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Secondary Organic Carbon and Aerosol Yields from the Irradiations of Isoprene and alpha -Pinene in the Presence of NO sub(X) and S0 sub(2)

A laboratory study was carried out to investigate the secondary organic carbon (SOC) yields of alpha -pinene and isoprene in the presence of SO sub(2), which produces acidic aerosol in the system. Experiments were based on irradiating each hydrocarbon (HC) with N0 sub(x) in a 14.5 m super(3) smog ch...

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Bibliographic Details
Published in:Environmental science & technology 2006-06, Vol.40 (12), p.3807-3812
Main Authors: Kleindienst, TE, Edney, E O, Lewandowski, M, Offenberg, J H, Jaoui, M
Format: Article
Language:English
Online Access:Get full text
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Summary:A laboratory study was carried out to investigate the secondary organic carbon (SOC) yields of alpha -pinene and isoprene in the presence of SO sub(2), which produces acidic aerosol in the system. Experiments were based on irradiating each hydrocarbon (HC) with N0 sub(x) in a 14.5 m super(3) smog chamber operated in the dynamic mode. The experimental design consisted of several multi-part experiments for each HC. In the first part of each experiment, an HC/NO sub(x) irradiation was conducted in the absence of SO sub(2) and was followed by irradiations with the addition of SO sub(2) in subsequent parts. Filter-based analyses for organic carbon were made using a thermal-optical approach either with an off-line instrument or in situ with an automated instrument. For isoprene in the absence of SO sub(2), the SOC yield was approximately 0.001, a value consistent with earlier work from this laboratory. With the addition of up to 200 ppb SO sub(2), the yield increased by a factor of 7. For alpha -pinene in the absence of SO2, the SOC yield of the irradiated mixture was found to average 0.096 from two experiments. With SO sub(2) in the system, the SOC yield increased on average to 0.132. These results suggest that SO sub(2), and by inference acidic aerosol, may play a role in increasing the yield of SOC from the photooxidation products of biogenic hydrocarbons or by the direct uptake of biogenic hydrocarbons onto acidic aerosol.
ISSN:0013-936X
DOI:10.1021/es052446r