Supplement of Atmos. Chem. Phys., 20, 14769–14785, 2020 https://doi.org/10.5194/acp-20-14769-2020-supplement © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
Supplement of Measurement report: Important contributions of oxygenated compounds to emissions and chemistry of volatile organic compounds in urban air
Caihong Wu et al.
Correspondence to: Bin Yuan ([email protected]) and Min Shao ([email protected])
The copyright of individual parts of the supplement might differ from the CC BY 4.0 License. 24 1. Sensitivity of VOCs in PTR-MS
25 Proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS) allows 26 the detection of a large number of VOCs in air through proton-transfer reaction with 27 H3O+ reagent ions and detection by a mass spectrometer. Measurement sensitivities can 28 be experimentally determined using calibration gases, but only the sensitivity of few 29 species can be obtained. For other species, the sensitivity can be calculated using the 30 rate constant for the proton-transfer reaction. 31 In PTR-ToF-MS, VOCs that have higher proton affinity than water will be ionized
+ 32 via proton transfer with H3O to produce the product ions.
+ + 33 VOC+H3O → VOC·H +H2O 34 According to the reaction rate equation, the concentration of VOC•H can be 35 calculated as follows:
+ 36 VOC·H = H3O 0(1-exp(- [VOC]∆ ))
+ + 37 Where k is the reaction rate constant, [H3O ]0 is the signal of H3O ions before 38 reaction, [VOC] is the number concentration of the VOC in the drift tube, and Δt is the
+ 39 reaction time for H3O traversing the drift tube.
+ 40 It is assumed that only a small amount of H3O has proton transfer reaction with 41 VOCs, the concentration of VOC•H can be calculated as follows:
+ 42 VOC·H H3O [VOC]∆
+ + 43 Where [H3O ] is the signal of H3O ions after the end of the drift tube. 44 Considering the possibility of fragmentation for the protonated ions, a term
+ + 45 VOC∙H can be introduced to represent the fraction of product ions detected as VOC•H
+ 46 ions (0 ≤ VOC∙H ≤1). The concentration of VOC·H becomes
+ + 47 VOC·H H3O [VOC]∆ VOC∙H
+ 48 The fraction of H3O that is converted into VOC·H+ ions can be expressed as: VOC·H + 49 + [VOC]∆ VOC∙H H3O 50 The signal of VOC·H is related to the transmission efficiency:
51 VOC·H+ VOC·H × VOC·H+
52 The factors VOC·H+ is the transmission efficiencies for VOC·H . These are
2
53 determined by (i) the extraction efficiency of ions from the drift tube into the mass 54 analyzer, (ii) the transmission efficiency of the analyzer, and (iii) the detection 55 efficiency of the detector for each mass (Sekimoto et al., 2017). 56 The measured sensitivity in PTR-TOF-MS is defined as the ion intensity of 57 VOC·H obtained at a volume-mixing ratio of 1 ppbv (parts per billion by volume; 58 10−9):
+ + VOC·H + VOC·H + 59 Sensitivity 10 ∆ H3O VOC∙H VOC + 10 H3O 60 For a certain VOC, the sensitivity is linearly related to the reaction rate constant. 61 Eq.3 suggests that if the measured sensitivity is corrected for fragmentation and 62 transmission efficiencies, the resulting sensitivity is linearly dependent on the reaction 63 rate constant k. This means that sensitivity can be calculated from the rate constants.
+ 64 Corrected Sensitivity Sensitivity ⁄ / VOC∙H 65 The transmission efficiency of ions is quantified by laboratory experiments. A 66 large variety of high concentrations of VOCs, including methanol, acetonitrile, 67 ethylamine, formic acid, acetone, pyrrole, furan, isoprene, MACR, DMF, 68 hydroxyacetone, phenol, furfural, styrene, benzaldehyde, cresol, guaiacol, naphthalene, 69 pinene, bromobenzene, iodobenzene, octamethylcyclotetrasiloxane (D4), 1,3- 70 diiodobenzene, decamethylcyclopentasiloxane (D5), are selected for introduction into 71 the PTR-ToF-MS, reagent ions are obviously consumed. The transmission efficiency 72 can be obtained according to the decrease of reagent ions and the increase of product 73 ions. Figure S7 shows the transmission efficiency curves based on laboratory 74 experiments. 75 The fragment ratio was obtained by using the relative proportions relationship 76 between the signal intensity of VOC and the fragment ions generated by its fracture at 77 the same time during the transmission efficiency experiment. The fragment ratio of 78 different VOCs are shown in Table S2. 79 2 Calculation of initial isoprene concentration 80 Isoprene is extremely reactive and therefore its concentration is poor to indicate 81 direct biogenic emissions. To correct this atmospheric photochemical loss, we 3
82 extrapolated the isoprene concentration back to the source using measurements of 83 isoprene and its photo-oxidized products, methyl vinyl ketone (MVK) and methacrolein 84 (MACR) (Karl et al., 2009). The reaction process of isoprene being oxidized by OH 85 radicals in the atmosphere is: 86 isoprene OH → 0.32MVK 0.23MACR
87 1 10 88 MVK OH → Products 1.9 10 89 MACR OH → Products 3.3 10
. . 90 1 ∆ 1 ∆ (1)
91 From the measured ratio between MVK + MACR and isoprene, the OH exposure 92 since emission can be determined, and the observed isoprene concentration can be 93 extrapolated back to the source(Figure S8c).
