Grantee Research Project Results
2023 Progress Report: Evaluating chemical mechanisms with recent field data to account for the contributions of volatile chemical product emissions to urban ozone pollution
EPA Grant Number: R840010Title: Evaluating chemical mechanisms with recent field data to account for the contributions of volatile chemical product emissions to urban ozone pollution
Investigators: Bates, Kelvin , Li, Meng , Stockwell, Chelsea , McDonald, Brian , Coggon, Matthew , Schwantes, Rebecca
Institution: University of Colorado at Boulder , NOAA Earth System Research Laboratories
EPA Project Officer: Chung, Serena
Project Period: August 1, 2020 through July 31, 2023 (Extended to April 30, 2024)
Project Period Covered by this Report: August 1, 2022 through July 31,2023
Project Amount: $396,135
RFA: Chemical Mechanisms to Address New Challenges in Air Quality Modeling (2019) RFA Text | Recipients Lists
Research Category: Early Career Awards , Air , Air Quality and Air Toxics
Objective:
The objective of this research is to improve the representation of reactions that describe the chemical oxidation of volatile chemical product (VCP) emissions in urban air quality models. The objectives for Year 3 were (1) use our field measurements and updated models to quantify the impacts of VCPs and cooking on ozone and peroxyacetyl nitrate (PAN) production in the Los Angeles region during SUNVEx and RECAP-CA, (2) conduct sensitivity analyses in WRF-Chem to determine the basin-wide impacts of VCPs, mobile sources, cooking emissions, and biogenic sources on ozone production, (3) use our box modeling for RECAP-CA to evaluate the impact of various chemical mechanisms on the production of key secondary gasses (e.g., ozone, PAN, formaldehyde), and evaluate simulations using chemical mechanisms, such as the Master Chemical Mechanism (MCM), to interpret our detailed suite of chemical measurements.
Progress Summary:
We have finalized two analyses and completed two manuscripts that describe our efforts to identify missing volatile organic compounds (VOC) chemistry from chemical mechanisms. These manuscripts are under internal review and will be submitted to peer-reviewed journals in the coming month.
Our first manuscript describes our efforts to update the chemical mechanisms used in WRF-Chem to better represent VCP emissions. The updated mechanism is built upon the RACM2_Berkeley scheme (Zare et al., 2018) and includes updates to the chemistry of alcohols and glycols that are common in consumer products. The new mechanism, termed RACM2B_VCP, also includes surrogates for VCP tracers such as D5-siloxane (personal care products) and parachlorobenzotrifluoride (PCBTF) (coatings) that enables a direct comparison between WRF-Chem simulations and ambient measurements. This manuscript fully describes these updates, compares the mechanism performance to previous WRF-Chem mechanisms (RACM_ESRL_VCP), and compares model outputs to aircraft and ground-based observations. These results will be submitted to Atmospheric Chemistry and Physics (ACP) (Zhu et al. in prep).
Our second manuscript describes our efforts to quantify cooking emissions in the Las Vegas and Los Angeles regions. This work was a part of our project goal to identify VOC emissions and chemistry that are currently missing from chemical transport models. We show that there is a large pool of aldehydes emitted to the urban atmosphere that cannot be explained by current emissions inventories. Using a combination of mobile laboratory and ground site data, we find that these emissions result from commercial and residential cooking and represent ~15-20% of the total anthropogenic VOC emissions in Las Vegas. We compare our measurements to the National Emissions Inventory (NEI) and FIVE-VCP emissions inventory and demonstrate that both models significantly underestimate the impact of cooking. These results will be submitted to ACP (Coggon et al. in prep).
We have leveraged the results of our source apportionment in Las Vegas to update our emissions inventories and chemical mechanisms used in WRF-Chem. We have incorporated cooking emissions into WRF-Chem and updated our chemical mechanisms to include reactions for long-chain aldehydes based on the known chemistry of aldehyde surrogates, such as nonanal (Bowman et al., 2003). The implications of these updates are under evaluation using our box model and WRF-Chem simulations.
We have built a box model that simulates the transport, emissions, and atmospheric chemistry of VOCs in the Los Angeles Basin. We conducted preliminary sensitivity analyses on the detailed emissions inventory used in WRF-Chem and evaluated the resulting output against our detailed chemical measurements from SUNVEx / RECAP-CA. We find that the model performs well in reproducing the observed mixing ratios of VCP, cooking, and mobile source VOC tracers and we continue to investigate the influence of anthropogenic VOC emissions on ozone and PAN formation in the LA Basin. We will continue to explore secondary formation from VCP and cooking VOC oxidation, which includes sensitivity tests to identify key processes. We are actively implementing other lumped chemical mechanism schemes (RACM2BVCP and CRACMM) and will evaluate product distributions & reactivity.
Future Activities:
Our final analyses will be conducted as part of a 9 month no-cost extension. These remaining activities will (1) finalize our efforts to incorporate cooking emissions and chemistry into our WRF-Chem and box model analyses, (2) finalize our box model evaluations of chemical mechanism updates, and (3) evaluate emission sector contributions to the production of ozone and other secondary pollutants in the LA basin during SUNVEx and RECAP-CA.
References:
Bowman, J. H., Barket, D. J., and Shepson, P. B. Atmospheric chemistry of nonanal, Environmental Science & Technology, 37, 2218-2225, 10.1021/es026220p, 2003.
Zare, A., Romer, P. S., Nguyen, T., Keutsch, F. N., Skog, K., and Cohen, R. C. A comprehensive organic nitrate chemistry: insights into the lifetime of atmospheric organic nitrates, Atmospheric Chemistry and Physics, 18, 15419-15436, 10.5194/acp-18-15419-2018, 2018.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 11 publications | 6 publications in selected types | All 6 journal articles |
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Type | Citation | ||
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Zhu Q, Schwantes R, Coggon M, Harkins C, Schnell J, He J, Pye H, Li M, Baker B, Moon Z, Shmadov R, Pfannerstill E, Place B, Wooldridge P, Schulze B, Arata C, Bucholtz A, Seinfeld J, Zu L, Warneke C, Stockwell C, Zuraski K, Robinson M, Newman J, Veres P, Brown S, Goldstein A, Cohen R, McDonald B. A better representation of volatile organic compound chemistry in WRF-Chem and its impact on ozone over Los Angeles. ATMOSPHERIC CHEMISTRY AND PHYSICS 2024;24(129):5265-5286 |
R840010 (2023) |
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Supplemental Keywords:
Urban ozone, peroxy acyl nitrates, cooking emissions, emission tracers
Relevant Websites:
AEROMMA, SUNVEx/RECAP-CA, FIREX-AQ
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.