Contribution of Organosulfur Compounds to Organic Aerosol Mass

Jun 25, 2012 - (10) This has prompted the question of how organosulfur ... respectively, in urban locations in Mexico, Pakistan, and the United States...
0 downloads 0 Views 895KB Size
Article pubs.acs.org/est

Contribution of Organosulfur Compounds to Organic Aerosol Mass Michael P. Tolocka* Department of Chemistry, University of North Carolina

Barbara Turpin Department of Environmental Sciences, Rutgers University S Supporting Information *

ABSTRACT: Organosulfates have been proposed as products of secondary organic aerosol formation. While organosulfates have been identified in ambient aerosol samples, a question remains as to the magnitude of their contribution to particulate organic mass. At the same time, discrepancies have been observed between total particulate sulfur measured by X-ray fluorescence (XRF) spectroscopy and sulfur present as inorganic sulfate measured by ion chromatography (IC) in fine particulate matter. These differences could be attributed to measurement bias and/or the contribution of other sulfur compounds, including organosulfates. Using the National Park Service IMPROVE PM2.5 database, we examined the disparity between the sulfur and sulfate measurements at 12 sites across the United States to provide upper-bound estimates for the annual average contributions of organosulfates to organic mass. The data set consists of over 150 000 measurements. The 12 sites include Brigantine, NJ, Cape Cod, MA, Washington, DC, Chassahowitzka, FL, Great Smoky Mountains National Park, NC, Okefenokee, GA, Bondville, IL, Mingo, MO, Phoenix, AZ, San Gabriel, CA, Crater Lake National Park, OR, and Spokane, WA. These sites are representative of the different regions of the country: Northeast, Southeast, Midwest, Southwest and Northwest. We estimate that organosulfur compounds could comprise as much as 5−10% of the organic mass at these sites. The contribution varies by season and location and appears to be higher during warm months when photochemical oxidation chemistry is most active.



INTRODUCTION Organosulfur compounds have been identified in fog, rainwater, and in ambient aerosols.1−7 It has been suggested that these compounds are important in secondary organic aerosol formation and are significant reservoirs for sulfur in the atmosphere.8 That is to say that organosulfur compounds are relatively unreactive, have long atmospheric lifetimes9 and could be a substantial contributor to ambient organic aerosol.10 This has prompted the question of how organosulfur compounds are formed in the atmosphere. Laboratory studies have provided several insights into organosulfur formation. For example, Hoffmann and co-workers explored reactions of bisulfite with glyoxal, methylglyoxal, and glyoxylic acid to form stable adducts of sulfur(IV).11−13 They found that adduct stability is a function of droplet acidity and the Taft polar substituent constant, which implies that the formation the sulfate adduct forms from the glyoxal dimer rather than another species. The kinetics of the reactions of alcohols and epoxides with sulfur(VI) have been described as well.14−17 It was found that the direct reactions of sulfuric acid with alcohols to form the product sulfate ester is perhaps too slow to be operative in the troposphere,14,18 but the reaction of epoxides with sulfuric acid is facile,19 where the competition between two nucleophiles, H2SO4 and H2O, favors © 2012 American Chemical Society

the former. In addition to these reaction channels, organosulfates can also form photochemically (e.g., through organic radical− sulfate radical reactions initiated hydrogen-atom abstraction from acidic sulfate by OH radical) in high concentration aqueous solutions,19,20 suggesting that photochemical production in wet aerosols is plausible.20,21 In fact, in a recent smog chamber study of glyoxal uptake onto wet neutral and acidic aerosols22 under both dark and irradiated conditions, it was found that the organosulfate derived from glyoxal only formed in the presence of light, suggesting the importance of a photochemical pathway. Organosulfate species have been measured in ambient aerosols. For example, a recent study by Hatch et al. showed that organosulfate species were found in 65−95% of the submicrometer particles in Atlanta,23 a biogenically influenced urban environment. Olson et al.9 measured lactic acid sulfate and glycolic acid sulfate concentrations of 0.4−3.8 ng/m3 and 1.9− 11.3 ng/m3, respectively, in urban locations in Mexico, Pakistan, and the United States. Froyd et al. showed that isoprene Received: Revised: Accepted: Published: 7978

