西安地区PM_2.5中环境持久性自由基(EPFRs)性质及来源研究

Environmental persistent free radicals (EPFRs) are environmental risk substances that have received much attention in recent years, which may have serious effects on human health. In this study, a solvent-extraction method was used to separate the BC-like (black carbon like) substance from the atmospheric PM_2.5 samples in Xi'an. The types and concentrations of EPFRs in PM_2.5 and BC-like substance were analyzed under different atmospheric pollution conditions with electron paramagnetic resonance (EPR) spectroscopy, respectively as well as the ability of catalyzing H₂O₂ to generate hydroxyl radicals. The results showed that about 85%~90% of the EPFRs in PM_2.5 were produced by the BC-like substance. Before and after the visible light (400~700 nm), the content of EPFRs in PM_2.5 increased by 10%~20%. In addition, it was found that the substances who could catalyze H₂O₂ to generate hydroxyl radicals in PM_2.5 were mainly water-soluble substances rather than BC-like substance. And this experiment also found that EPFRs in atmospheric PM_2.5 neither had significant ability to catalyze H₂O₂ to generate hydroxyl radicals nor converted O₂ molecules to generate reactive oxygen species.