Heterogeneous SO2 Oxidation in Sulfate Formation by Photolysis of

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Heterogeneous SO Oxidation in Sulfate Formation by Photolysis of Particulate Nitrate Masao Gen, Ruifeng Zhang, Dandan Huang, Yongjie Li, and Chak Keung Chan Environ. Sci. Technol. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.estlett.8b00681 • Publication Date (Web): 04 Jan 2019 Downloaded from http://pubs.acs.org on January 5, 2019

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Environmental Science & Technology Letters

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Heterogeneous SO2 Oxidation in Sulfate Formation by Photolysis of

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Particulate Nitrate

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Masao Gen1, Ruifeng Zhang1, Dan Dan Huang2, Yongjie Li3, Chak K. Chan1,*

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1School

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Kowloon, Hong Kong, China

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2Shanghai

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3Department

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of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Academy of Environmental Sciences, Shanghai 200233, China of Civil and Environmental Engineering, Faculty of Science and Technology,

University of Macau, Macau 999078, China

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*Author

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Email: [email protected]

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Telephone: +(852)-3442-5593.

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Fax: +(852)-3442-0688.

to whom correspondence should be addressed.

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ACS Paragon Plus Environment


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Abstract

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Heterogeneous oxidation of sulfur dioxide (SO2) is suggested to be one of the most important

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pathways for sulfate formation during extreme haze events in China. Yet, the exact mechanism

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remains highly uncertain. We propose a much less explored pathway for aqueous-phase SO2

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oxidation to form particulate sulfate by NO2 and OH radicals produced from photolysis of

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particulate nitrate. Reactive uptake experiments of SO2 by ammonium nitrate particles under

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UV irradiation show the measured SO2 uptake coefficients of ~10-5. Model calculations of

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sulfate production rates, comparing known oxidation mechanisms by O3, NO2, H2O2, and

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transition metal ions, and the nitrate photolysis mechanism suggest that the nitrate photolysis

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pathway could contribute significantly to the overall sulfate production at pH = 4 to 6. The

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present study provides a new insight into the current debate on sulfate production pathways

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under typical haze conditions in China.

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Introduction

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Sulfate (SO42-) is one of the most important particulate inorganic components in the atmosphere.

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1,2

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nuclei.3,4 In addition, SO42- can alter physicochemical properties of aerosols in terms of

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hygroscopicity,5,6 acidity,7,8 and reactivity.9,10 Furthermore, SO42- is found to be a key

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composition in particulate matter (PM) during severe haze events in China.11–13 SO42- is

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dominantly produced from the oxidation of sulfur dioxide (SO2). SO2 can be oxidized in gas

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phase by OH radicals, and in aqueous phase by H2O2, O3,14 and transition metal ions (TMIs;

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Fe(III) and Mn(II)),15 which are all incorporated in traditional air quality models.16 However,

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such models fail to predict sulfate production in heavily polluted episodes in China,12,16,17

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suggesting missing sulfate production pathways. Incorporating heterogeneous oxidation of SO2

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on aerosols in air quality models can greatly improve the model predictions.16 Currently

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proposed heterogeneous pathways are the reactions of SO2 on mineral dust, sea salt, and soot

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particles.18–20 While a recent air quality modelling study found SO2 uptake coefficients on the

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order of 10-5 for the best match between the model prediction and the field measurements,16

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the detailed mechanisms in heterogeneous SO2 oxidation are still unknown.

It can directly impact on the solar radiative balance and indirectly as cloud condensation

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High particulate nitrate content in aqueous phase is common under typical haze

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conditions in China.21 Particulate nitrate concentration is particularly high (e.g. 1 to 10 µg/m3)

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near urban regions2,22 due to the anthropogenic release of NOx,23 at times accounting for 25%

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of the water-soluble particulate matter.2 During the haze episodes, the high sulfate production

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was coincident with the similar magnitude production of nitrate (~160 µg m-3 of nitrate) to the

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sulfate production.13 Under the ongoing debate on the missing sulfate production pathways, we

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hypothesize that particulate nitrate can undergo photolysis to generate NO2 and OH radicals in

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the aqueous phase24 for significant SO2 oxidation. Nitrate photolysis is of great interest for a

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major source of NOx, nitrous acid and OH,25,26 and the formation of aqueous secondary organic

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aerosols.27,28 Although sunlight is dimmed by ambient PM during haze events, it is not

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completely absent and could contribute to in-particle photochemistry29 including photolysis of

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particulate nitrate. Recently, Li et al. have proposed that particulate nitrite is a photolytic source

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of OH radicals for sulfate formation.30 However, to the best of our knowledge, nitrate

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photolysis has not been considered as a potential pathway for the heterogeneous SO2 oxidation.

