Organic Peroxides and Sulfur Dioxide in Aerosol - ACS Publications

Subscriber access provided by Nottingham Trent University

Environmental Processes

Organic Peroxides and Sulfur Dioxide in Aerosol: Source of Particulate Sulfate Shunyao Wang, Shouming Zhou, Ye Tao, William Gang Tsui, Jianhuai Ye, Jian Zhen Yu, Jennifer Grace Murphy, V. Faye McNeill, Jonathan Abbatt, and Arthur W. H. Chan Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.9b02591 • Publication Date (Web): 16 Aug 2019 Downloaded from pubs.acs.org on August 17, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30

Environmental Science & Technology

1

Organic Peroxides and Sulfur Dioxide in Aerosol: Source of Particulate Sulfate 2 3 4

Shunyao Wang1, Shouming Zhou2, Ye Tao3, William G. Tsui4, Jianhuai Ye1,5

5

Jian Zhen Yu6, Jennifer G. Murphy2, V. Faye McNeill4, Jonathan P.D. Abbatt2 and Arthur W.H. Chan1*

6 7 8 1

9

Department of Chemical Engineering and Applied Chemistry, University of Toronto,

10

Toronto, Ontario, M5S 3E5, Canada

11

2

Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada

12

3

Department of Physical and Environmental Sciences, University of Toronto Scarborough,

13

Toronto, Ontario, M1C 1A4, Canada 4

14 15

New York, New York, 10027, United States 5

16 17 18

Department of Chemical Engineering, University of Columbia,

School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, 02138, United States

6

Department of Chemistry, Hong Kong University of Science and Technology, Hong Kong, China

19 20 21 22

*Correspondence to: Arthur W.H. Chan ([email protected])

1 ACS Paragon Plus Environment


23

Abstract

24

Sulfur oxides (SOx) are important atmospheric trace species in both gas and particulate phases,

25

and sulfate is a major component of atmospheric aerosol. One potentially important source of

26

particulate sulfate formation is the oxidation of dissolved SO2 by organic peroxides, which

27

comprise a major fraction of secondary organic aerosol (SOA). In this study, we investigated the

28

reaction kinetics and mechanisms between SO2 and condensed-phase peroxides. pH-dependent

29

aqueous phase reaction rate constants between S(IV) and organic peroxide standards were

30

measured. Highly oxygenated organic peroxides with O/C>0.6 in α-pinene SOA react rapidly

31

with S(IV) species in aqueous phase. The reactions between organic peroxides and S(IV) yield

32

both inorganic sulfate and organosulfates (OS), as observed by electrospray ionization ion

33

mobility mass spectrometry. For the first time, 34S labeling experiments in this study revealed

34

dissolved SO2 forms OS via direct reactions without forming inorganic sulfate as a reactive

35

intermediate. Kinetics of OS formation was estimated semi-quantitatively and such reaction was

36

found to account for 30-60% of sulfur reacted. The photochemical box model GAMMA was

37

applied to assess the implications of the measured SO2 consumption and OS formation rates. Our

38

findings indicate that this novel pathway of SO2-peroxide reaction is important for sulfate

39

formation in submicron aerosols.

40 41 42 43 44 45


Page 2 of 30

Page 3 of 30


46

Introduction

47

Sulfate in the troposphere is important for atmospheric new particle formation, particle growth,

48

climate change and public health.1-4 While oxidation of sulfur has been studied extensively, the

49

formation pathways of sulfate in submicron aerosol remain poorly understood, as highlighted by

50

the underestimation in sulfate by atmospheric models.5-7 In particular, during heavy haze events

51

when particulate matter (PM) levels were high, less than 50% of the observed sulfate can be

52

simulated using known mechanisms, and additional SO2 reactive uptake pathways are needed to

53

improve the model performance.6 In the gas phase, one of the dominant oxidizers of SO2 is the

54

hydroxyl radical (·OH) but stabilized Criegee Intermediates (sCIs) have recently been found to

55

oxidize SO2 at appreciable rates.8,9 It is also known that hydrogen peroxide (H2O2), ozone (O3),

56

nitrogen dioxide (NO2) and oxygen (O2) catalyzed by transition metals (TMIs) are oxidizers for

57

SO2 in cloud and fog droplets.10 Recent studies showed that, depending on pH, reactions with

58

NO2 and TMI are dominant sources of sulfate in ground-level PM.11-13 However, mechanisms by

59

which SO2 heterogeneously interacts with organic aerosol remain poorly understood.

60

In submicron aerosol, a large fraction is comprised of secondary organic aerosol (SOA), formed

61

from atmospheric oxidation of biogenic and anthropogenic volatile organic compounds

62

(VOCs).14 One major component in SOA is organic peroxides, which can form directly from

63

atmospheric oxidation initiated by ·OH or O3, and further autoxidation of radical products.15-20

64

Surratt et al.21 reported that peroxides contribute significantly (61% by mass) to isoprene SOA

65

via reactions between RO2 and HO2 radicals under low-NOx conditions. Large fractions of

66

organic peroxide in monoterpene SOA systems (20%-60%) have been reported in various

67

laboratory studies.16, 17 Organic peroxides can also account for 30% of SOA generated from

68

polycyclic aromatic hydrocarbons under both low- and high-NOx conditions.22 These organic



69

peroxides are highly reactive with short lifetimes in the atmosphere.17, 23 A synergistic decay of

70

SO2 and particulate peroxide content was observed in a previous chamber study under high

71

relative humidity,24 which may explain the significant reactive uptake of SO2 onto submicron

72

aerosol in polluted areas with high SO2 levels.

73

Interactions between reactive organics and sulfur-containing species lead to the formation of

74

organosulfates (OS). OS formation can enhance SOA yields, change acidity, hygroscopicity and

75

light scattering/absorbing properties of particles.4, 14, 25-29 Different types of OS have been

76

observed in numerous laboratory and field studies, accounting for up to 30% of organic mass.25-

77

32

78

unknown formation mechanisms. Many studies have proposed formation pathways of OS. One

79

of the earliest mechanisms proposed is esterification between inorganic sulfate and alcohols, but

80

the measured kinetics are too slow to be atmospherically relevant.33, 34 Organic nitrates can be

81

precursors for OS via nucleophilic substitution,35 which may be potentially important for urban

82

areas during nighttime. Reactive uptake of epoxides onto condensed phase sulfate was found to

83

form OS via ring-opening mechanisms.36, 37 OS may also be formed from reactions between

84

sulfate radical species and organics under light conditions in condensed phase.38-40 All of these

85

reactions require the formation of inorganic S(VI) species prior to reaction with reactive organic

86

intermediates. Organosulfur species have been found to form directly from SO2 and C=C/C=O

87

double bonds,40-43 which can be further catalyzed by transition metal ions,44, 45 highlighting the

88

potential for SO2 to directly form OS in the atmosphere.

89

In previous work,46 aqueous phase reaction rates between small organic peroxides and S(IV)

90

were found to be comparable to that of H2O2 via the nucleophilic displacement and acid-

91

catalyzed rearrangement mechanism, but very little is known about the kinetics for larger organic

However, the quantification of OS still remains a challenge due to the lack of standards and


Page 4 of 30

Page 5 of 30


92

peroxides. Given the ubiquity of organic peroxides, and their significant reactivity towards SO2

93

in submicron aerosol, there remains a critical research gap in comprehending the reaction

94

kinetics and mechanisms in order to assess the atmospheric relevance of such interactions. We

95

hypothesize that large (>C4) organic peroxides react with SO2 at appreciable rates to form both

96

inorganic and organic sulfates in the condensed phase. The main objectives of this study are

97

therefore to: (1) investigate the kinetics of the reaction between S(IV) and organic peroxides in

98

the bulk aqueous phase; (2) elucidate mechanisms of OS formation and (3) assess the importance

99

of the measured kinetics in suspended aerosol phase by photochemical box modeling.

