Atmospheric gas-phase degradation and global warming potentials of 2-fluoroethanol, 2,2-difluoroethanol, and 2,2,2-trifluoroethanol

摘要

The vapour phase reactions of 2-fluoroethanol, 2,2-difluoroethanol, and 2,2,2-trifluoroethanol with OH radicals and Cl atoms were studied at 298 K and 1013 mbar using long-path FTIR detection. The following reaction rate coefficients were determined by the relative rate method: k_(298)(OH + CH_2FCH_2OH) = (1.42 +- 0.11) x 10~(-12), k_(298)(OH + CHF_2CH_2OH) - (4.51 +- 0.06) x 10~(-13), k_(298)(OH + CF_3CH_2OH) = (1.23 +-0.06) x 10~(-13), k_(298)(Cl + CH_2FCH_2OH) = (2.67+-0.3)x10~(-11), k_(298)(Cl + CHF_2CH_2OH) = (3.12+-0.06)x10~(-12), and k_(298)(Cl + CF_3CH_2OH) = (7.42 +-0.12) x 10~(-13)cm~3 molecule~(-1) s~(-1), the reported uncertainties represent 3σ from the statistical analyses and do not include any systematic errors or uncertainties in the reference rate coefficients. Quantitative infrared cross-sections of the title compounds at 298 K are reported in the 4000-50 cm~(-1) region. A 3D chemistry transport model was applied to calculate the atmospheric distributions and lifetimes of the title compounds; the global and yearly averaged lifetimes were calculated as 20 days for CH_2FCH_2OH, 40 days for CHF_2CH_2OH, and 117 days for CF_3CH_2OH. Radiative forcing calculations were carried out assuming either constant vertical profiles or the distribution derived from the chemistry transport model. The Global Warming Potentials for the title compounds are insignificant compared to, e.g. CFC-11 (CCl_3F).