Fast sulfate formation from oxidation of SO2 by NO2 and HONO observed in Beijing haze

2020355 citationsJournal Articlegold Open Access

Authors

Junfeng Wang · Harvard University

Jingyi Li · Nanjing University of Information Science and Technology

Jianhuai Ye · Harvard University

Jian Zhao · Chinese Academy of Sciences

Yangzhou Wu · Nanjing University of Information Science and Technology

Jianlin Hu · Nanjing University of Information Science and Technology

Dantong Liu

Abstract

Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation of sulfur dioxide (SO2) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO2 oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO2 by nitrogen dioxide (NO2) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N2O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO2 by NO2, producing HONO which can in turn oxidize SO2 to yield N2O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.

Topics & Keywords

Atmospheric chemistry and aerosols Air Quality and Health Impacts Air Quality Monitoring and Forecasting

UN Sustainable Development Goals

Clean water and sanitation

Publication Details

Published in: Nature Communications

Volume 11, Issue 1, pp. 2844-2844

DOI: 10.1038/s41467-020-16683-x

Field-Weighted Citation Impact: 28.50