100

Experimental Section

101

Experiments conducted in this study are listed in Table S1. SOA formation and collection are

102

described in supporting information. The reactions between S(IV) species and organic

103

compounds (commercial peroxides or SOA) are investigated in bulk phase solution either by

104

bubbling SO2 or by reacting with sulfite salts (NaHSO3 or (NH4)2SO3).

105

Speciation of Organic Peroxides

106

In Exp.1-2, a high performance liquid chromatography (HPLC, Thermo Scientific Ultimate 3000)

107

coupled with atmospheric pressure chemical ionization-tandem mass spectrometer (APCI-

108

MS/MS, unit resolution, Thermo TSQ Endura) operated in positive mode was used for organic

109

hydroperoxide (ROOH) measurement.47 With the addition of NH4+, ROOH can form ion adduct

110

[ROOH-NH4]+, and characteristically lose NH3- H2O2 (51 Da) upon a 2 V collision energy with

111

0.5 mTorr Ar as collision gas, when observed using tandem mass spectrometry. The first and

112

third quadrupoles scan with a difference of -51 Da to specifically monitor ROOH so that peaks

113

presented in the mass spectra represent ROOH only (Fig.1a).



114

In Exp.1, cumene peroxide (80%, Sigma Aldrich) and sodium bisulfite (ACS reagent, Sigma

115

Aldrich) were dissolved in deionized water at concentrations of 7 μM and 70 μM, respectively,

116

which are similar to the concentrations used by Lind et al. 46 Solid phase extraction (SPE,

117

Supelclean™- ENVI-18 SPE Tube) was applied to remove the inorganic solute and quench the

118

reaction. The mixture was then injected into the HPLC-APCI-MS/MS for analysis under selected

119

ion mode. Fig. S1 shows the calibration curve for this method. In Exp.2, -pinene SOA and

120

ammonium acetate (for mass spectrometry, ≥99.0%, Sigma Aldrich) was dissolved in deionized

121

water with concentrations of 10 mM (assuming an averaged molecular mass of 200) and 12 mM,

122

respectively. Excess sodium bisulfite (1 M) was then added and placed under ambient for 30

123

minutes before processing via SPE. SOA solution with and without sodium bisulfite were

124

directly injected into the APCI-MS/MS at 10 µL min-1 by a syringe pump (Model Fusion 101,

125

Chemyx Inc., USA). While decomposition of ROOH has been shown by previous studies23, we

126

confirm that reaction with S(IV) is more likely to cause the signal reduction observed by APCI-

127

MS/MS as described in Fig. S3. Other details of the analytical method are described in

128

supporting information (S 1.2 and 1.3).

129

Measurement of Reaction Rate Constants

130

The reaction rates between commercially available organic peroxides and S(IV) in the bulk

131

phase (Exp. 3-5) were measured in a sealed IC sample tube (12 mL, for Metrohm-Peak IC

132

Autosampler, Cole-Parmer). Kinetics were quantified by reacting excess amount of organic

133

peroxides with NaHSO3, and both S(IV) and S(VI) were measured using ion chromatography (IC;

134

881 compact pro-anion, Metrohm, Switzerland). Details of IC analysis can be found in S1.4.

135

After confirming the stability of organic peroxide under acidic conditions (Fig. S5) using the

136

iodometric method,16 reaction rates between bisulfite and cumene hydroperoxide, tert-butyl


Page 6 of 30

Page 7 of 30


137

hydroperoxide (80%, Sigma Aldrich), 2-butanone peroxide (40%, Sigma Aldrich) were

138

measured across a range of initial pHs (4-6.5). The initial concentration of bisulfite was 6 µM for

139

all the experiments and the concentration of organic peroxide was in excess (at least 10 times

140

higher) such that pseudo first-order reaction kinetics can be assumed during each measurement.

141

In all cases, at least 50% of the bisulfite was consumed at the end of each kinetic measurement.

142

Concentrations of sulfite ion at four time points (2, 6, 18, 22 min) were recorded with minimum

143

of three replicates for each initial pH. A typical example of IC kinetic measurement is shown in

144

Fig. S6. The pH was adjusted by adding different amounts of HCl (37%, Sigma Aldrich) and was

145

measured before and after each reaction, with error bars denoted as the range of pH measured

146

(Fig. 2). It should be noted that as the reaction proceeds, sulfuric acid is produced and decreases

147

the pH, which in turn increases the reaction rate. When the initial pH was below 4, the reaction

148

became too fast to be measured. The IC sample tube was sealed to minimize the loss of bisulfite

149

due to reaction with dissolved oxygen or degassing of SO2. Calibration curves for sulfur species

150

can be found in Fig. S7. All the experiments were conducted under room temperature (298 ± 5 K)

151

and atmospheric pressure.

152

Analysis of Organosulfates

153

To analyze the products from reactions between SO2 and organic peroxides, gaseous SO2 (5.0

154

ppm, in N2, Linde, CA) was bubbled into organic peroxide solution (3mM in 50% MeOH)

155

continuously for 1 hour at 0.02 L min-1 (Exp. 6-8). As a control experiment, pure N2 was bubbled

156

into organic peroxide solutions at the same flow rate. The initial concentration of organic

157

peroxide was at least 10 times higher than that of the dissolved SO2 assuming all the bubbled

158

SO2 was completely dissolved. Normalized consumption of different organic peroxides after SO2

159

bubbling illustrated by the iodometric assay16 is shown in Fig. S9. Tert-butyl hydroperoxide,



160

benzoyl peroxide (≥98%, Sigma-Aldrich) and tert-butyl peroxybenzoate (98%, Sigma Aldrich)

161

were chosen to represent ROOH and ROOR type of organic peroxides. The solution was

162

delivered by a syringe pump (Legato100, KDS) at a flow rate of 2 μL min-1 to electrospray-ion

163

mobility-time of flight-mass spectrometry (ESI-IMS-ToF MS, TOFWERK, Switzerland,

164

hereafter referred to as IMS) immediately after the bubbling experiment. Details of IMS analysis

165

and data processing are described in S1.5 and previous work.48 Collision induced dissociation

166

(CID) was performed to confirm the organic sulfate moiety. As shown in Fig. S10 and S11, both

167

synthetic α-pinene OS standard49 and OS formed from tert-butyl hydroperoxide showed

168

dissociation from the parent ion to the sulfate ion (m/z 97). No sulfate fragment ion was observed

169

with IMS from benzoyl organosulfate, likely due to the stability of the benzoate ion (m/z 121)

170

which is the dominant fragment ion upon CID (Fig. S11b).

171

34S

172

34

173

formation, and, in particular, to distinguish between reactions with S(IV) and S(VI) to form OS.

174

In all experiments, HCl was added to control the acidity (pH =3). In Exp. 9 and 11, isotopically

175

labeled (NH4)234SO4 (CDN Isotopes, Canada) was added to organic peroxide solution. Unlabeled

176

SO2 was then bubbled into the mixture at 0.02 L min-1 for 60 min. The molar amount of

177

(NH4)234SO4 added was equal to the total amount of SO2 bubbled. Another set of experiments

178

(Exp. 10 and 12) were conducted by adding an equimolar amount of unlabeled (NH4)2SO3·H2O

179

(92%, Sigma Aldrich) and (NH4)234SO4 into organic peroxide solution, followed by bubbling N2

180

at 0.02 L min-1 for 60 min. To measure the kinetics of OS formation, Exp. 9 and 11 were

181

repeated with the same conditions while controlling the bubbling time to 0, 15, 30, 45 and 60

Labeling Experiments

S labeling experiments (Exp. 9-15) were conducted to investigate the mechanism of OS


Page 8 of 30

Page 9 of 30


182

min (Exp. 13 and 14). In parallel, kinetic data were also derived from the (NH4)2SO3·H2O group

183

(Exp. 15). After each experiment, IMS was used to estimate the amount of OS formed.