94 ∆ (2) 95 Here, we used the measured concentrations from online GC-MS/FID for isoprene, 96 as there are substantial interferences for PTR-TOF measurements of isoprene in urban 97 air (Yuan et al., 2017). MVK+MACR was only measured by PTR-ToF-MS. We 98 observed significant elevation of MVK+MACR concentrations in the evening when the 99 primary emissions are highest, indicating MVK+MACR concentrations measured by 100 PTR-ToF-MS are influenced by primary anthropogenic emissions (e.g. traffic), either 101 due to direct emissions of MVK or MACR from vehicles, or potential interferences 102 from other compounds that are emitted by vehicles. The data during the night time (20: 103 00-6: 00) was selected to determine the emission ratio of MVK + MACR relative to CO 104 (Figure S8a). MVK+MACR concentrations that are solely from biogenic sources can 105 be estimated by the following Eq. 3:
106 (3)
107 Where and are the concentration of MVK+MACR and
108 CO, respectively. is the tropospheric background of CO (100 ppb).
-4 109 is the emission ratio of MVK+MACR versus CO (6.0×10 ppb [ppb 110 CO]-1).
4
111 3 Calculation of photolysis rates 112 To estimate photolysis rates for OVOCs, we follow the method in de Gouw et al. 113 (2018). It is assumed that the photolysis rates for all OVOCs are reduced relative to
114 their clear-sky rates by the same factor as for jNO2 and use the following equation:
115 (4) 、 116 Where are clear-sky photolysis rates of OVOC
117 and NO2, respectively. Clear-sky photolysis rates for different compounds are 118 calculated in this study from the parameterization used in the Master Chemical 119 Mechanism v3.3.1 (Saunders et al., 2003): 120 l cos sec (5) 121 Where χ is the solar zenith angle and l, m, and n are parameters listed for different
122 photolysis rates. The photolysis rates of NO2, H2O2, and HCHO were measured on-site 123 using a PFS-100 Photolysis Spectrometer (Focused Photonics Inc.) during the
124 campaign. The above methods were used to calculate the photolysis rates of H2O2 and 125 HCHO, and compared with the measurements. It is found that the calculated values 126 show good agreement with the measurements for the two compounds (Figure S9). 127 Based on this, the photolysis frequencies of other OVOCs were calculated and then the 128 corrections to the rate constants of OH reaction for these OVOCs were estimated based 129 on Eq. 3 in the main text. 130
5
131 Table S1. Sensitivities of PTR-ToF-MS for various VOC species calibrated with 132 standard gas and Liquid Calibration Unit (LCU). VOC species Ion formula Sensitivity, cps/ppb
Species calibrated with gas standard
+ Formaldehyde CH2OH 1042
+ Methanol CH4OH 629.3
+ Acetonitrile C2H3NH 3374
+ Acetaldehyde C2H4OH 2767
+ Ethanol C2H6OH 99.23
+ Acrolein C3H4OH 4107
+ Acetone C3H6OH 4299
+ Furan C4H4OH 2544
+ Isoprene C5H8H 1888
+ MVK C4H6OH 3868
+ MEK C4H8OH 4467
+ Benzene C6H6H 3151
+ 2-Pentanone C5H10OH 4510
+ Toluene C7H8H 3978
+ Phenol C6H6OH 4076
+ Furfural C5H4O2H 7460
+ Methyl Isobutyl Ketone C6H12OH 3988
+ Styrene C8H8H 4289
+ O-xylene C8H10H 4241
+ m-Cresol C7H8OH 4299
+ 1,2,4-Teimethylbenzene C9H12H 4413
+ Naphthalene C10H8H 5117
+ a-Pinene C10H16H 2332
Species calibrated with the Liquid Calibration Unit (LCU).