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In this study, we propose that the NO2 and OH radicals produced from nitrate photolysis

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oxidize dissolved SO2, leading to sulfate formation. We experimentally study such a nitrate-

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photolysis pathway for SO2 oxidation (hereafter NO3- photolysis pathway). Heterogeneous

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oxidation of SO2 in deposited ammonium nitrate (AN) droplets was performed in a flow cell 3



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coupled with an in-situ Raman spectroscope under different RHs and particle pH conditions at

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250-nm irradiance. The in-situ Raman analysis provides a peak of sulfate at v(SO42-) mode as

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the reaction proceeds. Reactive uptake coefficients of SO2 for sulfate production in this

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proposed pathway are measured to be on the order of 10-5.

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Materials and Methods

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Aqueous stock solutions of sodium sulfite (>98%, Sigma-Aldrich), sodium nitrate (99.5%,

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Sigma-Aldrich), and ammonium nitrate (AN; 98.5%, Nacalai Tesque) are prepared by

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dissolving the corresponding salt in pure water. The stock solutions were atomized using a

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piezoelectric particle generator (Model 201, Uni-Photon Inc.) and its droplets were deposited

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on a hydrophobic fluorocarbon substrate (Model 5793, YSI Inc.).

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Figure S1 shows a schematic of experimental setup. Particles deposited on a substrate

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in the aerosol flow cell were observed using micro Raman spectroscopy (Text S1). The flow

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cell has two windows for Raman analysis (top) and UV illumination (bottom). It has been

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demonstrated to be useful for studying heterogeneous reactions of aerosols such as reactive

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uptake of ammonia, dimethylamine, and glyoxal.10,31 SO2 (7.7 ppm) in N2 or Air was

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introduced into the flow cell. The heterogeneous oxidation of SO2 was initiated by UV

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irradiation using a low-pressure mercury UV lamp (254 nm; Pen-Ray, UVP). A UV bandpass

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filter (250 ± 3 nm center, 11±3 nm FWHM; 10BPF10-250, Newport) was used to isolate 250

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nm from the UV lamp before the sample. The UV intensity after passing through the bandpass

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filter and the substrate was measured to be 0.11 × 1015 photons cm-2 s-1 using an optical power

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meter (1918-R, Newport) equipped with a detector (818-UV/DB, Newport).

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Results and discussion

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Heterogeneous SO2 oxidation during nitrate photolysis

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We first investigated the photolysis of particles containing nitrate and sulfite (1 to 1 molar

29

ratio) at 80% RH. The main conclusions of these experiments are that significant sulfate

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production was observed only in the presence of UV irradiation and air, suggesting the direct

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involvement of nitrate photolysis in sulfate production. A full discussion is presented in the

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Supporting Information (Text S2).

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Figure 1 shows the time evolution of normalized Raman spectra for the photolysis of

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AN particles in the presence of SO2 and oxygen (in air) at 80% RH, sulfate concentrations, 4


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[SO42-], under various conditions, and [SO42-] under various nitrate concentrations. Since the

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nitrate peak remained relatively constant with uptake time (less than 15% consumed at the end

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of the experiment, Figure S2), the Raman spectra was normalized to the nitrate peak to clearly

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display the trend of emerging sulfate peaks. Note that we normalized the peak area of sulfate

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to that of water to quantify [SO42-] (see Text S3 and Figure S3). A sulfate peak emerges as SO2

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uptake proceeds. The observed sulfate production is attributed to the oxidation of dissolved

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SO2 by both NO2 and OH radicals produced from nitrate photolysis. In the absence of oxygen

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(in N2), nitrate photolysis also shows sulfate production (Figure 1b), but the production rate is

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lower than that in the presence of oxygen. This suggests that even in the absence of oxygen

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when the OH-oxidation pathway is unlikely, aqueous-phase NO2 radicals can oxidize dissolved

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SO2 as proposed by earlier works.32,33 In the absence of UV illumination in air, no sulfate was

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produced.

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Furthermore, we examined the effect of the initial nitrate concentration on sulfate

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production rate (Figure 1c) by adding sodium chloride, which is not photoactive at 250 nm and

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does not alter nitrate absorption spectra34 in the stock solution, to produce droplets of different

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nitrate concentration, [NO3-], at 80% RH. Using the extended-aerosol inorganic model (E-

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AIM),35,36 the nitrate concentrations at 80% RH are estimated to be 6.7, 2.8, and 0.5 M at molar

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ratios of Cl-:NO3- = 0:1, 1:1, and 9:1, respectively. The sulfate production rate increases with

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increasing nitrate concentration, confirming the participation of nitrate in sulfate production.

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SO32- can be photo-oxidized when illuminated at 250 nm.37 However, in this study, the

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photooxidation of SO32- at 250 nm is not significant in the overall sulfate production observed

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because the sulfate production rate is sensitive to the [NO3-] (Figure 1c). If the photooxidation

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of SO32- is a main pathway in the sulfate production, we could not observe such [NO3-]

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dependence of sulfate production. The effect of UV light intensity on sulfate production rate is

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also ascertained in Figure S4, which shows a higher sulfate production rate at a light flux of

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2.4 × 1015 photons cm-2 s-1 than at 0.11 × 1015 photons cm-2 s-1 at 80% RH. These results confirm

27

that the SO2 oxidation in our experiments is driven by the photolysis of nitrate.

