Observations on the Formation, Growth and Chemical Composition of

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Observations on the Formation, Growth and Chemical Composition of Aerosols in an Urban Environment Leigh R. Crilley,† E. Rohan Jayaratne, Godwin A. Ayoko,* Branka Miljevic, Zoran Ristovski, and Lidia Morawska International Laboratory for Air Quality and Health, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4001, Australia S Supporting Information *

ABSTRACT: The charge and chemical composition of ambient particles in an urban environment were determined using a neutral particle and air ion spectrometer and an aerodyne compact time-of-flight aerosol mass spectrometer. Particle formation and growth events were observed on 20 of the 36 days of sampling, with eight of these events classified as strong. During these events, peaks in the concentration of intermediate and large ions were followed by peaks in the concentration of ammonium and sulfate, which were not observed in the organic fraction. Comparison of days with and without particle formation events revealed that ammonium and sulfate were the dominant species on particle formation days while high concentrations of biomass burning OA inhibited particle growth. Analyses of the degree of particle neutralization lead us to conclude that an excess of ammonium enabled particle formation and growth. In addition, the large ion concentration increased sharply during particle growth, suggesting that during nucleation the neutral gaseous species ammonia and sulfuric acid react to form ammonium and sulfate ions. Overall, we conclude that the mechanism of particle formation and growth involved ammonia and sulfuric acid, with limited input from organics.

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INTRODUCTION In the atmosphere, new particle formation is a frequently observed phenomenon in various environments.1 The classical mechanism for formation of these particles is thought to involve gaseous sulfuric acid and water, however this binary nucleation, considered as the sole formation mechanism, typically underestimates the observed nucleation rates in the atmosphere.2 Therefore, a ternary nucleation mechanism with a third species, along with sulfuric acid and water, has been proposed to account for experimental observations. Ammonia is prevalent in the atmosphere and has been shown to enhance new particle formation.3−5 However, recent results from the CLOUD chamber experiment suggest that typical boundary layer concentrations of sulfuric acid and ammonia ( 15 000 cm−3 h−1 were classified as strong PF events, while events with 4000 < dN/dt < 15 000 cm−3 h−1 were classified as weak PF events. All other days were classified as days with no particle formation (NPF). Data Analysis. TOF-AMS data was processed and analyzed using Squirrel v1.51 in IGOR Pro version 6.22. Squirrel was used to generate the organic and error matrix in the range of m/z 13−300 for analysis by Positive Matrix Factorization (PMF). PMF analysis was applied using PMF2 developed by Paatero and Tapper33 and the PMF evaluation tool (PET) for IGOR Pro as described in Ulbrich et al.34 Prior to PMF analysis the data pretreatment set out in Zhang et al.35 was applied to the data. The seed and F-peak values were varied to find the minimum. The number of factors was chosen based upon the guidelines given in Ulbrich et al.34 and Zhang et al.35 and the method employed in this paper is described in detail in Crilley et al.36 Estimations of the oxygen to carbon (O:C) ratios were calculated according to Aiken et al.37 for unit mass resolution data. Principal component analysis (PCA) was performed using the SIMCA v10 modeling tool on the TOF-AMS and NAIS data. The median concentration between 9am and 3 pm for each day was determined for each parameter and this was the value used in the PCA. Pearson’s correlations were calculated in SPSS v19.

In urban environments sulfates, ammonium, and organic species have been observed to contribute to new particle formation and growth.16,17 Nucleation events have been previously observed in Australia in urban environments,18,19 coastal,20 and in eucalypt forest environments.21,22 In Brisbane, gaseous emissions from industrial sources have been shown to influence nucleation events and thus they may be providing the precursors for particle formation.18 Aerosol mass spectrometry, with its high time resolution and ability to measure both particle size and chemical composition has been shown to be a powerful tool but is restricted to analyzing new particle growth due to its particle size cutoff.17 However, the picture is still unclear as to the relative contributions of the chemical species and the role of ions in particle formation and growth. Overall, our knowledge on the mechanisms of particle formation and growth in the atmosphere is incomplete. Thus, the present paper aimed to contribute to the knowledge base by conducting ambient measurements on the charge and chemical composition of particles in an urban environment. We specifically aimed to determine whether there are trends in ion concentration and chemical composition both diurnally and during particle formation and growth events. Particle formation and growth events were identified based upon short-term changes in the concentration of positive and negative ion (small, intermediate and large) and during these events we aimed to see whether there were relationships in the charge and chemical composition, and thus determine which of these factors are contributing to the observed growth events.

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EXPERIMENTAL METHOD Sampling Location. Sampling was conducted at the Queensland University of Technology, Gardens Point campus located in the central business district of Brisbane. An Aerodyne compact Time-Of-Flight Aerosol Mass Spectrometer (TOFAMS) and a Neutral particle and Air Ion Spectrometer (NAIS) both sampled ambient air from the International Laboratory for Air Quality and Health (ILAQH) laboratory on level 6 of M block, located in the center of the campus. To the south of the campus, approximately 200 m from M Block is the Riverside Expressway which records traffic flows of around 135 000 vehicles a day.23 Other potential sources near the campus include the Brisbane River and City botanic gardens. The major industrial area of Brisbane, which includes the Port of Brisbane and two oil refineries lie northeast of the campus, approximately 18km. Sampling for the AMS and NAIS was conducted continuously from 17:00 on the 1st November until 16:00 on the 7th December 2012. Meteorological data was obtained from the Bureau of Meteorology and included observations at 9 am and 3 pm for each day. TOF-AMS Operation. A TOF-AMS was used to measure the chemical composition of nonrefractory PM1 (NR-PM1). A description of the TOF-AMS and its operation can be found elsewhere.24,25 The TOF-AMS was operated in this study according to our previous work,26 with a 5 min sampling interval employed. Ambient air was sampled through a window using conductive rubber tubing approximately 80 cm in length. The use of conductive rubber tubing was not found to introduce artifacts into the measured mass spectra, as the m/z peaks associated with siloxanes27 were not abnormally elevated. Detection limits of the chemical species were determined as per our previous work26 and were 102, 14, 78, and 13, ng m−3 for ammonium, sulfate, organics, and nitrates, respectively which are within the ranges expected for a TOF-AMS.28 Calibrations