+ Formic acid CH2O2H 856.6
+ Acetic acid C2H4O2H 1711
6
+ Propionic acid C3H6O2H 2072
+ Butyric acid C4H8O2H 2358
+ Pyrrole C4H5NH 2842
+ Formamide CH3NOH 2871
+ Acetamide C2H5NOH 3992
133 134
7
135 Table S2. The fraction of product ions detected as VOC•H+ ions for different VOCs.
+ VOC species Ion formula VOC∙H
+ Formaldehyde CH2OH 1
+ Methanol CH4OH 1
+ Acetonitrile C2H3NH 1
+ Acetaldehyde C2H4OH 1
+ Ethanol C2H6OH 1
+ Acrolein C3H4OH 1
+ Acetone C3H6OH 0.97
+ Furan C4H4OH 1
+ Isoprene C5H8H 0.87
+ MVK C4H6OH 0.62
+ MEK C4H8OH 0.87
+ Benzene C6H6H 1
+ 2-Pentanone C5H10OH 0.94
+ Toluene C7H8H 1
+ Phenol C6H6OH 1
+ Furfural C5H4O2H 1
+ Styrene C8H8H 1
+ O-xylene C8H10H 1
+ m-Cresol C7H8OH 1
+ 1,2,4-Teimethylbenzene C9H12H 1
+ Naphthalene C10H8H 1
+ a-Pinene C10H16H 0.62
136 137
8
138 Table S3. Rate constants of OVOCs representing the combined loss to OH oxidation 139 and photolysis.
∗ jOVOC/[OH] f Species 10−12 cm3 molecule-1 s-1
Formaldehyde 9.4 7.86±0.120 17.26 1.84
Acetaldehyde 15 0.426±0.006 15.42 1.03
Propionaldehyde 20 1.89±0.026 21.89 1.09
n-butyraldehyde 24 3.26±0.046 27.26 1.14
i-butyraldehyde 24 5.64±0.080 29.64 1.24
MACR 29 1.99±0.030 30.99 1.07
Acetone 0.17 0.051±0.0007 0.22 1.29
MEK 1.22 0.368±0.005 1.59 1.30
MVK 20 3.22±0.049 23.22 1.16
Glyoxal 11 3.02±0.044 14.02 1.27
Methyl peroxide 5.5 0.628±0.009 6.13 1.11
Methyl nitrate 0.023 0.107±0.001 0.13 5.65
Ethyl nitrate 0.18 0.122±0.002 0.30 1.67
n-Propyl nitrate 0.58 0.163±0.002 0.74 1.28
i-Propyl nitrate 0.29 0.28±0.004 0.57 1.97
t-butyl nitrate 1.6 0.818±0.011 2.42 1.51
140 f represents the ratio of the rate constant representing the combined losses of reaction
∗ 141 with OH radical and photolysis ( ) and the OH rate constant ( ). 142
9 143 Table S4. The average concentrations of NMHCs measured by GC-MS/FID and their OH rate constants, which were used for calculating OH 144 reactivity.
Compound Average concentration (ppb) OH rate constant (10-12 cm3 molecule-1 s-1) Source of OH rate constants
Cyclohexane 0.075±0.081 6.97 Atkinson 2003 Cyclopentane 0.096±0.060 4.97 Atkinson 2003 Ethane 3.402±1.344 0.248 Atkinson 2003 i-Butane 1.759±1.398 2.12 Atkinson 1997 i-Pentane 1.387±1.234 3.6 Atkinson 1997 Methylcyclohexane 0.089±0.116 4.97 Atkinson 2003 Methylcyclopentane 0.121±0.125 5.2 Atkinson 2003 n-Nonane 0.043±0.032 9.7 Atkinson 2003 n-Butane 3.155±2.615 2.36 Atkinson 2003 n-Decane 0.029±0.028 11 Atkinson 2003 n-Dodecane 0.062±0.032 13.9 Atkinson 2003 n-Heptane 0.130±0.212 6.76 Atkinson 2003 n-Hexane 0.637±0.795 5.2 Atkinson 2003 n-Octane 0.050±0.049 8.11 Atkinson 2003 n-Pentane 0.774±0.789 3.8 Atkinson 2003 n-Undecane 0.021±0.017 12.3 Atkinson 2003 Propane 6.520±5.175 1.09 Atkinson 2003 2-Methylheptane 0.023±0.031 7 Atkinson 2003
10
2-Methylhexane 0.121±0.189 5.65 Atkinson 2003 2-Methylpentane 0.342±0.333 5.4 Atkinson 2003 2,2-Dimethylbutane 0.042±0.034 2.23 Atkinson 2003 2,2,4-Trimethylpentane 0.038±0.035 3.34 Atkinson 2003 2,3-Dimethylbutane 0.063±0.057 5.78 Atkinson 2003 2,3-Dimethylpentane 0.048±0.066 1.5 Atkinson 2003 2,3,4-Trimethylpentane 0.016±0.013 6.6 Atkinson 2003 2,4-Dimethylpentane 0.044±0.038 4.77 Atkinson 2003 3-Methylheptane 0.023±0.030 7 Yang 2017 3-Methylhexane 0.144±0.224 5.6 Yang 2017 3-Methylpentane 0.335±0.344 5.2 Atkinson 2003 cis-2-Butene 0.028±0.028 56.4 Atkinson 2003 cis-2-Pentene 0.007±0.012 65 Atkinson 2003 Ethene 1.856±1.220 8.52 Atkinson 2003 Isoprene 0.203±0.304 100 Atkinson 2003 Propene 0.458±0.492 26.3 Atkinson 2003 Styrene 0.126±0.188 58 Atkinson 2003 trans-2-Butene 0.038±0.038 56.4 Atkinson 2003 trans-2-Pentene 0.016±0.031 67 Atkinson 2003 1-Butene 0.089±0.066 31.4 Atkinson 2003 1-Hexene 0.025±0.022 37 Atkinson 2003 1-Pentene 0.030±0.020 31.4 Atkinson 2003
