Variation of biogenic VOC contribution to ozone formation with reduced anthropogenic precursor emissions: Coupling online observation and future scenario simulation

Yuhong Liu; Tianshu Chen; Zhaokun Ma; Qinyi Li; Yang Gao; Likun Xue; Wenxing Wang

doi:10.1016/j.scitotenv.2025.178380

Variation of biogenic VOC contribution to ozone formation with reduced anthropogenic precursor emissions: Coupling online observation and future scenario simulation

Sci Total Environ. 2025 Jan 9:961:178380. doi: 10.1016/j.scitotenv.2025.178380. Online ahead of print.

Authors

Yuhong Liu¹, Tianshu Chen², Zhaokun Ma³, Qinyi Li⁴, Yang Gao⁵, Likun Xue⁶, Wenxing Wang⁶

Affiliations

¹ Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, Shandong 266100, China; Environment Research Institute, Shandong University, Qingdao, Shandong 266237, China.
² Environment Research Institute, Shandong University, Qingdao, Shandong 266237, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China.
³ Shandong Academy for Environmental Planning, Jinan, Shandong 250101, China.
⁴ Environment Research Institute, Shandong University, Qingdao, Shandong 266237, China. Electronic address: [email protected].
⁵ Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao, Shandong 266100, China. Electronic address: [email protected].
⁶ Environment Research Institute, Shandong University, Qingdao, Shandong 266237, China.

PMID: 39793134
DOI: 10.1016/j.scitotenv.2025.178380

Abstract

As an essential component of urban natural sources, isoprene has strong interactions and synergies with anthropogenic precursors (volatile organic compounds and nitrogen oxides) of ozone (O₃), influencing O₃ formation in urban areas. However, the variability of these effects under different anthropogenic emission scenarios has not been fully understood. This study, utilizing observational data from Dezhou (a medium-sized city in the center of North China Plain) from May to September in both 2019 and 2020, and incorporating four future scenarios based on Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5), unravels the mechanisms of O₃ formation and the impact of isoprene on O₃ production using an observation-based box model. Our observation results showed that O₃ concentrations were lower in 2020 compared to 2019. The box model analysis suggests a shift in O₃ formation from a VOC-limited regime in 2019 to a transition regime in 2020, primarily due to a significant reduction in anthropogenic emissions. Isoprene photochemistry contributed to 7% and 11% of the daytime average net O₃ production rates in 2019 and 2020, respectively. The increase can be attributed to a notable rise in RO₂ radicals, from 14% in 2019 to 19% in 2020. Under the future scenario with the lowest projected anthropogenic emissions (SSP1-2.6), isoprene-derived RO₂ radicals (generated through isoprene oxidation) are expected to account for 36% of the total RO₂ radicals. We also use a quasi-EKMA diagram to illustrate the contribution of isoprene to O₃ concentrations, highlighting the nonlinear amplification or reduction of its contribution depending on changes in anthropogenic VOCs and NO_x concentrations. This nonlinear relationship is influenced by NO_x concentrations, with the impact of isoprene being reduced at lower NO_x levels. To effectively mitigate long-term O₃ pollution, especially given the growing contribution of biogenic precursors, it is crucial to focus on reducing NO_x emissions.

Keywords: Isoprene; North China Plain; Observation-based model; Ozone; Shared socioeconomic pathways.