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RESULTS AND DISCUSSION Meteorology during Sampling. Sampling was conducted during warmer months in Brisbane and this is reflected in the 6589

dx.doi.org/10.1021/es5019509 | Environ. Sci. Technol. 2014, 48, 6588−6596

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average maximum temperatures 28.8 ± 2.7 °C and an average of 10 ± 3 h of sunlight during sampling. The predominant wind direction was determined by a wind rose plot (Supporting Information (SI), Figure S1) and was North/Northeast. Significant daily rainfall (>2 mm) was only observed on 4 days (11th, 18th, 19th, and 28th November) with an average relative humidity over the sampling period of 55%. Composition and Concentration of Chemical Species. The chemical composition of the nonrefractory PM1 (NRPM1) during the sampling is summarized in Table S1 (SI), with the median diurnal cycle shown in Figure 1. Organics were the

Figure 2. Median diurnal cycles of the PMF-derived factors.

During sampling the predominant wind direction was not from the nearest road (Riverside Expressway) but from the northeast (SI Figure S1). Therefore, the vehicle emissions were slightly aged prior to sampling. In addition, the HOA diurnal cycle (Figure 2) did not follow peak hour traffic,43 which further suggests that the source was not local. The strong and sharp peaks observed in the total organics at around 6am during weekdays were due to HOA. During this time fuel-powered gardening and cleaning equipment was used on campus, and therefore was a likely source of the HOA peaks at this time. A COA source was also identified by PMF, owing to the observation of its diurnal cycle peaks at mealtimes (Figure 2) and higher intensity of the m/z 55 peak compared to the m/z 57 peak.44 The O:C ratio for the COA factor (0.12) was similar to COA factors derived from urban data sets42,45 and cooking source profiles.46 A biomass burning source was attributed to the strong peak at m/z 60 and 73, which is characteristic for biomass burning.39 The O:C ratio of 0.25 found for the BBOA factor is comparable to the expected ratio for BBOA.37 The flat diurnal cycle for the BBOA (Figure 2) and the strong peak at m/z 44 indicates that the source was more regional than local.47 The OOA factor had the characteristic strong signal at m/z 4439 and as indicated by the O:C ratio of 1.12 was highly oxidized. This O:C ratio was higher than observed in the Northern Hemisphere for OOA41 but similar to previous work in Brisbane.36 A peak in concentration centered at 1 pm was observed in the diurnal cycle of the OOA, which suggests the formation of secondary OA by photo-oxidation.17,48 The diurnal cycle of sulfate and ammonium also demonstrated a peak in concentration (Figure 1) at midday, just before the OOA peak. Thus, it may also be involved in the particle formation. Furthermore, the OOA time series was moderately correlated with sulfate (r2 = 0.27; N = 10735) and ammonium (r2 = 0.48; N = 10735) which suggests differing sources or formation mechanisms. In previous work with an AMS, Zhang et al.17 observed the concentration of sulfates increased before the organics during particle formation and growth events. Sulfates and ammonium have previously been identified in the literature as playing an important role in particle formation.15,49 Therefore, the PF events identified by the NAIS were investigated further, alongside the AMS data in the next section, to determine the contributing species to particle formation and growth. Characterization of Particle Formation Events. PF events were observed on 20 of the 36 days during which 24 h data was obtained. Eight of these days included strong PF

Figure 1. Median diurnal variation of chemical species measured by the AMS.

largest component of the NR-PM1 throughout sampling, accounting for 75% of the average mass concentrations (SI Table S1). The total organics displayed the most variation during the sampling, with large sharp peaks observed at around 6am on the weekdays only (Figure 1). The concentrations of sulfate and ammonium were found to be highly correlated throughout the sampling (r2 of 0.9) with peaks observed frequently around the middle of the day (Figure 1). The total organics and nitrate were also highly correlated (r2 of 0.9) but were not correlated with either sulfate or ammonium. This suggests that there were distinct and different sources or formation mechanisms in the atmosphere for ammonium sulfate, and total organics and nitrates. As the organic fraction was by far the largest component of the NR-PM1, PMF was applied to identify the main sources. A four factor solution was found to best represent the data owing to the residuals, trends in the quality of fit parameter (Q) and evidence of splitting in the five factor solution.35,38 The factors were assigned to hydrocarbon-like OA (HOA), cooking OA (COA), biomass burning OA (BBOA), and oxygenated OA (OOA). The diurnal variation of the factors is given in Figure 2, whereas the time series and mass spectra for the four factors are shown in the SI, Figures S3 and S4, respectively. These sources are typically found in urban environments and the reasons for the source identification are outlined below. The alkyl fragment ion series (m/z 41, 43, 55, 57, etc.) were the characteristic feature of the HOA factor profile (Figure 2) and was similar to HOA reference spectra.39 O:C ratio for this factor (0.18) was similar to that from direct measurements of diesel exhaust40 and within the range reported by Ng et al.41 from 43 urban data sets. The O:C ratio for the HOA was higher than the COA factor, which has been observed previously.42 6590



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events, and are listed in the SI, Table S2. The other 16 days showed no formation events or, if there was one, it had dN/dt < 4000 cm−3 h−1 and was therefore classified as NPF days. One of the strongest PF events recorded was on the 23rd November and this is used to demonstrate the species contributing to particle nucleation and growth. Figure 3 shows the diurnal

Figure 3. Variation of particle number concentration (charged and neutral) as measured with the NAIS on 23 November as a function of time.