11
Benzene 0.454±0.207 1.22 Atkinson 2003 Ethylbenzene 0.344±0.345 7 Atkinson 2003 i-Isopropylbenzene 0.013±0.011 6.3 Atkinson 2003 m-Ethyltoluene 0.039±0.038 11.8 Atkinson 2003 m+p-Xylene 0.927±0.932 18.9 Atkinson 2003 n-Propylbenzene 0.017±0.013 5.8 Atkinson 2003 o-Ethyltoluene 0.020±0.018 11.9 Atkinson 2003 o-Xylene 0.357±0.369 13.6 Atkinson 2003 1,4-Diethylbenzene 0.016±0.014 10 Gilman 2015 p-Ethyltoluene 0.025±0.023 18.6 Atkinson 2003 Toluene 2.056±1.917 5.63 Atkinson 2003 1,2,3-Trimethylbenzene 0.020±0.018 32.7 Atkinson 2003 1,2,4-Trimethylbenzene 0.079±0.088 32.5 Atkinson 2003 1,3,5-Trimethylbenzene 0.020±0.020 56.7 Atkinson 2003 145
12 146 Table S4. The average concentrations of VOCs measured by PTR-ToF-MS and their OH rate constants, which were used for calculating OH 147 reactivity. OH rate constant Ion exact Average Ion formula Compound (10-12 cm3 Source of OH rate constants mass (Th) concentration (ppb) molecule-1 s-1) Common OVOCs 30.0178 CH2O Formaldehyde 2.991±2.059 9.4 Atkinson 2003 32.0335 CH4O Methanol 11.43±7.612 0.8 Atkinson 2003 44.0335 C2H4O Acetaldehyde 2.027±1.292 15.0 Atkinson 2003 56.0335 C3H4O Acrolein 0.173±0.102 20.0 Gilman 2015 58.0491 C3H6O Acetone 3.798±2.508 0.2 Atkinson 2003 70.0491 C4H6O MVK+MACR 0.362±0.249 24.8 Koss 2018 72.0648 C4H8O MEK 1.420±1.309 5.5 Koss 2018 86.0804 C5H10O Pentanones 0.085±0.049 7.9 Atkinson 2003 100.096 C6H12O Hexanones 0.101±0.091 18.6 Koss 2018 NMHCs # 184.36 C13H28 Tridecane 0.066±0.060 15.3 Atkinson 2003 # 198.39 C14H30 Tetradecane 0.050±0.047 16.7 Atkinson 2003 # 212.41 C15H32 Pentadecane 0.045±0.042 18.1 Atkinson 2003 # 226.44 C16H34 Hexadecane 0.036±0.033 19.4 Atkinson 2003 # 240.46 C17H36 Heptadecane 0.021±0.020 20.7 Atkinson 2003 # 254.49 C18H38 Octadecane 0.013±0.014 21.9 Atkinson 2003 # 268.52 C19H40 Nonadecane 0.005±0.009 23 Atkinson 2003
13
# 282.54 C20H42 Eicosane 0.0007±0.004 24 Atkinson 2003
40.038 C3H4 1,2-Propadiene 0.758±0.971 0.695 Pfannerstill 2019
66.054 C5H6 Cyclopentadiene 0.038±0.029 92.0 Gilman 2015
82.085 C6H10 Methylcyclopentane 0.225±0.158 6.97 Atkinson 2003
84.101 C6H12 Hexene isomers 0.098±0.078 37 Atkinson 2003
94.085 C7H10 Terpene fragment 0.047±0.041 46.8 Pfannerstill 2019
96.101 C7H12 C7 cycloalkanes 0.103±0.073 9.64 Atkinson 2003
102.054 C8H6 Phenylacetylene 0.005±0.004 1.0 Gilman 2015
108.101 C8H12 Terpene fragment 0.036±0.041 107 Pfannerstill 2019
110.116 C8H14 C8 cycloalkanes 0.075±0.055 9.64 Atkinson 2003
116.07 C9H8 Indene 0.004±0.009 78.0 Atkinson 2003
118.086 C9H10 Indane 0.032±0.031 50.4 Atkinson 2003
128.07 C10H8 Naphthalene 0.052±0.061 23.0 Atkinson 2003
130.086 C10H10 Methyl indene 0.004±0.005 28.5 Koss 2018
132.101 C10H12 Tetrahydronaphthalene 0.028±0.026 33.0 Koss 2018
134.117 C10H14 C10 aromatics 0.133±0.141 9.5 Koss 2018
136.132 C10H16 Monoterpenes 0.161±0.245 162.8 Koss 2018
142.086 C11H10 Methyl naphthalene 0.015±0.017 50.0 Koss 2018
144.101 C11H12 C11 6-DBE 0.001±0.003 78.0 Koss 2018
146.116 C11H14 aromatic fragment 0.011±0.015 58 Pfannerstill 2019
148.132 C11H16 C11 aromatics 0.030±0.031 50.0 Koss 2018
152.07 C12H8 Acenaphtylene 0.001±0.003 15.1 Koss 2018
14 156.101 C12H12 C2 naphthalene 0.008±0.009 60.0 Koss 2018
160.132 C12H16 aromatic fragment 0.009±0.012 58 Pfannerstill 2019
162.148 C12H18 C12 aromatics 0.010±0.010 113.0 Koss 2018
174.148 C13H18 C13 5-DBE 0.005±0.008 38.5 Pfannerstill 2019
176.164 C13H20 C13 aromatics 0.009±0.010 113.0 Koss 2018 Novel OVOCs
46.0128 CH2O2 Formic acid 1.880±3.155 0.4 Koss 2018
46.0491 C2H6O Ethanol 5.634±5.192 3.2 Atkinson 2003
48.0284 CH4O2 Methane diol 0.005±0.003 7.0 Koss 2018
