Vehicle emissions are an important source of particulate matter (PM) in urban areas and have well-known adverse health effects on human health. Oxidative potential (OP) is used as a quantification metric for indexing PM toxicity. In this study, by using a liquid spot sampler (LSS) and the dithiothreitol (DTT) assay, the diurnal OP variation was assessed at a ground-level urban monitoring station. Besides, since the monitoring station was adjacent to the main road, the correlation between OP and traffic volume was also evaluated. PM components, including metals, water-soluble inorganic aerosols (WSIAs), black carbon (BC), and polycyclic aromatic hydrocarbons (PAHs), were also simultaneously monitored. The daytime and evening mean ± std volume-normalized OP (OPv) were 0.46 ± 0.27 and 0.48 ± 0.26 nmol/min/m³, and exhibited good correlations with PM_1.0 and BC; however, these concentrations were only weakly correlated with mass-normalized OP (OPm). The mean ± std OPm was higher in the daytime (41.3 ± 13.8 pmol/min/μg) than in the evening (36.1 ± 11.5 pmol/min/μg). According to the PMF analysis, traffic emissions dominated the diurnal OP contribution. Organic matter and individual metals associated with non-exhaust traffic emissions, such as Mn, Fe, and Cu, contributed substantially to OP. Diurnal variations of PAH concentrations suggest that photochemical reactions could enhance OP, highlighting the importance of atmospheric aging on PM toxicity.

车辆排放是城市地区颗粒物 (PM) 的重要来源，对人类健康具有众所周知的不利健康影响。氧化潜力 (OP) 被用作量化 PM 毒性的指标。在这项研究中，通过使用液体点采样器 (LSS) 和二硫苏糖醇 (DTT) 测定，在地面城市监测站评估了昼夜 OP 变化。此外，由于监测站毗邻主干道，因此还评估了OP与交通量之间的相关性。PM 成分，包括金属、水溶性无机气溶胶 (WSIA)、黑碳 (BC) 和多环芳烃 (PAH)，也同时受到监测。白天和晚上的平均值 ± 标准体积标准化 OP (OPv) 分别为 0.46 ± 0.27 和 0.48 ± 0.26 nmol/min/m ³，并与 PM _1.0和 BC表现出良好的相关性；然而，这些浓度与质量归一化 OP (OPm) 仅微弱相关。白天 (41.3 ± 13.8 pmol/min/μg) 的平均值 ± std OPm 高于晚上 (36.1 ± 11.5 pmol/min/μg)。根据 PMF 分析，交通排放在昼夜 OP 贡献中占主导地位。有机物和与非尾气交通排放相关的个别金属，如锰、铁和铜，对 OP 贡献很大。PAH 浓度的日变化表明光化学反应可以增强 OP，突出了大气老化对 PM 毒性的重要性。