variation of particles (charged and neutral) as measured with the NAIS on 23rd November, with a very strong PF event observed between 8.30 and 10.30 am. During this time, the total particle number concentration in the detection size range of the NAIS, 1.6−42 nm, increased by an order of magnitude, from about 15 000 cm−3 to 150 000 cm−3, giving a rate of increase of 67 500 cm−3 h−1. The corresponding value of dN/dt was 28 000 cm−3 h−1. A second burst of particles is observed at about 14 h and a secondary peak, probably due to cooking emissions (see previous section), is clearly visible in the late evening. Figure 4(A) shows that the time of the peak intermediate ion concentration precedes the time of the peak large ion concentration by between 30 min and 1 h. This is typical of all particle growth events. The small ion concentration falls as the large ions increase in number. This is also to be expected and occurs due to attachment of small ions to particles. As can also be seen in Figure 4, during PF events, the concentrations of intermediate and large ions peaks were followed by peaks in the concentrations of ammonium and sulfate. This time lag in peak concentration is to be expected during particle growth, due to the different particle size ranges sampled by the NAIS and AMS. The AMS does not sample particles smaller than 40 nm. Thus, it would only detect the newly formed particles once they reach this size. The observed increase in the concentrations of ammonium and sulfate suggest that the number of particles larger than 40 nm is increasing and indicates that there is particle growth. The total organics concentrations did not typically follow the trend exhibited by sulfate and ammonium. This therefore suggests that ammonium and sulfate rather than organic compounds are involved in the particle formation and growth process. In order to examine whether the trends observed on the 23rd November held, typical PF days were compared to days where there was no observed nucleation. We selected four typical strong PF days (November 4th, 5th, 23rd, and 24th) and four typical NPF days (November 2nd, 3rd, 15th, and December 6th) for further analysis on the characteristics of particle formation events.

Figure 4. Concentrations of ions (A) and chemical species (B) as a function of time on the 23rd November.

Comparison of Typical PF and NPF Days. The median diurnal variations of the ions, PNC and chemical species of the selected PF and NPF days were compared, and are shown in Figure 5. The smaller peak in large ion and PNC between 6 and 7 am (Figure 5A and B) is probably an artifact caused by cleaning activities in the university campus that occurred at around 6 am on weekdays (See previous section). No such peaks were observed during weekends. As expected when this smaller peak is ignored, the diurnal cycle of PNC on PF days demonstrated a peak in concentration during the middle of the day and the concentrations were elevated compared to NPF days. In addition, it is clear that the large ion concentration is at a minimum during the latter part of the night and increases to a maximum near midday. The mean maximum large ion concentration of 4380 cm−3 was significantly higher than the equivalent value of 2480 cm−3 on the NPF days and this difference was clearly due to new particle formation and growth. The large ion concentration showed a secondary peak in the evenings around 20−21 h and we attribute this to the presence of cooking emissions in the urban environment (Figure 2). The small ion concentration showed a much weaker diurnal variation, generally following an inverse relationship to the large ions,50 with a minimum coinciding with the midday large ion peak. The mean maximum small ion concentration was greater on NPF days compared to PF days. Of the chemical species measured by the TOF-AMS, the diurnal variation of the sulfate and ammonium concentrations was observed to more closely follow the trends for PNC and large ion concentrations (Figure 5C). The total organic and 6591



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Figure 5. Diurnal variation of (A) large and small ions, particle number concentration determined by the NAIS (B), inorganic ions (C) and selected PMF-derived organic factors (D) on PF days and NPF days.

nitrate concentration (SI, Figure S5) were also observed to have small peaks at around midday but lacked the sharp increase in concentration observed for ammonium and sulfate. In addition, as the concentrations of total organics and nitrates are lower on PF days, compared to NPF days (SI Figure S5), it would suggest that they were not involved in particle formation or growth. The similarities in the trends for the organics and nitrates indicate a similar source and this is examined further in the next section. In Figure 5D the median diurnal variation of the OOA and BBOA factors are given, and notable differences were observed between the PF and NPF days. First, the concentrations are higher on the NPF days compared to the PF days. There is also a peak in concentration of both OOA and BBOA in the morning, centered at 7am, unlike on PF days, which is indicative of a biomass burning plume. Therefore, this suggests that the presence of OOA, and in particular BBOA, inhibited particle formation and growth, as these particles are likely to be larger than those from other sources of OA51 and as such have more surface area for the low-volatility vapors to condense on. This may explain why no particle formation events were observed on some days that recorded high concentrations of organics, sulfate and ammonium such as 2nd November and 2nd, 3rd and 5th December. This suggests that while existing particles grew from ammonia and sulfates, there were no new particles being formed. Principal Component Analysis. To determine whether the relationships determined in the previous section for selected PF days held true over the whole sampling period, PCA was applied to the median concentrations of the measured parameters (9 am to 3 pm) during this study. The days classified as PF and NPF were analyzed separately and the loading plots for each analysis given in Figure 6. In both of the loadings plots, all of the organic factors and nitrate were correlated; however, the relationships among PNC, ion, sulfate, and ammonium varied from one loadings plot to the other. For the PF days, the PNC, large ion, sulfate, and ammonium concentration were highly correlated with each other (Figure

Figure 6. PCA loadings plots of PF (A) and NPF (B) days. Hrs Sun refers to the daily hours of sunlight and WS to wind speed.

