Open AccessA study of gas‐aerosol equilibrium and aerosol pH in the remote marine boundary layer during the First Aerosol Characterization Experiment (ACE 1)
Author(s) -
Fridlind A. M.,
Jacobson M. Z.
Publication year - 2000
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd900209
Subject(s) - aerosol , relative humidity , sea salt , sulfate aerosol , sulfate , sea salt aerosol , thermodynamic equilibrium , boundary layer , chemistry , environmental science , atmospheric sciences , meteorology , thermodynamics , geology , physics , organic chemistry
A thermodynamic equilibrium model was applied to study the interactions of gas‐phase NH 3 , HNO 3 , and HCl with size‐resolved aerosols and estimate aerosol pH in the remote marine boundary layer during the First Aerosol Characterization Experiment (ACE 1). Analysis of model results and field measurements indicates that accumulation‐mode aerosols were probably in equilibrium with NH 3 , HNO 3 , and HCl simultaneously. The largest coarse‐mode aerosols did not appear to be in equilibrium with HNO 3 , but may have been in equilibrium with NH 3 and HCl. The estimated pH of accumulation‐mode aerosols was 0–2, a function primarily of the amount of sulfate relative to sea salt present in that mode. By contrast, the estimated equilibrium pH of coarse‐mode aerosols was 2–5, a function primarily of relative humidity and gas‐phase HCl. Prior to exposure to HCl, the estimated pH of fresh sea spray aerosols was 7–9, a function primarily of relative humidity. Sensitivity tests showed that the drying of aerosols during the sampling process may have volatilized up to 30% of NH + 4 .