OH reaction kinetics and atmospheric impact of 1-bromopropane

The temperature-dependent rate constant for the reaction of the OH radical with 1-bromopropane has been measured using the discharge flow technique with laser-induced fluorescence detection of the OH radicals. Rate constants were measured as a function of temperature between T = 271 K and T = 363 K. The temperature dependence is well described by a simple Arrhenius expression, k(T) = A exp[-E/(RT)]. We find that A = (5.75 +/- 0.9) x 10(-12) cm(3) molecule(-1) s(-1) and E/R = 504 +/- 50 K for the OH reaction rate with CH3CH2CH2Br. The reaction rate at T = 277 K is 9.3 x 10(-13) cm(3) molecule(-1) s(-1), which implies that the atmospheric lifetime for CH3CH2CH2Br is approximately 15 days using the scaling method of Prather and Spivakovsky. In addition, the quantitative infrared spectrum for 1-bromopropane has been obtained using a Fourier transform spectrometer. Together with the atmospheric lifetime estimate, this spectrum implies global warming potentials of 1.0, 0.3, and 0.1 for integration time horizons of 20, 100, and 500 years, respectively. We have calculated the ozone depletion potential (ODP) for bromopropane based on the kinetic results using our 2-D model and using the standard semi-empirical approach. The semiempirical calculation of the ODP, using the 15 day lifetime and the model calculated vertical profile of 1-bromopropane, gives 0.0019. However, the 2-D model result is 0.027 using a fixed mixing ratio boundary condition for 1-bromopropane. It is likely that the semiempirical method is inappropriate for species with lifetimes as short as 15 days.