28

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Figure 1. Sulfate production during nitrate photolysis under various conditions and different

3

nitrate concentrations. (a) Time evolution of Raman spectra for photolysis of AN particles in

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the presence of SO2 at 80% RH, and (b) sulfate concentrations, [SO42-], as a function of

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uptake time in the presence of UV illumination in air and N2, and in the absence of UV

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illumination (dark) in air. Solid lines in (b) are the linear fitting to the data, which is used for

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estimating reactive uptake coefficients of SO2 for sulfate production (see Text S3). (c) [SO42-]

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as a function of uptake time at various nitrate concentrations in the presence of UV

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illumination in air. The nitrate concentrations varied from 6.7, 2.8, and 0.5 M at molar ratios

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of Cl-:NO3- = 0:1, 1:1, and 9:1, respectively, which were predicted by the E-AIM model.

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Uptake coefficients of SO2 as a function of RH have been used as input data in air

13

quality models to incorporate heterogeneous SO2 oxidation on aerosols.16,38 In this study, we

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calculated the reactive uptake coefficient of SO2 for sulfate production, 𝛾SO2, based on the

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earlier work by assuming that the loss rate of dissolved SO2 is equal to the sulfate production

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rate (Text S3).39 We then discuss the effects of RH and particle pH on 𝛾SO2, which are

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summarized in Table 1. To reduce the particle pH, a trace amount of nitric acid was added to

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the stock solutions of AN and the pH was predicted by the E-AIM model. Figure 2a shows that

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as RH decreases from 88% to 40%, 𝛾SO2 increases from 0.77×10-5 to 1.8×10-5. Decreasing RH

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results in an increase in nitrate concentration and a higher 𝛾SO2. The linear fitting yields

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𝛾SO2(RH)= −2.3×10-7 × %RH + 2.7×10-5. Earlier work reported that the direct oxidation of SO2

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by NO2 on oxalic acid aerosol has shown 𝛾SO2 of 8.3 ± 5.7 × 10−5.40 Furthermore, a 𝛾SO2 of the

6

order of 10-5 was found to yield predicted sulfate concentration that would be consistent during

7

haze events in China using the air quality model.16

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Figure 2b shows the effect of initial particle pH on 𝛾SO2. As sulfate is produced, the

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particle pH decreases and reduces the solubility of SO2. For instance, dissolved SO2

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concentration decreases by almost 6 orders of magnitude as the pH decreases from 6 to 0

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(Figure S5a). Hence, as the pH decreases, 𝛾SO2 is anticipated to decrease significantly if

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dissolution of SO2 is the only factor. Surprisingly, the measured 𝛾SO2 does not substantially

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drop as pH decreases from 4.4 to 0.9 (Table 1). At pH < 3, 𝛾SO2 is almost insensitive to the pH.

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We also calculated 𝛾SO2 as a function of pH at 80% RH by fitting model calculations of sulfate

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production rates (see Text S4) to experimentally determined 𝛾SO2 using the nitrate photolysis

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rate as a fitting parameter. The fitting of experimental 𝛾SO2 was limited to the data points at pH

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< 3 because 𝛾SO2 at pH > 3 in the model calculations was found to be very sensitive to the pH

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change. The fitted nitrate photolysis rate was 1.0 × 10-7 s-1. Our model calculations predict that

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the NO2 oxidation mechanism in the NO3- photolysis pathway gives at least 2 orders of

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magnitude smaller 𝛾SO2 than does the total NO3- photolysis (NO2 + OH) pathway over the pH

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range studied (Figure S5b). As shown in Eq. 6 in Text S4 and Table S1, the sulfate production

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rate in the model calculations is a function of the steady-state concentration of OH, [OH]SS,

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and the concentration of dissolved SO2 (mainly [HSO3-] at pH < 6). As mentioned earlier,

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[HSO3-] decreases by almost 6 orders of magnitude with decreasing pH from 6 to 0, whereas

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[OH]SS increases by almost 6 orders of magnitude (Figure S5a). Hence, under acidic conditions

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(i.e., pH < 3), the solubility of SO2 becomes very low compared to high pH conditions, but the

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[OH]SS can increase by the comparable orders of magnitude to offset the decrease in [HSO3-],

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resulting in a rather constant sulfate production rate.

