Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China

<p>Nitrate is an increasingly important component of fine particulate matter (<span class="inline-formula">PM<sub>2.5</sub></span>) in Chinese cities. The production of nitrate is not only related to the abundance of its precursor, but it is also supported by...

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Main Authors: M. Li, Z. Zhang, Q. Yao, T. Wang, M. Xie, S. Li, B. Zhuang, Y. Han
Format: Article
Language:English
Published: Copernicus Publications 2021-10-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/21/15135/2021/acp-21-15135-2021.pdf
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author M. Li
Z. Zhang
Q. Yao
T. Wang
M. Xie
S. Li
B. Zhuang
Y. Han
author_facet M. Li
Z. Zhang
Q. Yao
T. Wang
M. Xie
S. Li
B. Zhuang
Y. Han
author_sort M. Li
collection DOAJ
description <p>Nitrate is an increasingly important component of fine particulate matter (<span class="inline-formula">PM<sub>2.5</sub></span>) in Chinese cities. The production of nitrate is not only related to the abundance of its precursor, but it is also supported by the atmospheric photochemical oxidants, raising a new challenge for the current emission control actions in China. This paper uses comprehensive measurements and a regional meteorology–chemistry model with optimized mechanisms to establish the nonlinear responses between particulate nitrate and the emission controls of nitrogen oxides (<span class="inline-formula">NO<sub><i>x</i></sub></span>) in the megalopolises of China. Nitrate is an essential component of <span class="inline-formula">PM<sub>2.5</sub></span> in eastern China, accounting for 9.4 %–15.5 % and 11.5 %–32.1 % of the <span class="inline-formula">PM<sub>2.5</sub></span> mass for the warm and cold seasons. The hypothetical <span class="inline-formula">NO<sub><i>x</i></sub></span> emission reduction scenarios (<span class="inline-formula">−</span>10 % to <span class="inline-formula">−</span>80 %) during summer–autumn result in almost linearly lower <span class="inline-formula">PM<sub>2.5</sub></span> by <span class="inline-formula">−</span>2.2 % in Beijing–Tianjin–Hebei (BTH) and <span class="inline-formula">−</span>2.9 % in Yangtze River Delta (YRD) per 10 % reduction of <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions, whereas they lead to a rather complicated response of PM components in winter. Wintertime nitrate is found to increase by <span class="inline-formula">+</span>4.1 % in BTH and <span class="inline-formula">+</span>5.1 % in YRD per 10 % reduction of <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions, with nearly unchanged nitric acid (<span class="inline-formula">HNO<sub>3</sub></span>) and higher dinitrogen pentoxide (N<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>5</sub></span>) intermediate products produced from the increased atmospheric oxidant levels. An inflexion point appears at 30 %–50 % <span class="inline-formula">NO<sub><i>x</i></sub></span> emission reduction, and a further reduction in <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions is predicted to cause <span class="inline-formula">−</span>10.5 % reduction of nitrate for BTH and <span class="inline-formula">−</span>7.7 % for YRD per 10 % reduction of <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions. In addition, the 2012–2016 <span class="inline-formula">NO<sub><i>x</i></sub></span> control strategy actually leads to no changes or even increases of nitrate in some areas (8.8 % in BTH and 14.4 % in YRD) during winter. Our results also emphasize that ammonia (<span class="inline-formula">NH<sub>3</sub></span>) and volatile organic compounds (VOCs) are effective in controlling nitrate pollution, whereas decreasing the sulfur dioxide (<span class="inline-formula">SO<sub>2</sub></span>) and <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions may have counterintuitive effects on nitrate aerosols. This paper helps understand the nonlinear aerosol and photochemistry feedbacks and defines the effectiveness of proposed mitigations for the increasingly serious nitrate pollution in China.</p>