6A). In contrast on the NPF days, PNC was independent of the concentration of large ions, sulfate and to a lesser degree ammonium (Figure 6B). The sulfate and ammonium concentrations were anticorrelated with large ions concentration, pointing to competing processes when there was no new particle formation. In Figure 6B, the total OA and OOA concentrations were independent of the PNC, sulfate, ammonium and large ion concentrations, indicating that the 6592



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area which includes two major oil refineries and a fertilizer factory that emit 6.7 × 106 kg of SO2 and 2.2 × 105 kg of ammonia, respectively, into the atmosphere per annum,59 and these are the probable sources of the additional sulfate and ammonium. In fact, between the 23rd and 26th November, when we observed several strong PF events (SI Table S2), the general wind direction was from the Port of Brisbane (between 45°N and 90°N; see SI Figure S7). This further indicates the influence of industrial emissions of SO2 and ammonia on the observed PF events rather than a seasonal trend. In addition, the results from the previous section also show that the large ion concentration increases sharply during PF events, suggesting that ammonium and sulfate ions are formed during nucleation from the neutral gaseous species, ammonia and sulfuric acid. Overall, we conclude that the mechanism of particle formation and growth in this study involved principally ammonium and sulfate, along with possible involvement from amines but with limited input from other organics species.

organics were not involved in the particle formation and growth, unlike the ammonium and sulfate ions. Therefore, from the PCA, the observed correlations for the PF days suggest that it was sulfate, ammonium, and large ion concentration that are involved in the observed particle formation and growth. The precursor giving rise to the sulfate is likely to be sulfuric acid.52 This is in agreement with the relationships determined for the selected particle growth and nongrowth days, in the previous section. Mechanism of Particle Formation and Growth. Based upon the diurnal variations and PCA, it would appear that ammonium and sulfate are the chemical species principally involved in particle formation and growth during this study. This confirms previous observations at some other locations.17,21,49 For example, Pikridis et al.49 observed that particle formation and growth events occurred only when particles were neutralized and that acidic conditions limited the formation and growth. They suggested that the reason for this was that when the particles are acidic the available gas-phase ammonia is being used up by neutralizing the gaseous sulfuric acid. However, when there was sufficient ammonia to generate neutral particles, the remaining ammonia can participate in particle formation and subsequent growth. As ammonium and sulfate were implicated in particle formation and growth in this study, the molar ratios were examined between ammonium and the inorganic anions, sulfate, and nitrate to see whether the degree of acidity changed for PF and NPF days. Particle acidity was calculated according to the procedure described in Engelhart et al.53 and the resulting molar ratios for PF and NPF days are shown in Figure S6 (SI). The ratio of ammonium to the anions was higher than 1.0, indicating that there was an excess of ammonium than that required to neutralize the sulfate and nitrate present. On PF days the acidity ratio was 1.44 and this is significantly higher than that observed during corresponding NPF times (SI Figure S6). Therefore, we hypothesize that this excess ammonium enabled particle growth as observed by Pikridis et al.49 This excess ammonium may have also been due to organic amines, which have similar fragment ions (m/z 15, 16, and 17) and can thus artificially enhance the ammonium concentration measured by a TOF-AMS.54,55 However, an amine or nitrogen-enriched OA factor (e.g., ref 55) was not observed in the PMF analysis (see previous section), indicating amines were not likely to be a major component of the NRPM1. However, amines have been shown to induce nucleation at trace levels56 and thus may have, in addition to ammonium, been involved in particle formation. While other studies have previously identified a sulfuric acid−ammonia−water ternary nucleation,57 generally in particle formation events organic species have been shown to be the third species in remote and urban areas.8,16,20,21 However, while we cannot rule out the involvement of low-volatile organics in particle formation below the TOF-AMS particle size sampling range, it appears in this study that inorganic species (ammonium and sulfate) were principally involved, as has been observed elsewhere.52 This may be due to the sulfate and ammonium rich nature of the atmosphere in Brisbane during the study. While secondary sulfate concentrations have a seasonal variation that peaks in summer,58 the mean concentrations of sulfate and ammonium were 2−3 times higher in the current study, compared to the previous TOFAMS measurements conducted in Brisbane.26 During sampling, the prominent wind direction was from the Port of Brisbane

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ASSOCIATED CONTENT

S Supporting Information *

Mass spectra and time series of the PMF-derived OA factors and a table describing the observed strong growth events is included in the Supporting Information, as well as additional figures referred to in the text. This material is available free of charge via the Internet at http://pubs.acs.org/

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AUTHOR INFORMATION

Corresponding Author

*Phone: +61 7 3138 2586; fax: +61 7 3138 1804; e-mail: [email protected]. Present Address †

(L.R.C.) School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank the Australian Research Council for Discovery Grant DP0985726 and LEIF Grant LE0668513. REFERENCES

(1) Kulmala, M.; Vehkamäki, H.; Petäjä, T.; Dal Maso, M.; Lauri, A.; Kerminen, V. M.; Birmili, W.; McMurry, P. H. Formation and growth rates of ultrafine atmospheric particles: A review of observations. J. Aerosol Sci. 2004, 35 (2), 143−176. (2) Stanier, C. O.; Khlystov, A. Y.; Pandis, S. N. Nucleation events during the Pittsburgh Air Quality study: Description and relation to key meteororological, gas phase and aerosol parameters. Aerosol Sci. Technol. 2004, 38 (125), 253−264. (3) Weber, R. J.; McMurry, P. H.; Mauldin, L.; Tanner, D. J.; Eisele, F. L.; Brechtel, F. J.; Kreidenweis, S. M.; Kok, G. L.; Schillawski, R. D.; Baumgardner, D. A study of new particle formation and growth involving biogenic and trace gas species measured during ACE 1. J. Geophys. Res.: Atmos. 1998, 103 (D13), 16385−16396. (4) Yu, F. Effect of ammonia on new particle formation: A kinetic H2SO4-H2O-NH3 nucleation model constrained by laboratory measurements. J. Geophys. Res.: Atmos. 2006, 111 (D1), D01204. (5) Kirkby, J.; Curtius, J.; Almeida, J.; Dunne, E.; Duplissy, J.; Ehrhart, S.; Franchin, A.; Gagne, S.; Ickes, L.; Kurten, A.; Kupc, A.; Metzger, A.; Riccobono, F.; Rondo, L.; Schobesberger, S.; Tsagkogeorgas, G.; Wimmer, D.; Amorim, A.; Bianchi, F.; Breitenlechner, M.; David, A.; Dommen, J.; Downard, A.; Ehn, M.; 6593



