Atmospheric concentrations of the Cl atom, CIO radical, and HO radical in the coastal marine boundary layer

Atmospheric concentrations of chlorine atom (Cl-.), chlorine monoxide radical (ClO.), and hydroxyl radical (HO.) in the coastal marine boundary layer are estimated in this study. A steady-state approach to their concentrations in equilibrium with other atmospheric chemical species is used. Measurements of atmospheric trace species, HCl, Cl-2, HCHO, H2O2, CH3OOH, CH4, CO, SO2, NO, NO2, and O-3, were performed at four sites in Taiwan during the spring of 1999. The results indicate that the concentrations of the Cl-. atom and the ClO. and HO' radicals decrease significantly with cloud cover. The calculated average daytime concentrations of Cl-. ClO. and HO. are 3 x 10(5), 1 x .10(7), and 6 x 10(5) Molecules/cm(3), respectively. Due to the high reactivity of Cl-. with hydrocarbons land its concentration level competitive to that of HO. Cl-. should be a significant sink for hydrocarbons in these cases. (C) 2003 Elsevier Inc. All rights reserved.