Daytime SO ₂ chemistry on ubiquitous urban surfaces as a source of organic sulfur compounds in ambient air

Abstract

The reactions of sulfur dioxide (SO 2 ) with surface-bound compounds on atmospheric aerosols lead to the formation of organic sulfur (OS) compounds, thereby affecting the air quality and climate. Here, we show that the heterogeneous reaction of SO 2 with authentic urban grime under near-ultraviolet sunlight irradiation leads to a large suite of various organic compounds including OS released in the gas phase. Calculations indicate that at the core area of Guangzhou, building surface uptake of SO 2 is 15 times larger than uptake of SO 2 on aerosol surfaces, yielding ~20 ng m −3 of OS that represents an important fraction of the observed OS compounds (60 to 200 ng m −3 ) in ambient aerosols of Chinese megacities. This chemical pathway occurring during daytime can contribute to the observed fraction of OS compounds in aerosols and improve the understanding of haze formation and urban air pollution.

Production of Volatile Organic Compounds by Ozone Oxidation Chemistry at the South China Sea Surface Microlayer

“…A list of standard gases used for calibration is shown in Table S6 of the Supporting Information. Several studies have shown that peak abundance comparison between different compounds in mass spectrometry can be used to show the relative importance of different types of compounds, although this comparison is likely to produce uncertainty. − For the estimation of the normalized intensity, we used m / z 59 as a reference compound because it was the most abundant peak, under the assumption that the signal is entirely attributed to acetone. Indeed, the NDPH–HPLC–UV analysis has shown that the concentration ratio between acetone and propanal is about 7:1.…”

The Effect of Human Occupancy on Indoor Air Quality through Real-Time Measurements of Key Pollutants

“…Due to the lack of gas standards, we estimated the normalized intensity of product compounds (Tables S2 and S3) formed during the reaction of O 3 with primary VOCs by using the reference compound , C i = Int i Int STD × C STD where C i is the mixing ratio of the compound i detected during the experiments, Int STD is the intensity of standard gas, Int i is the intensity of the compound i , and C STD is the mixing ratio of standard gas.…”

“…Due to the lack of gas standards, we estimated the normalized intensity of product compounds (Tables S2 and S3) formed during the reaction of O 3 with primary VOCs by using the reference compound 62,63…”

SO2 enhances aerosol formation from anthropogenic volatile organic compound ozonolysis by producing sulfur-containing compounds

“…Recently, the impacts of inorganic gases on aerosol chemistry have received significant attention (Deng et al, 2022). In particular, there is increasing evidence that sulfur dioxide (SO 2 ) can modulate SOA formation and composition (Ye et al, 2018;Stangl et al, 2019;Liu et al, 2017).…”