Photooxidation of leaf-wound oxygenated compounds, 1-penten-3-ol, (Z)-3-hexen-1-ol, and 1-penten-3-one, initiated by OH radicals and sunlight.

An evaluation of the environmental impact of stressed-induced compounds, 1-penten-3-ol,(Z)-3-hexen-1-ol, and 1-penten-3-one (ethyl vinyl ketone, EVK), is presented in this paper. The removal processes considered here are the gas-phase reactions with hydroxyl (OH) radicals and photolysis in the actinic region (above 290 nm). The wavelength dependence of the gas-phase absorption cross-sections (sigma(lamda)) was measured by UV-visible spectroscopy (lamda = 200-390 nm). The kinetic study of the OH-reaction with pentenyl compounds has been performed as a function of temperature (T = 263-353 K) for the first time. The resulting Arrhenius expressions for the T-dependence of the OH-rate coefficient, k(OH) (in cm3 molecule(-1) s(-1) and uncertainties of +/-sigma), were (7.7 +/- 0.8) x 10(-12) exp{(606 +/- 30)/7} for 1-penten-3-ol and (4.4 +/- 1.4) x 10(-12) exp{(507 +/- 90)/7} for EVK, respectively. k(OH) for (Z)-3-hexen-1-ol is reported at 298 K. The experimental evidence shows that the major tropospheric removal of pentenyl compounds is the gas-phase reaction with OH radicals. However, O3 and NO3 radicals may compete with OH radicals as tropospheric sinks of (Z)-3-hexen-1-ol. Photolysis of these compounds is expected to be of minor importance in the troposphere.