Acid–base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer

Climate models show that particles formed by nucleation can affect cloud cover and, therefore, the earth's radiation budget. Measurements worldwide show that nucleation rates in the atmospheric boundary layer are positively correlated with concentrations of sulfuric acid vapor. However, current nucleation theories do not correctly predict either the observed nucleation rates or their functional dependence on sulfuric acid concentrations. This paper develops an alternative approach for modeling nucleation rates, based on a sequence of acid–base reactions. The model uses empirical estimates of sulfuric acid evaporation rates obtained from new measurements of neutral molecular clusters. The model predicts that nucleation rates equal the sulfuric acid vapor collision rate times a prefactor that is less than unity and that depends on the concentrations of basic gaseous compounds and preexisting particles. Predicted nucleation rates and their dependence on sulfuric acid vapor concentrations are in reasonable agreement with measurements from Mexico City and Atlanta.

[1]  P. Mcmurry,et al.  MEASURED ATMOSPHERIC NEW PARTICLE FORMATION RATES: IMPLICATIONS FOR NUCLEATION MECHANISMS , 1996 .

[2]  C. Kuang,et al.  Chemical ionization mass spectrometric measurements of atmospheric neutral clusters using the cluster-CIMS , 2010 .

[3]  D. R. Hanson,et al.  Measurement of the thermodynamics of the hydrated dimer and trimer of sulfuric acid. , 2006, The journal of physical chemistry. A.

[4]  M. McGrath,et al.  From quantum chemical formation free energies to evaporation rates , 2011 .

[5]  D. R. Hanson,et al.  First measurement of prenucleation molecular clusters , 2000 .

[6]  E. Lovejoy,et al.  Cluster Ion Thermal Decomposition (II): Master Equation Modeling in the Low-Pressure Limit and Fall-Off Regions. Bond Energies for HSO4-(H2SO4)x(HNO3)y , 2001 .

[7]  Matthew J. McGrath,et al.  Atmospheric Cluster Dynamics Code: a flexible method for solution of the birth-death equations , 2011 .

[8]  J. Smith,et al.  Growth rates of freshly nucleated atmospheric particles in Atlanta , 2005 .

[9]  T. Petäjä,et al.  Atmospheric ions and nucleation: a review of observations , 2010 .

[10]  Jorge Lima,et al.  Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation , 2011, Nature.

[11]  J. Smith,et al.  Size and time-resolved growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei , 2012 .

[12]  P. Mcmurry,et al.  Preface to topical collection on new particle formation in Atlanta , 2005 .

[13]  B. Finlayson‐Pitts,et al.  Simplified mechanism for new particle formation from methanesulfonic acid, amines, and water via experiments and ab initio calculations , 2012, Proceedings of the National Academy of Sciences.

[14]  D. R. Hanson,et al.  Measurement of prenucleation molecular clusters in the NH3, H2SO4, H2O system , 2002 .

[15]  R. Cohen,et al.  Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006 , 2007 .

[16]  T. Petäjä,et al.  The effect of H 2 SO 4 - amine clustering on chemical ionization mass spectrometry (CIMS) measurements of gas-phase sulfuric acid , 2011 .

[17]  R. Turco,et al.  Ion-mediated nucleation as an important global source of tropospheric aerosols , 2007 .

[18]  J. Smith,et al.  Hygroscopicity and volatility of 4-10 nm particles during summertime atmospheric nucleation events in urban Atlanta , 2005 .

[19]  Shan‐Hu Lee,et al.  Laboratory‐measured H2SO4‐H2O‐NH3 ternary homogeneous nucleation rates: Initial observations , 2009 .

[20]  Martijn Gough.  Climate change , 2009, Canadian Medical Association Journal.

[21]  C. Kuang,et al.  Dependence of nucleation rates on sulfuric acid vapor concentration in diverse atmospheric locations , 2008 .

[22]  Peter H. McMurry,et al.  First Measurements of Neutral Atmospheric Cluster and 1–2 nm Particle Number Size Distributions During Nucleation Events , 2011 .

[23]  Frank Arnold,et al.  Atmospheric sulphuric acid and aerosol formation : implications from atmospheric measurements for nucleation and early growth mechanisms , 2006 .

[24]  Hanna Vehkamäki,et al.  New parameterization of sulfuric acid‐ammonia‐water ternary nucleation rates at tropospheric conditions , 2007 .

[25]  G. Mann,et al.  Contribution of particle formation to global cloud condensation nuclei concentrations , 2008 .

[26]  C. Timmreck,et al.  An improved parameterization for sulfuric acid-water nucleation rates for tropospheric and stratospheric conditions , 2002 .

[27]  M. Johnston,et al.  Amine reactivity with charged sulfuric acid clusters , 2011 .

[28]  D. R. Hanson,et al.  Sulfuric acid nucleation: power dependencies, variation with relative humidity, and effect of bases , 2012 .

[29]  T. Petäjä,et al.  Atmospheric sulphuric acid and neutral cluster measurements using CI-APi-TOF , 2011 .

[30]  G. Mann,et al.  The contribution of boundary layer nucleation events to total particle concentrations on regional and global scales , 2006 .

[31]  James N. Smith,et al.  Chemical composition of atmospheric nanoparticles during nucleation events in Atlanta , 2005 .

[32]  J. Smith,et al.  A criterion for new particle formation in the sulfur-rich Atlanta atmosphere , 2005 .

[33]  A. Seth,et al.  Global climate change: An introduction and results from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) , 2007 .

[34]  K. Froyd,et al.  Cluster Ion Thermal Decomposition (I): Experimental Kinetics Study and Ab Initio Calculations for HSO4-(H2SO4)x(HNO3)y , 2001 .

[35]  I. Riipinen,et al.  Connections between atmospheric sulphuric acid and new particle formation during QUEST III–IV campaigns in Heidelberg and Hyytiälä , 2006 .

[36]  Hanna Vehkamäki,et al.  Formation and growth rates of ultrafine atmospheric particles: a review of observations , 2004 .

[37]  Peter H. McMurry,et al.  Photochemical aerosol formation from SO2: A theoretical analysis of smog chamber data , 1980 .

[38]  J. Smith,et al.  Estimating nanoparticle growth rates from size-dependent charged fractions: Analysis of new particle formation events in Mexico City , 2008 .

[39]  Howard Reiss,et al.  The Kinetics of Phase Transitions in Binary Systems , 1950 .

[40]  R. McGraw,et al.  Effects of amines on formation of sub‐3 nm particles and their subsequent growth , 2012 .

[41]  Timothy M. VanReken,et al.  Chemical composition of atmospheric nanoparticles formed from nucleation in Tecamac, Mexico: Evidence for an important role for organic species in nanoparticle growth , 2008 .