第七届青年地学论坛

The increasing O₃ concentration induced the coordinated pollution of O₃ and PM_2.5 has become a new air pollution issue in China, and the increased O₃ has been thought to enhance nitrate production. But how the increase O₃ affects the nitrate formation still lacks observational evidence. Here, we compared the dataset of aerosol δ¹⁸O-NO₃^‒ value and atmospheric pollutants (such as O₃ and PM_2.5), and estimated the concentrations of atmospheric oxidants (OH and HO₂ radicals) between December 2013-February 2014 (before the Clean Air Action) and December 2017-February 2018 (during the Clean Air Action).  Compared with winter of 2013-2014, the lower aerosol δ¹⁸O-NO3- values during winter of 2017-2018 were attributed to the increasing of atmospheric oxidation capicity. In particular, during daytime, more OH readicals were produced during winter of 2017-2018, which caused more aerosol NO3- produced by NO₂+OH pathway that with low δ¹⁸O-HNO₃ value (Fig. 5a). During night, higher nocturnal O₃ concentration during winter of 2017-2018 induced more nocturnal NO₂ production that with lowest δ¹⁸O-NO₂ value (Fig. 4), which would induce the HNO₃ prodcued by nocturnal formation pathways with lowest values of δ¹⁸O-HNO₃, resulting in decreasing of aerosol δ¹⁸O-NO3-.
 

stable isotopic oxygen,aerosol NO3-,formation pathways,atmospheric oxidation capacity