184

Box Modeling of Peroxide Chemistry

185

The measured kinetics in this work were applied to a photochemical box model, Gas Aerosol

186

Model for Mechanism Analysis (GAMMA, v. 3.2),50 to investigate the importance of this

187

peroxide/S(IV) pathway in previous chamber experiments. Mechanisms proposed in previous

188

work24 and the reaction rates measured in this study were imbedded into GAMMA (Fig. S15).

189

Temporal evolution of gas- (1) and particle-phase (2) species can be described by:

190

191

𝑑𝑃𝑖 𝑑𝑡 𝑑𝐶𝑖 𝑑𝑡

= −𝑘𝑚𝑡,𝑖 𝛼𝐿 𝑃𝑖 + =

𝑘𝑚𝑡,𝑖 𝑅𝑇

𝑘𝑚𝑡,𝑖 𝑎𝐿 𝐻𝑖∗

𝐶𝑖 + ∑𝑗 𝑟𝑖𝑗,𝑔𝑎𝑠 + 𝐸𝑖 − 𝐷𝑖

𝑘

𝑃𝑖 − 𝐻𝑚𝑡,𝑖 ∗ 𝑅𝑇 𝐶𝑖 + ∑𝑘 𝑟𝑖𝑘,𝑎𝑞

(1) (2)

𝑖

192

In Equation (1) and (2), 𝒌𝒎𝒕,𝒊 is the gas-aerosol mass transfer coefficient for species i,

193

𝑘𝑚𝑡,𝑖 =

194

where Rp is the volume-averaged particle radius, Dg,i is the gas-phase diffusion coefficient, ωi is

195

the thermal velocity, and αi is the accommodation coefficient. Other parameters in equation (1):

196

Pi is the partial pressure of species i in the gas phase, aL is the aerosol liquid volume fraction (m3

197

m−3 air), Ci is the concentration of species i in condensed phase, 𝑯∗𝒊 is the effective Henry’s Law

198

constant of species i, rij,gas is the gas phase reaction rate between species i and j, Ei and Di are the

199

emission and deposition rates of species i, respectively. In equation (2), R is the gas constant, T

200

is temperature, and rik,aq is the aqueous-phase reaction rate between species i and k.

201

Results and Discussion

202

Consumption of Organic Peroxides

1

(3)

𝑅2 4𝑅𝑝 𝑝 + 3𝐷𝑔,𝑖 3𝜔𝑖 𝛼𝑖



203

In previous work, a decreased total particle-phase peroxide mass fraction was observed by

204

iodometric assay for monoterpene SOA produced with SO2.24 Here, HPLC-APCI-MS/MS was

205

used to measure speciated ROOH and their reactions with dissolved S(IV) in order to gain

206

detailed insights into the mechanisms on a molecular level. First, cumene hydroperoxide, a

207

commercially available ROOH was measured in selected ion mode (Fig. S2), and showed

208

significant signal decay when reacted with an excess amount of S(IV). This rapid consumption

209

confirms the potential for particle-phase organic peroxides to be a sink of SO2 as suggested in

210

our earlier work with SOA.24 The reaction between ROOH and dissolved S(IV) was then

211

investigated for α-pinene SOA. APCI-MS/MS allows for monitoring individual reactions

212

between speciated ROOH in α-pinene SOA and bisulfite (Fig. 1). ROOH can form ionic adducts

213

ROOH-NH4+ with ammonium formate, and are detected by a neutral loss scan of 51 Da (-

214

NH3HOOH). The peaks shown in Fig. 1a obtained under 51 Da neutral loss scan therefore

215

represent ROOH-type peroxides.47 When reacted with excess bisulfite, many of the ROOH peaks

216

showed significant decrease in signal intensities (Fig. 1b), including peroxide structures that have

217

been proposed in previous literature (Fig. 1c).47, 51 To understand the relationship between

218

reaction rate and chemical composition, elemental formulas were proposed for the parent peaks

219

based on assumed ranges for carbon number and double bond equivalents (DBE). From the

220

elemental formulas, the elemental ratio (O/C, H/C), DBE and average carbon oxidation state

221

̅̅̅̅ c) of each peak were calculated. The fractional loss of each ion after 30 min of reaction with (𝑂𝑆

222

S(IV) is shown against number of oxygen (no) in Fig. 1d and Table S2, indicating that ROOH in

223

the α-pinene SOA system with higher no can react more quickly with dissolved S(IV). The

224

multidimensional relationships among m/z, O/C, ̅̅̅̅ 𝑂𝑆c, no, H/C and DBE of each peak were

225

investigated and is shown in Fig. S4. Peaks in m/z range of 200-300 exhibit greater decrease in


Page 10 of 30

Page 11 of 30


226

signals. Also, it should be noted that the O/C ratio for many peaks in this m/z range are above 0.6,

227

indicating these compounds, which have been classified as highly oxygenated multifunctional

228

compounds (HOMs), can react rapidly with dissolved SO2. HOMs formed from intramolecular

229

reactions of RO2 during rapid autoxidation have low vapor pressures18, 52 and may contribute

230

significantly to new particle formation.53 The rapid reactions between HOMs and dissolved SO2

231

may serve as an important sink for HOMs, and future exploration is warranted.

232

Reaction Rate Constants between S(IV) and Organic Peroxides

233

pH-dependent reaction rate constants were quantified for three commercially available organic

234

peroxides (Fig. 2a).Rate constants between the organic peroxides and S(IV) measured in the

235

present study have the same order of magnitude with that of H2O2 at high pH (pH>6).46, 54

236

Although the reaction rate constant increases with decreasing pH, the pH dependence for those

237

commercially available organic peroxides was found to be weaker than that of H2O2. As pH

238

decreases to 4, the measured reaction rate constants for the three measured organic peroxides

239

were found to be 100 times slower than that of H2O2 (around 1000 M-1 s-1).10 In a previous

240

study46 which measured the rate constants of organic peroxides (methylhydroperoxide, MHP and

241

peroxyacetic acid, PAA), the pH dependence was found to be comparable with that of H2O2.

242

Since the organic peroxides measured in this study are commercially available and are likely less

243

reactive than those found in ambient SOA, the rate constants likely range between those

244

measured in our study (lower bound) and those measured for MHP and PAA (upper bound). For

245

example, as shown in the previous section, many organic peroxides in SOA are multifunctional

246

and react more quickly than those with only 1 -OOH group. It should be noted that we were

247

unable to measure rate constants below pH 4, which is typical of ambient aerosol in continental



248

North America,55, 56 because the reaction was too fast to allow for measurements at multiple time

249

points with concentrations above the IC detection limit.

250

Estimated Sulfate Production Rate

251

Based on the range of rate constants measured in this study and by Lind et al.,46 S(VI) production

252

rates by peroxide oxidation are estimated for two scenarios: one representing a highly polluted

253

region such as heavy haze episodes in Beijing, and a second representing regional background

254

such as continental North American aerosol. The calculations follow the approach employed in

255

previous studies.11, 12 We assume that 1% and 10% of fine particle mass is comprised of organic

256

peroxides for Beijing and the US, which have an average molecular mass of 150 g mol-1. Rate

257

constants measured in this study and MHP (1.7 × 107 M-2 s-1)46 were used as the lower and upper

258

bond kinetics for the organic peroxide pathway, respectively. Details of initial conditions can be

259

found in S 1.6, and the results are shown in Fig. 2b and 2c.

