道路沥青中长寿命自由基特征及二次生成

本研究运用电子顺磁共振波谱方法（EPR）发现道路沥青中含有大量的环境持久性自由基（EPFRs），说明道路沥青可能是道路源大气颗粒物中EPFRs的重要来源途径.因此，进一步通过溶剂萃取从沥青中分离出不同极性组分，研究不同沥青组分中EPFRs的含量和种类分布特征，并且在这基础上探究道路沥青在光化学作用下二次生成EPFRs的潜能和特征.结果表明：沥青中含有的EPFRs类型是以碳原子为中心的自由基和以氧原子为中心的自由基混合存在（g=2.0032~2.0038），主要可能是芳烃类自由基和半醌自由基.沥青中EPFRs主要存在于不可萃取组分和二氯甲烷可萃取组分中，推测沥青大多数的EPFRs可能源于沥青中的大分子芳香化合物和酚类组分.沥青在模拟太阳光照射后，可生成10%~20%的二次EPFRs，并且发现新生成的主要是以g因子较大的氧原子为中心的EPFRs.

Characteristics and secondary formation of EPFRs in road asphalt

In this study, electron paramagnetic resonance (EPR) method was used to analysis the environmentally persistent free radicals EPFRs in road asphalt. It is found that the abundant EPFRs are present in the road asphalt, therefore it is speculated that road asphalt may be a potential source of EPFRs in road source atmospheric particles. This study was established to separate several components from asphalt by solvent extraction. The content and type distribution characteristics of EPFRs in different asphalt components were also studied. On the basis of this statement, the potential and characteristics of secondary EPFRs in road asphalt by photochemical reaction were explored. The results showed that the type of EPFRs in asphalt was a mixture of carbon centered and oxygen centered free radicals (g=2.0032~2.0038), mainly aromatic radicals and semiquinone radicals. The results also showed that 10%~20% of secondary EPFRs could be produced by asphalt after simulating sunlight irradiation, and it was found that the secondary EPFRs are mainly centered on oxygen atoms with larger g factor.