54.0178 C3H2O Propynal 0.005±0.057 20.0 Koss 2018
58.0128 C2H2O2 Glyoxal 0.001±0.002 11.0 Atkinson 2003
60.0284 C2H4O2 Acetic acid 4.618±4.681 3.7 Koss 2018
62.044 C2H6O2 Ethane diol 0.070±0.068 14.5 Pfannerstill 2019
64.023 CH4O3 formic acid water 0.039±0.048 7.1 Pfannerstill 2019 cluster 68.0335 C4H4O Furan 0.055±0.036 40.0 Gilman 2015
70.0128 C3H2O2 Propiolic acid 0.008±0.010 26.0 Koss 2018
72.0284 C3H4O2 Methyl glyoxal 0.143±0.093 21.1 Koss 2018
74.0441 C3H6O2 Propanoic acid 1.438±2.188 2.2 Koss 2018
76.059 C3H8O2 Propane diols 0.053±0.046 16.2 Pfannerstill 2019
80.0335 C5H4O Cyclopentadiene ketone 0.006±0.005 20.0 Gilman 2015 2-methylfuran
82.0491 C5H6O Methyl furan 0.081±0.063 37.1 Gilman 2015 cyclopentenone
15
84.0284 C4H4O2 Furanone 0.036±0.025 44.5 Gilman 2015
84.0648 C5H8O C5 ketones 0.060±0.043 11.5 Atkinson 2003, NIST Database
86.0441 C4H6O2 2,3-Butanedione ± 0.8 Gilman 2015, NIST Database
88.0233 C3H4O3 Pyruvic acid 0.009±0.026 0.1 Gilman 2015
88.0597 C4H8O2 Methyl propanoate 2.273±2.367 0.9 Koss 2018
94.0491 C6H6O Phenol 0.039±0.030 28.0 Gilman 2015
96.0284 C5H4O2 Furfural 0.023±0.020 35.6 Gilman 2015
96.0648 C6H8O Dimethyl or ethyl furan 0.039±0.025 132.0 Gilman 2015 25dimethylfuran
98.0441 C5H6O2 Methyl furanone 0.050±0.033 13.6 Koss 2018
98.0804 C6H10O Hexenones 0.262±0.278 6.4 Atkinson 2003 cyclohexanone
100.023 C4H4O3 Dihydro furandione 0.040±0.062 20.0 Koss 2018
100.06 C5H8O2 Methyl methacrylate 0.248±0.163 30.3 Gilman 2015
102.039 C4H6O3 Acetic anhydride 0.026±0.020 43.0 Koss 2018
102.0753 C5H10O2 Pentanoic acids 0.058±0.055 8.71 Pfannerstill 2019
106.049 C7H6O Benzaldehyde 0.104±0.099 12.0 Atkinson 2003
108.028 C6H4O2 Benzoquinone 0.016±0.015 4.6 NIST Database
108.065 C7H8O Cresols 0.028±0.023 26.2 NIST Database
110.044 C6H6O2 Methyl furfural 0.022±0.017 80.1 Koss 2018
110.08 C7H10O C3 furan 0.026±0.017 23.3 Koss 2018
112.023 C5H4O3 Methylfurandione 0.052±0.049 49.0 Koss 2018
112.06 C6H8O2 Dimethylfuranone 0.043±0.031 57.0 Koss 2018
112.096 C7H12O Ethyl cyclopentanone 0.029±0.028 10.0 NIST Database cycloheptanone
16
114.039 C5H6O3 C5 3-oxy 3DBE 0.029±0.024 100.0 Koss 2018
114.075 C6H10O2 C6 diketone isomers 0.075±0.057 20.0 Koss 2018
114.112 C7H14O heptanal 0.019±0.013 21.4 Atkinson 2003
116.055 C5H8O3 C5 3-oxy 2-DBE 0.022±0.017 5.0 Koss 2018 isomers 116.091 C6H12O2 Butyl ester acetic acid 0.135±0.136 6.0 NIST Database
118.049 C8H6O Benzofuran 0.006±0.007 37.0 NIST Database
120.065 C8H8O Tolualdehyde 0.056±0.044 16.0 Atkinson 2003 average tolualdehydes
122.044 C7H6O2 Salicyladehyde 0.022±0.023 38.0 Koss 2018
122.08 C8H10O Ethylphenol 0.012±0.012 46.6 Koss 2018
124.023 C6H4O3 Hydroxy 0.002±0.002 4.6 Koss 2018 benzoquiunone 124.06 C7H8O2 guaiacol 0.014±0.011 75.0 NIST Database
124.096 C8H12O C4 furan 0.018±0.010 40.4 Pfannerstill 2019
126.039 C6H6O3 Hydroxymethyl furfural 0.012±0.009 100.0 Koss 2018
126.111 C8H14O Cyclooctanone 0.024±0.027 98.8 Pfannerstill 2019
128.055 C6H8O3 Methyl hydroxy 0.023±0.019 132.0 Koss 2018 dihydrofurfural 128.127 C8H16O Octanal 0.021±0.015 11 Pfannerstill 2019
132.065 C9H8O Methyl benzofurans 0.004±0.005 37.0 Gilman 2015
134.08 C9H10O 3-methylacetophenone 0.012±0.010 4.5 NIST Database
136.06 C8H8O2 Methyl benzoic acid 0.019±0.018 12.0 Koss 2018
138.075 C8H10O2 Creosol 0.008±0.007 100.0 NIST Database
17
140.127 C9H16O C9 carbonyl +1DBE 0.014±0.010 43.5 Pfannerstill 2019
144.05 C6H8O4 C6 diacid +1DBE 0.004±0.003 4.6 Koss 2018
144.065 C10H8O Ethenyl benzofuran 0.001±0.002 37.0 Koss 2018
146.08 C10H10O Dimethylbenzofuran 0.004±0.004 37.0 Koss 2018