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The model calculations can reproduce the experimentally determined 𝛾SO2 at pH < 3

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(Figure 2b) but it overestimates 𝛾SO2 at pH = 4.4. This overestimation may be due to the rapid

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decrease in particle pH during sulfate production. For instance, the E-AIM model predicts that

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the presence of 1-mM sulfate in the form of sulfuric acid in AN particles (6.66 M) at 80% RH

33

significantly reduces the particle pH from 4.4 to 2.5. In our Raman analysis, the sulfate peak is

7



1

discernible at [SO42-] > 10 mM after 180-min uptake of SO2. Hence, when the sulfate peak was

2

detected in Raman spectra, the particle pH may have already been reduced to as low as 3,

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yielding a smaller 𝛾SO2 than that predicted by the model calculation based on the initial pH

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estimated (4.4). In fact, the particle pH shifted from 4.6 to 3.8 after 180 min of SO2 uptake, as

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experimentally measured using the pH indicator paper (Figure S6).41 As shown in Figure 1b,

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[SO42-] increases linearly with uptake time, suggesting a constant apparent sulfate production

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rate, despite that pH decreases during sulfate production. Overall, the 𝛾SO2 was insensitive to

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pH at pH < 3 due to the competing effects of increasing [OH]SS and decreasing [HSO3-] as pH

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decreases.

10

11 12

Figure 2. Reactive uptake coefficients of SO2, 𝛾SO2, as functions of (a) RH and (b) pH at

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80% RH. Note that the pH in (a) decreases from 4.6 to 4.2 as RH decreases from 88 to 40%.

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The blue solid line in (a) is the linear fitting to the data; 𝛾SO2(RH)= −2.3×10-7×RH + 2.7×10-5.

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The red solid line is the model fitting to 𝛾SO2 as a function of pH using the average particle

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size of 25.2 µm in radius and the nitrate photolysis rate as a fitting parameter. The circular

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symbol indicates the experimentally determined pH shift to pH = 3.8 after 180 min of

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reaction. Error bars represent one standard deviation in the linear fitting of Raman spectral

2

analysis. Note that error bars in (b) are smaller than the symbols.

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Table 1. Reactive uptake coefficients of SO2, 𝛾SO2, under various RH and initial particle pH

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conditions. RH (%)

pHa

𝛾SO2

88

4.6

(7.7±0.38) × 10-6

4.4(3.8b)

(8.8±0.38) × 10-6

2.9

(4.7±0.28) × 10-6

1.9

(4.4±0.19) × 10-6

0.9

(3.9±0.18) × 10-6

60

4.2

(1.4±0.16) × 10-5

40

4.2

(1.8±0.33) × 10-5

80

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a) The initial pH was predicted by the E-AIM model. Note that the pH is expected to decrease

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during sulfate production.

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b) Experimentally determined pH after 180-min uptake time.

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Atmospheric Implications

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In this study, we used UV irradiation at 250 nm to initiate nitrate photolysis and estimated a

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photolysis rate of 1.0 × 10-7 s-1 based on the model fitting of 𝛾SO2 as a function of pH (Figure

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2b). This rate is very close to the reported values (1.23 × 10-7 s-1) obtained from the photolysis

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of nitrate under atmospherically relevant irradiation (𝜆 > 290 nm).42 At 𝜆 > 280 nm, nitrate

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photolysis necessarily produces NO2 and OH as well as nitrite and atomic oxygen (O(3P)).24,43

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Nitrite photolysis further generates OH radicals, and the reaction of O(3P) with dissolved

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oxygen produces O3.24,44 Hence, the nitrate photolysis at 𝜆 > 280 nm could produce more OH

25

radicals and O3 available for SO2 oxidation. We performed additional experiments using

9



1

identical experimental setup with the current study except the wavelength for nitrate photolysis

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(300-nm LED lamp, M300L4, Thorlabs). To achieve a comparable nitrate photolysis rate to

3

the 250-nm nitrate photolysis, about 9 times higher light intensity of 1.20 × 1015 photons cm-2

4

s-1 at 300 nm was used to compensate for the difference of the quantum yield for OH production

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at 250 nm (~9%) and 300 nm (~1%).45 Figure S7 shows Raman spectra of ammonium nitrate

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at 80% RH in air during the 300-nm photolysis in the presence of SO2, the sulfate production

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rates under various conditions, and the effect of the light intensity on the sulfate production

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rates. The Raman spectra clearly presents the increasing sulfate peak as well as the decreasing

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nitrate peak as the reactions proceed. The sulfate production is observed only when both 300-

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nm irradiation and SO2 are present. The sulfate production rate at 300-nm nitrate photolysis is

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about 3 times higher than that at 250-nm nitrate photolysis. Furthermore, the sulfate production

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rates are found to be sensitive to the light intensity. Further experiments at 300-nm nitrate

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photolysis are undergoing in our laboratory to study this NO3- photolysis pathway under more

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atmospherically relevant conditions.