February 16, 2012 June 15, 2012 June 25, 2012 June 25, 2012 dx.doi.org/10.1021/es300651v | Environ. Sci. Technol. 2012, 46, 7978−7983

Environmental Science & Technology

Article

carbon (OC) by thermal-optical reflectance (TOR)33 measured from 1992 to 2007 were used in this work. XRF sulfur was multiplied by 3 to convert it to sulfate and directly compared to IC sulfate (Figure 1). The sampling frequency for the IMPROVE network is a 1 day in 3 protocol from 1998 to today. Before 1998, samples were collected twice a week.

derivative sulfate ester is therefore one of the most abundant single organic compounds measured in atmospheric aerosol using single particle mass spectrometry.10 Despite these observations, it remains unclear how ubiquitous and abundant organosulfates are. Discrepancies have been observed between the measured sulfur mass concentrations by X-ray fluorescence (XRF) spectroscopy and measured sulfate mass concentrations by ion chromatography (IC).24,25 If particulate sulfur was entirely comprised of inorganic sulfate, then the sulfate mass measured by IC should equal three times the sulfur mass concentration measured by XRF, since the molar mass of sulfur and sulfate are 32 and 96 g/mol, respectively.26 While the 3S/SO42‑ ratio is near 1 at many locations, there are cases where there is more particulate sulfur (by XRF) than can be accounted for by inorganic sulfate (by IC).27 This could indicate either a sampling/analytical bias or the presence of additional sulfurcontaining compounds. While corrections are typically made for self-absorption28,29 of the sample from XRF measurements, there remains a difference between XRF and IC measurements. Some of the differences30 at the lowest concentrations may be due to an underestimation of the sulfur mass by XRF as light elements are more prone to self-attenuation;31 conversely, differences at the highest sample loadings may be affected by nonlinearities in XRF measurements caused by deviations in Beer’s law. By considering both ensemble averages and medians of the data sets, the work herein minimizes the effects of such discrepancies on the analyses performed. In this work, we use XRF and IC measurements to provide upper-bound estimates of the annual contribution of organosulfates to the organic aerosol budget. For this purpose, twelve sites were chosen from the National Park Service IMPROVE database32 that are representative of different geographic regions throughout the United States.

Figure 1. Sulfate measured by ion chromatography and three times total sulfur measured using X-ray fluorescence spectroscopy.

To quantify sulfur in ambient aerosol filter samples, X-ray fluorescence is used. Method details for IMPROVE are provided elsewhere.28,29,31,34 An excellent overview of measurement uncertainties35 is found in Gutknecht et al.29 In their efforts to harmonize measurements across different samplers and XRF analysis protocols for the U.S. EPA Chemical Speciation Network, they found the estimated error from the IMPROVE network across a decade of operation was 4.9% for sulfur. While uncertainties were considerable for some elements (e.g., aluminum31), uncertainties for sulfur were modest. For quantitative sulfate analysis of ambient filter samples, ion chromatography is used. IMPROVE analytical details are published elsewhere.36−38 The error associated with this measurement is on the order of a few percent.39 In order to validate our approach for using the median values throughout the following analysis we analyzed the ratios of (3× sulfur)/sulfate at each site for normality using the Shapiro-Wilk and Kolomogorov-Smirnov tests. Examples are shown in Figure 2. The ratios and the logarithm of the ratios are normally distributed at the 90% confidence level, although not at the 95% level. The least-squares fits to the frequency distribution histograms are quite good (Figure 2), with coefficients of determination usually greater than 0.95 (See Table 2.) Better fits were obtained with the frequency distribution of ratios themselves rather than the logarithm of the ratios. The output of the frequency distribution fits give the median values for the ratios of (3× sulfur) to sulfate (Table 2; Figure 2). Note that if differences between 3 x sulfur and sulfate were entirely due to measurement uncertainties, we would expect this ratio to be normally distributed around 1.0. We also calculated the differences between the 3× sulfur and sulfate for individual measurements and the upper-bound fractional contribution of organosulfates to the organic mass ( fos) using the following equation:



