Grantee Research Project Results
Source-Specific Molecular Signatures for Light-Absorbing Carbonaceous AerosolsEPA Grant Number: FP917360
Title: Source-Specific Molecular Signatures for Light-Absorbing Carbonaceous Aerosols
Investigators: Priest, Amanda S
Institution: Old Dominion University
EPA Project Officer: Just, Theodore J.
Project Period: August 1, 2011 through July 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011)
Research Category: Fellowship - Clean Air , Academic Fellowships
There is strong evidence that suggests emissions resulting from industrialized society (industrial and transportation-related emissions) have played a key role in changing the chemical composition of the atmosphere, resulting in a net global warming. Theory suggests that the chemical composition of organic aerosols will determine their radiative effect; however, there is no unambiguous chemical definition for organic aerosol light-absorbing components, including black carbon and brown carbon. This project will focus on the chemical characterization of lightabsorbing components in organic aerosols from various emission sources and will seek to identify the sources that make the largest contribution to atmospheric aerosols from these contaminants.Approach:
Ambient aerosol samples will be collected from key natural and anthropogenic emission sources, including an industrial region, a high traffic area, a biomass burning event and a rural background site. Samples from each site will be evaluated using a combination of ultraviolet visible spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. These techniques will allow for the determination of light-absorbing character and molecular composition for the collected samples, and the data will be used to establish the relationship between degree of aromaticity and light-absorption. Finally, multivariate statistical analysis will be employed to determine sourcespecific molecular components.Expected Results:
A direct correlation of light absorption is expected to be found with several mass spectrometric measurements, including degree of aromaticity, the types and abundances of condensed aromatic compounds and specific combustion-derived chemical markers. Such important relationships have always been considered to exist intuitively, but have not been explicitly demonstrated. Emission sources having large contributions from combustion-derived material, such as fossil fuel emissions, are expected to have the most aromatic character, thus absorbing the most light. Using the chemical information obtained from ultrahigh resolution mass spectral analysis, multivariate statistical analysis can reveal relationships between the various aerosol emission sources.
Potential to Further Environmental / Human Health Protection
Determining the specific relationship between light-absorbing character and chemical signatures will provide a more comprehensive accounting for light-absorbing carbonaceous aerosols and will help to pinpoint the emission sources that have the most detrimental effect on the Earth’s radiative budget. This information will reduce uncertainties related to current climate modeling schemes and allow policy-makers to implement more effective mitigation strategies to target problem pollutants from abundant sources.Supplemental Keywords:
light-absorbing carbon, black carbon, brown carbon, organic aerosols, atmospheric particulate matter, FT-ICR MS, climate change, anthropogenic effects, atmospheric chemistry,