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We estimate the sulfate production rates of the NO3- photolysis pathways as well as the

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prevailing pathways: i.e., aqueous-phase SO2 oxidation by O3, NO2, H2O2, and TMIs under

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atmospherically relevant conditions (Text S4).14 We consider the characteristic conditions

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during the haze in China.46 The haze day characteristics have weaker radiation due to the direct

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radiative effects of aerosol particles (the aerosol dimming effect) and higher RH than the clean

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day conditions do.13 In the calculations of sulfate production rates from NO3- photolysis

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pathway, the nitrate photolysis rate under the haze conditions was estimated to be 2.96 × 10-9

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s-1 (Text S4) which is two orders of magnitude smaller than the atmospherically relevant nitrate

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photolysis rate (1.23 × 10-7 s-1).42

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Figure 3 shows sulfate production rates from different pathways including NO3-

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photolysis pathway under characteristic conditions. Among each pathway, the O3 pathway

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generally has the least effect on the overall sulfate production at pH < 5 due to its low

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concentration (1 ppb). At pH < 5, the TMI pathway dominates over the other pathways, but it

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competes with the NO3- photolysis, H2O2, and NO2 pathways at pH > 5. The sulfate production

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from the NO3- photolysis pathway at [NO3-] = 10 M is the highest at pH > 4.4 among all the

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other pathways except the TMI pathway, whereas it is higher than the NO2 pathway, and at

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least 1 order of magnitude smaller than the H2O2 pathways at pH < 4. In summary, at pH > 5,

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NO3- photolysis pathway is competitive over the other pathways, whereas its competitiveness

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depends on [NO3-] at pH < 5.

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Figure 3. Comparison of aqueous phase SO2 oxidation pathways under haze characteristic

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conditions. Shaded areas indicate sulfate production rates from the proposed nitrate

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photolysis pathway (NO3- pathway) at various nitrate concentrations, [NO3-]. Conditions

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assumed are adopted from Cheng et al.46; [SO2] = 40 ppb; [NO2] = 66 ppb; [H2O2] = 0.01

6

ppb; [O3] = 1 ppb; [Fe(III)] and [Mn(II)] as a function of pH are taken from Cheng et al.46;

7

particle radius = 0.15 µm; nitrate photolysis rate = 2.96 × 10-9 s-1; [NO3-] = 0.1 to 10 M. Note

8

that the reaction of gas phase NO2 with H2O to form NO3- is not considered.

9 10 11

Recently, an important question under debate on the haze events in China is the particle

12

acidity.40,47–50 Sulfate production rates are highly dependent on the pH (Figure 3). A threshold

13

of pH value of 5 determines the major contributor to the sulfate production: conventionally the

14

NO2 pathway (red, Figure 3b) dominates at pH > 5, whereas the TMI pathway (green, Figure

15

3b) does so at pH < 5. At either pH range, the NO3- photolysis pathway could significantly

16

contribute to the overall sulfate production if [NO3-] is sufficiently high (i.e., > 1 M). In fact,

17

the observation of high sulfate concentrations during the Beijing haze event was coincident

18

with high concentrations of nitrate in comparable magnitude (~160 µg m-3).13 Hence, [NO3-]

19

in ambient PM during the haze may be potentially as high as 1 M to initiate the efficient NO3-

20

photolysis for SO2 oxidation.

21

Lastly, OH radicals can react with a broad range of organic compounds either in the

22

particle phase, in the gas phase after evaporation,51 or at the particle-air interface.52–54

23

Dissolved SO2 and organic compounds compete for the OH radicals produced from photolysis

11



1

of particulate nitrate. The role of nitrate photolysis in aqueous SOA formation, especially in

2

the presence of SO2, needs to be investigated.

3 4 5

Acknowledgements

6

Support from the National Natural Science Foundation of China (41675120, 41875142) and

7

the Science and Technology Development Fund of Macau (136/2016/A3) are gratefully

8

acknowledged.

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References

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

(12) (13)

