Formation of PAH-Quinones During the Gas Phase Reaction of PAHs with the OH Radical

JI YI LEE (1), Yu Cheng (2), Douglas A. Lane (2), Yong Pyo Kim (1)

(1) Department of Environment Science and Engineering, Ewha Womans University (2) Air quality research division, Science and Technology Branch, Environment Canada

     Abstract Number: 372
     Last modified: May 11, 2010

Abstract
Atmospheric quinones of aromatic molecules have recently received considerable attention due to their potential toxicity to human health. The measurements of quinones in ambient air samples and from motor vehicle emissions have been carried out to understand the characteristics and the sources of quinones in the atmosphere. The major compounds observed in ambient air samples comprised two or three benzene rings and included PAH-quinones such as 1,2-naphthalenequinone (1,2-NQ), 1,4-naphthalenequinone (1,4-NQ), 9,10-phenanathrenequione (9,10-PQ), and 9,10-anthraquinone (9,10-AQ). These PAH-quinones can also be formed by the photochemical reaction of gas phase PAHs. Previous studies have detected 1,2-NQ and 1,4-NQ from the gas phase reaction of naphthalene (Naph) with the OH radical. 9,10-PQ and 1,4-phenanathrenequinone (1,4-PQ) have been reported as products of the gas phase reaction of phenanathrene (Phen) with the OH radical. In this study, to allow an assessment of the importatance of the atmospheric formation of PAH-quinones and to have better understanding on the sources of PAH-quinones in the atmosphere, the formation yields of the PAH-quinones from the gas phase Naph and Phen reactions with the OH radical were measured in a reaction chamber. For naphthoquinones (NQs), the formation yields (%) of 1,4-NQ and 1,2-NQ were 1.5±0.4 and 4.7±3.4, respectively. The measured yields (%) of PQs were 3.6 ± 0.8 for 9,10-PQ and 2.7±1.1 for 1,4-PQ. In addition, the phase distribution of the PAH-quinones was determined to understand the gas to particle partitioning of the PAH-quinones. From the measured yields data, the atmospheric formation of PAH-quinones was estimated and the importance of atmospheric formation of PAH-quinones from the gas phase reaction of PAHs with the OH radical is discussed.