HR: 0830h
AN: A51E-0721    [PDF]
TI: Aerosol Acidity in the New England Coastal Atmosphere During Summer 2002
AU: * Pszenny, A A
EM: alex.pszenny@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans \& Space, Morse Hall, Room 350, Durham, NH 03824 United States
AU: * Pszenny, A A
EM: alex.pszenny@unh.edu
AF: Mount Washington Observatory, P. O. Box 2310, North Conway, NH 03860 United States
AU: Keene, W C
EM: wck@virginia.edu
AF: University of Virginia, Department of Environmental Sciences, Clark Hall, Charlottesville, VA 22904-4123 United States
AU: Maben, J R
EM: jrm@virginia.edu
AF: University of Virginia, Department of Environmental Sciences, Clark Hall, Charlottesville, VA 22904-4123 United States
AU: Stevenson, E
EM: eric.stevenson@maui.afmc.af.mil
AF: Mount Washington Observatory, P. O. Box 2310, North Conway, NH 03860 United States
AU: Stevenson, E
EM: eric.stevenson@maui.afmc.af.mil
AF: Air Force Research Laboratories, Maui Space Surveillance Site, Boeing LTS, 535 Lipoa Parkway, Suite 200, Kihei, HI 96753 United States
AU: Wall, A
EM: awall@mountwashington.org
AF: Mount Washington Observatory, P. O. Box 2310, North Conway, NH 03860 United States
AB: Aerosol pH controls important multiphase chemical pathways in the atmosphere but absolute values are poorly constrained. As part of the New England Air Quality Study, aerosol pH was quantified based on multiple independent approaches and results were intercompared for consistency. Soluble, reactive trace gases with pH-dependent solubilities (HNO$_{3}$, NH$_{3}$, HCl, HCOOH, and CH$_{3}$COOH) were sampled with mist chambers. Size-segregated aerosols were sampled in parallel with cascade impactors and analyzed for major ionic constituents. H$^{+}$ was measured directly in minimally diluted, 5-$\mu$L spots on surfaces of impaction substrates with a flat-surface, field-effect transistor. Aerosol liquid water contents (LWCs) were calculated with hygrospocity models. Aerosol pHs required to sustain the measured phase partitioning of each analyte were inferred based on corresponding thermodynamic properties and direct pH measurements were extrapolated to ambient LWCs. The ensemble of approaches yielded coherent results. Sea-salt pHs ranged from about 2 to the mid 4s and sub-$\mu$m aerosol pHs ranged from $<$1 to the mid 3s. The H$^{+}$ + SO$_{4}$$^{2-}\leftrightarrow$ HSO$_{4}$$^{-}$ equilibrium strongly buffered aerosol pH in all size fractions.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting