Reactivity of aromatic contaminants towards nitrate radical in tropospheric gas and aqueous phase.

Aromatic compounds (ACs) give a substantial contribution to the anthropogenic emissions of volatile organic compounds. Nitrate radicals (NO) are significant oxidants in the lower troposphere during nighttime, with concentrations of (2-20) × 10 molecules cm. In this study, the tropospheric gas and liquid phase reactions of ACs with nitrate radical are investigated using theoretical computational methods, which can give a deep insight into the reaction mechanisms and kinetics. Results show that the reactivity of ACs with nitrate radicals decreases as the electron donating characteristics of the functional group on the ACs decrease, as ΔG of the reaction with NO increasing from -1.17 to 17.84 kcal mol. The reaction of NO towards ACs in the aqueous phase is more preferable, with the atmospheric lifetime 0.07-1281 min. An assessment of the aquatic toxicity of ACs and their degradation products indicated that the risk of their degradation products remains and should be given more attention.