Influence of gas-to-particle partitioning on the hygroscopic and droplet activation behaviour of alpha-pinene secondary organic aerosol.

Hygroscopic properties of secondary organic aerosol (SOA) formed by photooxidation of different concentrations (10-27 or 220-270 ppb) of alpha-pinene precursor were investigated at different relative humidities (RH) using a hygroscopicity tandem differential mobility analyzer (HTDMA, RH=95-97%) and using the mobile version of the Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile, RH=98-99.3%). In addition, the cloud condensation nuclei (CCN) activity was measured applying two CCN counters (CCNC). An apparent single-hygroscopicity parameter, kappa, of approximately 0.09, approximately 0.07-0.13, and approximately 0.02-0.04 was derived from CCNC, HTDMA and LACIS data, respectively, assuming the surface tension of pure water. Closure between HTDMA and CCNC data was achieved within experimental uncertainty, whereas closure between LACIS and CCNC was only achieved by assuming a concentration-dependent surface tension reduction, consequently resulting in lower CCNC-derived kappa values. Comparing different experimental techniques at varying precursor concentrations in more detail reveals further open questions. Varying precursor concentration influences hygroscopic growth factors at subsaturated RH, while it has no effect on the CCN activation. This difference in behaviour might be caused by precursor concentration-dependent surface tension depression or changing droplet solution concentration dependence of the water activity coefficient with varying SOA composition. Furthermore, evidence was found that the SOA might need several seconds to reach the equilibrium growth factor at high RH.

[1]  M. Facchini,et al.  Surface tension of atmospheric wet aerosol and cloud/fog droplets in relation to their organic carbon content and chemical composition , 2000 .

[2]  Z. Ristovski,et al.  Intercomparison study of six HTDMAs: results and recommendations , 2009 .

[3]  A. Nenes,et al.  A Continuous-Flow Streamwise Thermal-Gradient CCN Chamber for Atmospheric Measurements , 2005 .

[4]  T. Peter,et al.  A combined particle trap/HTDMA hygroscopicity study of mixed inorganic/organic aerosol particles , 2008 .

[5]  Remo Guidieri.  Res , 1995, RES: Anthropology and Aesthetics.

[6]  A. Nenes,et al.  Inferring thermodynamic properties from CCN activation experiments: single-component and binary aerosols , 2007 .

[7]  Ernest Weingartner,et al.  Secondary organic aerosol formation by irradiation of 1,3,5-trimethylbenzene-NOx-H2O in a new reaction chamber for atmospheric chemistry and physics. , 2005, Environmental science & technology.

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

[9]  S. Twomey.  Pollution and the Planetary Albedo , 1974 .

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

[11]  Frank Stratmann,et al.  Hygroscopic growth and activation of HULIS particles: Experimental data and a new iterative parameterization scheme for complex aerosol particles , 2007 .

[12]  Hugh Coe,et al.  A curved multi-component aerosol hygroscopicity model framework: Part 1 Inorganic compounds , 2005 .

[13]  G. Mcfiggans,et al.  Inversion of tandem differential mobility analyser (TDMA) measurements , 2009 .

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

[15]  F. Stratmann,et al.  White-light optical particle spectrometer for in situ measurements of condensational growth of aerosol particles. , 2005, Applied optics.

[16]  J. Seinfeld,et al.  Organic atmospheric particulate material. , 2003, Annual review of physical chemistry.

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

[18]  U. Baltensperger,et al.  Identification of Polymers as Major Components of Atmospheric Organic Aerosols , 2004, Science.

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

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

[21]  Martin Gysel,et al.  Hygroscopic growth and water uptake kinetics of two-phase aerosol particles consisting of ammonium sulfate, adipic and humic acid mixtures , 2007 .

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

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

[24]  John H. Seinfeld,et al.  Cloud condensation nucleus activation properties of biogenic secondary organic aerosol , 2005 .

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

[26]  Thomas de Quincey.  [C] , 2000, The Works of Thomas De Quincey, Vol. 1: Writings, 1799–1820.

[27]  John H. Seinfeld,et al.  Hygroscopicity of secondary organic aerosols formed by oxidation of cycloalkenes, monoterpenes, sesquiterpenes, and related compounds , 2006 .

[28]  S. Pandis,et al.  Cloud condensation nuclei activation of monoterpene and sesquiterpene secondary organic aerosol , 2005 .

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

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

[31]  Laboratory Studies and Numerical Simulations of Cloud Droplet Formation under Realistic Supersaturation Conditions , 2004 .

[32]  Ulrich Pöschl,et al.  Calibration and measurement uncertainties of a continuous-flow cloud condensation nuclei counter (DMT-CCNC): CCN activation of ammonium sulfate and sodium chloride aerosol particles in theory and experiment , 2007 .

[33]  Andrew G. Glen,et al.  APPL , 2001 .

[34]  F. Stratmann,et al.  Measured and modeled equilibrium sizes of NaCl and (NH4)2SO4 particles at relative humidities up to 99.1 , 2005 .

[35]  K. M. Nolan,et al.  R J , 2022 .

[36]  Arthur Garforth,et al.  A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber , 2006 .