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Title: | PM2.5 acidity at a background site in the Pearl River Delta region in fall-winter of 2007-2012 | Authors: | Fu, X Guo, H Wang, X Ding, X He, Q Liu, T Zhang, Z |
Issue Date: | 9-Apr-2015 | Source: | Journal of hazardous materials, 9 Apr. 2015, v. 286, p. 484-492 | Abstract: | Based on field observations and thermodynamic model simulation, the annual trend of PM2.5 acidity and its characteristics on non-hazy and hazy days in fall-winter of 2007-2012 in the Pearl River Delta region were investigated. Total acidity ([H+]total) and in-situ acidity ([H+]in-situ) of PM2.5 significantly decreased (F-test, p<0.05) at a rate of -32±1.5nmolm-3year-1 and -9±1.7nmolm-3year-1, respectively. The variation of acidity was mainly caused by the change of the PM2.5 component, i.e., the decreasing rates of [H+]total and [H+]in-situ due to the decrease of sulfate (SO42-) exceeded the increasing rate caused by the growth of nitrate (NO3-). [H+]total, [H+]in-situ and liquid water content on hazy days were 0.9-2.2, 1.2-3.5 and 2.0-3.0 times those on non-hazy days, respectively. On hazy days, the concentration of organic matter (OM) showed significant enhancement when [H+]in-situ increased (t-test, p<0.05), while this was not observed on non-hazy days. Moreover, when the acidity was low (i.e., R=[NH4+]/(2×[SO42-]+[NO3-])>0.6), NH4NO3 was most likely formed via homogenous reaction. When the acidity was high (R≤0.6), the gas-phase formation of NH4NO3 was inhibited, and the proportion of NO3- produced via heterogeneous reaction of N2O5 became significant. | Keywords: | Haze Nitrate PM2.5 acidity Secondary organic carbon Sulfate |
Publisher: | Elsevier | Journal: | Journal of hazardous materials | ISSN: | 0304-3894 | EISSN: | 1873-3336 | DOI: | 10.1016/j.jhazmat.2015.01.022 | Rights: | © 2015 Elsevier B.V. All rights reserved. © 2015. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/ The following publication Fu, X., Guo, H., Wang, X., Ding, X., He, Q., Liu, T., & Zhang, Z. (2015). PM2. 5 acidity at a background site in the Pearl River Delta region in fall-winter of 2007–2012. Journal of Hazardous Materials, 286, 484-492. is available at https://doi.org/10.1016/j.jhazmat.2015.01.022. |
Appears in Collections: | Journal/Magazine Article |
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Acidity_Background.pdf | Pre-Published version | 1.4 MB | Adobe PDF | View/Open |
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