260

Xue et al. showed through modeling calculations that the gas phase SO2 oxidation by ·OH and

261

Criegee intermediates are slower than the dissolved O3 and NO2 oxidation pathway by at least an

262

order of magnitude during haze events13. The authors invoked aerosol uptake pathways in order

263

to explain the SO2 oxidation, which may include the organic peroxide pathway proposed in this

264

work and transition metal catalyzed O2 oxidation. Based on the range of rate constants reported

265

in the previous section, particle-phase S(VI) production rate from organic peroxides is estimated

266

to be competitive with transition metal ion (TMI)-catalyzed O2 oxidation at low pH (4). TMI are normally rich in large particles.

268

Also, one of the major unknowns in this calculation is the effect of ionic strength for each of the

269

pathways, as rate constants are often measured at more dilute concentrations. The TMI pathway


Page 12 of 30

Page 13 of 30


270

is known to be suppressed by ionic strength in concentrated aerosol phase due to the formation of

271

intermediates.11

272

It should also be noted that the heterogeneous and aqueous decomposition of organic peroxides

273

in SOA can lead to the formation of ·OH and H2O2,57-60 which can react even faster with

274

dissolved SO2. While these decomposition pathways are likely minimized in our experimental

275

work due to high sulfite concentrations employed, future experimental and modeling work is

276

warranted to further explore how important these reactions are to SO2 oxidation in aerosol

277

aqueous phase. Overall, our results show that organic peroxides in submicron aerosol are an

278

important source of particulate sulfate.

279

Mechanism of Organosulfate Formation from Organic Peroxides

280

Our IC measurements (Fig. S8) showed that inorganic sulfate did not account for all of the S(IV)

281

reacted, suggesting that the reactions between SO2 and condensed-phase organic peroxides also

282

yield organosulfates, consistent with our previous observations.24 Since OS contribute

283

substantially to organic mass, and are commonly used as tracers for atmospheric processes, 25-28,

284

32, 61

285

formation of OS from direct reaction between organic peroxides and S(IV) in aqueous phase. Fig.

286

3 shows significant OS peaks detected by IMS, confirming OS is indeed produced from the bulk

287

phase reaction between organic peroxides (both ROOH and ROOR) and dissolved SO2. Results

288

from CID analysis confirm the sulfate moiety in the proposed OS molecules, and the molecular

289

formula of each OS is consistent with the backbone of the corresponding organic peroxide (Fig.

290

3 and Fig. S11). Together with the OS found in monoterpene SOA previously,24 this is strong

291

evidence showing that organic peroxides react with dissolved SO2 to form OS.

their formation mechanisms need to be clearly elucidated. Here, we investigate the



Page 14 of 30

292

OS have been proposed to form from reactions between inorganic sulfate (SO42-) and organic

293

species, such as alcohol (10-8-10-7 M-1 s-1) 34 and epoxides (1.3×10-3-15 M-1 s-1).37, 62 It is

294

therefore plausible that in our experiments, dissolved SO2 is oxidized by peroxides first to SO42-

295

before forming OS, though the alcohol esterification reaction might be slow (with a lifetime over

296

4000 days).34 Here we present evidence for direct OS formation from the reaction between

297

organic peroxide and dissolved SO2. In the experiments involving 34S labeled sulfate (Exp. 13

298

and 14), despite the excess amount of 34SO42- in the system, only unlabeled OS was observed

299

after 32SO2 was gradually bubbled into the organic peroxide solution (Fig.4). Formation of

300

unlabeled OS (and the lack of labeled OS) was observed with both ROOH and ROOR (Fig. 4a

301

and 4c). The dominance of 32S in OS formed after SO2 bubbling was also confirmed using CID

302

(Fig. 4b and 4d). Another set of experiments using a mixture of unlabeled S(IV) ((NH4)232SO3)

303

and labeled S(VI) ((NH4)234SO4) yielded similar results (Fig. 4a, 4c and Fig. S12). To investigate

304

the kinetics, unlabeled SO2 (Exp. 13 and 14) or (NH4)232SO3 (Exp. 15) was introduced into the

305

solution with organic peroxide and (NH4)234SO4 prior to IMS analysis at different time points. It

306

should be noted that unlabeled inorganic sulfate (m/z 97, H32SO4-) was also observed (Fig. 5 and

307

Fig.S13a), likely via direct reaction with organic peroxides, hydrolysis of OS under acidic

308

conditions (pH= 3) or fragmentation of OS upon IMS analysis. The signal for labeled sulfate

309

(m/z 99, H34SO4-) was found to be relatively constant (Fig. S13b), suggesting that inorganic

310

sulfate was not consumed or converted to OS. Therefore we conclude that a significant branch of

311

the peroxide-SO2 reaction pathway directly forms OS, and the mechanisms are proposed:

312

(4)

313

(5)

314

(6)


Page 15 of 30


315

The amount of OS formed is estimated semi-quantitatively based on the ratios of IMS signals

316

(Exp. 13-15). Since no labeled OS (RO34SO3-) was observed, we can assume that the relatively

317

stable signal of H34SO4- (m/z 99) corresponds to the known amount of 34S initially added in each

318

experiment (Fig. 5a, 5c and S13b), which can therefore be used to quantify unlabeled inorganic

319

sulfate H32SO4- (m/z 97) assuming similar signal sensitivities. The amount of OS was then

320

estimated by subtracting the amount of inorganic sulfate from the known amount of unlabeled

321

sulfur introduced to the system, either by bubbling SO2 (Exp. 13 and 14) or by adding

322

(NH4)232SO3 (Exp. 15). Based on this calculation, the OS formation yield (β) from peroxide-S(IV)

323

reaction is estimated to be 0.3-0.6 (Fig. S14), with the remainder assumed to be inorganic sulfate.

324

By multiplying the yield and the second-order rate constant derived earlier, a second-order OS

325

formation rate is estimated to be 2.7-5.4 M-1 s-1. Such an estimate is likely a conservative one

326

since some of the OS may undergo hydrolysis35 to produce inorganic sulfate under acidic

327

conditions. Given the abundance of organic peroxides in SOA and the high yields of OS

328

formation, this reaction pathway is a potentially significant OS source in the atmosphere,

329

particularly those from monoterpenes.26, 29, 63, 64 For example, the gas-phase epoxide molar yield

330

from monoterpene ozonolysis is around 5%,65 whereas peroxide molar yields from monoterpene

331

ozonolysis are around 3-12%.16 It should also be noted that organic peroxides are ubiquitous and

332

can originate from a variety of hydrocarbon precursors. Therefore this reaction may provide a

333

viable pathway for OS formation from different sources, such as aromatic OS.26, 29 Future work

334

should investigate the relative contributions of different OS formation pathways in order to fully

335

understand its role in physicochemical processes of organic aerosol.

336

Photochemical Box Modeling and Atmospheric Implications

337

Aqueous phase reaction rate constants measured in this study and proposed reaction mechanisms



338

were modeled using GAMMA (v. 3.2) to constrain the relative importance of this newly

339

proposed sulfate formation pathway in our previous chamber experiments.24 An effective

340

Henry’s Law constant for all the gas-phase organic peroxides during limonene ozonolysis was

341

estimated to be 107 M atm-1 based on chamber experiments without SO2,24 which is similar to

342

former measured value for hydroxymethyl hydroperoxide.66 A mass fraction of 20% organic

343

peroxide was simulated in the particle phase, similar to previously measured SOA peroxide

344

content via the iodometric assay.24 The initial pH of the aerosol was calculated using E-AIM II

345

model67 to be 4.7, corresponding to the pH of ammonium sulfate seed at the measured RH of

346

55%. Other initial conditions for chamber experiments of limonene ozonolysis and model

347

mechanisms for the simulation are described in Fig. S15. A model predicted SO2 decay was 15.2

348

ppb over 5 hours (Fig. 6a) and this is consistent with 15.5 ppb observed over the experiment.24

349

The measured kinetics in aqueous phase are able to explain the decay of SO2 during its

350

interaction with aerosol, indicating differences between the bulk and aerosol phase (such as ionic

351

strength) might not pose a constraint for this SO2 oxidation pathway. The mole fraction of OS

352

was predicted to be 39% of all S(VI) species formed at the end (Fig. 6a) based on the OS yield

353

(40%) and reaction rates measured for tert-butyl hydroperoxide in this study. sCIs were found to

354

react primarily with water and water dimer with negligible contributions to SO2 decay or sulfate

355

production. Therefore, aqueous phase sulfate was found to be formed from two major pathways:

356

organic peroxides and dissolved O3 (Fig. 6b). Evolution of other species can be found in Fig. S16.

