Atmospheric nitrous acid (HONO) at a rural coastal site in North China: Seasonal variations and effects of biomass burning

Abstract

Nitrous acid (HONO) plays a significant role in atmospheric chemistry due to its contribution to hydroxyl radical (OH). However, no scientific consensus has been achieved about the daytime HONO formation mechanisms. To identify the seasonal variations of HONO chemistry and the impacts of biomass burning (BB), we performed a twophased field study in winter-spring and summer (covering a harvest season) in 2017 at a rural coastal site in North China. Though the mean HONO concentration in winter-spring (0.26 � 0.28 ppbv) was higher than in summer (0.17 � 0.19 ppbv), the maximum HONO concentrations were comparable (~2 ppbv) in the two campaigns. Both the HONO/NO x ratio and nocturnal heterogeneous conversion efficiency of HONO (C HONO ) in summer were over twice of that in winter-spring. The daytime budget analysis also revealed that the strength of P other (i.e., the HONO sources apart from the reaction of OH þ NO) in summer was double of that in winter-spring. BB affected the HONO concentration by enhancing the contribution of heterogeneous HONO production on the aerosol surface but weakening the role of photo-related HONO formation. HONO photolysis was a significant source of OH in both winter-spring and summer, and its contribution could be further enhanced during the BB episode in summer. Our study demonstrates the significant seasonal variations of HONO and the effects of BB, and suggests needs for more multiseason observations and considerations of BB, especially during the harvest time, in HONO research.

Evidence for Strong HONO Emission from Fertilized Agricultural Fields and its Remarkable Impact on Regional O3 Pollution in the Summer North China Plain

“…The largest P(OH)HONO reached 10.7 ppbv h -1 at 13:00 on 18 th June when HONO reached as high as 3.1 ppbv under high solar irradiance expressed as J(NO2)=6.2×10 -3 s -1 . To the best of our knowledge, such a high OH production rate from HONO photolysis, is the largest one found in rural sites, including (fertilized) agricultural sites 18,20,25,30 , forest sites 2,17 , grass sites [42][43][44] , or other rural sites 23,28 , suggesting the crucial role of soil HONO emission in the atmospheric oxidizing capacity in this region. The evident rises of O3 and H2O2 (Figure 1B and 1C) after fertilization could be attributed to the remarkable increase of P(OH)HONO that dominates the enhanced OH production, which could consequently promote the production of O3 and H2O2 through reactions (1)-( 5):…”

“…Even the non-agricultural site is ~15 km west of the sea, air mass during the measurement periods was mainly originated from the inner NCP, and no fertilization was conducted within 20 km around this site, leading to an excellent background site to verify the regional impact of agricultural fertilization. 23 At both sites, HONO was continuously measured online by the LOPAP technique (LOng Path Absorption Photometer, Model-03, QUMA GmbH, Germany) 24 . Other instruments used at the two stations are shown in Text S1 of the Supporting Information (SI).…”

Influence of Chinese New Year overlapping COVID-19 lockdown on HONO sources in Shijiazhuang

“…Field experiments were carried out at different environments worldwide in the last few decades ( Acker et al, 2006 ; Crilley et al, 2016 ; Lee et al, 2016 ; Levy et al, 2014 ; Michoud et al, 2014 ; Spataro and Ianniello, 2014 ; Zhang et al, 2012a ). The HONO concentrations varied from a few pptv in remote areas ( Beine et al, 2001 ; Gu et al, 2020 ; Honrath et al, 2002 ; Liao et al, 2006 ; Spataro et al, 2017 ; Zhang et al, 2012a ; Zhou et al, 2001 ) to several ppbv in polluted urban environment ( Crilley et al, 2016 ; Hu et al, 2002 ; Spataro et al, 2013 ; Zhang et al, 2019e ). In China, the concentration and budget of atmospheric HONO have also been extensively studied ( Spataro et al, 2013 ), such as in Beijing ( Hendrick et al, 2014 ; Hu et al, 2002 ; Spataro et al, 2013 ; Wang et al, 2017 ; Zhang et al, 2019e ), Shanghai ( Wang et al, 2013 ; Zhang et al, 2019b ), Guangzhou ( Hu et al, 2002 ; Su et al, 2008a ), Hongkong ( Xu et al, 2015 ), Ji'nan ( Li et al, 2018 ) and Xi'an ( Huang et al, 2017 ).…”

Source Apportionment of Regional Ozone Pollution Observed at Mount Tai, North China: Application of Lagrangian Photochemical Trajectory Model and Implications for Control Policy

“…ZHANG ET AL. Previous studies have reported the significant impacts of biomass burning on regional air quality over the NCP in June, the winter-wheat harvest season in northern China (Chen et al, 2017;Gu et al, 2020). In this study, we focused on the impact of biomass burning on regional O 3 concentrations.…”