148.096 C10H12O Methyl chavicol 0.008±0.007 50.0 NIST Database: 1-methoxy-4-(2- (estragole) propenyl) benzene 150.075 C9H10O2 Vinyl guaiacol 0.004±0.004 100.0 Koss 2018
152.055 C8H8O3 Vanillin 0.016±0.010 85.0 Koss 2018
152.127 C10H16O Camphor 0.028±0.018 4.3 Atkinson 2003
154.07 C8H10O3 Syringol 0.004±0.004 100.0 Koss 2018
154.143 C10H18O Linalool 0.012±0.009 25.0 NIST Database Fenchol, Borneol
156.159 C10H20O Decanal 0.051±0.066 13.0 Atkinson 2003 2-decanone
164.091 C10H12O2 Eugenol 0.003±0.003 100.0 Koss 2018 N/S-containing species 27.0182 HCN HCN 0.003±0.002 0.0 Cicerone 1983 33.995 H2S Hydrogen sulfide 0.005±0.004 4.6 NIST database
41.0338 C2H3N Acetonitrile 0.412±2.258 0.02 Gilman 2015
43.0495 C2H5N Etheneamine 0.010±0.011 0.2 Koss 2018
45.0287 CH3NO Formamide 0.046±0.092 1.5 NIST database: CH2=NOH
45.0651 C2H7N Ethylamine 0.004±0.007 45.5 Koss 2018
48.0106 CH4S Methane thiol 0.012±0.014 33.0 NIST database
53.0338 C3H3N Acrylonitrile 0.011±0.007 4.0 Gilman 2015
18
55.0495 C3H5N Propane nitrile 0.003±0.004 0.3 Gilman 2015
57.0287 C2H3NO Methyl isocyanate 0.011±0.007 0.1 Koss 2018
57.0651 C3H7N Propene amine 0.004±0.005 15.0 Koss 2018
59.0444 C2H5NO Acetamide 0.029±0.055 8.6 NIST database
61.0237 CH3NO2 Nitromethane 0.006±0.006 0.3 Gilman 2015
62.0263 C2H6S Dimethyl sulfide 0.010±0.012 6.0 NIST database
65.0338 C4H3N Cyanoallene isomers 0.001±0.007 4.0 Koss 2018
67.0495 C4H5N Pyrrole 0.006±0.007 111.4 Gilman 2015
69.0651 C4H7N Dihydropyrrole 0.008±0.004 7.7 Koss 2018
71.0808 C4H9N Butene amines 0.001±0.001 25.0 Koss 2018
73.0237 C2H3NO2 Nitroethene 0.001±0.007 1.2 NIST Database
73.06 C3H7NO C3 amides 0.350±0.616 12.5 Pfannerstill 2019
75.0393 C2H5NO2 Nitroethane 0.005±0.004 0.1 NIST Database
77.0008 CH3NOS Sulfinyl methanamine 0.001±0.001 0.2 Koss 2018
79.0495 C5H5N Pyridine 0.010±0.006 5.6 Koss 2018
81.0651 C5H7N Methyl pyrrole 0.004±0.006 62.7 Gilman 2015
83.0808 C5H9N C5 nitrile 0.007±0.003 0.5 Koss 2018
89.055 C3H7NO2 Nitropropanes 0.001±0.002 1.2 NIST Database
93.0287 C5H3NO 2-furancarbonitrile 0.000±0.001 40.0 Koss 2018
93.0651 C6H7N 2-methyl pyridine 0.006±0.005 2.6 NIST Database methylpyridines average
93.9984 C2H6S2 Dimethyl disulfide 0.004±0.005 230.0 NIST Database
95.0444 C5H5NO 4-Pyridinol 0.001±0.001 0.5 Koss 2018
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95.0808 C6H9N 1-ethyl pyrrole 0.001±0.001 145.0 Koss 2018
97.0964 C6H11N 4-methylpentanenitrile 0.002±0.001 5.0 Koss 2018
103.049 C7H5N Benzonitrile 0.008±0.006 1.0 Gilman 2015
105.065 C7H7N Vinylpyridine 0.001±0.003 57.0 NIST Database
107.044 C6H5NO nitrosobenzene or 0.002±0.002 12.0 Koss 2018 pyridine aldehyde 107.081 C7H9N Toluidine 0.004±0.005 3.2 NIST Database
109.096 C7H11N C7 acrylonitrile 0.001±0.001 89.4 Koss 2018
111.039 C5H5NO2 Dihydroxy pyridine 0.002±0.001 10.3 Koss 2018
113.019 C4H3NO3 Nitrofuran 0.005±0.005 40.0 Koss 2018
117.05 C4H7NO3 Butene nitrates 0.004±0.005 50.8 Koss 2018
117.065 C8H7N Indole 0.003±0.003 1.2 Koss 2018
119.081 C8H9N Dihydro pyridine 0.000±0.001 0.5 Koss 2018
123.039 C6H5NO2 Nitrobenzene 0.003±0.005 0.1 NIST Database
125.128 C8H15N C8 nitriles 0.000±0.001 8.0 Koss 2018
131.081 C9H9N Methyl indole 0.001±0.001 5.6 Koss 2018
137.055 C7H7NO2 Nitrotoluene 0.002±0.002 0.1 Koss 2018
149.127 C10H15N C10 aromatic amines 0.000±0.001 148 Pfannerstill 2019 148 # # The concentrations of these higher alkanes were measured by NO+ PTR-ToF-MS.
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149 150 Figure S1. The sampling site at Guangzhou Geochemistry Institute, Chinese Academy 151 of Sciences and its surrounding environment in Guangzhou, China. Note that the map 152 is extracted from © Google Maps by the authors.