357

One of the most uncertain parameters in these simulations is the aerosol pH. In the base case

358

simulation, the pH was assumed to be constant at its initial pH of 4.7, corresponding to aqueous

359

ammonium sulfate. Since the pH is likely decreasing as sulfate is produced, the simulations were

360

therefore repeated with pH ranging from 3 to 6 that is constant within each simulation. Fig. 6b


Page 16 of 30

Page 17 of 30


361

shows the comparison between the amount of SO2 reacting with peroxides and dissolved O3

362

within such pH range. At lower pH, the relative importance of the peroxide pathway becomes

363

even more pronounced, as the dissolved O3 reaction rate decreases significantly. As mentioned

364

before, the rate constants from our bulk measurements are likely lower than those in SOA. Even

365

with these conservative estimates, we conclude that the SO2 decay observed in these chamber

366

experiments is consistent with organic peroxide reactions. Future work should focus on

367

understanding such kinetics of multifunctional organic peroxides in SOA.

368

Organic peroxides are important atmospheric oxidation products and ubiquitous in various SOA

369

systems.16, 22, 68, 69 In this work, we characterized in detail the interactions between condensed-

370

phase organic peroxides and gas-phase SO2, revealing their role as an atmospheric sink of SO2

371

and source of OS. In addition to aqueous-phase sulfur oxidation chemistry in fog and cloud

372

droplets, here we present the importance of the novel SO2 oxidation pathway as a source of

373

sulfate in submicron aerosol. In particular, these reactions are efficient pathways for OS

374

formation, which may explain the variety of OS carbon backbone structures observed in

375

ambient.70,71 The formation of OS could also vary the viscosity, interfacial tension and reactivity

376

of aerosol.72-74 Detailed knowledge about the kinetics and mechanisms of OS formation

377

presented in the current study will lead to a better understanding of the sources and underlying

378

impacts of ambient sulfate75, one of the most important classes of compounds in ambient aerosol.

379

380

381

382



383

Supporting Information

384

Supporting material consists of 2 tables and 16 figures.

385 386 387

Notes

388

The authors declare no competing financial interest.

389 390 391

Acknowledgments

392

This work was supported by Natural Sciences and Engineering Research Council Discovery

393

Grant and the Ontario Early Researcher Award. The authors would like to thank Dr. Greg Evans,

394

Dr. Cheol Heon Jeong, Dr. ManNin Chan, Dr. Hongyu Guo and Dr. Tengyu Liu for helpful

395

discussions. Special thanks to Dr. Al-Amin Dhirani, Dr. Yoshinori Suganuma and Dr.

396

Parviz Shahbazikhah for providing IC equipment.

397

398 399 400 401 402 403 404 405


Page 18 of 30

Page 19 of 30


406

References

407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455

(1) Sipilä, M.; Berndt, T.; Petäjä, T.; Brus, D.; Vanhanen, J.; Stratmann, F.; Patokoski, J.; Mauldin, R. L.; Hyvärinen, A.-P.; Lihavainen, H. The role of sulfuric acid in atmospheric nucleation. Science 2010, 327 (5970), 1243-1246. (2) Fan, J.; Rosenfeld, D.; Zhang, Y.; Giangrande, S. E.; Li, Z.; Machado, L. A.; Martin, S. T.; Yang, Y.; Wang, J.; Artaxo, P. Substantial convection and precipitation enhancements by ultrafine aerosol particles. Science 2018, 359 (6374), 411-418. (3) Burnett, R.; Chen, H.; Szyszkowicz, M.; Fann, N.; Hubbell, B.; Pope, C. A.; Apte, J. S.; Brauer, M.; Cohen, A.; Weichenthal, S. Global estimates of mortality associated with long-term exposure to outdoor fine particulate matter. P. Natl. Acad. Sci. 2018, 115 (38), 9592-9597. (4) Nguyen, T. B.; Lee, P. B.; Updyke, K. M.; Bones, D. L.; Laskin, J.; Laskin, A.; Nizkorodov, S. A. Formation of nitrogen- and sulfur-containing light-absorbing compounds accelerated by evaporation of water from secondary organic aerosols. J. Geophys. Res. Atmos. 2012, 117 (D1). (5) 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. (6) 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). (7) Goto, D.; Nakajima, T.; Dai, T.; Takemura, T.; Kajino, M.; Matsui, H.; Takami, A.; Hatakeyama, S.; Sugimoto, N.; Shimizu, A.; Ohara, T. An evaluation of simulated particulate sulfate over East Asia through global model intercomparison. J. Geophys. Res. Atmos. 2015, 120 (12), 6247-6270. (8) Mauldin Iii, R.; Berndt, T.; Sipilä, M.; Paasonen, P.; Petäjä, T.; Kim, S.; Kurtén, T.; Stratmann, F.; Kerminen, V.-M.; Kulmala, M. A new atmospherically relevant oxidant of sulphur dioxide. Nature 2012, 488 (7410), 193. (9) Huang, H.-L.; Chao, W. Kinetics of a Criegee intermediate that would survive high humidity and may oxidize atmospheric SO2. P. Natl. Acad. Sci. 2015, 112 (35), 10857-10862. (10) Seinfeld, J. H.; Pandis, S. N. Atmospheric chemistry and physics: from air pollution to climate change. John Wiley & Sons: 2012. (11) Cheng, Y.; Zheng, G.; Wei, C.; Mu, Q.; Zheng, B.; Wang, Z.; Gao, M.; Zhang, Q.; He, K.; Carmichael, G.; Pöschl, U.; Su, H. Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China. Sci Adv. 2016, 2 (12), e1601530. (12) 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, 12109. (13) Xue, J.; Yuan, Z.; Griffith, S. M.; Yu, X.; Lau, A. K. H.; Yu, J. Z. Sulfate formation enhanced by a cocktail of high NOx, SO2, particulate matter, and droplet pH during haze-fog events in megacities in China: an observation-based modeling investigation. Environ. Sci. Technol. 2016, 50 (14), 7325-7334. (14) Hallquist, M.; Wenger, J. C.; Baltensperger, U.; Rudich, Y.; Simpson, D.; Claeys, M.; Dommen, J.; Donahue, N. M.; George, C.; Goldstein, A. H.; Hamilton, J. F.; Herrmann, H.; Hoffmann, T.; Iinuma, Y.; Jang, M.; Jenkin, M. E.; Jimenez, J. L.; Kiendler-Scharr, A.; Maenhaut, W.; McFiggans, G.; Mentel, T. F.; Monod, A.; Prevot, A. S. H.; Seinfeld, J. H.; Surratt, J. D.; Szmigielski, R.; Wildt, J. The formation, properties and impact of secondary organic aerosol: current and emerging issues. Atmos. Chem. Phys. 2009, 9 (14), 5155-5236. (15) Xu, L.; Møller, K. H.; Crounse, J. D.; Otkjær, R. V.; Kjaergaard, H. G.; Wennberg, P. O. Unimolecular reactions of peroxy radicals formed in the oxidation of α-pinene and β-pinene by hydroxyl radicals. J. Phys. Chem. A. 2019, 123, 1661−1674. (16) Docherty, K. S.; Wu, W.; Lim, Y. B.; Ziemann, P. J. Contributions of organic peroxides to secondary aerosol formed from reactions of monoterpenes with O3. Environ. Sci. Technol. 2005, 39 (11), 4049-4059. 19 ACS Paragon Plus Environment


