Investigation of HO2 uptake mechanisms onto multiple-component ambient aerosols collected in summer and winter time in Yokohama, Japan
Yoshizumi Kajii , Jun Zhou , Yukiko Fukusaki , Kentaro Murano , Tania Gautam , Yu Bai , Yoshimi Inomata , Hiroaki Komatsu , Mayuko Takeda , Bin Yuan , Min Shao , Yosuke Sakamoto
DOI:10.1016/j.jes.2023.02.030
Received September 12, 2022,Revised , Accepted February 13, 2023, Available online February 24, 2023
Volume 36,2024,Pages 18-29
The heterogeneous loss of HO2 radicals onto ambient aerosols plays an important role in tropospheric chemistry. However, sparse investigation of the dominating parameters controlling the HO2 uptake coefficients onto ambient aerosols (HO2) has largely hindered the application of the measured HO2 to the global spatial prediction. Here we induced an offline method using LFP-LIF technique to measure the kinetics of HO2 uptake onto ambient aerosols collected in summertime and wintertime in Yokohama city, a regional urban site near Tokyo, Japan. By controlling the dominating parameters which influence HO2, we were able to investigate the detailed HO2 uptake mechanism. We characterized the chemical composition of the collected ambient aerosols, including organics, inorganics, transition metals ions, etc. and modeled HO2 using different mechanisms. Results show that HO2 increased with the increase in RH, and the aerosol states (“dry” or wet/aqueous) have large effects on HO2. With fixed RH and aerosol chemical composition, HO2was highly dependent on pH and inversely correlated with [HO2]0. By combing the measured HO2 values with the modeled ones, we found that both the HO2 self-reaction and transition metal-catalyzed reactions should be accounted for to yield a single parameterization to predict HO2, and different chemical compositions may have collective effects on HO2. Results may serve for extending the HO2 values measured at one observation site to different environmental conditions, which will help us to achieve more accurate modeling results concerning secondary pollutant formation (i.e., ozone).