MATERIALS AND METHODS Twelve sites (Table 1) that are representative of the major geographical regions and atmospheric conditions throughout the United States were chosen from the IMPROVE database (See SI Figure S1 for a map of these locations). Fine particle mass (PM2.5), sulfate measured using IC, sulfur by XRF, and organic Table 1. IMPROVE Sites Used in This Analysis (See SI Figure S1 for a Map of These Locations) geographical region

location code

state

Northeast

Brigantine NWR Cape Cod Washington DC.

location

BRIG1 CACO1 WASH1

NJ MA DC

Southeast

Chassahowitzka NWR Great Smoky Mountains NP Okefenokee NWR

CHAS1 GRSM1 OKEF1

FL NC GA

Midwest

Bondville Mingo

BOND1 MING1

IL MO

Northwest

Crater Lake NP Spokane Res.

CRLA1 SPOK1

OR WA

Southwest

Phoenix San Gabriel

PHOE1 SAGA1

AZ CA 7979

dx.doi.org/10.1021/es300651v | Environ. Sci. Technol. 2012, 46, 7978−7983

Environmental Science & Technology

Article

Table 2. Median Sulfur and Sulfate Concentrations across the United States and the Ratio of (3× Sulfur)/Sulfate Which Result from the Fits of the Frequency Distributionsa

a

location code BRIG1 CACO1 WASH1 CHAS1 GRSM1 OKEF1 BOND1 MING1 CRLA1 SPOK1 PHOE1 SAGA1

state

number of samples

average 3 × sulfur (μg/ m3)

average sulfate (μg/m3)

(3× sulfur)/ sulfate

adjusted r2

NJ MA DC FL NC GA IL MO OR WA AZ CA

1824 760 1763 1299 1879 1686 832 807 1639 390 1738 693

3.5 2.5 4.3 3.4 3.6 3.5 3.5 4.0 0.34 0.58 1.2 0.97

3.3 2.5 4.4 3.4 3.5 3.5 3.4 3.9 0.32 0.52 1.1 0.91

1.03 1.07 1.02 1.00 1.03 1.02 1.06 1.03 1.10 1.16 1.06 1.08

0.99 0.99 0.99 0.99 0.99 0.99 0.97 0.97 0.96 0.98 0.99 0.99

The adjusted r2 values give an indication of the goodness of these fits.

Where m3×S, mSO2− and moc are the 3× sulfur, sulfate, and organic 4 carbon concentrations, respectively. On the right-hand side of the equation is the difference between the XRF and the IC concentration measurements normalized by the concentration of organic matter in the collected aerosol. The 1.8 factor is an estimate of the average organic molecular weight to carbon weight.37 Although there is some debate as to the multiplicative factor required to convert OC to organic mass40 1.8 is used here as it is throughout the IMPROVE database since 2005, based on the analysis of Turpin and Lim,33 because most of the sites in IMPROVE are the recipients of aged aerosol.41 OM/OC ratios of 1.8−1.9 have been measured in several locations that are recipients of aged aerosol(see Polidori and references therein).42 An estimate of the organosulfate molecular weight is given by MwOS, and the molecular weight of sulfate is MwSO4. For the former, two estimates were used (156 and 334 u) because the most important organosulfate formation pathways and distribution of organosulfate products are poorly understood.43 These proxies for low and high MW particle-phase organosulfates are within the range of 140−347 u found in Table 3 of Surratt et al.3 Table 3. Site Median Estimates of the Upper Bound Contribution of Organosulfate to Total Organic Mass (Mass Fraction, f OS) Assuming an Average Organosulfate Molecular Weight is 334 u and of 156 ua mass fraction of organosulfur compound to total organic mass ( f OS)

Figure 2. Frequency distributions of (3 × sulfur/sulfate) from the following sites: A. Brigantine, NJ, median value = 1.03, B. Okeefenokee, GA, median value = 1.01 C. Mingo, MO, median value = 1.04 D. Phoenix, AZ, median value = 1.07 E. Spokane, WA, median value = 1.15.