456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505

(17) Epstein, S. A.; Blair, S. L.; Nizkorodov, S. A. Direct photolysis of α-pinene ozonolysis secondary organic aerosol: effect on particle mass and peroxide content. Environ. Sci. Technol. 2014, 48 (19), 11251-11258. (18) Mentel, T.; Springer, M.; Ehn, M.; Kleist, E.; Pullinen, I.; Kurtén, T.; Rissanen, M.; Wahner, A.; Wildt, J. Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes–deduced from structure–product relationships. Atmos. Chem. Phys. 2015, 15 (12), 6745-6765. (19) Criegee, R., Mechanism of ozonolysis. Angew. Chem. Int. Ed. 1975, 14 (11), 745-752. (20) Jokinen, T.; Sipilä, M.; Richters, S.; Kerminen, V. M.; Paasonen, P.; Stratmann, F.; Worsnop, D.; Kulmala, M.; Ehn, M.; Herrmann, H., Rapid autoxidation forms highly oxidized RO2 radicals in the atmosphere. Angew. Chem. Int. Ed. 2014, 53 (52), 14596-14600. (21) Surratt, J. D.; Murphy, S. M.; Kroll, J. H.; Ng, N. L.; Hildebrandt, L.; Sorooshian, A.; Szmigielski, R.; Vermeylen, R.; Maenhaut, W.; Claeys, M. Chemical composition of secondary organic aerosol formed from the photooxidation of isoprene. J. Phys. Chem. A. 2006, 110 (31), 9665-9690. (22) Kautzman, K.; Surratt, J.; Chan, M.; Chan, A.; Hersey, S.; Chhabra, P.; Dalleska, N.; Wennberg, P.; Flagan, R.; Seinfeld, J. Chemical composition of gas-and aerosol-phase products from the photooxidation of naphthalene. J. Phys. Chem. A. 2009, 114 (2), 913-934. (23) Krapf, M.; El Haddad, I.; Bruns, E. A.; Molteni, U.; Daellenbach, K. R.; Prévôt, A. S.; Baltensperger, U.; Dommen, J. Labile peroxides in secondary organic aerosol. Chem 2016, 1 (4), 603-616. (24) Ye, J.; Abbatt, J. P.; Chan, A. W. Novel pathway of SO2 oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol. Atmos. Chem. Phys. 2018, 18 (8), 5549-5565. (25) Surratt, J. D.; Gómez-González, Y.; Chan, A. W.; Vermeylen, R.; Shahgholi, M.; Kleindienst, T. E.; Edney, E. O.; Offenberg, J. H.; Lewandowski, M.; Jaoui, M. Organosulfate formation in biogenic secondary organic aerosol. J. Phys. Chem. A. 2008, 112 (36), 8345-8378. (26) Kundu, S.; Quraishi, T.; Yu, G.; Suarez, C.; Keutsch, F.; Stone, E. Evidence and quantitation of aromatic organosulfates in ambient aerosols in Lahore, Pakistan. Atmos. Chem. Phys. 2013, 13 (9), 48654875. (27) Wang, Y.; Hu, M.; Guo, S.; Wang, Y.; Zheng, J.; Yang, Y.; Zhu, W.; Tang, R.; Li, X.; Liu, Y. The secondary formation of organosulfates under interactions between biogenic emissions and anthropogenic pollutants in summer in Beijing. Atmos. Chem. Phys. 2018, 18 (14), 10693-10713. (28) Tolocka, M. P.; Turpin, B. Contribution of organosulfur compounds to organic aerosol mass. Environ. Sci. Technol. 2012, 46 (15), 7978-7983. (29) Huang, R. J.; Cao, J.; Chen, Y.; Yang, L.; Shen, J.; You, Q.; Wang, K.; Lin, C.; Xu, W.; Gao, B.; Li, Y.; Chen, Q.; Hoffmann, T.; O'Dowd, C. D.; Bilde, M.; Glasius, M. Organosulfates in atmospheric aerosol: synthesis and quantitative analysis of PM2.5 from Xi'an, northwestern China. Atmos. Meas. Tech. 2018, 11 (6), 3447-3456. (30) Chan, M.; Surratt, J.; Chan, A.; Schilling, K.; Offenberg, J.; Lewandowski, M.; Edney, E.; Kleindienst, T.; Jaoui, M.; Edgerton, E. Influence of aerosol acidity on the chemical composition of secondary organic aerosol from β-caryophyllene. Atmos. Chem. Phys. 2011, 11 (4), 1735-1751. (31) Frossard, A. A.; Shaw, P. M.; Russell, L. M.; Kroll, J. H.; Canagaratna, M. R.; Worsnop, D. R.; Quinn, P. K.; Bates, T. S. Springtime Arctic haze contributions of submicron organic particles from European and Asian combustion sources. J. Geophys. Res. Atmos. 2011, 116 (D5). (32) Riva, M.; Tomaz, S.; Cui, T.; Lin, Y.-H.; Perraudin, E.; Gold, A.; Stone, E. A.; Villenave, E.; Surratt, J. D. Evidence for an unrecognized secondary anthropogenic source of organosulfates and sulfonates: gas-phase oxidation of polycyclic aromatic hydrocarbons in the presence of sulfate aerosol. Environ. Sci. Technol. 2015, 49 (11), 6654-6664. (33) Surratt, J. D.; Kroll, J. H.; Kleindienst, T. E.; Edney, E. O.; Claeys, M.; Sorooshian, A.; Ng, N. L.; Offenberg, J. H.; Lewandowski, M.; Jaoui, M. Evidence for organosulfates in secondary organic aerosol. Environ. Sci. Technol. 2007, 41 (2), 517-527.


