Seasonal variations and intercorrelations of polycyclic aromatic hydrocarbons, heavy metals and environmentally persistent free radicals in PM in Ulaanbaatar, Mongolia.

Simulated combustion experiments have identified polycyclic aromatic hydrocarbons (PAHs) and metal oxides as critical species in the formation of environmental persistent free radicals (EPFRs). However, little evidence exists regarding the interactions among PAHs, metals, and EPFRs in the real atmosphere. In this study, we collected PM samples in downtown Ulaanbaatar in four seasons from 2020 to 2021, and analyzed the seasonal variations of 16 PAHs, 14 heavy metals and EPFRs in PM.