fos =

OS ⎛ m MW 3 × S − mSO24 − ⎞ ⎜ ⎟ OS24 − ⎝ 1.8 × m OC ⎠ MW

location

high MW assumption

low MW assumption

BRIG1 CACO1 WASH1 CHAS1 GRSM1 OKEF1 BOND1 MING1 CRLA1 SPOK1 PHOE1 SAGA1

0.11 ± 0.044 0.20 ± 0.086 0.036 ± 0.017 0.057 ± 0.021 0.075 ± 0.018 0.030 ± 0.020 0.14 ± 0.058 0.14 ± 0.037 0.067 ± 0.040 0.053 ± 0.013 0.033 ± 0.0053 0.11 ± 0.017

0.065 ± 0.026 0.12 ± 0.053 0.022 ± 0.010 0.032 ± 0.012 0.043 ± 0.010 0.016 ± 0.010 0.084 ± 0.034 0.067 ± 0.017 0.041 ± 0.025 0.026 ± 0.0061 0.020 ± 0.0033 0.061 ± 0.0095

(1) a

7980

The error delineated in each column is the 95% confidence interval. dx.doi.org/10.1021/es300651v | Environ. Sci. Technol. 2012, 46, 7978−7983

Environmental Science & Technology

Article

(CRLA1), and the Great Smoky Mountains (GRSM1)) the minimum value occurs in summer and the highest upper bound organosulfate fractions occurring in the colder seasons. The reason for this is not clear. It is noteworthy that Midwest (BOND1 and MING1) sites have the highest contribution during summertime. The MING1 site is located within the “isoprene volcano,”45 an area with extraordinary emissions of isoprene from the high abundance of oak trees in the Ozarks, while BOND1 is northeast of it; both sites have their highest organosulfur contributions in the summer when photochemical activity is highest. Although the concentrations of sulfate are higher on the East coast than the West coast,37 the (3× sulfur)/sulfate ratio is higher at the West coast sites (Table 2), suggesting that organosulfate is a larger contributor to total measured sulfate in locations where sulfate is low (Figure 4). At the same time organosulfate is a

The lower estimate (156 u) is the molecular weight of 2-hydroxy2-sulfethanoic acid, which is known to form from fog/cloud processing1,12,13 of small organic molecules. The larger estimate (334 u) is the molecular weight of 2,3-dihydroxy-2-methyl-4(1,3,4-trihydroxy-2-methylbutoxy)butyl hydrogen sulfate, which forms from aerosol-phase organic oxidation in the presence of acidic sulfate.3,4 While the second case results in a greater contribution of organosulfate to the organic mass, this should be considered an upper limit to the contributions of organosulfates to the organic mass.44 To illustrate the statistical significance of these estimates, 95% confidence intervals were calculated: zσ μ = X̅ ± (2) n where μ is the population mean, X̅ is the arithmetic experimental mean value, z is the standard normal deviate for n samples, and σ is the standard deviation.



RESULTS AND DISCUSSION The site median fos values (Table 3), which represent upper-limit fractional contributions of organosulfate to the total organic mass, range from 2 to 12% using the low molecular weight assumption and from 3 20% using the high molecular weight assumption. The Midwest has the highest fraction of organosulfur to organic mass concentrations, followed by the East Coast sites; Phoenix has the lowest. The fraction of organic matter that is organosulfate does not show a clear association with the sulfate concentration (r2 = 0.1). However, there appears to be some association of f OS to organic mass (SI Figure S2) where the highest fractions of organosulfur compounds are observed for the lowest organic mass concentrations. Figure 3 shows the seasonal variation of fos (the upper bound organosulfate fraction of the organic mass). There can be

Figure 4. (3× sulfur) to sulfate ratio versus sulfate concentration.