21 153 154 Figure S2. Schematic drawing of the inlet system for PTR-ToF-MS during the 155 campaign. 156
22 157 158 Figure S3. The mass spectra from measurements of zero air and diluted gas standard 159 with 5 ppb of various VOCs from a 16-component VOC gas standard. 160
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161 162 Figure S4. Calibration results of PTR-ToF-MS for different species during the 163 campaign. From October 27 to 31, the sensitivity reduction is due to the unstable current 164 of the ion source.
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165 166 Figure S5. The humidity dependence of benzene, toluene, o-xylene, formaldehyde, 167 acetone and acetaldehyde from laboratory experiments.
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168 169 Figure S6. Scatter plots of the PTR-ToF-MS and online GC-MS/FID measurements for 170 (a) toluene, (b) styrene, (c) C8 aromatics, (d) C9 aromatics, (e) Scatter plots of 171 formaldehyde between PTR-ToF-MS and the Hantzsch formaldehyde analyzer. The 172 blue and black lines correspond to the linear regression fits for all data points and the 173 1:1 relationship, respectively.
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174 175 Figure S7. (a) The relationship between mass resolving power and m/Q. (b) High 176 resolution peak fitting for m/z 69 to separate ion peaks of isoprene and furan for the 177 average mass spectrum of PTR-ToF-MS on a typical day (Sep. 20, 2018).
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178 + 179 Figure S8. The transmission efficiency of various VOC masses relative to H3O (H2O). 180
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181 182 Figure S9. The average fractions of different OVOCs species in the total concentrations 183 of OVOCs with one oxygen atom measured by PTR-ToF-MS during the campaign.
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184 185 Figure S10 (a) Correlations of MVK+MACR with isoprene. (b) Time series of the 186 measured MVK+MACR concentrations and MVK+MACR concentrations after 187 deducting anthropogenic sources emissions. (c) Time series of ambient concentrations 188 of MVK+MACR and isoprene and isoprene concentrations converted back to the
189 source (isopreneinitial). 190
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191 192 Figure S11. Comparisons of measured and calculated photolysis rates of H2O2 and 193 HCHO.
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194 195 Figure S12. Scatter plot of the concentrations of acetylene versus CO during the 196 campaign. The blue line is the linear fit to the data points in the plot. 197
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198 199 Figure S13. (a) Diurnal variations of m+p-xylene/ethylbenzene concentration ratios. 200 Red dots are measured ratios during the campaign. Blue line indicates hourly geometric 201 average, and gray areas are geometric standard deviations. (b) Correlation of m+p- 202 xylene with ethylbenzene. The dashed lines in both graphs indicate the estimated initial 203 emission ratio of m +p-xylene/benzene. 204 205
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206 207 Figure S14. Comparisons of measured and calculated concentrations for (a) CxHyO1,
208 (c) CxHyO2, and (e) CxHyO≥3. The different colors represent the four different terms of
209 Eq. 1. Scatterplots of the calculated and measured concentrations for (b) CxHyO1, (d)
210 CxHyO2, and (f) CxHyO≥3. 211
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212 213 Figure S15. Scatter plot of the measured OH reactivity and the concentrations of CO 214 during the campaign. The blue line is the linear fit to the data points in the plot.
