Characterization and source apportionment of oxidative potential of ambient PM2.5 in Nanjing, a megacity of Eastern China

Abstract

Oxidative potential (OP) reflects integratedtoxicity of PM2.5. Therefore, OP of PM2.5 samples collected from traditional central and suburban areas (Gulou and Xianlin) in Nanjing, a megacity of China, from Jan. 2020 to Jun. 2021 was analyzed by using two abiotic assays, DTT and AA assays (OPDTT and OPAA). Values of OPDTTv and OPAAv were  0.82 ~ 3.82  and    0.15 ~ 2.22 nmol/min/m3, respectively. The OP values of PM2.5 samples collected from the Xianlin were higher than those from the Gulou by using both the DTT assay and the AA assay in this study, suggesting the seasonal and spatial variation. Moreover, OP values analyzed by using DTT assay were higher than those by using AA assay. Based on Positive Matrix Factorization (PMF), the major pollution source of the OP of PM2.5 in Nanjing was combustion source. This study may be helpful for evaluating adverse health risks of PM2.5 in a megacity.