Oxidative potential of urban PM2.5 in relation to chemical composition: Importance of fossil driven sources

초록

For a comprehensive evaluation of the key factors determining the oxidative potential (OP) of PM2.5, 75 samples of PM2.5 were collected in urban Seoul, South Korea, during 2019-2021, and dithiothreitol consumption (DTTv) was measured using a DTT assay, coupled with an analysis of major constituents and stable isotope ratios of PM2.5. For the entire sample set, the mean DTTv value was 0.58 +/- 0.48 nmol m-3 min-1 for PM2.5 of 29.1 +/- 12.2. DTTv exhibited a general dependence on of PM2.5 concentrations and major constituents, including NO4+, SO42-, NH4+, and organic carbon (OC). Specifically, NO3-and NH4+ demonstrated the most robust correlation with DTTv during the cold season, whereas only elemental carbon (EC) showed a significant correlation with DTTv in the warm season. The delta 13C of total carbon (TC) and delta 15N of total nitrogen (TN) displayed an inverse correlation concerning DTT activities, suggesting the significant contribution from solid fossil fuels and biomass burning to the oxidative potential of PM2.5, particularly during the cold season when PM2.5 was notably high. In contrast, vehicle emissions were found to influence DTTv even at low PM2.5 levels in warm seasons. This study provides insights into the intricate dynamics influencing the oxidative potential of PM2.5.

키워드