2014 Progress Report: Novel Measurements of Volatility- and Polarity-Separated Organic Aerosol Composition and Associated Hygroscopicity to Investigate the Influence of Mixed Anthropogenic-Biogenic Emissions on Atmospheric Aging Processes

EPA Grant Number: R835402
Title: Novel Measurements of Volatility- and Polarity-Separated Organic Aerosol Composition and Associated Hygroscopicity to Investigate the Influence of Mixed Anthropogenic-Biogenic Emissions on Atmospheric Aging Processes
Investigators: Williams, Brent
Institution: Washington University
EPA Project Officer: Hunt, Sherri
Project Period: April 1, 2013 through March 31, 2016
Project Period Covered by this Report: April 1, 2014 through March 31,2015
Project Amount: $298,747
RFA: Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications (2012) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Climate Change , Air

Objective:

Coupling of anthropogenic and biogenic emissions and subsequent atmospheric aging processes are hypothesized to be the leading single contribution to global organic aerosol (OA) mass concentrations, and also perhaps are the least understood single contribution to OA. Improved understanding of this coupling is a high priority topic in the field of atmospheric chemistry in order to determine mitigation strategies for OA control, a pollutant that alters climate and causes detrimental health effects. The primary objective of this proposed work is to better characterize the controlling factors in enhanced secondary organic aerosol (SOA) formation from combined anthropogenic and biogenic emission sources through innovative laboratory and field studies using novel instrumentation.

Progress Summary:

In the first 2 years of this project, we worked to develop a volatility and polarity separator (VAPS) for improved chemical characterization of organic aerosol and deployed it on two different field studies. We also built a custom multi-channel tandem differential mobility analyzer (MC-TDMA) for particle sizing, volatility, and hygroscopicity, and deployed it on a first field study. We also have performed several rounds of laboratory-based measurements of the oxidation of isoprene (the dominant biogenic emission globally and in the southeastern U.S.), toluene (representative of an anthropogenic VOC), and several types of biomass combustion emissions under varying concentrations, oxidant exposures, and mixtures with NOx. A major lesson in the first round of lab studies was to improve the design and operation of the PAM reaction chamber to ensure stable mixing and oxidation of precursor gases, and development of improved methods of calibrating oxidant exposures for each individual experiment. We are in the process of modeling the residence time distribution of the PAM chamber over a range of commonly utilized flow rates. Major findings from VAPS deployment to Centreville, AL as part of the Southern Oxidant and Aerosol Study (SOAS) include observation of highly oxygenated aerosol and identification of several major types of oxygenated biogenic aerosol, the largest contribution coming from low-NOx isoprene oxidation. Very little anthropogenic aerosol was observed. 

A wide array of gas and particle measurements also were made in East St. Louis, IL, a site with significantly higher anthropogenic pollutants from Greater St. Louis and periodic impact from air masses with high concentration of biogenic isoprene and its oxidation products. Initial analysis reveals evidence of nighttime particle growth events when biogenic (isoprene) emissions (transported from the Ozark Mountains to the southwest of St. Louis) were impacting the region along with locally elevated nitrate radical concentrations. These nighttime growth events always were smaller in scale to daytime growth events a decade ago (Qian Shi, Master’s Thesis with P. McMurry, U.Minnesota) but overwhelmed any evidence of strong daytime growth events during our recent measurement period (August-October 2013).  SO2 has dropped by approximately a factor of 5 and NOx has decreased by approximately a factor of 2 since that time period; however, O3 has actually slightly increased in the same time period. It is estimated that nighttime O3 is not completely titrated away as often as it once had been, leaving the potential for increased nighttime NO3 formation and associated increased potential for nocturnal chemistry and particle formation. During high isoprene impact periods, it was observed on nights with active NO3 oxidation chemistry that isoprene is largely reacted away and on nights when NO3 was not formed, the remaining isoprene provided fuel for elevated ozone production the following morning.  In this case, it appears nighttime NO3 chemistry contributes to increases in fine particulate matter, but can actually help to limit ozone production the next day. 