Chan, C. K.; Yao, X. Air Pollution in Mega Cities in China. Atmos. Environ. 2008, 42 (1), 1–42. Yao, X.; Chan, C. K.; Fang, M.; Cadle, S.; Chan, T.; Mulawa, P.; He, K.; Ye, B. The Water-Soluble Ionic Composition of PM2.5 in Shanghai and Beijing, China. Atmos. Environ. 2002, 36 (26), 4223–4234. Tsigaridis, K.; Kanakidou, M. The Present and Future of Secondary Organic Aerosol Direct Forcing on Climate. Curr. Clim. Chang. Reports 2018, 4 (2), 84–98. Pillar-Little, A. E.; Guzman, I. M. An Overview of Dynamic Heterogeneous Oxidations in the Troposphere. Environments 2018, 5 (9), 104. Choi, M. Y.; Chan, C. K. The Effects of Organic Species on the Hygroscopic Behaviors of Inorganic Aerosols. Environ. Sci. Technol. 2002, 36 (11), 2422–2428. Chan, M. N.; Chan, C. K. Hygroscopic Properties of Two Model Humic-like Substances and Their Mixtures with Inorganics of Atmospheric Importance. Environ. Sci. Technol. 2003, 37 (22), 5109–5115. Cao, J.; Tie, X.; Dabberdt, W. F.; Jie, T.; Zhao, Z.; An, Z.; Shen, Z.; Feng, Y. On the Potential High Acid Deposition in Northeastern China. J. Geophys. Res. Atmos. 2013, 118 (10), 4834–4846. Pathak, R. K.; Yao, X.; Lau, A. K. H.; Chan, C. K. Acidity and Concentrations of Ionic Species of PM2.5 in Hong Kong. Atmos. Environ. 2003, 37 (8), 1113–1124. Lee, A. K. Y.; Zhao, R.; Li, R.; Liggio, J.; Li, S. M.; Abbatt, J. P. D. Formation of light Absorbing Organo-nitrogen Species from Evaporation of Droplets Containing Glyoxal and Ammonium Sulfate. Environ. Sci. Technol. 2013, 47 (22), 12819–12826. Gen, M.; Huang, D. D.; Chan, C. K. Reactive Uptake of Glyoxal by AmmoniumContaining Salt Particles as a Function of Relative Humidity. Environ. Sci. Technol. 2018, 52 (12), 6903–6911. Huang, R. J.; Zhang, Y.; Bozzetti, C.; Ho, K. F.; Cao, J. J.; Han, Y.; Daellenbach, K. R.; Slowik, J. G.; Platt, S. M.; Canonaco, F. et al. High Secondary Aerosol Contribution to Particulate Pollution During Haze Events in China. Nature 2015, 514 (7521), 218–222. Guo, S.; Hu, M.; Zamora, M. L.; Peng, J.; Shang, D.; Zheng, J.; Du, Z.; Wu, Z.; Shao, M.; Zeng, L. et al. Elucidating Severe Urban Haze Formation in China. Proc. Natl. Acad. Sci. 2014, 111 (49), 17373–17378. Zheng, G. J.; Duan, F. K.; Su, H.; Ma, Y. L.; Cheng, Y.; Zheng, B.; Zhang, Q.; Huang, T.; Kimoto, T.; Chang, D. et al. Exploring the Severe Winter Haze in Beijing: The 12


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(17)

(18) (19) (20) (21)

(22) (23) (24) (25) (26) (27)

(28) (29) (30)

Impact of Synoptic Weather, Regional Transport and Heterogeneous Reactions. Atmos. Chem. Phys. 2015, 15 (6), 2969–2983. Seinfeld, J. H.; Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change; Wiley: New York, 2006. Ibusuki, T.; Takeuchi, K. Sulfur Dioxide Oxidation by Oxygen Catalyzed by Mixtures of Manganese(II) and Iron(III) in Aqueous Solutions at Environmental Reaction Conditions. Atmos. Environ. 1987, 21 (7), 1555–1560. Zheng, B.; Zhang, Q.; Zhang, Y.; He, K. B.; Wang, K.; Zheng, G. J.; Duan, F. K.; Ma, Y. L.; Kimoto, T. Heterogeneous Chemistry: A Mechanism Missing in Current Models to Explain Secondary Inorganic Aerosol Formation During the January 2013 Haze Episode in North China. Atmos. Chem. Phys. 2015, 15 (4), 2031–2049. Wang, J.; Wang, S.; Jiang, J.; Ding, A.; Zheng, M.; Zhao, B.; Wong, D. C.; Zhou, W.; Zheng, G.; Wang, L. et al. Impact of Aerosol-meteorology Interactions on Fine Particle Pollution During China’s Severe Haze Episode in January 2013. Environ. Res. Lett. 2014, 9 (9), 094002. Laskin, A.; Gaspar, D. J.; Wang, W.; Hunt, S. W.; Cowin, J. P.; Colson, S. D.; Finlayson-Pitts, B. J. Reactions at Interfaces as a Source of Sulfate Formation in Seasalt Particles. Science 2003, 301 (5631), 340–344. Usher, C. R.; Michel, A. E.; Grassian, V. H. Reactions on Mineral Dust. Chem. Rev. 2003, 103 (12), 4883–4940. Zhao, Y.; Liu, Y.; Ma, J.; Ma, Q.; He, H. Heterogeneous Reaction of SO2 with Soot: The Roles of Relative Humidity and Surface Composition of Soot in Surface Sulfate Formation. Atmos. Environ. 2017, 152, 465–476. Liu, Y.; Wu, Z.; Wang, Y.; Xiao, Y.; Gu, F.; Zheng, J.; Tan, T.; Shang, D.; Wu, Y.; Zeng, L. et al. Submicrometer Particles Are in the Liquid State During Heavy Haze Episodes in the Urban Atmosphere of Beijing, China. Environ. Sci. Technol. Lett. 2017, 4 (10), 427–432. Wang, Z.; Zhang, D.; Liu, B.; Li, Y.; Chen, T.; Sun, F.; Yang, D.; Liang, Y.; Chang, M.; Yang, L. et al. Analysis of Chemical Characteristics of PM2.5 in Beijing over a 1year Period. J. Atmos. Chem. 2016, 73 (4), 407–425. Handley, S. R.; Clifford, D.; Donaldson, D. J. Photochemical Loss of Nitric Acid on Organic Films: A Possible Recycling Mechanism for NOX. Environ. Sci. Technol. 2007, 41 (11), 3898–3903. Mack, J.; Bolton, J. R. Photochemistry of Nitrite And Nitrate in Aqueous Solution: A Review. J. Photochem. Photobiol. A Chem. 1999, 128 (1–3), 1–13. McFall, A. S.; Edwards, K. C.; Anastasio, C. Nitrate Photochemistry at the Air-ice Interface and in Other Ice Reservoirs. Environ. Sci. Technol. 2018, 52 (10), 5710– 5717. Bao, F.; Li, M.; Zhang, Y.; Chen, C.; Zhao, J. Photochemical Aging of Beijing Urban PM2.5: HONO Production. Environ. Sci. Technol. 2018, 52 (11), 6309–6316. Huang, D. D.; Zhang, Q.; Cheung, H. H. Y.; Yu, L.; Zhou, S.; Anastasio, C.; Smith, J. D.; Chan, C. K. Formation and Evolution of aqSOA from Aqueous-phase Reactions of Phenolic Carbonyls: Comparison Between Ammonium Sulfate and Ammonium Nitrate Solutions. Environ. Sci. Technol. 2018, 52 (16), 9215–9224. Minero, C.; Bono, F.; Rubertelli, F.; Pavino, D.; Maurino, V.; Pelizzetti, E.; Vione, D. On the Effect of pH in Aromatic Photonitration upon Nitrate Photolysis. Chemosphere 2007, 66 (4), 650–656. Xia, S. S.; Eugene, A. J.; Guzman, M. I. Cross Photoreaction of Glyoxylic and Pyruvic Acids in Model Aqueous Aerosol. J. Phys. Chem. A 2018, 122 (31), 6457–6466. Li, L.; Hoffmann, M. R.; Colussi, A. J. Role of Nitrogen Dioxide in the Production of

