarbons, carbon monoxide (CO), and related tracers to place new constraints on North American halocarbon emissions and quantify their global warming potential. Using a chemical transport model (GEOS-Chem) we find that the ensemble of observations are consistent with our prior best estimate of the U.S. anthropogenic CO source, but suggest a 30% underestimate of Mexican emissions. We develop an optimized CO emission inventory on this basis and quantify halocarbon emissions from their measured enhancements relative to CO. Emissions continue for many compounds restricted under the Montreal Protocol, and we show that halocarbons make up an important fraction of the total greenhouse gas source for both countries: our best estimate is 9% (uncertainty range 6-12%) and 32% (21-52%) of equivalent CO2 emissions for the U.S. and Mexico, respectively, on a 20 year time scale. Performance of bottom-up emission inventories is variable, with underestimates for some compounds and overestimates for others. Ongoing methylchloroform emissions are significant in the U.S. (2.8 Gg/y in 2004-2006), in contrast to bottom-up estimates (< 0.05 Gg), with implications for tropospheric OH calculations. Mexican methylchloroform emissions are minor.
Asunto(s)
Contaminantes Atmosféricos/análisis , Efecto Invernadero , Hidrocarburos Halogenados/análisis , Monóxido de Carbono/análisis , Clorofluorocarburos/análisis , Clorofluorocarburos de Etano , Radical Hidroxilo/análisis , México , Tricloroetanos/análisis , Estados UnidosRESUMEN
The use of ethylene oxide as a sterilizing agent has been frequently practiced, especially taking into account the huge variety of medical devices produced with heat sensitive materials. Mixtures of ethylene oxide and inert gases have been widely adopted in order to decrease the undesirable flammable and explosive properties of ethylene oxide. This article provides a study regarding the sterilizing effectiveness of two ethylene oxide blends: Oxyfume 2002R (using HCFCs 22 and 124) and Oxyfume 12R (using CFC 12), at different temperatures (45, 55, and 65 degrees C). To accomplish this procedure, sub-lethal challenges were performed (0, 3, 6, 9, 12, and 15 minutes) using biological indicators (obtained in the laboratory) made of Bacillus subtilis var. niger ATCC 9372. The sterilizing efficacy of both mixtures was equivalent at the gas concentration of 600 mg/L. The influence of higher temperatures was thus proved.