larger contributor to total measured organic matter where sulfate is high. There are two possible explanations for the trend observed in this figure. First, it is possible that there is a systematic bias between the XRF and IC measurements that persists even in the median of the distribution (Figure 2). Another is that in locations where regional SO2 emissions are low, organosulfur compounds in the background aerosol are a measurable contributor to total sulfur.46 Such organosulfur compounds could be emitted directly for example from marine sources47 or formed in the atmosphere, for example from isoprene-derived glycoaldehyde, hydroxyacetone, glyoxal, and isoprene epoxydiol,23 or from oceanic organosulfur emissions (e.g., methane sulfonic acid from dimethyl sulfide).48 In other words, the organosulfates found Atlanta may not be unique to that area, and this chemistry could occur for both urban and rural airsheds, making these compounds ubiquitous. Because organosulfates are hypothesized to form through aqueous aerosol-phase chemistry, it would be informative to examine associations between organosulfate and aerosol liquid water concentrations. However, the limitations inherent in analyses that make use of small differences between large values (i.e., 3S and sulfate) are substantial. Such an analysis should be conducted with time-resolved organosulfate measurements where liquid water can be measured or calculated from RH and aerosol composition.

Figure 3. Seasonal variation of the upperbound fraction of organosulfate to organic mass (fOS) according to site location for the high mass assumption for organosulfur compounds (see text for additional details).

considerable variability in the contribution at a particular site. For example, for Bondville, IL (BOND1) the organosulfur mass fraction is at its lowest in winter at ca. 0.05 and highest in summer at ca. 0.25. However, there is less variability in at Okeefenokee, FL (OKEF1) or Phoenix, AZ (PHOE1) where the mass fraction of organosulfur species changes only by a factor of 2. Significantly, at five sites this quantity peaks in summer, at another five sites it peaks in the fall, consistent with a role for photochemistry. The same is true for median organosulfur concentrations (shown in SI Figure S3) which were calculated from the median (3× sulfur) minus sulfate concentrations. However, for three sites (Chassahowitzka (CHAS1), Crater Lake 7981