Page 20 of 30

Page 21 of 30

506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555


(34) Minerath, E. C.; Casale, M. T.; Elrod, M. J. Kinetics feasibility study of alcohol sulfate esterification reactions in tropospheric aerosols. Environ. Sci. Technol. 2008, 42 (12), 4410-4415. (35) Hu, K.; Darer, A. I.; Elrod, M. J. Thermodynamics and kinetics of the hydrolysis of atmospherically relevant organonitrates and organosulfates. Atmos. Chem. Phys. 2011, 11 (16), 83078320. (36) Iinuma, Y.; Böge, O.; Kahnt, A.; Herrmann, H. Laboratory chamber studies on the formation of organosulfates from reactive uptake of monoterpene oxides. Phys.Chem.Chem.Phys. 2009, 11 (36), 79857997. (37) Minerath, E. C.; Elrod, M. J. Assessing the potential for diol and hydroxy sulfate ester formation from the reaction of epoxides in tropospheric aerosols. Environ. Sci. Technol. 2009, 43 (5), 1386-1392. (38) Rudziński, K.; Gmachowski, L.; Kuznietsova, I. Reactions of isoprene and sulphoxy radicalanions–a possible source of atmospheric organosulphites and organosulphates. Atmos. Chem. Phys. 2009, 9 (6), 2129-2140. (39) Nozière, B.; Ekström, S.; Alsberg, T.; Holmström, S. Radical-initiated formation of organosulfates and surfactants in atmospheric aerosols. Geophys. Res. Lett. 2010, 37 (5), L05806. (40) Wach, P.; Spólnik, G.; Rudziński, K. J.; Skotak, K.; Claeys, M.; Danikiewicz, W.; Szmigielski, R. Radical oxidation of methyl vinyl ketone and methacrolein in aqueous droplets: characterization of organosulfates and atmospheric implications. Chemosphere 2019, 214, 1-9. (41) Olson, T. M.; Hoffmann, M. R. Hydroxyalkylsulfonate formation: its role as a S(IV) reservoir in atmospheric water droplets. Atmos. Environ. (1967) 1989, 23 (5), 985-997. (42) Passananti, M.; Kong, L.; Shang, J.; Dupart, Y.; Perrier, S.; Chen, J.; Donaldson, D. J.; George, C. Organosulfate formation through the heterogeneous reaction of sulfur dioxide with unsaturated fatty acids and long-chain alkenes. Angew Chem. Int. Ed. 2016, 55 (35), 10336-10339. (43) Moch, J. M.; Dovrou, E.; Mickley, L. J.; Keutsch, F. N.; Cheng, Y.; Jacob, D. J.; Jiang, J.; Li, M.; Munger, J. W.; Qiao, X. Contribution of hydroxymethane sulfonate to ambient particulate matter: A potential explanation for high particulate sulfur during severe winter haze in Beijing. Geophys. Res. Lett. 2018, 45 (21), 11,969-11,979. (44) Coddens, E. M.; Huang, L.; Wong, C.; Grassian, V. H. Influence of glyoxal on the catalytic oxidation of S (IV) in acidic aqueous media. ACS Earth Space Chem. 2018, 3 (1), 142-149. (45) Huang, L.; Cochran, R.; Coddens, E.; Grassian, V. H. Formation of organosulfur compounds through transition metal ion-catalyzed aqueous phase reactions. Environ. Sci. Tech. Let. 2018, 5 (6) 315321. (46) Lind, J. A.; Lazrus, A. L.; Kok, G. L. Aqueous phase oxidation of sulfur (IV) by hydrogen peroxide, methylhydroperoxide, and peroxyacetic acid. J. Geophys. Res. Atmos. 1987, 92 (D4), 41714177. (47) Zhou, S.; Rivera-Rios, J. C.; Keutsch, F. N.; Abbatt, J. P. Identification of organic hydroperoxides and peroxy acids using atmospheric pressure chemical ionization–tandem mass spectrometry (APCI-MS/MS): application to secondary organic aerosol. Atmos. Meas. Tech. 2018, 11 (5), 3081-3089. (48) Wang, S.; Ye, J.; Soong, R.; Wu, B.; Yu, L.; Simpson, A. J.; Chan, A. W. Relationship between chemical composition and oxidative potential of secondary organic aerosol from polycyclic aromatic hydrocarbons. Atmos. Chem. Phys. 2018, 18 (6), 3987-4003. (49) Wang, Y.; Ren, J.; Huang, X. H.; Tong, R.; Yu, J. Z. Synthesis of four monoterpene-derived organosulfates and their quantification in atmospheric aerosol samples. Environ. Sci. Technol. 2017, 51 (12), 6791-6801. (50) McNeill, V. F.; Woo, J. L.; Kim, D. D.; Schwier, A. N.; Wannell, N. J.; Sumner, A. J.; Barakat, J. M. Aqueous-phase secondary organic aerosol and organosulfate formation in atmospheric aerosols: a modeling study. Environ. Sci. Technol. 2012, 46 (15), 8075-8081. (51) Jenkin, M. Modelling the formation and composition of secondary organic aerosol from α-and βpinene ozonolysis using MCM v3. Atmos. Chem. Phys. 2004, 4 (7), 1741-1757.



556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606

(52) Ehn, M.; Thornton, J. A.; Kleist, E.; Sipila, M.; Junninen, H.; Pullinen, I.; Springer, M.; Rubach, F.; Tillmann, R.; Lee, B.; LopezHilfiker, F. D.; Andres, S.; Acir, I.-H.; Rissanen, M.; Jokinen, T.; Schobesberger, S.; Kangasluoma, J.; Kontkanen, J.; Nieminen, T.; Kurten, T.; Nielsen, L. B.; Jorgensen, S.; Kjaergaard, H. G.; Canagaratna, M. R.; Dal Maso, M.; Berndt, T.; Petaja, T.; Wahner, A.; Kerminen, V.-M.; Kulmala, M.; Worsnop, D. R.; Wildt, J.; Mentel,T. F. A large source of low-volatility secondary organic aerosol. Nature. 2014, 506, 476−479. (53) Schobesberger, S.; Junninen, H.; Bianchi, F.; Lönn, G.; Ehn, M.; Lehtipalo, K.; Dommen, J.; Ehrhart, S.; Ortega, I. K.; Franchin, A. Molecular understanding of atmospheric particle formation from sulfuric acid and large oxidized organic molecules. P. Natl. Acad. Sci. 2013, 110 (43), 17223-17228. (54) Kunen, S.; Lazrus, A.; Kok, G.; Heikes, B. Aqueous oxidation of SO2 by hydrogen peroxide. J. Geophys. Res. Oceans 1983, 88 (C6), 3671-3674. (55) Nah, T.; Guo, H.; Sullivan, A. P.; Chen, Y.; Tanner, D. J.; Nenes, A.; Russell, A.; Ng, N. L.; Huey, L. G.; Weber, R. J. Characterization of aerosol composition, aerosol acidity, and organic acid partitioning at an agriculturally intensive rural southeastern US site. Atmos. Chem. Phys. 2018, 18 (15), 11471-11491. (56) Lawal, A. S.; Guan, X.; Liu, C.; Henneman, L. R. F.; Vasilakos, P.; Bhogineni, V.; Weber, R. J.; Nenes, A.; Russell, A. G. Linked response of aerosol acidity and ammonia to SO2 and NOx emissions reductions in the United States. . Environ. Sci. Technol. 2018, 52 (17), 9861-9873. (57) Li, H.; Chen, Z.; Huang, L.; Huang, D. Organic peroxides' gas-particle partitioning and rapid heterogeneous decomposition on secondary organic aerosol. Atmos. Chem. Phys. 2016, 16 (3), 1837-1848. (58) Tong, H.; Arangio, A. M.; Lakey, P. S.; Berkemeier, T.; Liu, F.; Kampf, C. J.; Brune, W. H.; Pöschl, U.; Shiraiwa, M. Hydroxyl radicals from secondary organic aerosol decomposition in water. Atmos. Chem. Phys. 2016, 16 (3), 1761-1771. (59) Lim, Y. B.; Turpin, B. J. Laboratory evidence of organic peroxide and peroxyhemiacetal formation in the aqueous phase and implications for aqueous OH. Atmos. Chem. Phys. 2015, 15 (22), 12867-12877. (60) Badali, K. M.; Zhou, S.; Aljawhary, D.; Antiñolo, M.; Chen, W. J.; Lok, A.; Mungall, E.; Wong, J. P. S.; Zhao, R.; Abbatt, J. P. D. Formation of hydroxyl radicals from photolysis of secondary organic aerosol material. Atmos. Chem. Phys. 2015, 15 (14), 7831-7840. (61) Ma, Y.; Xu, X.; Song, W.; Geng, F.; Wang, L. Seasonal and diurnal variations of particulate organosulfates in urban Shanghai, China. Atmos. Environ. 2014, 85, 152-160. (62) Eddingsaas, N. C.; VanderVelde, D. G.; Wennberg, P. O. Kinetics and products of the acidcatalyzed ring-opening of atmospherically relevant butyl epoxy alcohols. J. Phys. Chem. A. 2010, 114 (31), 8106-8113. (63) Zhang, H.; Yee, L. D.; Lee, B. H.; Curtis, M. P.; Worton, D. R.; Isaacman-VanWertz, G.; Offenberg, J. H.; Lewandowski, M.; Kleindienst, T. E.; Beaver, M. R. Monoterpenes are the largest source of summertime organic aerosol in the southeastern United States. P. Natl. Acad. Sci. 2018, 115 (9), 2038-2043. (64) Zhao, Y.; Thornton, J. A.; Pye, H. O. Quantitative constraints on autoxidation and dimer formation from direct probing of monoterpene-derived peroxy radical chemistry. P. Natl. Acad. Sci. 2018, 115 (48), 12142-12147. (65) Lee, A., Goldstein, A.H., Keywood, M.D., Gao, S., Varutbangkul, V., Bahreini, R., Ng, N.L., Flagan, R.C. and Seinfeld, J.H. Gas-phase products and secondary aerosol yields from the ozonolysis of ten different terpenes. J. Geophys. Res. Atmos. 2006, 111 (D17), D07302. (66) Staffelbach, T. A.; Kok, G. L. Henry's law constants for aqueous solutions of hydrogen peroxide and hydroxymethyl hydroperoxide. J. Geophys. Res. Atmos. 1993, 98 (D7), 12713-12717. (67) Clegg, S.L.; Brimblecombe, P.; Wexler, A.S. Thermodynamic model of the system H+− NH4+− 2SO4 − NO3-− H2O at tropospheric temperatures. J. Phys. Chem. A. 1998, 102 (12), 2137-2154. (68) Praske, E.; Otkjær, R. V.; Crounse, J. D.; Hethcox, J. C.; Stoltz, B. M.; Kjaergaard, H. G.; Wennberg, P. O. Atmospheric autoxidation is increasingly important in urban and suburban North America. P. Natl. Acad. Sci. 2018, 115 (1), 64-69. 22 ACS Paragon Plus Environment