Article

on particle number concentration within the urban airshed. Atmos. Chem. Phys. 2012, 12 (11), 4951−4962. (20) Modini, R. L.; Ristovski, Z. D.; Johnson, G. R.; He, C.; Surawski, N.; Morawska, L.; Suni, T.; Kulmala, M. New particle formation and growth at a remote, sub-tropical coastal location. Atmos. Chem. Phys. 2009, 9 (19), 7607−7621. (21) Ristovski, Z. D.; Suni, T.; Kulmala, M.; Boy, M.; Meyer, N. K.; Duplissy, J.; Turnipseed, A.; Morawska, L.; Baltensperger, U. The role of sulphates and organic vapours in growth of newly formed particles in a eucalypt forest. Atmos. Chem. Phys. 2010, 10 (6), 2919−2926. (22) Suni, T.; Kulmala, M.; Hirsikko, A.; Bergman, T.; Laakso, L.; Aalto, P. P.; Leuning, R.; Cleugh, H.; Zegelin, S.; Hughes, D.; van Gorsel, E.; Kitchen, M.; Vana, M.; Hõrrak, U.; Mirme, S.; Mirme, A.; Sevanto, S.; Twining, J.; Tadros, C. Formation and characteristics of ions and charged aerosol particles in a native Australian eucalypt forest. Atmos. Chem. Phys. 2008, 8 (1), 129−139. (23) Crilley, L. R.; Knibbs, L. D.; Miljevic, B.; Cong, X.; FairfullSmith, K. E.; Bottle, S. E.; Ristovski, Z. D.; Ayoko, G. A.; Morawska, L. Concentration and oxidative potential of on-road particle emissions and their relationship with traffic composition: Relevance to exposure assessment. Atmos. Environ. 2012, 59 (0), 533−539. (24) Drewnick, F.; Hings, S. S.; DeCarlo, P. F.; Jayne, J. T.; Gonin, M.; Fuhrer, K.; Weimer, S.; Jimenez, J. L.; Demerjian, K. L.; Borrmann, S.; Worsnop, D. R. A new time-of-flight aerosol mass spectrometer (TOF-AMS)Instrument description and first field deployment. Aerosol Sci. Technol. 2005, 39 (7), 637−658. (25) Canagaratna, M. R.; Jayne, J. T.; Jimenez, J. L.; Allan, J. D.; Alfarra, M. R.; Zhang, Q.; Onasch, T. B.; Drewnick, F.; Coe, H.; Middlebrook, A.; Delia, A.; Williams, L. R.; Trimborn, A. M.; Northway, M. J.; DeCarlo, P. F.; Kolb, C. E.; Davidovits, P.; Worsnop, D. R. Chemical and microphysical characterization of ambient aerosols with the Aerodyne aerosol mass spectrometer. Mass Spectrom. Rev. 2007, 26, 185−222. (26) Crilley, L. R.; Ayoko, G. A.; Jayaratne, E. R.; Salimi, F.; Morawska, L. Aerosol mass spectrometric analysis of the chemical composition of nonrefractory PM1 samples from school environments in Brisbane, Australia. Sci. Total Environ. 2013, 458−460, 81− 89. (27) Timko, M. T.; Yu, Z.; Kroll, J.; Jayne, J. T.; Worsnop, D. R.; Miake-Lye, R. C.; Onasch, T. B.; Liscinsky, D.; Kirchstetter, T. W.; Destaillats, H.; Holder, A. L.; Smith, J. D.; Wilson, K. R. Sampling artifacts from conductive silicone tubing. Aerosol Sci. Technol. 2009, 43 (9), 855−865. (28) Drewnick, F.; Hings, S. S.; Alfarra, M. R.; Prevot, A. S. H.; Borrmann, S. Aerosol quantification with the Aerodyne aerosol mass spectrometer: Detection limits and ionizer background effects. Atmos. Meas. Technol. 2009, 2 (1), 33−46. (29) Jayne, J. T.; Leard, D. C.; Zhang, X.; Davidovits, P.; Smith, K. A.; Kolb, C. E.; Worsnop, D. R. Development of an aerosol mass spectrometer for size and composition analysis of submicron particles. Aerosol Sci. Technol. 2000, 33 (1), 49−70. (30) Jimenez, J. L.; Jayne, J. T.; Shi, Q.; Kolb, C. E.; Worsnop, D. R.; Yourshaw, I.; Seinfeld, J. H.; Flagan, R. C.; Zhang, X.; Smith, K. A.; Morris, J. W.; Davidovits, P. Ambient aerosol sampling using the Aerodyne aerosol mass spectrometer. J. Geophys. Res. 2003, 108 (D7), 8425−8438. (31) Manninen, H. E.; Petäjä, T.; Asmi, E.; Riipinen, I.; Nieminen, T.; Mikkilä, J.; Hõrrak, U.; Mirme, A.; Mirme, S.; Laakso, L.; Kerminen, V.-M.; Kulmala, M. Long-term field measurements of charged and neutral clusters using neutral cluster and air ion spectrometer (NAIS). Boreal Environ. Res. 2009, 14, 591−605. (32) Mirme, S.; Mirme, A. The mathematical principles and design of the NAISA spectrometer for the measurement of cluster ion and nanometer aerosol size distributions. Atmos. Meas. Technol. 2013, 6 (4), 1061−1071. (33) Paatero, P.; Tapper, U. Positive matrix factorization: A nonnegative factor model with optimal utilization of error estimates of data values. Environmetrics 1994, 5 (2), 111−126.

