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Title: Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol

Abstract

The light-absorbing organic aerosol (OA), commonly referred to as “brown carbon (BrC)”, has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various VOC precursors, NOx concentrations, photolysis time and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficients (MAC) value is observed from toluene SOA products formed under high NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organonitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible and UVmore » light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed-SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1340829
Report Number(s):
PNNL-SA-118548
Journal ID: ISSN 1680-7316
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Atmospheric Chemistry and Physics; Journal Volume: 16; Journal Issue: 9
Country of Publication:
United States
Language:
English
Subject:
Secondary Organic Aerosol; Brown Carbon; Light Absorption

Citation Formats

Liu, Jiumeng, Lin, Peng, Laskin, Alexander, Laskin, Julia, Kathmann, Shawn M., Wise, Matthew E., Caylor, Ryan, Imholt, Felisha, Selimovic, Vanessa, and Shilling, John E. Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol. United States: N. p., 2016. Web. doi:10.5194/acp-16-12815-2016.
Liu, Jiumeng, Lin, Peng, Laskin, Alexander, Laskin, Julia, Kathmann, Shawn M., Wise, Matthew E., Caylor, Ryan, Imholt, Felisha, Selimovic, Vanessa, & Shilling, John E. Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol. United States. doi:10.5194/acp-16-12815-2016.
Liu, Jiumeng, Lin, Peng, Laskin, Alexander, Laskin, Julia, Kathmann, Shawn M., Wise, Matthew E., Caylor, Ryan, Imholt, Felisha, Selimovic, Vanessa, and Shilling, John E. Fri . "Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol". United States. doi:10.5194/acp-16-12815-2016.
@article{osti_1340829,
title = {Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol},
author = {Liu, Jiumeng and Lin, Peng and Laskin, Alexander and Laskin, Julia and Kathmann, Shawn M. and Wise, Matthew E. and Caylor, Ryan and Imholt, Felisha and Selimovic, Vanessa and Shilling, John E.},
abstractNote = {The light-absorbing organic aerosol (OA), commonly referred to as “brown carbon (BrC)”, has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various VOC precursors, NOx concentrations, photolysis time and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficients (MAC) value is observed from toluene SOA products formed under high NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organonitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible and UV light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed-SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.},
doi = {10.5194/acp-16-12815-2016},
journal = {Atmospheric Chemistry and Physics},
number = 9,
volume = 16,
place = {United States},
year = {Fri Oct 14 00:00:00 EDT 2016},
month = {Fri Oct 14 00:00:00 EDT 2016}
}