The hygroscopicity parameter (κ) of ambient organic aerosol at a field site subject to biogenic and anthropogenic influences: relationship to degree of aerosol oxidation

Abstract. Cloud condensation nuclei (CCN) concentrations were measured at Egbert, a rural site in Ontario, Canada during the spring of 2007. The CCN concentrations were compared to values predicted from the aerosol chemical composition and size distribution using κ-Kohler theory, with the specific goal of this work being to determine the hygroscopic parameter (κ) of the oxygenated organic component of the aerosol, assuming that oxygenation drives the hygroscopicity for the entire organic fraction of the aerosol. The hygroscopicity of the oxygenated fraction of the organic component, as determined by an Aerodyne aerosol mass spectrometer (AMS), was characterised by two methods. First, positive matrix factorization (PMF) was used to separate oxygenated and unoxygenated organic aerosol factors. By assuming that the unoxygenated factor is completely non-hygroscopic and by varying κ of the oxygenated factor so that the predicted and measured CCN concentrations are internally consistent and in good agreement, κ of the oxygenated organic factor was found to be 0.22±0.04 for the suite of measurements made during this five-week campaign. In a second, equivalent approach, we continue to assume that the unoxygenated component of the aerosol, with a mole ratio of atomic oxygen to atomic carbon (O/C) ≈ 0, is completely non-hygroscopic, and we postulate a simple linear relationship between κorg and O/C. Under these assumptions, the κ of the entire organic component for bulk aerosols measured by the AMS can be parameterised as κorg=(0.29±0.05)·(O/C), for the range of O/C observed in this study (0.3 to 0.6). These results are averaged over our five-week study at one location using only the AMS for composition analysis. Empirically, our measurements are consistent with κorg generally increasing with increasing particle oxygenation, but high uncertainties preclude us from testing this hypothesis. Lastly, we examine select periods of different aerosol composition, corresponding to different air mass histories, to determine the generality of the campaign-wide findings described above.

[1]  Spyros N. Pandis,et al.  An Algorithm for the Calculation of Secondary Organic Aerosol Density Combining AMS and SMPS Data , 2007 .

[2]  D. Toohey,et al.  CC BY 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Cloud Activating Properties of Aerosol Observed during CELTIC , 2007 .

[3]  H. Hansson,et al.  Organic atmospheric aerosols: Review and state of the science , 2000 .

[4]  P. Quinn,et al.  Atmospheric Chemistry and Physics Discussions Interactive comment on “ Influence of particle size and chemistry on the cloud nucleating properties of aerosols ” , 2007 .

[5]  J. Slowik,et al.  Slower CCN growth kinetics of anthropogenic aerosol compared to biogenic aerosol observed at a rural site , 2010 .

[6]  S. Twomey.  The Influence of Pollution on the Shortwave Albedo of Clouds , 1977 .

[7]  M. Andreae,et al.  Sensitivity of CCN spectra on chemical and physical properties of aerosol: A case study from the Amazon Basin , 2002 .

[8]  J. Seinfeld,et al.  Organic aerosol components observed in worldwide datasets from aerosol mass spectrometry , 2009 .

[9]  Qi Zhang,et al.  Deconvolution and quantification of hydrocarbon-like and oxygenated organic aerosols based on aerosol mass spectrometry. , 2005, Environmental science & technology.

[10]  Sonia M. Kreidenweis,et al.  A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 3: Including surfactant partitioning , 2012 .

[11]  R. Martin,et al.  Characterization of a large biogenic secondary organic aerosol event from eastern Canadian forests , 2009 .

[12]  H. Köhler.  The nucleus in and the growth of hygroscopic droplets , 1936 .

[13]  J. Abbatt,et al.  Chemical evolution of secondary organic aerosol from OH-initiated heterogeneous oxidation , 2010 .

[14]  I. George.  OH-initiated Heterogeneous Oxidation of Atmospheric Organic Aerosols , 2010 .

[15]  J. Seinfeld,et al.  Global distribution and climate forcing of carbonaceous aerosols , 2002 .

[16]  M. Petters,et al.  Towards closing the gap between hygroscopic growth and activation for secondary organic aerosol: Part 1 – Evidence from measurements , 2009 .

[17]  M. Ziese,et al.  Influence of gas-to-particle partitioning on the hygroscopic and droplet activation behaviour of alpha-pinene secondary organic aerosol. , 2009, Physical chemistry chemical physics : PCCP.

[18]  M. Ziese,et al.  Influence of gas-to-particle partitioning on the hygroscopic and droplet activation behaviour of alpha-pinene secondary organic aerosol. , 2009, Physical chemistry chemical physics : PCCP.

[19]  K. Broekhuizen,et al.  Partially soluble organics as cloud condensation nuclei: Role of trace soluble and surface active species , 2004 .

[20]  Hans Moosmüller,et al.  Observations of OM/OC and specific attenuation coefficients (SAC) in ambient fine PM at a rural site in central Ontario, Canada , 2010 .

[21]  W. Landman.  Climate change 2007: the physical science basis , 2010 .