13



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

(31) (32) (33) (34) (35) (36) (37) (38)

(39) (40) (41)

(42)

(43) (44) (45) (46)

Sulfate During Chinese Haze-aerosol Episodes. Environ. Sci. Technol. 2018, 52 (5), 2686–2693. Sauerwein, M.; Chan, C. K. Heterogeneous Uptake of Ammonia and Dimethylamine into Sulfuric and Oxalic Acid Particles. Atmos. Chem. Phys. 2017, 17 (10), 6323– 6339. Lee, Y. N.; Schwartz, S. E. Kinetics of Oxidation of Aqueous Sulfur (IV) by Nitrogen Dioxide. In Precipitation Scavenging, Dry Deposition and Resuspension; Elsevier New York, 1983; Vol. 1, pp 453–470. Clifton, C. L.; Altstein, N.; Huie, R. E. Rate Constant for the Reaction of Nitrogen Dioxide with Sulfur(IV) over the pH Range 5.3-13. Environ. Sci. Technol. 1988, 22 (5), 586–589. Wingen, L. M.; Moskun, A. C.; Johnson, S. N.; Thomas, J. L.; Roeselová, M.; Tobias, D. J.; Kleinman, M. T.; Finlayson-Pitts, B. J. Enhanced Surface Photochemistry in Chloride-nitrate Ion Mixtures. Phys. Chem. Chem. Phys. 2008, 10 (37), 5668–5677. Clegg, S. L.; Brimblecombe, P.; Wexler, A. S. Thermodynamic Model of the System H+–NH4+–SO42-–NO3-–H2O at Tropospheric Temperatures. J. Phys. Chem. A 1998, 102 (12), 2137–2154. Clegg, S. L.; Brimblecombe, P.; Wexler, A. S. Thermodynamic Model of the System H+–NH4+–Na+–SO42-–NO3-–Cl-–H2O at 298.15 K. J. Phys. Chem. A 1998, 102 (12), 2155–2171. Deister, U.; Warneck, P. Photooxidation of Sulfite (SO32-) in Aqueous Solution. J. Phys. Chem. 1990, 94 (5), 2191–2198. Wang, Y.; Zhang, Q.; Jiang, J.; Zhou, W.; Wang, B.; He, K.; Duan, F.; Zhang, Q.; Philip, S.; Xie, Y. Enhanced Sulfate Formation During China’s Severe Winter Haze Episode in January 2013 Missing from Current Models. J. Geophys. Res. Atmos. 2014, 119 (17), 10425–10440. Zhao, D.; Song, X.; Zhu, T.; Zhang, Z.; Liu, Y.; Shang, J. Multiphase Oxidation of SO2 by NO2 on CaCO3 Particles. Atmos. Chem. Phys. 2018, 18 (4), 2481–2493. Wang, G.; Zhang, R.; Gomez, M. E.; Yang, L.; Zamora, M. L.; Hu, M.; Lin, Y.; Peng, J.; Guo, S.; Meng, J. et al. Persistent Sulfate Formation from London Fog to Chinese Haze. Proc. Natl. Acad. Sci. 2016, 113 (48), 13630–13635. Craig, R. L.; Peterson, P. K.; Nandy, L.; Lei, Z.; Hossain, M. A.; Camarena, S.; Dodson, R. A.; Cook, R. D.; Dutcher, C. S.; Ault, A. P. Direct Determination of Aerosol pH: Size-resolved Measurements of Submicrometer and supermicrometer Aqueous Particles. Anal. Chem. 2018, 90 (19), 11232–11239. Bianco, A.; Passananti, M.; Perroux, H.; Voyard, G.; Mouchel-Vallon, C.; Chaumerliac, N.; Mailhot, G.; Deguillaume, L.; Brigante, M. A Better Understanding of Hydroxyl Radical Photochemical Sources in Cloud Waters Collected at the Puy de Dôme Station - Experimental Versus Modelled Formation Rates. Atmos. Chem. Phys. 2015, 15 (16), 9191–9202. Herrmann, H. On the Photolysis of Simple Anions and Neutral Molecules as Sources of O-/OH, SOx- and Cl in Aqueous Solution. Phys. Chem. Chem. Phys. 2007, 9 (30), 3935–3964. Goldstein, S.; Rabani, J. Mechanism of Nitrite Formation by Nitrate Photolysis in Aqueous Solutions: The Role of Peroxynitrite, Nitrogen Dioxide, and Hydroxyl Radical. J. Am. Chem. Soc. 2007, 129 (34), 10597–10601. Mark, G.; Korth, H. G.; Schuchmann, H. P.; Von Sonntag, C. The Photochemistry of Aqueous Nitrate Ion Revisited. J. Photochem. Photobiol. A Chem. 1996, 101 (2–3), 89–103. Cheng, Y.; Zheng, G.; Wei, C.; Mu, Q.; Zheng, B.; Wang, Z.; Gao, M.; Zhang, Q.; He,

