KINETICS OF THE GAS-PHASE REACTIONS OF BETA-PHELLANDRENE WITH OH AND NO3 RADICALS AND O3 AT 297-K +/- 2-K

Rate constants for the gas-phase reactions of the biogenically emitted monoterpene beta-phellandrene with OH and NO3 radicals and O3 have been measured at 297 +/- 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained were (in cm3 molecule-1 s-1 units): for reaction with the OH radical, (1.68 +/- 0.41) x 10(-10); for reaction with the NO3 radical, (7.96 +/- 2.82) x 10(-12); and for reaction with O3, (4.77 +/- 1.23) x 10(-17), where the error limits include the estimated uncertainties in the reference reaction rate constants. Using these rate constants, the lifetime of beta-phellandrene in the lower troposphere due to reaction with these species is calculated to be in the range of ca. 1-8 h, with the OH radical reaction being expected to dominate over the O3 reaction as a loss process for beta-phellandrene during daylight hours.