Seasonal variation of driving factors of ambient PM2.5 oxidative potential in Shenzhen, China

Reactive oxygen species (ROS) play a central role in health effects of ambient fine particulate matter (PM). In this work, we screened for efficient and complementary oxidative potential (OP) measurements by comparing the response values of multiple chemical probes (OP, OP, OP) to ambient PM in Shenzhen, China. Combined with meteorological condition and PM chemical composition analysis, we explored the effects of different chemical components and emission sources on the ambient PM OP and analyzed their seasonal variations. The results show that OP(mass-normalized) and OP were highly correlated (r = 0.77). OP was mainly influenced by organic carbon, while OP was highly dominated by heavy metals. The combination of OP and OP provides an efficient and comprehensive measurement of OP. Temporally, the OPs were substantially higher in winter than in summer (1.4 and 4 times higher for OP and OP, respectively). The long-distance transported biomass burning sources from the north dominated the OP in winter, while the ship emissions mainly influenced the summer OP. The OP increased sharply with the decrease of PM mass concentration, especially when the PM concentration was lower than 30 μg/m. The huge differences in wind fields between the winter and summer cause considerable variations in PM concentrations, components, and OP. Our work emphasizes the necessity of long-term, multi-method, multi-component assessment of the OP of PM.