Flagan, R. C.; Haider, S.; Hansel, A.; Hauser, D.; Jud, W.; Junninen, H.; Kreissl, F.; Kvashin, A.; Laaksonen, A.; Lehtipalo, K.; Lima, J.; Lovejoy, E. R.; Makhmutov, V.; Mathot, S.; Mikkila, J.; Minginette, P.; Mogo, S.; Nieminen, T.; Onnela, A.; Pereira, P.; Petaja, T.; Schnitzhofer, R.; Seinfeld, J. H.; Sipila, M.; Stozhkov, Y.; Stratmann, F.; Tome, A.; Vanhanen, J.; Viisanen, Y.; Vrtala, A.; Wagner, P. E.; Walther, H.; Weingartner, E.; Wex, H.; Winkler, P. M.; Carslaw, K. S.; Worsnop, D. R.; Baltensperger, U.; Kulmala, M. Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation. Nature 2011, 476 (7361), 429−433. (6) Berndt, T.; Stratmann, F.; Sipila, M.; Vanhanen, J.; Petaja, T.; Mikkila, J.; Gruner, A.; Spindler, G.; Lee Mauldin, R., III; Curtius, J.; Kulmala, M.; Heintzenberg, J. Laboratory study on new particle formation from the reaction OH + SO2: Influence of experimental conditions, H2O vapour, NH3 and the amine tert-butylamine on the overall process. Atmos. Chem. Phys. 2010, 10 (15), 7101−7116. (7) Zhang, R.; Inseon, S.; Zhao, J.; Zhang, D.; Fortner, E. C.; Tie, X.; Molina, L. T.; Molina, M. J. Atmospheric new particle formation enhanced by organic acids. Science 2004, 304 (5676), 1487−1490. (8) Kulmala, M.; Kontkanen, J.; Junninen, H.; Lehtipalo, K.; Manninen, H. E.; Nieminen, T.; Petä j ä , T.; Sipilä , M.; Schobesberger, S.; Rantala, P.; Franchin, A.; Jokinen, T.; Järvinen, E.; Ä ijälä, M.; Kangasluoma, J.; Hakala, J.; Aalto, P. P.; Paasonen, P.; Mikkilä, J.; Vanhanen, J.; Aalto, J.; Hakola, H.; Makkonen, U.; Ruuskanen, T.; Mauldin, R. L.; Duplissy, J.; Vehkamäki, H.; Bäck, J.; Kortelainen, A.; Riipinen, I.; Kurtén, T.; Johnston, M. V.; Smith, J. N.; Ehn, M.; Mentel, T. F.; Lehtinen, K. E. J.; Laaksonen, A.; Kerminen, V.-M.; Worsnop, D. R. Direct observations of atmospheric aerosol nucleation. Science 2013, 339 (6122), 943−946. (9) Yu, F.; Turco, R. P. Ultrafine aerosol formation via ion-mediated nucleation. Geophys. Res. Lett. 2000, 27 (6), 883−886. (10) Iida, K.; Stolzenburg, M.; McMurry, P.; Dunn, M. J.; Smith, J. N.; Eisele, F.; Keady, P. Contribution of ion-induced nucleation to new particle formation: Methodology and its application to atmospheric observations in Boulder, Colorado. J. Geophys. Res.: Atmos. 2006, 111 (D23), D23201. (11) Iribarne, J. V.; Cho, H. R. Atmospheric Physics; Reidel: Holland, 1980. (12) Hirsikko, A.; Nieminen, T.; Gagné, S.; Lehtipalo, K.; Manninen, H. E.; Ehn, M.; Hõrrak, U.; Kerminen, V. M.; Laakso, L.; McMurry, P. H.; Mirme, A.; Mirme, S.; Petäjä, T.; Tammet, H.; Vakkari, V.; Vana, M.; Kulmala, M. Atmospheric ions and nucleation: A review of observations. Atmos. Chem. Phys. 2011, 11 (2), 767−798. (13) Hõrrak, U.; Salm, J.; Tammet, H. Diurnal variation in the concentration of air ions of different mobility classes in a rural area. J. Geophys. Res.: Atmos. 2003, 108 (D20), 4653. (14) Jayaratne, E. R.; Ling, X.; Morawska, L. Ions in motor vehicle exhaust and their dispersion near busy roads. Atmos. Environ. 2010, 44 (30), 3644−3650. (15) Kulmala, M.; Riipinen, I.; Sipilä, M.; Manninen, H. E.; Petäjä, T.; Junninen, H.; Maso, M. D.; Mordas, G.; Mirme, A.; Vana, M.; Hirsikko, A.; Laakso, L.; Harrison, R. M.; Hanson, I.; Leung, C.; Lehtinen, K. E. J.; Kerminen, V.-M. Toward direct measurement of atmospheric nucleation. Science 2007, 318 (5847), 89−92. (16) Zhang, Y. M.; Zhang, X. Y.; Sun, J. Y.; Lin, W. L.; Gong, S. L.; Shen, X. J.; Yang, S. Characterization of new particle and secondary aerosol formation during summertime in Beijing, China. Tellus 2011, 63 (3), 382−394. (17) Zhang, Q.; Stanier, C. O.; Canagaratna, M. R.; Jayne, J. T.; Worsnop, D. R.; Pandis, S. N.; Jimenez, J. L. Insights into the chemistry of new particle formation and growth events in Pittsburgh based on aerosol mass spectrometry. Environ. Sci. Technol. 2004, 38 (18), 4797−4809. (18) Cheung, H. C.; Morawska, L.; Ristovski, Z. D. Observation of new particle formation in subtropical urban environment. Atmos. Chem. Phys. 2011, 11 (8), 3823−3833. (19) Cheung, H. C.; Morawska, L.; Ristovski, Z. D.; Wainwright, D. Influence of medium range transport of particles from nucleation burst 6594



