How aerosol pH responds to nitrate to sulfate ratio of fine-mode particulate

Aerosol acidity (pH), one of key properties of fine-mode particulate (PM2.5), depends largely on nitrate and sulfate in particle. The mass contribution of nitrate relative to sulfate in PM2.5 has tended to increase in many regions globally, but how this change affects aerosol pH remains in debate. In this way, we measured PM2.5 ionic species and oxygen isotopic composition of nitrate in the eastern China, and predicted aerosol pH using the ISORROPIA-II model. When nitrate to sulfate molar ratio increases and thus PM2.5 is gradually enriched in ammonium nitrate (NH4NO3), aerosol pH tends to increase. The oxidation of nitrogen dioxide (NO2) by hydroxyl radical is responsible for most of nitrate formation (generally above 60%). These indicate that nitrate formation through gas-to-particle conversion involving ammonia and nitric acid results in increasing aerosol pH with increasing molar ratio of nitrate to sulfate. Conversely, aerosol pH is expected to decrease with increasing relative abundance of nitrate as ammonia emissions are lowered. Our research concludes that it should be considered to reduce aerosol NH4NO3 by reducing the precursors of nitric oxide and ammonia emissions, to substantially improve the air quality (i.e., reduce PM2.5 levels and potential nitrate deposition) in China.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:27

Enthalten in:

Environmental science and pollution research international - 27(2020), 28 vom: 25. Okt., Seite 35031-35039

Sprache:

Englisch

Beteiligte Personen:

Cao, Yansheng [VerfasserIn]
Zhang, Zhongyi [VerfasserIn]
Xiao, Hongwei [VerfasserIn]
Xie, Yajun [VerfasserIn]
Liang, Yue [VerfasserIn]
Xiao, Huayun [VerfasserIn]

Links:

Volltext

Themen:

Aerosol pH
Aerosols
Air Pollutants
Journal Article
Nitrate formation
Nitrate to sulfate ratio
Particle nitrate
Particulate Matter
Sulfates

Anmerkungen:

Date Completed 28.08.2020

Date Revised 21.12.2021

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1007/s11356-020-09810-0

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM311614914