We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Modeling the Impacts of Volatile Chemical Product Emissions on Atmospheric Photochemistry and Ozone Formation in Los Angeles.
- Authors
Chen, Tianshu; Gilman, Jessica; Kim, Si‐Wan; Lefer, Barry; Washenfelder, Rebecca; Young, Cora J.; Rappenglueck, Bernhard; Stevens, Philip S.; Veres, Patrick R.; Xue, Likun; de Gouw, Joost
- Abstract
The dominant fraction of anthropogenic volatile organic compound (VOC) emissions shifted from transportation fuels to volatile chemical products (VCP) in Los Angeles (LA) in 2010. This shift in VOC composition raises the question about the importance of VCP emissions for ozone (O3) formation. In this study, O3 chemistry during the CalNex 2010 was modeled using the Master Chemical Mechanism (MCM) version 3.3.1 and a detailed representation of VCP emissions based on measurements combined with inventory estimates. The model calculations indicate that VCP emissions contributed to 23% of the mean daily maximum 8‐hr average O3 (DMA8 O3) during the O3 episodes. The simulated OH reactivity, including the contribution from VCP emissions, aligns with observations. Additionally, this framework was employed using four lumped mechanisms with simplified representations of emissions and chemistry. RACM2‐VCP showed the closest agreement with MCM, with a slight 4% increase in average DMA8 O3 (65 ± 13 ppb), whereas RACM2 (58 ± 13 ppb) and SAPRC07B (59 ± 14 ppb) exhibited slightly lower levels. CB6r2, however, recorded reduced concentrations (37 ± 10 ppb). Although emissions of O3 precursors have declined in LA since 2010, O3 levels have not decreased significantly. Model results ascribed this trend to the rapid reduction in NOX emissions. Moreover, given the impact of COVID‐19, an analysis of 2020 reveals a shift to a NOX‐limited O3 formation regime in LA, thereby diminishing the influence of VCPs. This study provides new insights into the impact of VCP emissions on O3 pollution from an in‐depth photochemical perspective. Plain Language Summary: In the 2010 CalNex study, researchers found that volatile organic compounds (VOCs) were predominantly emitted from volatile chemical products (VCPs) like solvents. In our subsequent research, using a detailed chemical model, we discovered that about a quarter of the mean daily maximum 8‐hr average ozone was contributed by these everyday products during ozone episodes. This insight is critical as it underscores how these emissions significantly speed up ozone formation through accelerated chemical reactions. We also evaluated various simplified chemical mechanisms for ozone prediction, finding that the one incorporating key reactions of VOC species was most accurate. Further, our analysis suggests that the slight increase in Los Angeles' ozone levels since 2010 can likely be attributed to faster reductions in NOX emissions relative to VOCs. Notably, the reduction in NOX emissions by 2020 considerably diminished the impact of VCPs on ozone levels. However, given the uncertain future of NOX emissions and the ongoing rise in emissions from everyday products, it remains essential to control these emissions. Key Points: Volatile chemical product emissions accounted for 23% of mean daily max 8‐hr ozone in ozone episodes, as per the 2010 CalNex studyVCP emissions boost ozone formation by increasing primary production and efficient recycling of ROx radicals, thus enhancing pollution2020s reduction in NOx emissions in Los Angeles, potentially due to COVID‐19, led to a NOx‐limited state, lessening VCPs' impact on ozone
- Subjects
LOS Angeles (Calif.); ATMOSPHERIC ozone; PHOTOCHEMICAL smog; NITROGEN oxides emission control; EMISSIONS (Air pollution); VOLATILE organic compounds; CHEMICAL models; EMISSION control
- Publication
Journal of Geophysical Research. Atmospheres, 2024, Vol 129, Issue 11, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2024JD040743