Article

(34) Ulbrich, I. M.; Canagaratna, M. R.; Zhang, Q.; Worsnop, D. R.; Jimenez, J. L. Interpretation of organic components from positive matrix factorization of aerosol mass spectrometric data. Atmos. Chem. Phys. 2009, 9 (9), 2891−2918. (35) Zhang, Q.; Jimenez, J.; Canagaratna, M.; Ulbrich, I.; Ng, N.; Worsnop, D.; Sun, Y. Understanding atmospheric organic aerosols via factor analysis of aerosol mass spectrometry: A review. Anal Bioanal Chem. 2011, 401 (10), 3045−3067. (36) Crilley, L. R.; Ayoko, G. A.; Morawska, L. First measurements of source apportionment of organic aerosols in the southern hemisphere. Environ. Pollut. 2013, 184, 81−88. (37) Aiken, A. C.; DeCarlo, P. F.; Kroll, J. H.; Worsnop, D. R.; Huffman, J. A.; Docherty, K. S.; Ulbrich, I. M.; Mohr, C.; Kimmel, J. R.; Sueper, D.; Sun, Y.; Zhang, Q.; Trimborn, A.; Northway, M.; Ziemann, P. J.; Canagaratna, M. R.; Onasch, T. B.; Alfarra, M. R.; Prevot, A. S. H.; Dommen, J.; Duplissy, J.; Metzger, A.; Baltensperger, U.; Jimenez, J. L. O/C and OM/OC ratios of primary, secondary, and ambient organic aerosols with high-resolution time-of-flight aerosol mass spectrometry. Environ. Sci. Technol. 2008, 42 (12), 4478−4485. (38) Ulbrich, I. M.; Canagaratna, M. R.; Zhang, Q.; Worsnop, D. R.; Jimenez, J. L. Interpretation of organic components from positive matrix factorization of aerosol mass spectrometric data. Atmos. Chem. Phys. 2009, 9 (9), 2891−2918. (39) Ng, N. L.; Canagaratna, M. R.; Jimenez, J. L.; Zhang, Q.; Ulbrich, I. M.; Worsnop, D. R. Real-time methods for estimating organic component mass concentrations from aerosol mass spectrometer data. Environ. Sci. Technol. 2011, 45 (3), 910−916. (40) Chirico, R.; DeCarlo, P. F.; Heringa, M. F.; Tritscher, T.; Richter, R.; Prévôt, A. S. H.; Dommen, J.; Weingartner, E.; Wehrle, G.; Gysel, M.; Laborde, M.; Baltensperger, U. Impact of aftertreatment devices on primary emissions and secondary organic aerosol formation potential from in-use diesel vehicles: Results from smog chamber experiments. Atmos. Chem. Phys. 2010, 10 (23), 11545−11563. (41) Ng, N. L.; Canagaratna, M. R.; Zhang, Q.; Jimenez, J. L.; Tian, J.; Ulbrich, I. M.; Kroll, J. H.; Docherty, K. S.; Chhabra, P. S.; Bahreini, R.; Murphy, S. M.; Seinfeld, J. H.; Hildebrandt, L.; Donahue, N. M.; DeCarlo, P. F.; Lanz, V. A.; Prévôt, A. S. H.; Dinar, E.; Rudich, Y.; Worsnop, D. R. Organic aerosol components observed in northern hemispheric datasets from aerosol mass spectrometry. Atmos. Chem. Phys. 2010, 10 (10), 4625−4641. (42) Huang, X. F.; He, L. Y.; Hu, M.; Canagaratna, M. R.; Sun, Y.; Zhang, Q.; Zhu, T.; Xue, L.; Zeng, L. W.; Liu, X. G.; Zhang, Y. H.; Jayne, J. T.; Ng, N. L.; Worsnop, D. R. Highly time-resolved chemical characterization of atmospheric submicron particles during 2008 Beijing Olympic Games using an Aerodyne high-resolution aerosol mass spectrometer. Atmos. Chem. Phys. 2010, 10 (18), 8933−8945. (43) Mejía, J. F.; Wraith, D.; Mengersen, K.; Morawska, L. Trends in size classified particle number concentration in subtropical Brisbane, Australia, based on a 5 year study. Atmos. Environ. 2007, 41 (5), 1064− 1079. (44) Mohr, C.; DeCarlo, P. F.; Heringa, M. F.; Chirico, R.; Slowik, J. G.; Richter, R.; Reche, C.; Alastuey, A.; Querol, X.; Seco, R.; Peñuelas, J.; Jiménez, J. L.; Crippa, M.; Zimmermann, R.; Baltensperger, U.; Prévôt, A. S. H. Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data. Atmos. Chem. Phys. 2012, 12 (4), 1649−1665. (45) Aiken, A. C.; Salcedo, D.; Cubison, M. J.; Huffman, J. A.; DeCarlo, P. F.; Ulbrich, I. M.; Docherty, K. S.; Sueper, D.; Kimmel, J. R.; Worsnop, D. R.; Trimborn, A.; Northway, M.; Stone, E. A.; Schauer, J. J.; Volkamer, R. M.; Fortner, E.; de Foy, B.; Wang, J.; Laskin, A.; Shutthanandan, V.; Zheng, J.; Zhang, R.; Gaffney, J.; Marley, N. A.; Paredes-Miranda, G.; Arnott, W. P.; Molina, L. T.; Sosa, G.; Jimenez, J. L. Mexico City aerosol analysis during MILAGRO using high resolution aerosol mass spectrometry at the urban supersite (T0) − Part 1: Fine particle composition and organic source apportionment. Atmos. Chem. Phys. 2009, 9 (17), 6633−6653. (46) Mohr, C.; Huffman, J. A.; Cubison, M. J.; Aiken, A. C.; Docherty, K. S.; Kimmel, J. R.; Ulbrich, I. M.; Hannigan, M.; Jimenez, J. L. Characterization of primary organic aerosol emissions from meat

