Abstract Both water-soluble and insoluble components of ambient particulate matter (PM) have been shown to contribute to the oxidative potential (OP) of PM. In this study, we used the dithiothreitol (DTT) assay to assess the water-soluble (OPWS−DTT) and total OP (OPtotal−DTT) of ambient fine particles (PM2.5), with water-insoluble OP (OPWI−DTT) determined by difference. Ambient PM2.5 filter samples were collected daily during 2017 in urban Atlanta and were analyzed for OP and major PM components. Results from measurements suggested a measurable contribution of water-insoluble components to OPDTT, which comprised on average 20% of total PM OP. Strong seasonal trends were observed in both volume- and mass-normalized OPtotal−DTT and OPWI−DTT, with higher values in the winter than in the summer, possibly driven by biomass burning emission seasonality. Correlation analysis indicated that all forms of OPDTT measurements were related to organic species and metals. OPtotal−DTT and OPWI−DTT were correlated with brown carbon (BrC) and total metals, especially total crustal elements. A multivariate regression model was developed for OPtotal−DTT based on particle composition data. The model suggested that the variability of OPtotal−DTT was primarily affected by BrC, followed by EC, total Cu and an antagonistic interaction between BrC and total Cu.

中文翻译：

---

使用二硫苏糖醇测定法表征 PM2.5 的水不溶性氧化电位

摘要 环境颗粒物 (PM) 的水溶性和不溶性成分已被证明对 PM 的氧化势 (OP) 有贡献。在本研究中，我们使用二硫苏糖醇 (DTT) 测定来评估环境细颗粒 (PM2.5) 的水溶性 (OPWS-DTT) 和总 OP (OPtotal-DTT)，以及不溶于水的 OP (OPWI-DTT) ) 由差异决定。2017 年在亚特兰大市区每天收集环境 PM2.5 过滤器样本，并分析 OP 和主要 PM 成分。测量结果表明，水不溶性组分对 OPDTT 的贡献是可测量的，平均占 PM OP 总量的 20%。在体积和质量标准化的 OPtotal-DTT 和 OPWI-DTT 中都观察到了强烈的季节性趋势，冬季的值高于夏季，这可能是由生物质燃烧排放季节性驱动的。相关性分析表明，所有形式的 OPDTT 测量都与有机物种和金属有关。OPtotal-DTT 和 OPWI-DTT 与褐碳 (BrC) 和总金属，尤其是总地壳元素相关。基于粒子组成数据为 OPtotal-DTT 开发了多元回归模型。该模型表明 OPtotal-DTT 的变异性主要受 BrC 影响，其次是 EC、总 Cu 以及 BrC 和总 Cu 之间的拮抗相互作用。