Semi-volatile components of PM2.5 in an urban environment: volatility profiles and associated oxidative potential.
Semi-volatile components of PM2.5 in an urban environment: volatility profiles and associated oxidative potential.
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城市环境中 PM2.5 的半挥发性成分：挥发性特征和相关的氧化潜力。
DOI：
10.1016/j.atmosenv.2019.117197
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Sioutas,Constantinos
中科院分区：
文献类型：
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作者：
Pirhadi,Milad;Mousavi,Amirhosein;Taghvaee,Sina;Shafer,MartinM;Sioutas,Constantinos
研究了洛杉矶市中心PM2. 5半挥发性化合物的挥发性分布及其与城市空气颗粒物氧化电位的关系。采用多功能气溶胶浓度富集系统（VACES）与热扩散器相结合，在温暖和寒冷的季节收集环境和热扩散细颗粒物（PM2.5）。当在50 °C和100 °C下操作时，VACES/热扩散器系统分别去除约50%和75%的PM2.5vol浓度。PM2.5中的大多数半挥发性物质包括有机碳（OC）、水溶性有机碳（WSOC）、多环芳烃（PAH）、有机酸、正构烷烃和左旋葡聚糖，以及无机离子（即，硝酸盐、硫酸盐和铵）的浓度损失分别为40-66%和67- 92%。PM2.5中的元素碳（EC）和无机元素（包括微量金属）等物质受加热过程的影响最小，因此可以被认为是耐火材料。平均而言，近一半的PM2.5氧化潜力（通过二氯二氢荧光素（DCFH）肺泡巨噬细胞体外试验测量）与通过将气溶胶加热到仅50 °C而去除的半挥发性物质有关，突出了这种相当易挥发的隔室对环境PM2.5毒性的重要性。在将气溶胶加热至100 °C时，PM2.5氧化电位损失的部分进一步增加至约75- 85%。此外，我们还记录了PM2.5氧化电位与来自一级和二级来源的不同半挥发性有机化合物（包括OC）之间的统计学显著相关性（Rwarm和Rcold）（0.86和0.74），WSOC（0.60和0.98），多环芳烃（0.88和0.76），有机酸（0.76和0.88），以及正烷烃（0.67）和0.83），而氧化电位与生物质燃烧的示踪物左旋葡聚糖之间存在较强的相关性，仅在寒冷季节观察到（Rcold= 0.81）。
The volatility profiles of PM2.5semi-volatile compounds and relationships to the oxidative potential of urban airborne particles were investigated in central Los Angeles, CA. Ambient and thermodenuded fine (PM2.5) particles were collected during both warm and cold seasons by employing the Versatile Aerosol Concentration Enrichment System (VACES) combined with a thermodenuder. When operated at 50 °C and 100 °C, the VACES/thermodenuder system removed about 50% and 75% of the PM2.5vol concentration, respectively. Most of the quantified PM2.5semi-volatile species including organic carbon (OC), water soluble organic carbon (WSOC), polycyclic aromatic hydrocarbons (PAHs), organic acids, n-alkanes, and levoglucosan, as well as inorganic ions (i.e., nitrate, sulfate, and ammonium) exhibited concentration losses in the ranges of 40–66% and 67–92%, respectively, as the thermodenuder temperature increased to 50 °C and 100 °C. Species in the PM2.5such as elemental carbon (EC) and inorganic elements (including trace metals) were minimally impacted by the heating process – thus can be considered refractory. On average, nearly half of the PM2.5oxidative potential (as measured by the dichlorodihydrofluorescein (DCFH) alveolar macrophage in vitro assay) was associated with the semi-volatile species removed by heating the aerosols to only 50 °C, highlighting the importance of this quite volatile compartment to the ambient PM2.5toxicity. The fraction of PM2.5oxidative potential lost upon heating the aerosols to 100 °C further increased to around 75–85%. Furthermore, we document statistically significant correlations between the PM2.5oxidative potential and different semi-volatile organic compounds originating from primary and secondary sources, including OC (Rwarm, and Rcold) (0.86, and 0.74), WSOC (0.60, and 0.98), PAHs (0.88, and 0.76), organic acids (0.76, and 0.88), and n-alkanes (0.67, and 0.83) in warm and cold seasons, respectively, while a strong correlation between oxidative potential and levoglucosan, a tracer of biomass burning, was observed only during the cold season (Rcold= 0.81).