Page 22 of 30

Page 23 of 30

607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625


(69) Karl, T.; Striednig, M.; Graus, M.; Hammerle, A.; Wohlfahrt, G. Urban flux measurements reveal a large pool of oxygenated volatile organic compound emissions. P. Natl. Acad. Sci. 2018, 115 (6) 11861191. (70) Hettiyadura, A. P. S.; Al-Naiema, I. M.; Hughes, D. D.; Fang, T.; Stone, E. A. Organosulfates in Atlanta, Georgia: anthropogenic influences on biogenic secondary organic aerosol formation. Atmos. Chem. Phys. 2019, 19 (5), 3191-3206. (71) Kristensen, K.; Glasius, M. Organosulfates and oxidation products from biogenic hydrocarbons in fine aerosols from a forest in North West Europe during spring. Atmos. Environ. 2011, 45 (27), 45464556. (72) Liu, P.; Song, M.; Zhao, T.; Gunthe, S. S.; Ham, S.; He, Y.; Qin, Y. M.; Gong, Z.; Amorim, J. C.; Bertram, A. K. Resolving the mechanisms of hygroscopic growth and cloud condensation nuclei activity for organic particulate matter. Nat. Commun. 2018, 9 (1), 4076. (73) Ovadnevaite, J.; Zuend, A.; Laaksonen, A.; Sanchez, K. J.; Roberts, G.; Ceburnis, D.; Decesari, S.; Rinaldi, M.; Hodas, N.; Facchini, M. C. Surface tension prevails over solute effect in organicinfluenced cloud droplet activation. Nature 2017, 546 (7660), 637. (74) Faust, J. A.; Abbatt, J. P. D. Organic surfactants protect dissolved aerosol components against heterogeneous oxidation. J. Phys. Chem. A. 2019, 123 (10), 2114-2124. (75) Pöschl, U.; Shiraiwa, M. Multiphase chemistry at the atmosphere–biosphere interface influencing climate and public health in the anthropocene. Chem. Rev. 2015, 115 (10), 4440-4475.

626 627 628 629 630 631 632 633 634

635

636

637

638



639

640

Figure 1. Results from APCI-MS/MS. Mass spectra of ROOH in α-pinene SOA (10 mM) with

641

(red)/without (black) S(IV) (1 M) derived under 51 Da neutral loss scan; (b) Difference in

642

signal intensities between the two mass spectra in (a), showing reduced signal intensity by

643

reacting with S(IV); (c) Mass spectra for m/z 170–240, showing signal variation upon reacting

644

with S(IV) for organic peroxides with proposed structures in α-pinene SOA; (d) Relationship

645

between signal reduction and molecular oxygen number (Table S2). Marker size is proportional

646

to m/z value. Larger molecules in α-pinene SOA with higher oxygen number presents a greater

647

signal reduction in general.

648 649

650


Page 24 of 30

Page 25 of 30


651

652

Figure 2. (a) Second-order rate constants derived from IC measurement for cumene

653

hydroperoxide (green); tert-butyl hydroperoxide (red) and 2-butanone peroxide (blue). Data

654

were interpreted as mean ± standard error of the mean (SEM, n = 3). Aerosol aqueous phase

655

sulfate production rate of organic peroxides upper limit (kinetics for MHP10) and lower limit

656

(measured in this work) were plotted against other oxidation pathways following initial

657

conditions for Beijing haze (b) and continental North America (c). The red dashed lines represent

658

the pH range beyond which rate constant measurements of organic peroxides were not available,

659

and estimates were projected by extrapolation of kinetics measured from the higher pH range.

660

661



662

663

Figure 3. IMS mass spectra for (a) tert-butyl hydroperoxide; (b) benzoyl peroxide; (c) tert-butyl

664

peroxybenzoate bubbled by SO2. In all cases, OS with molecular structures corresponding to the

665

precursor organic peroxide were observed for both ROOH (a) and ROOR (b and c) types.

666

667

668

669

670 26 ACS Paragon Plus Environment

Page 26 of 30

Page 27 of 30


671

672

Figure 4. IMS mass spectra for 34S labeling experiments. (a) Tert-butyl hydroperoxide after

673

bubbling with SO2 (red) and mixed with (NH4)232SO3 (black); (b) Signals of parent OS ion

674

derived from tert-butyl hydroperoxide and OS fragment ion as a function of CID voltage (0-60V)

675

for the SO2 bubbled group; (c) Benzoyl peroxide after bubbling with SO2 (red) and mixed with

676

(NH4)232SO3 (black); (d) Signals of parent OS ion derived from benzoyl peroxide and fragment

677

ion as a function of CID voltage (0-60V) for the SO2 bubbled group. In all cases, no labeled OS

678

(m/z 155 or m/z 203) was observed even with an excess amount of H34SO4- (m/z 99).

679

680

681



683

684

Figure 5. Kinetics of OS formation during 34S labeling experiments. Time evolution of IMS

685

spectra for tert-butyl hydroperoxide (a) and benzoyl peroxide (c). Relative signal abundance of

686

OS to H34SO4- (used as an internal standard) for tert-butyl hydroperoxide (b) and benzoyl

687

peroxide (d) after SO2 bubbling. Data were interpreted as mean ± SEM (n = 3).

688

689

690

691

692


Page 28 of 30

Page 29 of 30


694

695

Figure 6. Results from GAMMA simulation for chamber experiments.24 The initial mixing ratio

696

of SO2 and limonene before experiments was 144.3 ppb and 33.7 ppb, respectively. O3 was

697

gradually added into the chamber at a rate of 2.5 ppb min-1 with a final mixing ratio of 150 ppb

698

during the first 1 hour of the 5-hour chamber experiment. (a) Model prediction of gas phase SO2

699

decay (blue) and aqueous phase OS fraction of the total formed S(VI) (red); (b) Gas phase SO2

700

decay contributed by organic peroxide and dissolved ozone pathways as a function of pH.

701 702 703 704 705 706 707 708 709 710 711 29 ACS Paragon Plus Environment


712

TOC

713 714


Page 30 of 30

Organic Peroxides and Sulfur Dioxide in Aerosol - ACS Publications

Recommend Documents