Atmospheric environment

Review of heterogeneous photochemical reactions of NOy on aerosol-A possible daytime source of nitrous acid (HONO) in the atmosphere

Jinzhu Ma , Yongchun Liu , Chong Han , Qingxin Ma , Chang Liu , Hong He


Received June 07, 2012,Revised September 27, 2012, Accepted , Available online February 02, 2013

Volume ,2013,Pages 326-334

As an important precursor of hydroxyl radical, nitrous acid (HONO) plays a key role in the chemistry of the lower atmosphere. Recent atmospheric measurements and model calculations show strong enhancement for HONO formation during daytime, while they are inconsistent with the known sources in the atmosphere, suggesting that current models are lacking important sources for HONO. In this article, heterogeneous photochemical reactions of nitric acid/nitrate anion and nitrogen oxide on various aerosols were reviewed and their potential contribution to HONO formation was also discussed. It is demonstrated that HONO can be formed by photochemical reaction on surfaces with deposited HNO3, by photocatalytic reaction of NO2 on TiO2 or TiO2-containing materials, and by photochemical reaction of NO2 on soot, humic acids or other photosensitized organic surfaces. Although significant uncertainties still exist in the exact mechanisms and the yield of HONO, these additional sources might explain daytime observations in the atmosphere.

Copyright © Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.京ICP备05002858号-3