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spelling doaj.art-fe703602629a43008182bec9850fb0a22022-12-21T19:18:53ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242021-10-0121151351515210.5194/acp-21-15135-2021Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of ChinaM. Li0Z. Zhang1Q. Yao2T. Wang3M. Xie4S. Li5B. Zhuang6Y. Han7School of Atmospheric Sciences, Nanjing University, Nanjing 210023, ChinaSchool of Atmospheric Sciences, Nanjing University, Nanjing 210023, ChinaStatistical Bureau of Qingjiangpu District, Huaian 223001, ChinaSchool of Atmospheric Sciences, Nanjing University, Nanjing 210023, ChinaSchool of Atmospheric Sciences, Nanjing University, Nanjing 210023, ChinaSchool of Atmospheric Sciences, Nanjing University, Nanjing 210023, ChinaSchool of Atmospheric Sciences, Nanjing University, Nanjing 210023, ChinaGuangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, School of Atmospheric Sciences, Sun Yat-Sen University, Guangzhou 510000, China<p>Nitrate is an increasingly important component of fine particulate matter (<span class="inline-formula">PM<sub>2.5</sub></span>) in Chinese cities. The production of nitrate is not only related to the abundance of its precursor, but it is also supported by the atmospheric photochemical oxidants, raising a new challenge for the current emission control actions in China. This paper uses comprehensive measurements and a regional meteorology–chemistry model with optimized mechanisms to establish the nonlinear responses between particulate nitrate and the emission controls of nitrogen oxides (<span class="inline-formula">NO<sub><i>x</i></sub></span>) in the megalopolises of China. Nitrate is an essential component of <span class="inline-formula">PM<sub>2.5</sub></span> in eastern China, accounting for 9.4 %–15.5 % and 11.5 %–32.1 % of the <span class="inline-formula">PM<sub>2.5</sub></span> mass for the warm and cold seasons. The hypothetical <span class="inline-formula">NO<sub><i>x</i></sub></span> emission reduction scenarios (<span class="inline-formula">−</span>10 % to <span class="inline-formula">−</span>80 %) during summer–autumn result in almost linearly lower <span class="inline-formula">PM<sub>2.5</sub></span> by <span class="inline-formula">−</span>2.2 % in Beijing–Tianjin–Hebei (BTH) and <span class="inline-formula">−</span>2.9 % in Yangtze River Delta (YRD) per 10 % reduction of <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions, whereas they lead to a rather complicated response of PM components in winter. Wintertime nitrate is found to increase by <span class="inline-formula">+</span>4.1 % in BTH and <span class="inline-formula">+</span>5.1 % in YRD per 10 % reduction of <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions, with nearly unchanged nitric acid (<span class="inline-formula">HNO<sub>3</sub></span>) and higher dinitrogen pentoxide (N<span class="inline-formula"><sub>2</sub></span>O<span class="inline-formula"><sub>5</sub></span>) intermediate products produced from the increased atmospheric oxidant levels. An inflexion point appears at 30 %–50 % <span class="inline-formula">NO<sub><i>x</i></sub></span> emission reduction, and a further reduction in <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions is predicted to cause <span class="inline-formula">−</span>10.5 % reduction of nitrate for BTH and <span class="inline-formula">−</span>7.7 % for YRD per 10 % reduction of <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions. In addition, the 2012–2016 <span class="inline-formula">NO<sub><i>x</i></sub></span> control strategy actually leads to no changes or even increases of nitrate in some areas (8.8 % in BTH and 14.4 % in YRD) during winter. Our results also emphasize that ammonia (<span class="inline-formula">NH<sub>3</sub></span>) and volatile organic compounds (VOCs) are effective in controlling nitrate pollution, whereas decreasing the sulfur dioxide (<span class="inline-formula">SO<sub>2</sub></span>) and <span class="inline-formula">NO<sub><i>x</i></sub></span> emissions may have counterintuitive effects on nitrate aerosols. This paper helps understand the nonlinear aerosol and photochemistry feedbacks and defines the effectiveness of proposed mitigations for the increasingly serious nitrate pollution in China.</p>https://acp.copernicus.org/articles/21/15135/2021/acp-21-15135-2021.pdf
spellingShingle M. Li
Z. Zhang
Q. Yao
T. Wang
M. Xie
S. Li
B. Zhuang
Y. Han
Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China
Atmospheric Chemistry and Physics
title Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China
title_full Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China
title_fullStr Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China
title_full_unstemmed Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China
title_short Nonlinear responses of particulate nitrate to NO<sub>x</sub> emission controls in the megalopolises of China
title_sort nonlinear responses of particulate nitrate to no sub x sub emission controls in the megalopolises of china
url https://acp.copernicus.org/articles/21/15135/2021/acp-21-15135-2021.pdf
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