2014 Progress Report: Emission, Fate, and Contribution of Biogenic Volatile Organic Compounds to Organic Aerosol Formation in the Presence of Anthropogenic Pollution: Measurements and Modeling during SOAS

EPA Grant Number: R835407
Title: Emission, Fate, and Contribution of Biogenic Volatile Organic Compounds to Organic Aerosol Formation in the Presence of Anthropogenic Pollution: Measurements and Modeling during SOAS
Investigators: Mak, John E , Goldstein, Allen H. , Guenther, Alex
Institution: The State University of New York at Stony Brook , National Center for Atmospheric Research , University of California - Berkeley
EPA Project Officer: Hunt, Sherri
Project Period: April 1, 2013 through March 31, 2016
Project Period Covered by this Report: May 1, 2014 through April 30,2015
Project Amount: $399,964
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:

The overall goal of this project is to quantify biogenic volatile organic compound (VOC) emission and VOC deposition to terrestrial ecosystems and characterize VOC atmospheric oxidation and the impact of anthropogenic pollution on secondary organic aerosol (SOA) formation. Our specific objectives include:

1)      Constrain and understand the processes controlling biogenic VOC emission, atmospheric oxidation and deposition;

2)      Elucidate the oxidation pathways of primary organics to form secondary organics in clean and polluted atmospheres;

3)      Evaluate the relative contributions of biogenic and anthropogenic emissions to the regional SOA burden in the southeastern United States;

4)      Search for previously unidentified/unmeasured semi-volatile organic compounds (SVOCs) that would help explain why observations of SOA often are up to an order of magnitude higher than traditional models predict; and

5)      Investigate the impacts of urban development patterns on biogenic and anthropogenic emissions and determine the implications for regional climate. 

Progress Summary:

During the second and final year of the project all investigators continued their work on the interpretation and analysis of the observations that were made both during the field component in Alabama in the summer of 2013, and the laboratory chamber studies carried out at Cal Tech in early 2014. Mak’s group prepared and subsequently published one paper in the journal Atmospheric Chemistry and Physics Discussions (ACPD) using data from the field component (see the Publications). In this paper, we quantify the fluxes of isoprene and monoterpenes from the top of the forest canopy using observations of vertical profiles of VOCs above the canopy and within the canopy. We then use a boundary layer chemistry model to simulate VOC and O3 abundances under varying NOx and HOx conditions. We define the effective chemical condition by the HO2/NO ratio rather than simple ‘high NOx’ or ‘low NOx’ conditions. We find that the emissions of isoprene peak in the late morning, but the abundance of isoprene within the forest canopy peaks earlier, because of the increased removal rate of isoprene during the afternoon (both due to chemistry and transport). Model simulations suggest the removal of isoprene from the canopy via transport/mixing is of the same magnitude as its chemical lifetime. We also investigated the relative importance of various production pathways for ISOPOO, a key isoprene oxidation product, under different NO:HO2 ratios and find that contributions among the different mechanisms vary by more than a factor of 5 over a span of HO2/NO ratios between 1 and 20 (which are all found within the atmospheric conditions during SOAS). This work highlights the sensitivity of the dominant isoprene oxidation pathway under different ambient conditions. Furthermore, this work illustrates the greater relevance of the HO2/NO ratio to define the atmospheric condition compared to ‘high NOx’ and ‘low NOx’ that has been historically used.

A second paper was prepared and submitted during the second year of the project, and recently has been published in Nature Scientific Reports. In this paper, Misztal, et al. (including Goldstein, Guenther, and Mak as co authors; Misztal is in Goldstein’s group) calculate the biogenic contribution of benzenoids to the global budget. Historically, it has been assumed that aromatic compounds were emitted almost exclusively by industrial activities. This mostly is because there simply have not been many measurements of aromatic compound emissions from plants. Using a multitude of observations from a multitude of investigators, including our measurements during the SAS campaign, the authors calculate that the global contribution of benzenoids from biogenic sources is on par with the total estimated flux of anthropogenically derived aromatics (~10 Tg/yr from each source). This discovery has a significant impact on the regional distribution and total amount of SOA formation, and should be taken into account when discussing regulatory control over SOA precursors.

A third paper was prepared and submitted during the second year of the project, and it has been published in Geophysical Research Letters. This paper reports SAS observations that, for the first time, provide a comprehensive experimental budget of isoprene in the planetary boundary layer based on airborne flux measurements along with in-situ OH observations in the Southeast and Central United States. Our PTRMS VOC eddy covariance measurements were the key measurement for this study. Our findings show that surface heterogeneity of isoprene emissions leads to a physical separation of isoprene and OH resulting in an effective slowdown in the chemistry. Depending on surface heterogeneity, the intensity of segregation (Is) could locally slow down isoprene chemistry up to 30%. The effect of segregated reactants in the planetary boundary layer (PBL) on average has an influence on modeled OH radicals that is comparable to that of recently proposed radical recycling mechanisms.

Five presentations, each discussing various components of the project, were made during the AGU meeting in December 2014. They are included in the list of publications and presentations for this grant.

Future Activities:

Future activities will include a continuing interpretation of our data and incorporation into other researchers’ models. We expect to have at least three more publications resulting from this work. 


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

Other project views: All 14 publications 8 publications in selected types All 8 journal articles
Type Citation Project Document Sources
Journal Article Kaser L, Karl T, Yuan B, Mauldin III RL, Cantrell CA, Guenther AB, Patton EG, Weinheimer AJ, Knote C, Orlando J, Emmons L, Apel E, Hornbrook R, Shertz S, Ullmann K, Hall S, Graus M, de Gouw J, Zhou X, Ye C. Chemistry-turbulence interactions and mesoscale variability influence the cleansing efficiency of the atmosphere. Geophysical Research Letters 2015;42(24):10894-10903. R835407 (2014)
R835407 (Final)
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  • Journal Article Misztal PK, Hewitt CN, Wildt J, Blande JD, Eller ASD, Fares S, Gentner DR, Gilman JB, Graus M, Greenberg J, Guenther AB, Hansel A, Harley P, Huang M, Jardine K, Karl T, Kaser L, Keutsch FN, Kiendler-Scharr A, Kleist E, Lerner BM, Li T, Mak J, Nolscher AC, Schnitzhofer R, Sinha V, Thornton B, Warneke C, Wegener F, Werner C, Williams J, Worton DR, Yassaa N, Goldstein AH. Atmospheric benzenoid emissions from plants rival those from fossil fuels. Scientific Reports 2015;5:12064 (10 pp.). R835407 (2014)
    R835407 (Final)
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  • Journal Article Su L, Patton EG, Vila-Guerau de Arellano J, Guenther AB, Kaser L, Yuan B, Xiong F, Shepson PB, Zhang L, Miller DO, Brune WH, Baumann K, Edgerton E, Weinheimer A, Mak JE. Understanding isoprene photo-oxidation using observations and modelling over a subtropical forest in the Southeast US. Atmospheric Chemistry and Physics Discussions 2015;15:31621-31663. R835407 (2014)
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  • Supplemental Keywords:

    Volatile organic compounds, VOCs, SAS, atmospheric chemistry, air pollution, Alabama

    Progress and Final Reports:

    Original Abstract
    2013 Progress Report
    Final Report