Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

Christos Fountoukis, A. Nenes, A. Sullivan, R. Weber, T. Van Reken, M. Fischer, E. Matías, M. Moya, D. Farmer, R. C. Cohen

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1μm diameter, semi-volatile partitioning requires 15-30 min to equilibrate; longer time is typically required during the night and early morning hours. Aerosol and gas-phase speciation always exhibits substantial temporal variability, so that aerosol composition measurements (bulk or size-resolved) obtained over large integration periods are not reflective of its true state. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as "equivalent sodium" (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramati- cally. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.

Original languageEnglish
Pages (from-to)2141-2156
Number of pages16
JournalAtmospheric Chemistry and Physics
Volume9
Issue number6
Publication statusPublished - 2009
Externally publishedYes

Fingerprint

thermodynamics
aerosol
partitioning
nitrate
aerosol composition
water uptake
city
gas
ammonium
ammonia
diagram
particle size
sodium
sulfate
prediction
calculation

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Fountoukis, C., Nenes, A., Sullivan, A., Weber, R., Van Reken, T., Fischer, M., ... Cohen, R. C. (2009). Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006. Atmospheric Chemistry and Physics, 9(6), 2141-2156.

Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006. / Fountoukis, Christos; Nenes, A.; Sullivan, A.; Weber, R.; Van Reken, T.; Fischer, M.; Matías, E.; Moya, M.; Farmer, D.; Cohen, R. C.

In: Atmospheric Chemistry and Physics, Vol. 9, No. 6, 2009, p. 2141-2156.

Research output: Contribution to journalArticle

Fountoukis, C, Nenes, A, Sullivan, A, Weber, R, Van Reken, T, Fischer, M, Matías, E, Moya, M, Farmer, D & Cohen, RC 2009, 'Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006', Atmospheric Chemistry and Physics, vol. 9, no. 6, pp. 2141-2156.
Fountoukis C, Nenes A, Sullivan A, Weber R, Van Reken T, Fischer M et al. Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006. Atmospheric Chemistry and Physics. 2009;9(6):2141-2156.
Fountoukis, Christos ; Nenes, A. ; Sullivan, A. ; Weber, R. ; Van Reken, T. ; Fischer, M. ; Matías, E. ; Moya, M. ; Farmer, D. ; Cohen, R. C. / Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006. In: Atmospheric Chemistry and Physics. 2009 ; Vol. 9, No. 6. pp. 2141-2156.
@article{e048f9bbcdfb4f35a883d4f50aade06a,
title = "Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006",
abstract = "Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1μm diameter, semi-volatile partitioning requires 15-30 min to equilibrate; longer time is typically required during the night and early morning hours. Aerosol and gas-phase speciation always exhibits substantial temporal variability, so that aerosol composition measurements (bulk or size-resolved) obtained over large integration periods are not reflective of its true state. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as {"}equivalent sodium{"} (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramati- cally. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.",
author = "Christos Fountoukis and A. Nenes and A. Sullivan and R. Weber and {Van Reken}, T. and M. Fischer and E. Mat{\'i}as and M. Moya and D. Farmer and Cohen, {R. C.}",
year = "2009",
language = "English",
volume = "9",
pages = "2141--2156",
journal = "Atmospheric Chemistry and Physics",
issn = "1680-7316",
publisher = "European Geosciences Union",
number = "6",

}

TY - JOUR

T1 - Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

AU - Fountoukis, Christos

AU - Nenes, A.

AU - Sullivan, A.

AU - Weber, R.

AU - Van Reken, T.

AU - Fischer, M.

AU - Matías, E.

AU - Moya, M.

AU - Farmer, D.

AU - Cohen, R. C.

PY - 2009

Y1 - 2009

N2 - Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1μm diameter, semi-volatile partitioning requires 15-30 min to equilibrate; longer time is typically required during the night and early morning hours. Aerosol and gas-phase speciation always exhibits substantial temporal variability, so that aerosol composition measurements (bulk or size-resolved) obtained over large integration periods are not reflective of its true state. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as "equivalent sodium" (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramati- cally. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.

AB - Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1μm diameter, semi-volatile partitioning requires 15-30 min to equilibrate; longer time is typically required during the night and early morning hours. Aerosol and gas-phase speciation always exhibits substantial temporal variability, so that aerosol composition measurements (bulk or size-resolved) obtained over large integration periods are not reflective of its true state. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as "equivalent sodium" (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramati- cally. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.

UR - http://www.scopus.com/inward/record.url?scp=74849087231&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=74849087231&partnerID=8YFLogxK

M3 - Article

VL - 9

SP - 2141

EP - 2156

JO - Atmospheric Chemistry and Physics

JF - Atmospheric Chemistry and Physics

SN - 1680-7316

IS - 6

ER -