西安市大气 PM_2.5 分子演化和来源对其氧化潜势的影响

To investigate the seasonal variation and source of oxidative potential (OP) in atmospheric fine particulate matter (PM_2.5) in Xi’an, the mass normalized OP (OP^DTTm) was measured using the dithiothreitol (DTT) method, and the influence of chemical components of PM_2.5 on OP^DTTm was analyzed, and the contributions of different sources to OP^DTTm was quantified using a positive matrix factorization coupled with an artificial neural network multilayer perceptron (PMF-ANN-MLP) model. The findings revealed that OP^DTTm in Xi’an was highest during summer ((13.2 ± 5.4) pmol(min·µg)) and lowest in winter ((5.6 ± 2.7) pmol(min·µg)). Correlation analysis indicated that nitro-containing aromatic compounds and carboxylic acids have a significant impact on OP^DTTm, and the difference in molecular abundance was the main reason for the seasonal variation of OP^DTTm. Source apportionment showed that dust (26.7%), traffic (35.1%), secondary formation (23.2%), and biomass burning (24.5%) and coal combustion (25.8%) were the predominant contributors to OP^DTTm during spring, summer, autumn, and winter, respectively. These results provide a scientific foundation for developing effective air pollution control measures aimed at safeguarding public health.