2014 Progress Report: Development of a Quantitative Accounting Framework for Black Carbon and Brown Carbon from Emissions Inventory to Impacts

EPA Grant Number: R835039
Title: Development of a Quantitative Accounting Framework for Black Carbon and Brown Carbon from Emissions Inventory to Impacts
Investigators: Schauer, James J. , Bergin, Michael
Institution: University of Wisconsin - Madison , Georgia Institute of Technology
EPA Project Officer: Chung, Serena
Project Period: October 1, 2011 through September 30, 2014 (Extended to September 30, 2016)
Project Period Covered by this Report: October 1, 2013 through September 30,2014
Project Amount: $899,600
RFA: Black Carbon's Role In Global To Local Scale Climate And Air Quality (2010) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Climate Change , Air


The overall goal of this project is to develop a framework, and the necessary supporting data, to quantitatively account for the contributions of source emissions and atmospheric processing to the radiative absorption by carbonaceous aerosols in the atmosphere.  This goal is being accomplished via two integrated approaches: 1) quantification of the relationships of the optical and chemical properties of the major components of light absorbing carbon in the emissions from key air pollution sources, and 2) elucidating how these relationships evolve during atmospheric processing and transport.  The project team will integrate expertise in molecular marker source apportionment tools as well as in the measurement of aerosol optical properties that will provide a mechanism to quantitatively determine the source contributions to light absorbing carbon. The work will combine direct measurements of the emissions of dominant light absorbing carbon sources with field measurements in both urban and background locations to understand the influence of sources and atmospheric aging on aerosol light absorption. 

Progress Summary:

The following sections describe the ongoing research activities that have been conducted by the UW-Madison and Georgia Tech.  These activities are a continuation of previously reported work summarized in the 2014 “Black Carbon” EPA grant progress report.  The current progress focuses on data analysis and reporting of previous source and ambient sampling with a focus on quantification of organic carbons’ role in multi-wavelength visible light absorption.  Source sampling black and brown carbon results have been investigated and quantified.  These results are being compared to ambient measurements that have taken place in an urban location in the southeastern US (Atlanta, GA), a rural location in the SE US (Centreville, AL), and in an extremely high aerosol loading region influenced primarily by biomass burning (Kanpur, India). 

In addition, measurements were more recently conducted in Beijing China during the Asia Pacific Economic Cooperation (APEC) meeting, in which regional pollution controls were promulgated, allowing the unique opportunity to investigate source specific drivers of optical properties.  Specifically, the following research tasks have been conducted: 1) Results from diesel engine testing have been published, assessing the impact of engine condition and after-treatment on the quantification of black carbon emissions and to estimate the brown carbon contribution of diesel engine sources.  2) Source sample investigation results from multiple combustion fuels have been submitted for consideration of publication.  These results utilized a test specific correction methodology and segregated the absorption of brown and black carbon from unique fuel type emissions; of particular interest is the reported source specific brown and black carbon absorption cross-section at multiple visible wavelengths. 3) Ambient samples from urban, rural, and a high-loading biomass influenced region have been collected. The brown and black carbon fractions are being quantified at multiple wavelengths using both Aethalometer methodologies, but also the solvent extracted component will be investigated using UV-Vis Photospectrometry.  4) Three months of urban China Ambient air samples have been collected both under the APEC emission control regimes and without controls. The brown and black carbon fractions are being quantified at multiple wavelengths using both Aethalometer methodologies, but also solvent extracted component will be investigated using UV-Vis Photospectrometry.  Source apportionment techniques (CMB) will be applied to chemical speciation results and optical measurements will be reconstructed using the previously established source absorption cross-sections. 

Source Testing

Source testing of specific emission sources with unique optical properties has been completed.  Emission sources investigated include: diesel engine under multiple load and control conditions, lignite and bituminous coal, wood pellet, agricultural waste pellet, leaf litter, peat briquettes, kerosene, and incense. 

Diesel engine emissions are a major source of black carbon and under special operating conditions can also have significant UV brown carbon absorption. Engine operating conditions and after-treatment technologies have been investigated and these results have been recently published.  The results show engine operating conditions and after-treatment technology can be an important factor in EC and OC emissions.  These findings add to an already strong understating of diesel engine emissions; however, the research gives new insight on the impact diesel engines can have on brown carbon emissions. 

Water and organic solvent soluble fraction of emission impact on absorption

Direct measurement of the organic carbon absorption at multiple wavelengths is conducted through the atomization of both water soluble and organic solvent extractions.  This allows a direct measurement of the brown carbon component of absorption from sources.  Through the application of these methods we can quantify the organic aerosols absorption without interference from black carbon absorption and mixing state artifacts. Utilizing SMPS size distribution data and the scattering coefficients measured during atomization, the wavelength specific refractive index can be calculated using MIE theory.  In addition, the extracted organic compounds have been analyzed using UV-Vis photospectrometer to give detailed wavelength absorption spectra of both water soluble and organic solvent soluble components. 

