Some observations on times to equilibrium for semivolatile polycyclic aromatic hydrocarbons

Journal Article · Sun Jan 01 04:00:00 EST 1995 · Environmental Science and Technology; (United States)

DOI:https://doi.org/10.1021/es00001a005· OSTI ID:6592415

Kamens, R; Odum, J; Fan, Z H ^[1]

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1. Univ. of North Carolina, Chapel Hill, NC (United States)

The relative time scales at which semivolatile gas and particle PAH approach equilibrium under both moderate and cool temperatures were investigated. Combustion particles were added directly from a diesel car and a wood stove to a 190 m[sup 3] outdoor Teflon film chamber. The rate of migration of a gas-phase semivolatile PAH to combustion particles at a warm outdoor temperature was explored by volatilizing solid deuterated pyrene (d10-py) in a hot injector (200[degrees]C) into the rural background air in the chamber atmosphere. After 2 h, diesel exhaust was added to the chamber. Results show an initial rapid migration of d10-py from the gas to the particle phase in an attempt to re-establish equilibrium. The relative closeness to equilibrium was monitored by calculating the equilibrium constant K[sub p] over time as measured by PAH[sub part]/(PAH[sub gas] [times] TSP). As gas-phase PAH concentrations changed in the chamber, due to wall losses, particle off-gassing occurred so that K[sub p] was reasonably constant over time. Under cool outdoor conditions (-1 to -4[degrees]C), PAH loss from the particle phase could not keep up with gas-phase PAH wall losses, and the system departed from equilibrium. 25 refs., 9 figs., 1 tab.

• OSTI ID: 6592415
• Journal Information: Environmental Science and Technology; (United States), Journal Name: Environmental Science and Technology; (United States) Vol. 29:1; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AEROSOLS
AROMATICS
COLLOIDS
COMBUSTION PRODUCTS
CONDENSED AROMATICS
DATA
DISPERSIONS
ENVIRONMENTAL TRANSPORT
EQUILIBRIUM
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
MASS TRANSFER
MATTER
NUMERICAL DATA
ORGANIC COMPOUNDS
PHASE STUDIES
PHENANTHRENE
POLYCYCLIC AROMATIC HYDROCARBONS
PYRENE
SOLS
VOLATILE MATTER