[22]  J. D. de Gouw,et al.  Measurements of volatile organic compounds in the earth's atmosphere using proton-transfer-reaction mass spectrometry. , 2007, Mass spectrometry reviews.

[23]  Kenneth A. Smith,et al.  Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Submicron Particles , 2000 .

[24]  P. Brimblecombe,et al.  Thermodynamic Model of the System H + − NH 4 + − Na + − SO 42-− NO 3-− Cl-− H 2 O at 298 . 15 K , 2009 .

[25]  Qi Zhang,et al.  Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically‐influenced Northern Hemisphere midlatitudes , 2007 .

[26]  M. Petters,et al.  Chemical aging and the hydrophobic‐to‐hydrophilic conversion of carbonaceous aerosol , 2006 .

[27]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[28]  M. Petters,et al.  A single parameter representation of hygroscopic growth and cloud condensation nucleus activity , 2006 .

[29]  John H. Seinfeld,et al.  Organic aerosol components observed in Northern Hemispheric datasets from Aerosol Mass Spectrometry , 2010 .

[30]  Shao-Meng Li,et al.  Determination of OM/OC ratios and specific attenuation coefficients (SAC) in ambient fine PM at a rural site in southern Ontario: implications for emission sources, particle aging, and radiative forcing , 2009 .

[31]  U. Lohmann,et al.  An Intensive Study of the Size and Composition of Submicron Atmospheric Aerosols at a Rural Site in Ontario, Canada , 2005 .

[32]  S. Martin,et al.  Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity , 2009 .

[33]  D. Worsnop,et al.  Physicochemical properties and origin of organic groups detected in boreal forest using an aerosol mass spectrometer , 2009 .

[34]  S. Pandis,et al.  Cloud activation of single‐component organic aerosol particles , 2002 .

[35]  M. Petters,et al.  Towards closing the gap between hygroscopic growth and activation for secondary organic aerosol - Part 2: Theoretical approaches , 2008 .

[36]  Martin Gysel,et al.  Cloud forming potential of secondary organic aerosol under near atmospheric conditions , 2008 .

[37]  J. Abbatt,et al.  Comparison between measured and predicted CCN concentrations at Egbert, Ontario: Focus on the organic aerosol fraction at a semi-rural site , 2007 .

[38]  Christoph Hueglin,et al.  Source apportionment of submicron organic aerosols at an urban site by factor analytical modelling of aerosol mass spectra , 2007 .

[39]  V. K. Saxena,et al.  Operation of a Thermal Diffusion Chamber for Measurements on Cloud Condensation Nuclei. , 1970 .

[40]  P. Paatero.  Least squares formulation of robust non-negative factor analysis , 1997 .

[41]  P. Kumar,et al.  Formation of cloud condensation nuclei by oxidative processing: Unsaturated fatty acids , 2004 .

[42]  A. Vlasenko,et al.  Modification of cloud condensation nucleus activity of organic aerosols by hydroxyl radical heterogeneous oxidation , 2009 .

[43]  J. Wilson,et al.  A global black carbon aerosol model , 1996 .

[44]  B. Albrecht.  Aerosols, Cloud Microphysics, and Fractional Cloudiness , 1989, Science.

[45]  J. Abbatt,et al.  Cloud condensation nucleus activity of internally mixed ammonium sulfate/organic acid aerosol particles , 2005 .

[46]  James D. Lee,et al.  Contributions from transport, solid fuel burning and cooking to primary organic aerosols in two UK cities , 2009 .

[47]  G. Evans,et al.  Atmospheric Chemistry and Physics Simultaneous Factor Analysis of Organic Particle and Gas Mass Spectra: Ams and Ptr-ms Measurements at an Urban Site , 2022 .

[48]  Y. H. Zhang,et al.  Cloud condensation nuclei in polluted air and biomass burning smoke near the mega-city Guangzhou, China – Part 1: Size-resolved measurements and implications for the modeling of aerosol particle hygroscopicity and CCN activity , 2008 .

[49]  Qi Chen,et al.  Loading-dependent elemental composition of α-pinene SOA particles , 2008 .

[50]  M. Petters,et al.  Cloud condensation nucleation activity of biomass burning aerosol , 2009 .

[51]  Susan Budavari,et al.  The Merck index , 1998 .

[52]  J. Jimenez,et al.  Aerosol optical properties relevant to regional remote sensing of CCN activity and links to their organic mass fraction : airborne observations over Central Mexico and the US West Coast during MILAGRO / , 2009 .

[53]  Spyros N. Pandis,et al.  CCN activity and droplet growth kinetics of fresh and aged monoterpene secondary organic aerosol , 2008 .

[54]  C. J. Hahn,et al.  Measurements of aromatic hydrocarbon ratios and NOx concentrations in the rural troposphere: Observation of air mass photochemical aging and NOx removal , 1984 .

[55]  James M. Roberts,et al.  Budget of organic carbon in a polluted atmosphere: Results from the New England Air Quality Study in 2002 , 2005 .