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215 216 Figure S16. The correlation coefficients between concentrations of different VOCs and 217 the missing OH reactivity. 218 219
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220 References 221 Atkinson, R.: Gas-Phase Tropospheric Chemistry of Volatile Organic Compounds: 1. 222 Alkanes and Alkenes, Journal of Physical and Chemical Reference Data - J PHYS 223 CHEM REF DATA, 26, 215-290, 10.1063/1.556012, 1997. 224 Atkinson, R., and Arey, J.: Atmospheric Degradation of Volatile Organic Compounds, 225 Chemical Reviews, 103, 4605-4638, 10.1021/cr0206420, 2003. 226 de Gouw, J. A., Gilman, J. B., Kim, S.-W., Alvarez, S. L., Dusanter, S., Graus, M., 227 Griffith, S. M., Isaacman-VanWertz, G., Kuster, W. C., Lefer, B. L., Lerner, B. M., 228 McDonald, B. C., Rappenglück, B., Roberts, J. M., Stevens, P. S., Stutz, J., Thalman, 229 R., Veres, P. R., Volkamer, R., Warneke, C., Washenfelder, R. A., and Young, C. J.: 230 Chemistry of Volatile Organic Compounds in the Los Angeles Basin: Formation of 231 Oxygenated Compounds and Determination of Emission Ratios, Journal of 232 Geophysical Research: Atmospheres, 123, 2298-2319, 10.1002/2017jd027976, 2018. 233 Gilman, J. B., Lerner, B. M., Kuster, W. C., Goldan, P. D., Warneke, C., Veres, P. R., 234 Roberts, J. M., de Gouw, J. A., Burling, I. R., and Yokelson, R. J.: Biomass burning 235 emissions and potential air quality impacts of volatile organic compounds and other 236 trace gases from fuels common in the US, Atmospheric Chemistry and Physics, 15, 237 13915-13938, 10.5194/acp-15-13915-2015, 2015. 238 Karl, T., Guenther, A., Turnipseed, A., Tyndall, G., Artaxo, P., and Martin, S.: Rapid 239 formation of isoprene photo-oxidation products observed in Amazonia, Atmos. Chem. 240 Phys., 9, 7753-7767, 10.5194/acp-9-7753-2009, 2009. 241 Koss, A. R., Sekimoto, K., Gilman, J. B., Selimovic, V., Coggon, M. M., Zarzana, K. 242 J., Yuan, B., Lerner, B. M., Brown, S. S., Jimenez, J. L., Krechmer, J., Roberts, J. M., 243 Warneke, C., Yokelson, R. J., and de Gouw, J.: Non-methane organic gas emissions 244 from biomass burning: identification, quantification, and emission factors from PTR- 245 ToF during the FIREX 2016 laboratory experiment, Atmospheric Chemistry and 246 Physics, 18, 3299-3319, 10.5194/acp-18-3299-2018, 2018. 247 Pfannerstill, E. Y., Wang, N., Edtbauer, A., Bourtsoukidis, E., Crowley, J. N., Dienhart, 248 D., Eger, P. G., Ernle, L., Fischer, H., Hottmann, B., Paris, J. D., Stönner, C., Tadic, I., 249 Walter, D., Lelieveld, J., and Williams, J.: Shipborne measurements of total OH 250 reactivity around the Arabian Peninsula and its role in ozone chemistry, Atmos. Chem. 251 Phys., 19, 11501-11523, 10.5194/acp-19-11501-2019, 2019. 252 Saunders, S. M., Jenkin, M. E., Derwent, R. G., and Pilling, M. J.: Protocol for the 253 development of the Master Chemical Mechanism, MCM v3 (Part A): tropospheric 254 degradation of non-aromatic volatile organic compounds, Atmos. Chem. Phys., 3, 161- 255 180, 10.5194/acp-3-161-2003, 2003. 256 Sekimoto, K., Li, S.-M., Yuan, B., Koss, A., Coggon, M., Warneke, C., and de Gouw, 257 J.: Calculation of the sensitivity of proton-transfer-reaction mass spectrometry (PTR- 258 MS) for organic trace gases using molecular properties, International Journal of Mass 259 Spectrometry, 421, 71-94, https://doi.org/10.1016/j.ijms.2017.04.006, 2017. 260 Yang, Y., Shao, M., Keßel, S., Li, Y., Lu, K., Lu, S., Williams, J., Zhang, Y., Zeng, L., 261 Nölscher, A. C., Wu, Y., Wang, X., and Zheng, J.: How the OH reactivity affects the 262 ozone production efficiency: case studies in Beijing and Heshan, China, Atmos. Chem.
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263 Phys., 17, 7127-7142, 10.5194/acp-17-7127-2017, 2017. 264 Yuan, B., Koss, A. R., Warneke, C., Coggon, M., Sekimoto, K., and de Gouw, J. A.: 265 Proton-Transfer-Reaction Mass Spectrometry: Applications in Atmospheric Sciences, 266 Chemical Reviews, 117, 13187-13229, 10.1021/acs.chemrev.7b00325, 2017. 267
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