Measurement of overall uptake coefficients for HO2 radicals by aerosol particles sampled from ambient air at Mts. Tai and Mang (China)
1Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohoma, Kanagawa 236-0001, Japan
2Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
3Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo 060-0819, Japan
4Asia Center for Air Pollution Research, Japan Environment Sanitation Center, 1182 Sowa, Nishi-ku, Niigata 950-2144, Japan
Abstract. HO2 uptake coefficients for ambient aerosol particles, collected on quartz fiber filter using a high-volume air sampler in China, were measured using an aerosol flow tube coupled with a chemical conversion/laser-induced fluorescence technique at 760 Torr and 298 K, with a relative humidity of 75%. Aerosol particles were regenerated with an atomizer using the water extracts from the aerosol particles. Over 10 samples, the measured HO2 uptake coefficients for the aerosol particles at the Mt. Tai site were ranged from 0.13 to 0.34, while those at the Mt. Mang site were in the range of 0.09–0.40. These values are generally larger than those previously reported for single-component particles, suggesting that reactions with the minor components such as metal ions and organics in the particle could contribute to the HO2 uptake. A box model calculation suggested that the heterogeneous loss of HO2 by ambient particles could significantly affect atmospheric HOx concentrations and chemistry.