Ground-level ozone (O₃) pollution has been a severe environmental and health problem for decades. The importance of biogenic volatile organic compounds (BVOCs) in the formation of tropospheric photochemistry O₃ has been highlighted, especially in areas of rapid urbanization. We conducted simultaneous measurements of trace gases, including NO, NO_X, O₃, and BVOCs (i.e., isoprene and α-pinene), in the urban and rural forest areas of Beijing to determine the relationships between them. The results highlight the differences between the urban and rural forest areas of Beijing in terms of ambient air concentrations of BVOCs and O₃, and the interrelationships between BVOCs, NO_X, and ozone were quantified. Moreover, the isoprene concentration was found to be higher in the atmosphere of the urban site than of the rural site, which had higher α-pinene concentrations and higher O₃ concentrations. The NO_X concentration was higher at the urban site than at the rural site, and there was a significant exponential relationship between NO_X and O₃ at the urban site, indicating that the impact of NOx on O₃ at the urban site was greater than that at the rural site. The O₃ concentration increased with rising isoprene and α-pinene in both sites. In the case of substantially increased BVOC concentrations, declining NO_X concentrations strongly promote the formation of O₃. Consideration should be given to planting tree species with low-BVOC emissions, as they are crucial for mitigating O₃ pollution in urban areas. Additionally, the relationships between BVOCs, NO_X, and O₃ should be considered in policymaking related to O₃ control.

Rate coefficients for the reactions of OH radicals with C₃–C₁₁ alkanes were determined using the multivariate relative-rate technique. A total of 25 relative-rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative-rate coefficient for 3-methylheptane that had not been previously reported was determined, and the obtained k_OH value (in units of 10⁻¹² cm³ molec.⁻¹ s⁻¹) was 7.71 ± 0.35. Interestingly, whilst results for n-alkanes agreed well with available structure–activity relationship (SAR) calculations of Kwok and Atkinson (1995), Neeb (2000), Wilson et al. (2006), Jenkin et al. (2018), and McGillen et al. (2020), the three cycloalkanes (cyclopentane, methylcyclopentane, cyclohexane) and one branched alkane (2,2,4-trimethylpentane) were found to be less reactive than predicted by the SAR approach. Conversely, the SAR estimates for 2,3-dimethylbutane were approximately 25 % lower than the experimental values, with the exception of those estimated by the Wilson group, highlighting that there may be additional factors that govern the reactivity of highly branched alkanes that are not captured by current SAR techniques. Arrhenius expressions (in units of cm³ molec.⁻¹ s⁻¹) for the reactions of various branched alkanes with OH radicals were determined for the first time: 2-methylheptane, $\left(\mathrm{1.37}\pm \mathrm{0.48}\right)\times {\mathrm{10}}^{-\mathrm{11}}\exp \left[-\left(\mathrm{209}\pm \mathrm{100}\right)/T\right]$ , and 3-methylheptane, $\left(\mathrm{3.54}\pm \mathrm{0.45}\right)\times {\mathrm{10}}^{-\mathrm{11}}\exp \left[-\left(\mathrm{374}\pm \mathrm{49}\right)/T\right]$ . The reactivity relation of saturated alkanes with OH radicals and chlorine atoms was obtained: ${\log }_{\mathrm{10}}\left(k_{(\mathrm{Cl}+\mathrm{alkanes})}\right)=\mathrm{0.569}\times {\log }_{\mathrm{10}}\left(k_{(\mathrm{OH}+\mathrm{alkanes})}\right)-\mathrm{3.111}$ (R² = 0.86). In addition, the rate coefficients for the 24 previously studied OH + alkanes reactions were consistent with existing literature values, demonstrating the reliability and efficiency of this method for the simultaneous investigation of gas-phase reaction kinetics.

Rate coefficients for the reactions of OH radicals with C3-C11 alkanes were determined using the multivariate relative rate technique in various bath gases (N₂, Air, O₂). A total of 25 relative rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative rate constant for 3-methylheptane that had not been previously reported were determined, and the obtained K_OH values (in units of 10^-12 cm³·molecule^-1·s^-1) in different bath gases were N₂, 7.90±0.25; Air, 7.93±0.33; and O₂, 7.36±0.11. Interestingly, whilst results for n-alkanes agreed well with available structure activity relationship (SAR) calculations, the three cyclo-alkanes and two trimethylpentane were found to be less reactive than predicted by SAR. Conversely, the SAR estimate for 2,3-dimethylbutane were approximately 22 % lower than the experimental value, highlighting that the limited understanding of the oxidation chemistry of these compounds. Arrhenius expressions (in units of cm³·molecule^-1·s^-1) for the reactions of various cyclo- and branched alkanes with OH were determined for the first time: methylcyclopentane, (1.62±0.14)×10^-11exp [-(256±25)/T]; 2-methylhexane, (1.22±0.04)×10^-11exp [-(206±9)/T]; 3-methylhexane, (2.27±0.31)×10^-11exp [-(559±42)/T; 2-methylheptane, (1.62±0.37)×10^-11exp [-(265±70)/T, and 3-methylheptane, (3.54±0.45)×10^-11exp [-(374±49)/T]. In addition, the rate coefficients for the 24 previous studied OH + alkanes reactions in different bath gases were consistent with existing literature values, demonstrating the reliability and efficiency of this method for simultaneous investigation of gas-phase reaction kinetics.