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Page 14 of 15

Page 15 of 15

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32


(47)

(48) (49) (50) (51) (52) (53) (54)

K.; Carmichael, G. et al. Reactive Nitrogen Chemistry in Aerosol Water as a Source of Sulfate During Haze Events in China. Sci. Adv. 2016, 2 (12), e1601530. Wang, G.; Zhang, F.; Peng, J.; Duan, L.; Ji, Y.; Marrero-Ortiz, W.; Wang, J.; Li, J.; Wu, C.; Cao, C. et al. Particle Acidity and Sulfate Production During Severe Haze Events in China Cannot Be Reliably Inferred by Assuming a Mixture of Inorganic Salts. Atmos. Chem. Phys. 2018, 18 (14), 10123–10132. Guo, H.; Weber, R. J.; Nenes, A. High Levels of Ammonia Do Not Raise Fine Particle pH Sufficiently to Yield Nitrogen Oxide-dominated Sulfate Production. Sci. Rep. 2017, 7 (1), 12109. Song, S.; Gao, M.; Xu, W.; Shao, J.; Shi, G.; Wang, S.; Wang, Y.; Sun, Y.; McElroy, M. B. Fine-particle pH for Beijing Winter Haze as Inferred from Different Thermodynamic Equilibrium Models. Atmos. Chem. Phys. 2018, 18 (10), 7423–7438. Liu, M.; Song, Y.; Zhou, T.; Xu, Z.; Yan, C.; Zheng, M.; Wu, Z.; Hu, M.; Wu, Y.; Zhu, T. Fine Particle pH During Severe Haze Episodes in Northern China. Geophys. Res. Lett. 2017, 44 (10), 5213–5221. Herrmann, H.; Hoffmann, D.; Schaefer, T.; Bräuer, P.; Tilgner, A. Tropospheric Aqueous-phase Free-radical Chemistry: Radical Sources, Spectra, Reaction Kinetics and Prediction Tools. ChemPhysChem 2010, 11 (18), 3796–3822. Pillar, E. A.; Guzman, M. I. Oxidation of Substituted Catechols at the Air-water Interface: Production of Carboxylic Acids, Quinones, and Polyphenols. Environ. Sci. Technol. 2017, 51 (9), 4951–4959. Pillar, E. A.; Zhou, R.; Guzman, M. I. Heterogeneous Oxidation of Catechol. J. Phys. Chem. A 2015, 119 (41), 10349–10359. Pillar, E. A.; Camm, R. C.; Guzman, M. I. Catechol Oxidation by Ozone and Hydroxyl Radicals at the Air-water Interface. Environ. Sci. Technol. 2014, 48 (24), 14352– 14360.

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Heterogeneous SO2 Oxidation in Sulfate Formation by Photolysis of

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