| Paper Code |
20230016 |
| Title |
Comparison of chemical composition and acidity of size-resolved inorganic aerosols at the top and foot of Mt. Hua, Northwest China: The role of the gas-particle distribution of ammonia. |
| Authors |
Feng Qiao |
| Corresponding Author |
Zhou Bianhong; Li Jianjun |
| Year |
2023 |
| Title of Journal |
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| Volume |
905 |
| Number |
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| Page |
166985 |
| Abstract |
Aerosol pH is not only a diagnostic indicator of secondary aerosol formation, but also a key factor in the specific chemical reaction routes that produce sulfate and nitrate. To understand the characteristics of aerosol acidity in the Mt. Hua, the chemical fractions of water-soluble inorganic ions in the atmospheric PM2.5 and size-resolved particle at the top and foot of Mt. Hua in summer 2020 were studied. The results showed the mass concentrations of PM2.5 and water-soluble ions at the foot were 2.0-2.6 times higher than those at the top. The secondary inorganic ions, i.e., SO42-, NO3-, and NH4+ (SNA) were 56%-61% higher by day than by night. SO42- was mainly distributed in the fine particles (Dp<2.1mum). NO3- showed a unimodal size distribution (peaking at 0.7-1.1mum) at the foot and a bimodal (0.7-1.1mum and 4.7-5.8mum) size distribution at the top. At the top site, the distribution of NO3- in coarse particles (> 2.1mum) was mainly attributed to the gaseous HNO3 volatilized from fine particles reacting with cations in coarse particles to form non-volatile salts (such as Ca(NO3)2). The pH values of PM2.5 were 2.7±1.3 and 3.3±0.42 at the top and foot, respectively. NH4+/NH3(g) plays a decisive role in stabilizing aerosol acidity. In addition, the increase of the liquid water content (LWC) at the foot facilitates the gas-particle conversion of NH3, while the H+ concentration was diluted, resulting in a decrease in acidity at the foot. NH4+/NH3 had good linear correlations with SO42-, NO3-, and LWC during the daytime at both sites, indicating that SO42-, NO3-, and LWC together affect the gas-particle distribution of ammonia by day: however, the effect of LWC at night was not evident. |
| Full Text |
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| Full Text Link |
https://doi.org/10.1016/j.scitotenv.2023.166985 |
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© 2015 Institute of Earth Environment,CAS