Rate coefficients for the reactions of OH radicals with C3-C11 alkanes were determined using the multivariate relative rate technique in various bath gases (N₂, Air, O₂). A total of 25 relative rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative rate constant for 3-methylheptane that had not been previously reported were determined, and the obtained K_OH values (in units of 10^-12 cm³·molecule^-1·s^-1) in different bath gases were N₂, 7.90±0.25; Air, 7.93±0.33; and O₂, 7.36±0.11. Interestingly, whilst results for n-alkanes agreed well with available structure activity relationship (SAR) calculations, the three cyclo-alkanes and two trimethylpentane were found to be less reactive than predicted by SAR. Conversely, the SAR estimate for 2,3-dimethylbutane were approximately 22 % lower than the experimental value, highlighting that the limited understanding of the oxidation chemistry of these compounds. Arrhenius expressions (in units of cm³·molecule^-1·s^-1) for the reactions of various cyclo- and branched alkanes with OH were determined for the first time: methylcyclopentane, (1.62±0.14)×10^-11exp [-(256±25)/T]; 2-methylhexane, (1.22±0.04)×10^-11exp [-(206±9)/T]; 3-methylhexane, (2.27±0.31)×10^-11exp [-(559±42)/T; 2-methylheptane, (1.62±0.37)×10^-11exp [-(265±70)/T, and 3-methylheptane, (3.54±0.45)×10^-11exp [-(374±49)/T]. In addition, the rate coefficients for the 24 previous studied OH + alkanes reactions in different bath gases were consistent with existing literature values, demonstrating the reliability and efficiency of this method for simultaneous investigation of gas-phase reaction kinetics.

Rate coefficients for the reactions of OH radicals with C3-C11 alkanes were determined using the multivariate relative rate technique in various bath gases (N₂, Air, O₂). A total of 25 relative rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative rate constant for 3-methylheptane that had not been previously reported were determined, and the obtained K_OH values (in units of 10^-12 cm³·molecule^-1·s^-1) in different bath gases were N₂, 7.90±0.25; Air, 7.93±0.33; and O₂, 7.36±0.11. Interestingly, whilst results for n-alkanes agreed well with available structure activity relationship (SAR) calculations, the three cyclo-alkanes and two trimethylpentane were found to be less reactive than predicted by SAR. Conversely, the SAR estimate for 2,3-dimethylbutane were approximately 22 % lower than the experimental value, highlighting that the limited understanding of the oxidation chemistry of these compounds. Arrhenius expressions (in units of cm³·molecule^-1·s^-1) for the reactions of various cyclo- and branched alkanes with OH were determined for the first time: methylcyclopentane, (1.62±0.14)×10^-11exp [-(256±25)/T]; 2-methylhexane, (1.22±0.04)×10^-11exp [-(206±9)/T]; 3-methylhexane, (2.27±0.31)×10^-11exp [-(559±42)/T; 2-methylheptane, (1.62±0.37)×10^-11exp [-(265±70)/T, and 3-methylheptane, (3.54±0.45)×10^-11exp [-(374±49)/T]. In addition, the rate coefficients for the 24 previous studied OH + alkanes reactions in different bath gases were consistent with existing literature values, demonstrating the reliability and efficiency of this method for simultaneous investigation of gas-phase reaction kinetics.

Rate coefficients for the reactions of OH radicals with C3-C11 alkanes were determined using the multivariate relative rate technique in various bath gases (N₂, Air, O₂). A total of 25 relative rate coefficients at room temperature and 24 Arrhenius expressions in the temperature range of 273–323 K were obtained. Notably, a new room temperature relative rate constant for 3-methylheptane that had not been previously reported were determined, and the obtained K_OH values (in units of 10^-12 cm³·molecule^-1·s^-1) in different bath gases were N₂, 7.90±0.25; Air, 7.93±0.33; and O₂, 7.36±0.11. Interestingly, whilst results for n-alkanes agreed well with available structure activity relationship (SAR) calculations, the three cyclo-alkanes and two trimethylpentane were found to be less reactive than predicted by SAR. Conversely, the SAR estimate for 2,3-dimethylbutane were approximately 22 % lower than the experimental value, highlighting that the limited understanding of the oxidation chemistry of these compounds. Arrhenius expressions (in units of cm³·molecule^-1·s^-1) for the reactions of various cyclo- and branched alkanes with OH were determined for the first time: methylcyclopentane, (1.62±0.14)×10^-11exp [-(256±25)/T]; 2-methylhexane, (1.22±0.04)×10^-11exp [-(206±9)/T]; 3-methylhexane, (2.27±0.31)×10^-11exp [-(559±42)/T; 2-methylheptane, (1.62±0.37)×10^-11exp [-(265±70)/T, and 3-methylheptane, (3.54±0.45)×10^-11exp [-(374±49)/T]. In addition, the rate coefficients for the 24 previous studied OH + alkanes reactions in different bath gases were consistent with existing literature values, demonstrating the reliability and efficiency of this method for simultaneous investigation of gas-phase reaction kinetics.