西安地区PM_(2.5)中环境持久性自由基(EPFRs)性质及来源研究

Study on the properties and sources of environmental persistent free radicals (EPFRs) in PM_(2.5) in Xi′an

环境持久性自由基(environmental persistent free radicals, EPFRs)是一种近年来备受关注的环境风险物质,可能会危害人体健康.本研究利用溶剂萃取方法从西安市大气PM_(2.5)样品中分离出物质,运用电子顺磁共振波谱(EPR)技术分析了不同大气污染状况下大气PM_(2.5)样品及类黑碳成分中EPFRs的种类和含量,并分别测定PM_(2.5)和类黑碳成分催化H_2O_2产生羟基自由基的能力.结果表明:PM_(2.5)中的EPFRs约有85%～90%是由类黑碳成分产生的.可见光照(400～700 nm)前后,PM_(2.5)样品中EPFRs的含量增加10%～20%.此外,实验结果亦表明PM_(2.5)中能催化H_2O_2产生羟基自由基的物质主要是PM_(2.5)中水溶性物质而不是类黑碳.大气PM_(2.5)中的EPFRs没有显著催化H_2O_2产生羟基自由基的能力,也不能将O_2分子转化为活性氧物质.

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 PM2.5 samples in Xi′an.The types and concentrations of EPFRs in PM2.5 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 PM2.5 were produced by the BC-like substance.Before and after the visible light(400~700 nm),the content of EPFRs in PM2.5 increased by 10%~20%.In addition,it was found that the substances who could catalyze H2O2 to generate hydroxyl radicals in PM2.5 were mainly water-soluble substances rather than BC-like substance.And this experiment also found that EPFRs in atmospheric PM2.5 neither had significant ability to catalyze H2O2 to generate hydroxyl radicals nor converted O2 molecules to generate reactive oxygen species.