cooking, trash burning, and motor vehicles with high-resolution aerosol mass spectrometry and comparison with ambient and chamber observations. Environ. Sci. Technol. 2009, 43 (7), 2443−2449. (47) Cubison, M. J.; Ortega, A. M.; Hayes, P. L.; Farmer, D. K.; Day, D.; Lechner, M. J.; Brune, W. H.; Apel, E.; Diskin, G. S.; Fisher, J. A.; Fuelberg, H. E.; Hecobian, A.; Knapp, D. J.; Mikoviny, T.; Riemer, D.; Sachse, G. W.; Sessions, W.; Weber, R. J.; Weinheimer, A. J.; Wisthaler, A.; Jimenez, J. L. Effects of aging on organic aerosol from open biomass burning smoke in aircraft and laboratory studies. Atmos. Chem. Phys. 2011, 11 (23), 12049−12064. (48) de Gouw, J. A.; Welsh-Bon, D.; Warneke, C.; Kuster, W. C.; Alexander, L.; Baker, A. K.; Beyersdorf, A. J.; Blake, D. R.; Canagaratna, M.; Celada, A. T.; Huey, L. G.; Junkermann, W.; Onasch, T. B.; Salcido, A.; Sjostedt, S. J.; Sullivan, A. P.; Tanner, D. J.; Vargas, O.; Weber, R. J.; Worsnop, D. R.; Yu, X. Y.; Zaveri, R. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study. Atmos. Chem. Phys. 2009, 9 (10), 3425−3442. (49) Pikridas, M.; Riipinen, I.; Hildebrandt, L.; Kostenidou, E.; Manninen, H.; Mihalopoulos, N.; Kalivitis, N.; Burkhart, J. F.; Stohl, A.; Kulmala, M.; Pandis, S. N. New particle formation at a remote site in the eastern Mediterranean. J. Geophys. Res.: Atmos. 2012, 117 (D12), D12205. (50) Ling, X.; Jayaratne, R.; Morawska, L. The relationship between airborne small ions and particles in urban environments. Atmos. Environ. 2013, 79 (0), 1−6. (51) Ulbrich, I. M.; Canagaratna, M. R.; Cubison, M. J.; Zhang, Q.; Ng, N. L.; Aiken, A. C.; Jimenez, J. L. Three-dimensional factorization of size-resolved organic aerosol mass spectra from Mexico City. Atmos. Meas. Technol. 2012, 5 (1), 195−224. (52) Bzdek, B. R.; Horan, A. J.; Pennington, M. R.; DePalma, J. W.; Zhao, J.; Jen, C. N.; Hanson, D. R.; Smith, J. N.; McMurry, P. H.; Johnston, M. V. Quantitative and time-resolved nanoparticle composition measurements during new particle formation. Faraday Discuss. 2013, 165, 25−43. (53) Engelhart, G. J.; Hildebrandt, L.; Kostenidou, E.; Mihalopoulos, N.; Donahue, N. M.; Pandis, S. N. Water content of aged aerosol. Atmos. Chem. Phys. 2011, 11 (3), 911−920. (54) Hersey, S. P.; Craven, J. S.; Schilling, K. A.; Metcalf, A. R.; Sorooshian, A.; Chan, M. N.; Flagan, R. C.; Seinfeld, J. H. The Pasadena Aerosol Characterization Observatory (PACO): Chemical and physical analysis of the Western Los Angeles basin aerosol. Atmos. Chem. Phys. 2011, 11 (15), 7417−7443. (55) Docherty, K. S.; Aiken, A. C.; Huffman, J. A.; Ulbrich, I. M.; DeCarlo, P. F.; Sueper, D.; Worsnop, D. R.; Snyder, D. C.; Peltier, R. E.; Weber, R. J.; Grover, B. D.; Eatough, D. J.; Williams, B. J.; Goldstein, A. H.; Ziemann, P. J.; Jimenez, J. L. The 2005 Study of Organic Aerosols at Riverside (SOAR-1): Instrumental intercomparisons and fine particle composition. Atmos. Chem. Phys. 2011, 11 (23), 12387−12420. (56) Almeida, J.; Schobesberger, S.; Kurten, A.; Ortega, I. K.; Kupiainen-Maatta, O.; Praplan, A. P.; Adamov, A.; Amorim, A.; Bianchi, F.; Breitenlechner, M.; David, A.; Dommen, J.; Donahue, N. M.; Downard, A.; Dunne, E.; Duplissy, J.; Ehrhart, S.; Flagan, R. C.; Franchin, A.; Guida, R.; Hakala, J.; Hansel, A.; Heinritzi, M.; Henschel, H.; Jokinen, T.; Junninen, H.; Kajos, M.; Kangasluoma, J.; Keskinen, H.; Kupc, A.; Kurten, T.; Kvashin, A. N.; Laaksonen, A.; Lehtipalo, K.; Leiminger, M.; Leppa, J.; Loukonen, V.; Makhmutov, V.; Mathot, S.; McGrath, M. J.; Nieminen, T.; Olenius, T.; Onnela, A.; Petaja, T.; Riccobono, F.; Riipinen, I.; Rissanen, M.; Rondo, L.; Ruuskanen, T.; Santos, F. D.; Sarnela, N.; Schallhart, S.; Schnitzhofer, R.; Seinfeld, J. H.; Simon, M.; Sipila, M.; Stozhkov, Y.; Stratmann, F.; Tome, A.; Trostl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Viisanen, Y.; Virtanen, A.; Vrtala, A.; Wagner, P. E.; Weingartner, E.; Wex, H.; Williamson, C.; Wimmer, D.; Ye, P.; Yli-Juuti, T.; Carslaw, K. S.; Kulmala, M.; Curtius, J.; Baltensperger, U.; Worsnop, D. R.; Vehkamaki, H.; Kirkby, J. Molecular understanding of sulphuric acid-amine particle nucleation in the atmosphere. Nature 2013, 502 (7471), 359−363. 6595



Article

(57) Kulmala, M.; Korhonen, P.; Napari, I.; Karlsson, A.; Berresheim, H.; O’Dowd, C. D. Aerosol formation during PARFORCE: Ternary nucleation of H2SO4, NH3 and H2O. J. Geophys. Res.: Atmos. 2002, 107 (D19), 8111. (58) Friend, A. J.; Ayoko, G. A.; Stelcer, E.; Cohen, D. Source apportionment of PM2.5 at two receptor sites in Brisbane, Australia. Environ. Chem. 2011, 8 (6), 569−580. (59) NPI National Pollution Inventory, Australian Government Department of Sustainability, Environment, Water, Population and Communities. http://www.npi.gov.au/ (accessed 26 September 2013).

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