A Caltech Library Service

Some Observations on Times to Equilibrium for Semivolatile Polycyclic Aromatic Hydrocarbons

Kamens, Richard and Odum, Jay and Fan, Zhi-Hua (1995) Some Observations on Times to Equilibrium for Semivolatile Polycyclic Aromatic Hydrocarbons. Environmental Science and Technology, 29 (1). pp. 43-50. ISSN 0013-936X. doi:10.1021/es00001a005.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


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^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 °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 Kp overtime as measured by PAH_(part)/(PAH_(gas) x TSP). As gas-phase PAH concentrations changed in the chamber, due to wall losses, particle off-gassing occurred so that Kp was reasonably constant over time. Under cool outdoor conditions (-1 to -4 °C), PAH loss from the particle phase could not keep up with gas-phase PAH wall losses, and the system departed from equilibrium. Kinetic simulations suggested that tens of hours would be required to reestablish 90% of equilibrium concentrations for compounds like phenanthrene and pyrene once they had departed from equilibrium in the particle phase by 34 and 18%, respectively.

Item Type:Article
Related URLs:
URLURL TypeDescription
Additional Information:© 1995 American Chemical Society. Received for review March 1, 1994. Revised manuscript received September 6, 1994. Accepted September 27, 1994. This work was supported by a gift from the Ford Motor Co. to the University of North Carolina, under the direction of Paul Killgoar and Dennis Schuetzle; Cooperative Agreement CR819675 from the U.S. EPA, under the direction of William Wilson and Larry Cupitt; and a research grant (R816678) from the office of Exploratory Research U.S. EPA, under the direction of Deran Pashayan. We are extremely grateful to Drs. Lara Gundel and Joan Daisey from Lawrence Berkeley Laboratories, who shared with us their newly developed denuder technology long before they had a chance to publish this very important work. We also acknowledge the efforts of Jian-xin Hu, Jianbo Zhang, and Heejeong Latimer, who helped collect and analyze some of the data presented in this study.
Funding AgencyGrant Number
Ford Motor CompanyUNSPECIFIED
Environmental Protection Agency (EPA)CR819675
Environmental Protection Agency (EPA)R816678
Issue or Number:1
Record Number:CaltechAUTHORS:20180510-152206566
Persistent URL:
Official Citation:Some Observations on Times to Equilibrium for Semivolatile Polycyclic Aromatic Hydrocarbons Richard. Kamens, Jay. Odum, and Zhi-Hua. Fan Environmental Science & Technology 1995 29 (1), 43-50 DOI: 10.1021/es00001a005
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86357
Deposited By: George Porter
Deposited On:14 May 2018 17:00
Last Modified:15 Nov 2021 20:37

Repository Staff Only: item control page