Future Activities:

In the final reporting period we will continue to develop VAPS and MC-TDMA for improved operation, portability, minimized power requirements, and robustness.  We will focus efforts on laboratory studies using our emissions/combustion chamber, PAM reaction chamber, and a wide variety of gas and particle characterization instrumentation (including aerosol chemical characterization by VAPS and aerosol volatility/hygroscopicity by MC-TDMA). Specific attention will be devoted to development of a high-NOx addition method to the PAM chamber as well as a NO3 oxidation mode. 


Journal Articles on this Report : 5 Displayed | Download in RIS Format

Other project views: All 34 publications 5 publications in selected types All 5 journal articles
Type Citation Project Document Sources
Journal Article Baasandorj M, Millet DB, Hu L, Mitroo D, Williams BJ. Measuring acetic and formic acid by proton-transfer-reaction mass spectrometry: sensitivity, humidity dependence, and quantifying interferences. Atmospheric Measurement Techniques 2015;8(3)1303-1321. R835402 (2014)
R835402 (Final)
  • Full-text: AMT-Full Text-PDF
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  • Abstract: AMT-Abstract
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  • Other: ResearchGate-Full Text-PDF
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  • Journal Article Martinez RE, Williams BJ, Zhang Y, Hagan D, Walker M, Kreisberg NM, Hering SV, Hohaus T, Jayne JT, Worsnop DR. Development of a volatility and polarity separator (VAPS) for volatility-and polarity-resolved organic aerosol measurement. Aerosol Science and Technology 2016;50(3):255-271. R835402 (2014)
    R835402 (Final)
  • Full-text: Taylor & Francis-Full Text-PDF
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  • Abstract: Taylor & Francis-Abstract
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  • Other: ResearchGate-Abstract
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  • Journal Article Millet DB, Baasandorj M, Farmer DK, Thornton JA, Baumann K, Brophy P, Chaliyakunnel S, de Gouw JA, Graus M, Hu L, Koss A, Lee BH, Lopez-Hilfiker FD, Neuman JA, Paulot F, Peischl J, Pollack IB, Ryerson TB, Warneke C, Williams BJ, Xu J. A large and ubiquitous source of atmospheric formic acid. Atmospheric Chemistry and Physics 2015;15(11):6283-6304. R835402 (2014)
    R835402 (Final)
    R835406 (Final)
  • Full-text: ACP-Full-text-PDF
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  • Abstract: ACP-Abstract
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  • Other: ResearchGate-Abstract
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  • Journal Article Millet DB, Baasandorj M, Hu L, Mitroo D, Turner J, Williams BJ. Nighttime chemistry and morning isoprene can drive urban ozone downwind of a major deciduous forest. Environmental Science & Technology 2016;50(8):4335-4342. R835402 (2014)
    R835402 (Final)
  • Abstract from PubMed
  • Full-text: ACS-Full Text-PDF
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  • Abstract: ACS-Abstract
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  • Other: Harvard University-Abstract
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  • Journal Article Williams BJ, Zhang Y, Zuo X, Martinez RE, Walker MJ, Kreisberg NM, Goldstein AH, Docherty KS, Jimenez JL. Organic and inorganic decomposition products from the thermal desorption of atmospheric particles. Atmospheric Measurement Techniques 2016;9(4):1569-1586. R835402 (2014)
    R835402 (Final)
  • Full-text: AMT-Full Text-PDF
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  • Abstract: AMT-Abstract
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  • Other: Harvard University-Abstract
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  • Supplemental Keywords:

    Air quality, air toxics, global climate change, atmospheric chemistry, organic aerosol, mass spectrometry, biogenic emissions, anthropogenic emissions, atmospheric oxidation, nighttime NO3 chemistry;

    Relevant Websites:

    Washington University | Atmospheric Chemistry and Technology Lab Exit

    Progress and Final Reports:

    Original Abstract
    2013 Progress Report
    Final Report