dx.doi.org/10.1021/es300651v | Environ. Sci. Technol. 2012, 46, 7978−7983

Environmental Science & Technology



Article

(17) Eddingsaas, N. C.; VanderVelde, D. G.; Wennberg, P. O. J. Phys. Chem. A 2010, 114, 8106−8113. (18) Deno, N. C.; Newman, M. S. J. Am. Chem. Soc. 1950, 72, 3852− 3856. (19) Darer, A. I.; Cole-Filipiak, N. C.; O’Connor, A. E.; Elrod, M. J. Environ. Sci. Technol. 2011, 45, 1895−1902. (20) Nozière, B.; Ekström, S.; Alsberg, T.; Holmström, S. Geophys. Res. Lett. 2010, 37, L05806. (21) Perri, M. J.; Lim, Y. B.; Seitzinger, S. P.; Turpin, B. J. Atmos. Environ. 2010, 44, 2658−2664. (22) Galloway, M. M.; Chhabra, P. S.; Chan, A. W. H.; Surratt, J. D.; Flagan, R. C.; Seinfeld, J. H.; Keutsch, F. N. Atmos. Chem. Phys. 2009, 9, 3331−3345. (23) Hatch, L. E.; Creamean, J. M.; Ault, A. P.; Surratt, J. D.; Chan, M. N.; Seinfeld, J. H.; Edgerton, E. S.; Su, Y.; Prather, K. A. Environ. Sci. Technol. 2011, 45, 5105−5111. (24) He, K.; Yang, F.; Ma, Y.; Zhang, Q.; Yao, X.; Chan, C. K.; Cadle, S.; Chan, T.; Mulawa, P. Atmos. Environ. 2001, 35, 4959−4970. (25) Wu, Y.; Hao, J.; Fu, L.; Hu, J.; Wang, Z.; Tang, U. Sci. Total Environ. 2003, 317, 159−172. (26) Stevens, R. K.; Dzubay, T. G.; Russwurm, G.; Rickel, D. Atmos. Environ. (1967) 1978, 12, 55−68. (27) White, W. H.; Ashbaugh, L. L.; Hyslop, N. P.; McDade, C. E. Atmos. Environ. 2005, 39, 6857−6867. (28) Dzubay, T. G.; Stevens, R. K. Environ. Sci. Technol. 1975, 9, 633− 638. (29) Gutknecht, W.; Flanagan, J.; McWilliams, A.; Jayanty, R. K. M.; Kellogg, R.; Rice, J.; Duda, P.; Sarver, R. H. J. Air Waste Manage. Assoc. 2010, 60, 184−194. (30) Hyslop, N. P.; White, W. H. Environ. Sci. Technol. 2008, 42, 5235− 5240. (31) Formenti, P.; Nava, S.; Prati, P.; Chevailler, S.; Klaver, A.; Lafon, S.; Mazzei, F.; Calzolai, G.; Chiari, M. J. Geophys. Res. 2010, 115, doi:10.10129/12009JD012701. (32) Hyslop, N. P.; White, W. H. Atmos. Environ. 2008, 42, 2691− 2705. (33) Chow, J. C.; Watson, J. G.; Chen, L.-W. A.; Chang, M. C. O.; Robinson, N. F.; Trimble, D.; Kohl, S. J. Air Waste Manage. Assoc. 2007, 57, 1014−1023. (34) Ro, C.-U.; Oh, K.-Y.; Kim, H.; Kim, Y. P.; Lee, C. B.; Kim, K. H.; Kang, C. H.; Osan, J.; DeHoog, J.; Worobiec, A.; van Grieken, R. Environ. Sci. Technol. 2001, 35, 4487−4494. (35) Kim, E.; Hopke, P. K. Atmos. Environ. 2007, 41, 567−575. (36) Gao, N.; Cheng, M.-D.; Hopke, P. K. Atmos. Environ. 1994, 28, 1447−1470. (37) Tolocka, M. P.; Solomon, P. A.; Mitchell, W.; Gemmill, D.; Wiener, R. W.; Homolya, J.; Natarajan, S.; Vanderpool, R. W. Aerosol Sci. Technol. 2001, 34, 88−96. (38) Weiss, J.; Weiss, J. Handbook of Ion Chromatography; Wiley-VCH: Weinheim; [Great Britain], 2004. (39) Mosello, R.; Tartari, G. A.; Marchetto, A.; Polesello, S.; Bianchi, M.; Muntau, H. Accredit. Qual. Assur. 2004, 9, 242−246. (40) Turpin, B. J.; Lim, H.-J. Aerosol Sci. Technol. 2001, 35, 602−610. (41) El-Zanan, H. S.; Lowenthal, D. H.; Zielinska, B.; Chow, J. C.; Kumar, N. Chemosphere 2005, 60, 485−496. (42) Polidori, A.; Turpin, B. J.; Davidson, C. I.; Rodenburg, L. A.; Maimone, F. Aerosol Sci. Technol. 2008, 42, 233−246. (43) Romero, F.; Oehme, M. J. Atmos. Chem. 2005, 52, 283−294. (44) Surratt, J. D.; Gómez-González, Y.; Chan, A. W. H.; Vermeylen, R.; Shahgholi, M.; Kleindienst, T. E.; Edney, E. O.; Offenberg, J. H.; Lewandowski, M.; Jaoui, M.; Maenhaut, W.; Claeys, M.; Flagan, R. C.; Seinfeld, J. H. J. Phys. Chem. A 2008, 112, 8345−8378. (45) Wiedinmyer, C.; Greenberg, J.; Guenther, A.; Hopkins, B.; Baker, K.; Geron, C.; Palmer, P. I.; Long, B. P.; Turner, J. R.; Pétron, G.; Harley, P.; Pierce, T. E.; Lamb, B.; Westberg, H.; Baugh, W.; Koerber, M.; Janssen, M. J. Geophys. Res. 2005, 110, D18307. (46) Claeys, M.; Wang, W.; Vermeylen, R.; Kourtchev, I.; Chi, X.; Farhat, Y.; Surratt, J. D.; Gómez-González, Y.; Sciare, J.; Maenhaut, W. J. Aerosol Sci. 2010, 41, 13−22.

CONCLUSIONS The historical record of total sulfur measurements by XRF compared to sulfate measurements by IC for 12 sites across the United States showed a positive bias. While it is possible that other sulfur-containing species or measurement bias could account for this difference, this difference provides an upperbound estimate of 0.1−1 μg/m3 organosulfate or 1−20% of OC. For most sites, the peak organosulfate (upper-bound) fraction occurs in the summer or fall, coincident with photochemical activity. This is consistent with chamber studies showing that these compounds are secondary in origin.