Atmospheric Measurements

Light Absorption measurements

In addition to the atmospheric sampling locations described in the previous project reports two additional sites were selected for their unique atmospheric PM characteristic.  First, a location in rural northern Wisconsin was selected to investigate the optical properties of PM dominated by biogenic SOA. A seven day long sampling event was conducted in August 2014 in which real-time optical measurements were collected parallel to filter based sampling activates.  Data analysis from this sampling event is on-going.  However, preliminary data suggests extremely low BC content in the samples and elevated absorption in the UV range of the spectrum only.  Hi-Vol samples were collected for chemical speciation, UV-Vis photospectrometer analysis, and water and organic solvent extractable resuspension.  These results will give important insight into the brown carbon characteristics of SOA.  A second intensive ambient site sampling event was conducted in Beijing, China.  For 3 months before, during, and after the APEC meeting in November 2014, we monitored optical characteristics and sampled using Hi-Volume filter samplers. Sampling at the Beijing site was completed on January 15, 2015 and data analysis will be conducted starting in February 2015.  The APEC sampling site allowed the opportunity to investigate the light absorption in the region while temporary emission controls were put in place for the meeting.  Filter samples will be analyzed and organic traces (as well as EC, OC, Ions) and source apportionment (CMB) methods will be applied to determine dominated source during these events.  In addition, select composites of these samples will be extracted for both UV-Vis photospectrometry and resuspension.  Applying the result of the source apportionment and utilizing the previous derived source MAC, we will reconstruct the measured multiple wavelength absorption during the meeting and assess the ability of chemical speciation data to predict the ambient optical conditions.    

Field Measurements of BC and BrC: A volatility Based Approach

The volatile component of light absorption contributes roughly ~60% to the overall absorption underscoring the importance of light absorbing organic compounds to particulate light absorption. Even at visible wavelengths (500-700 nm) the light absorption by volatile compounds contributes from 10-40% to the total aerosol light absorption. By contrast, the remote location of Centreville, Alabama is characterized by a very modest contribution of semi-volatile particulate compounds to BCaeth at all wavelengths. This is likely due to the fact that organic particulate matter is dominated by biogenic SOA formation having compounds that are not particularly absorbing. Furthermore, the contrast between the urban and downwind rural locations indicates that as organic PM is transported from urban to rural regions, the light absorbing properties evolve. That is, primary organic PM as well as SOA formed near urban sources become less absorbing as they age.

Size-Resolved Absorption of both BC and BrC

The relatively high particulate loadings (50-300 mgm-3) in Kanpur, India allowed for size-resolved impactor sampling to determine the relative contributions of BC and BrC to be estimated. The light absorption coefficients of BC and BrC have been estimated using Mie Theory based on concentrations for EC estimated from standard thermal evolution, and BrC estimated from UV light absorption in both water and methanol extracts.   In general, light absorption at UV wavelengths is 2-5 times higher for BrC than for BC in Kanpur. These results indicate that near sources of biomass burning it is possible for BrC to dominate PM light absorption. 

Future Activities:

The bulk of the sampling and experimental procedures has been completed.  During the month of February 2015 a select number of samples will be resuspended and investigated using the previously developed atomization methodology.  Ongoing chemical analysis will occur during the first quarter of 2015, with an expected completion date in April 2015.  Calculation of RI utilizing Mie theory model will be ongoing throughout the beginning of 2015 and will be applied to resuspension results as they become available.

The primary thrust of work activities is the completion of manuscripts for publication. 

Journal Articles on this Report : 3 Displayed | Download in RIS Format

Other project views: All 13 publications 12 publications in selected types All 12 journal articles
Type Citation Project Document Sources
Journal Article Olson MR, Garcia MV, Robinson MA, Van Rooy P, Dietenberger MA, Bergin M, Schauer JJ. Investigation of black and brown carbon multiple-wavelength-dependent light absorption from biomass and fossil fuel combustion source emissions. Journal of Geophysical Research: Atmospheres 2015;120(13):6682-6697. R835039 (2014)
R835039 (2015)
R835039 (Final)
  • Full-text: U.S. Forest Service-Full Text PDF
  • Abstract: Wiley Online-Abstract
  • Other: Wiley Online-Full Text PDF
  • Journal Article Robinson MA, Olson MR, Liu ZG, Schauer JJ. The effects of emission control strategies on light-absorbing carbon emissions from a modern heavy-duty diesel engine. Journal of the Air & Waste Management Association 2015;65(6):759-766. R835039 (2014)
    R835039 (2015)
    R835039 (Final)
  • Abstract from PubMed
  • Full-text: Taylor & Francis-Full Text HTML
  • Abstract: Taylor & Francis-Abstract
  • Other: Taylor & Francis-Full Text PDF
  • Journal Article Robinson M, Liu Z, Olson M, Schauer J. Comparison of measurement strategies for light absorbing aerosols from modern diesel engines. SAE International Journal of Fuels and Lubricants 2014;7(2):543-550. R835039 (2014)
    R835039 (Final)
  • Abstract: SAE-Abstract
  • Other: ResearchGate-Abstract
  • Supplemental Keywords:

    Elemental Carbon, EC, BC, Brown Carbon 

    Progress and Final Reports:

    Original Abstract
  • 2012 Progress Report
  • 2013 Progress Report
  • 2015 Progress Report
  • Final Report