[56]  Ulrike Lohmann,et al.  Erratum: ``Prediction of the number of cloud droplets in the ECHAM GCM'' , 1999 .

[57]  Z. Jurányi,et al.  CLOUD FORMING POTENTIAL OF SECONDARY ORGANIC AEROSOL , 2008 .

[58]  Jian Wang,et al.  Effects of aerosol organics on cloud condensation nucleus (CCN) concentration and first indirect aerosol effect , 2008 .

[59]  P. Saxena,et al.  Water-soluble organics in atmospheric particles: A critical review of the literature and application of thermodynamics to identify candidate compounds , 1996 .

[60]  D. Worsnop,et al.  Mass spectral evidence that small changes in composition caused by oxidative aging processes alter aerosol CCN properties. , 2007, The journal of physical chemistry. A.

[61]  B. Svenningsson,et al.  CCN activation of slightly soluble organics: the importance of small amounts of inorganic salt and particle phase , 2004 .

[62]  M. Petters,et al.  A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 2: Including solubility , 2008 .

[63]  J. Slowik,et al.  Measurements of VOCs by proton transfer reaction mass spectrometry at a rural Ontario site: Sources and correlation to aerosol composition , 2009 .

[64]  S. Pandis,et al.  Formation of cloud droplets by multicomponent organic particles , 2003 .

[65]  R. Draxler.  HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website , 2010 .

[66]  Kenneth A. Smith,et al.  Aerosol mass spectrometer for size and composition analysis of submicron particles , 1998 .

[67]  A. Wexler,et al.  Thermodynamic Model of the System H+−NH4+−Na+−SO42-−NO3-−Cl-−H2O at 298.15 K , 1998 .

[68]  Sonia M. Kreidenweis,et al.  Cloud droplet activation of secondary organic aerosol , 2007 .

[69]  A. Nenes,et al.  Cloud condensation nuclei closure during the International Consortium for Atmospheric Research on Transport and Transformation 2004 campaign: Effects of size-resolved composition , 2007 .

[70]  Qi Zhang,et al.  Time- and size-resolved chemical composition of submicron particles in Pittsburgh: Implications for aerosol sources and processes , 2005 .

[71]  M. Cubison,et al.  Prediction of cloud condensation nucleus number concentration using measurements of aerosol size distributions and composition and light scattering enhancement due to humidity , 2007 .

[72]  P. Paatero,et al.  Positive matrix factorization: A non-negative factor model with optimal utilization of error estimates of data values† , 1994 .

[73]  J. Jimenez,et al.  Interpretation of organic components from Positive Matrix Factorization of aerosol mass spectrometric data , 2008 .

[74]  Stephan Borrmann,et al.  A New Time-of-Flight Aerosol Mass Spectrometer (TOF-AMS)—Instrument Description and First Field Deployment , 2005 .

[75]  D. A. Palmer,et al.  Osmotic and Activity Coefficients of Aqueous (NH4)2SO4 as a Function of Temperature, and Aqueous (NH4)2SO4−H2SO4 Mixtures at 298.15 K and 323.15 K , 1996 .

[76]  Shao-Meng Li,et al.  Closure between measured and modeled cloud condensation nuclei ( CCN ) using size-resolved aerosol compositions in downtown Toronto , 2005 .

[77]  Qi Zhang,et al.  O/C and OM/OC ratios of primary, secondary, and ambient organic aerosols with high-resolution time-of-flight aerosol mass spectrometry. , 2008, Environmental science & technology.

[78]  P. DeCarlo,et al.  Elemental analysis of organic species with electron ionization high-resolution mass spectrometry. , 2007, Analytical chemistry.

[79]  Charles E. Kolb,et al.  Ambient aerosol sampling using the Aerodyne Aerosol Mass Spectrometer , 2003 .

[80]  Jian Wang,et al.  CCN predictions using simplified assumptions of organic aerosol composition and mixing state: a synthesis from six different locations , 2009 .

[81]  J. Seinfeld,et al.  Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry , 2010, Proceedings of the National Academy of Sciences.

[82]  Hugh Coe,et al.  Simplification of the representation of the organic component of atmospheric particulates. , 2005, Faraday discussions.

[83]  J. Seinfeld,et al.  Cloud condensation nuclei activity, closure, and droplet growth kinetics of Houston aerosol during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) , 2009 .

[84]  Kimberly A. Prather,et al.  The influence of chemical composition and mixing state of Los Angeles urban aerosol on CCN number and cloud properties , 2008 .

[85]  A. Wexler,et al.  Atmospheric aerosol models for systems including the ions H+, NH4+, Na+, SO42−, NO3−, Cl−, Br−, and H2O , 2002 .

[86]  J. Abbatt,et al.  Organic acids as cloud condensation nuclei: Laboratory studies of highly soluble and insoluble species , 2003 .

[87]  D. R. Worsnop,et al.  Evolution of Organic Aerosols in the Atmosphere , 2009, Science.

[88]  J. Pierce,et al.  Mass spectra deconvolution of low, medium, and high volatility biogenic secondary organic aerosol. , 2009, Environmental science & technology.