ASSOCIATED CONTENT

S Supporting Information *

This material is available free of charge via the Internet at http:// pubs.acs.org.



AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.



ACKNOWLEDGMENTS We thank those involved with the IMPROVE program who made their data and their publications available to us including Chuck McDade at UC Davis Crocker Laboratory, Jim Flanagan and Bill Gutknecht at RTI, and Paul Solomon at the U.S. EPA.



REFERENCES

(1) Altieri, K. E.; Turpin, B. J.; Seitzinger, S. P. Atmos. Chem. Phys. 2009, 9, 2533−2542. (2) Munger, J. W.; Tiller, C.; Hoffmann, M. R. Science 1986, 231, 247− 249. (3) Surratt, J. D.; Kroll, J. H.; Kleindienst, T. E.; Edney, E. O.; Claeys, M.; Ng, A. S. N. L.; Offenberg, J. H.; Lewandowski, M.; Jaoui, M.; Flagan, R. C.; Seinfeld, J. H. Environ. Sci. Technol. 2007, 41, 517−527. (4) Iinuma, Y.; Muller, C.; Berndt, T.; Boge, O.; Claeys, M.; Herrmann, H. Environ. Sci. Technol. 2007, 41, 6678−6683. (5) Mazzoleni, L. R.; Ehrmann, B. M.; Shen, X.; Marshall, A. G.; Collett, J. L. Environ. Sci. Technol. 2010, 44, 3590−3597. (6) Altieri, K. E.; Turpin, B. J.; Seitzinger, S. P. Environ. sci. Technol. 2009, 43, 6950−6955; Environ. Sci. Technol. 2009, 43, 6950−6955. (7) Blando, J. D.; Porcia, R. J.; Li, T.-H.; Bowman, D.; Lioy, P. J.; Turpin, B. J. Environ. Sci. Technol. 1998, 32, 604−613. (8) Lukács, H.; Gelencsár, A.; Hoffer, A.; Kiss, G.; Horváth, K.; Hartyáni, Z. Atmos. Chem. Phys. 2009, 9, 231−238. (9) Olson, C. N.; Galloway, M. M.; Yu, G.; Hedman, C. J.; Lockett, M. R.; Yoon, T.; Stone, E. A.; Smith, L. M.; Keutsch, F. N. Environ. Sci. Technol. 2011, 45, 6468−6474. (10) Froyd, K. D.; Murphy, S. M.; Murphy, D. M.; de Gouw, J. A.; Eddingsaas, N. C.; Wennberg, P. O. Proc. Natl. Acad. Sci. 2010, 107, 21360−21365. (11) Betterton, E. A.; Hoffmann, M. R. J. Phys. Chem. 1987, 91, 3011− 3020. (12) Olson, T. M.; Hoffmann, M. R. J. Phys. Chem. 1988, 92, 4246− 4253. (13) Olson, T. M.; Hoffmann, M. R. J. Phys. Chem. 1988, 92, 533−540. (14) Minerath, E. C.; Casale, M. T.; Elrod, M. J. Environ. Sci. Technol. 2008, 42, 4410−4415. (15) Minerath, E. C.; Elrod, M. J. Environ. Sci. Technol. 2009, 43, 1386− 1392. (16) Cole-Filipiak, N. C.; O’Connor, A. E.; Elrod, M. J. Environ. Sci. Technol. 2010, 44, 6718−6723. 7982

dx.doi.org/10.1021/es300651v | Environ. Sci. Technol. 2012, 46, 7978−7983

Environmental Science & Technology

Article

(47) Hawkins, L. N.; Russell, L. M.; Covert, D. S.; Quinn, P. K.; Bates, T. S. J. Geophys. Res. 2010, 115, D13201. (48) Barnes, I.; Hjorth, J.; Mihalopoulos, N. Chem. Rev. 2006, 106, 940−975.

7983

dx.doi.org/10.1021/es300651v | Environ. Sci. Technol. 2012, 46, 7978−7983