Intercomparison of OH radical measurement in a complex atmosphere in Chengdu, China

Guoxian Zhang; Renzhi Hu; Pinhua Xie; Keding Lu; Shengrong Lou; Xiaoyan Liu; Xin Li; Fengyang Wang; Yihui Wang; Xinping Yang; Haotian Cai; Yue Wang; Wenqing Liu

doi:10.1016/j.scitotenv.2022.155924

Intercomparison of OH radical measurement in a complex atmosphere in Chengdu, China

Sci Total Environ. 2022 Sep 10;838(Pt 1):155924. doi: 10.1016/j.scitotenv.2022.155924. Epub 2022 May 14.

Authors

Guoxian Zhang¹, Renzhi Hu², Pinhua Xie³, Keding Lu⁴, Shengrong Lou⁵, Xiaoyan Liu⁶, Xin Li⁴, Fengyang Wang⁷, Yihui Wang⁷, Xinping Yang⁴, Haotian Cai⁷, Yue Wang⁷, Wenqing Liu⁷

Affiliations

¹ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, China; University of Science and Technology of China, Hefei, China.
² Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, China. Electronic address: [email protected].
³ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, China; University of Science and Technology of China, Hefei, China; CAS Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China; College of Resources and Environment, University of Chinese Academy of Science, Beijing, China. Electronic address: [email protected].
⁴ State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China.
⁵ State Environmental Protection Key Laboratory of the Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai, China.
⁶ College of Pharmacy, Anhui Medical University, Hefei, China.
⁷ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, China.

PMID: 35577098
DOI: 10.1016/j.scitotenv.2022.155924

Abstract

Atmospheric oxidation is a driving force of complex air pollution, and accurate hydroxyl radical (OH) measurement is helpful in investigating the radical-cored photooxidation mechanism in the troposphere. A self-developed laser-induced fluorescence instrument by the Anhui Institute of Optics Fine Mechanics, Chinese Academy of Sciences (AIOFM-LIF), was able to measure OH concentration with high sensitivity and good time resolution, and a detection limit of 1.7 × 10⁵ cm^-3 (1σ, 30 s). A long-period, multi-level intercomparison of hydroxyl radical (OH) measurements between AIOFM-LIF and PKU-LIF (the Peking University laser-induced fluorescence system) was conducted in Chengdu, China. The measurement between two instruments was in excellent agreement in the 5-min time resolution. Linear regression analysis reported a linear slope of 0.96 with a 0.68 × 10⁶ cm^-3 offset, and the correlation coefficient R² was 0.85. The overall linearity with only a slight offset indicated a negligible influence on OH measurement. No noticeable artifacts from ozonolysis were observed under the condition of high ozone and ozonolysis-related compound concentrations. In addition to the subtraction of background signal through wavelength modulation, the dynamic correction on ozone photolysis interference ensured high intercomparison quality in both relatively constant and rapidly varying periods. Based on the reliability of OH_AIOFM and OH_PKU, comparisons under different oxidation-related species (NOx, VOCs, O₃, PM_2.5) levels and typical scenarios (rich-BVOC and high-reactivity) were carried out to evaluate the performance under complex atmospheres. A slightly higher drift was observed in a certain scenario, but the general data variability due to environmental changes did not affect the measurement accuracy. The intercomparison demonstrated that both systems are able to achieve reliable OH data under typical conditions of complex atmospheric pollution in China. Additional improvements are necessary for future intercomparisons in order to enhance the confidence in OH detection accuracy.

Keywords: AIOFM-LIF; Hydroxyl radical; Intercomparison; Interference; PKU-LIF.

MeSH terms

Air Pollutants* / analysis
Air Pollution* / analysis
Atmosphere / analysis
Humans
Hydroxyl Radical
Ozone* / analysis
Reproducibility of Results

Substances

Air Pollutants
Hydroxyl Radical
Ozone