2016 Progress Report: Aerosol Optical Properties and Biogenic SOA: Effect on Hygroscopic Properties and Light Absorption

EPA Grant Number: R835411
Title: Aerosol Optical Properties and Biogenic SOA: Effect on Hygroscopic Properties and Light Absorption
Investigators: Khlystov, Andrey , Ramachandran, Subramanian
Institution: Dessert Research Institute , Carnegie Mellon University
EPA Project Officer: Chung, Serena
Project Period: April 1, 2013 through March 31, 2016 (Extended to March 31, 2018)
Project Period Covered by this Report: April 1, 2016 through March 31,2017
Project Amount: $398,318
RFA: Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications (2012) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Climate Change , Air


Secondary organic aerosol (SOA) from biogenic sources is a major contributor to the global aerosol burden. It is estimated to have a profound effect on regional and global climate. There is strong evidence that biogenic SOA can influence optical properties of ambient aerosol by altering its hygroscopicity and contributing to light absorption directly via formation of brown carbon and indirectly by enhancing light absorption by black carbon (“lensing effect”). The magnitude of these effects remains highly uncertain. It was suggested that organo-nitrogen (ON) compounds are the substances responsible for formation of brown carbon in biogenic SOA. No evidence exists yet for such a link in ambient aerosol. The goal of this project is to provide comprehensive characterization of optical properties of anthropogenically-influenced biogenic SOA, its contribution to aerosol hygroscopicity and light absorption via formation of brown carbon and “lensing” effect, and investigate the link between ON and brown carbon.


Progress Summary:

Two field campaigns were carried out to study contribution of biogenic SOA to light scattering and absorption by the ambient aerosol – one within the Southern Oxidant and Aerosol Study (SOAS) at a site near Centerville, AL (6/1/13 – 7/15/13), the other at Duke Forest near Chapel Hill, NC (5/30/15 – 6/26/15). Preliminary analysis indicates that during the SOAS, organic aerosol appeared to be relatively hydrophobic. SOA contribution to light absorption during the SOAS is the subject of the current statistical data analysis, but appears to be very small. At Duke Forest, on the other hand, SOA contributed to light absorption. The strongest light absorption by SOA was observed in the afternoon, suggesting photochemical production that involves anthropogenic emissions. Black carbon particles appear to be externally mixed and coated with a material that has the same volatility properties as the rest of the particles. Data analysis is ongoing.

Future Activities:

The main activity planned for the next reporting period is to finalize and report data collected during the two field campaigns. A comparison of aerosol properties measured at the two sites will help discern the effect of anthropogenic sources on optical properties of biogenic SOA.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other project views: All 12 publications 1 publications in selected types All 1 journal articles
Type Citation Project Document Sources
Journal Article Saha PK, Khlystov A, Yahya K, Zhang Y, Xu L, Ng NL, Grieshop AP. Quantifying the volatility of organic aerosol in the southeastern US. Atmospheric Chemistry and Physics 2017;17(1):501-520. R835411 (2014)
R835411 (2015)
R835411 (2016)
R835411 (Final)
R835403 (2015)
R835403 (Final)
  • Full-text: ACP-Full Text PDF
  • Abstract: ACP-Abstract
  • Other: ResearchGate-Abstract & Full Text PDF
  • Supplemental Keywords:

    ambient air, global climate, tropospheric, particulates, organics, environmental chemistry, physics, analytical, measurement methods, southeast

    Progress and Final Reports:

    Original Abstract
  • 2013 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report
  • Final Report