The atmospheric fate of ethyl and neopentyl nitrates: ·OH-oxidation mechanism, kinetic property, and environmental impacts

Organic nitrate (RONO₂) is an important component of secondary organic aerosol. Ethyl nitrate (EN) and neopentyl nitrate (NN) are prototypical RONO₂ with high atmospheric concentrations, but their fate remains unclear. Herein, the ·OH-initiated degradation mechanism and kinetics of EN and NN were investigated using quantum chemical calculations and kinetics modeling. The environmental persistence of EN and NN was evaluated by calculating atmospheric lifetimes. Unexpectedly, the aqueous water has an inhibitory effect on the degradation of reactants by increasing the Gibbs-free barrier, and the air-water interfaces could accelerate EN transformation into CH₃CHO. Notably, the subsequent evolution process of C-center radicals can form polyfunctional oxygenated organic pollutants, aldehydes, and peroxyacyl nitrates in the presence of ·OH, O_2, HO_x, and NO_x. The toxicological assessment showed that EN and NN had harmful effects on ecosystems. This work provides a deeper theoretical insight into the atmospheric fate and influence of RONO₂.