Distribution characteristics of volatile organic compounds and its multidimensional impact on ozone formation in arid...

Volatile Organic Compounds (VOCs) are key components of atmospheric pollution and play a critical role in ozone (O₃) formation. Understanding their distribution and pollution sources is essential to grasping the multifaceted impact of VOCs on O₃ production. This study, conducted at the Yinchuan Urban Ecosystem Research Station, carried out simultaneous field observations to collect data on VOCs, meteorological factors, and O₃. Machine learning algorithms were employed to analyze the sources of VOCs pollution and evaluate their impact on O₃ formation. Results show that the monthly average volume fraction of total VOCs was 29.28 × 10^-9, with alkanes dominating, accounting for 51.1 % of total VOCs during summer at high altitudes. Ethane (3.55 × 10^-9), n-hexane (3.36 × 10^-9), and propane (2.85 × 10^-9) were identified as key components. Artificial source contributed 78.6 % of VOCs emissions in summer, with hydrocarbon volatile emission source (31.6 %) and vehicle emission source (30.1 %) being the major sources, while natural emissions accounted for only 21.4 %. VOCs exhibited a notable negative impact on O₃ levels, reflected by a total effect value of -0.29. Among the VOCs components, aromatics, halocarbons, and alkanes were identified as the primary contributors to O₃ dynamics, with respective effect values of 0.84, 0.75, and 0.71, and their contribution rates were quantified as 21.8 %, 19.4 %, and 18.4 %, respectively. Among meteorological factors, temperature was a key determinant of O₃ levels, with a significant positive effect (effect value of 0.58). Temperature, wind speed, and relative humidity primarily influenced O₃ through direct effects, while photosynthetically active radiation indirectly influenced O₃ by affecting VOCs. The findings of this study link pollution sources, meteorological factors, and air quality management. Through systematic multidimensional analysis, it offers deeper insights into the complex relationships between meteorological factors, VOCs, and O₃ in high-altitude areas. These insights provide a scientific basis for formulating precise, region-specific, and component-targeted air pollution control measures.