Abstract
This study aims to establish the influence of primary emission sources and atmospheric transformation process contributing to the concentrations of quinones associated to particulate matter of less than 2.5 µm (PM2.5) in three sites within the Metropolitan Area of Guadalajara (MAG), namely Centro (CEN), Tlaquepaque (TLA) and Las Águilas (AGU). Environmental levels of quinones extracted from PM2.5 filters were analyzed using Gas Chromatography coupled to Mass Spectrometry (GC-MS). Overall, primary emissions in combination with photochemical and oxidation reactions contribute to the presence of quinones in the urban atmosphere of MAG. It was found that quinones in PM2.5 result from the contributions from direct emission sources by incomplete combustion of fossil fuels such as diesel and gasoline that relate mainly to vehicular activity intensity in the three sampling sites selected. However, this also suggests that the occurrence of quinones in MAG can be related to photochemical transformation of the parent Polycyclic Aromatic Hydrocarbons (PAHs), to chemical reactions with oxygenated species, or a combination of both routes. The higher concentration of 1,4-Chrysenequinone during the rainy season compared to the warm-dry season indicates chemical oxidation of chrysene, since the humidity could favor singlet oxygen collision with parent PAH present in the particle phase. On the contrary, 9,10-Anthraquinone/Anthracene and 1,4-Naftoquinone/Naphthalene ratios were higher during the warm-dry season compared to the rainy season, which might indicate a prevalence of the photochemical formation during the warm-dry season favored by the large solar radiation typical of the season. In addition, the estimated percentage of photochemical formation of 9,10-Phenanthrenequinone showed that the occurrence of this compound in Tlaquepaque (TLA) and Las Águilas (AGU) sites is mainly propagated by conditions of high solar radiation such as in the warm-dry season and during long periods of advection of air masses from emission to the reception areas. This was shown by the direct association between the number hourly back trajectories arriving in the TLA and AGU from Centro and other areas in MAG and the highest photochemical formation percentage.
Highlights
Epidemiological studies have demonstrated that long- and short-term exposure to high environmental levels of breathable airborne particulates with an aerodynamic diameter of less than2.5 μm (PM2.5 ) is associated with several adverse health effects in humans [1,2]
PM2.5 can penetrate deeply into the alveoli and may induce human health effects, it has been found that specific chemicals substances present in PM2.5, such as trace metals, inorganic ions, or polycyclic aromatic hydrocarbons and their derivatives nitrogenated Polycyclic Aromatic Hydrocarbons (PAHs) (NPAHs) and oxygenated PAHs (OPAHs), might have a highlighted role in determining the toxicity of PM2.5 [3]
Seven quinones and their PAHs precursors were simultaneously determined in PM2.5 collected in the Guadalajara Metropolitan Area (Table 1)
Summary
2.5 μm (PM2.5 ) is associated with several adverse health effects in humans [1,2]. PM2.5 can penetrate deeply into the alveoli and may induce human health effects, it has been found that specific chemicals substances present in PM2.5 , such as trace metals, inorganic ions, or polycyclic aromatic hydrocarbons and their derivatives nitrogenated PAHs (NPAHs) and oxygenated PAHs (OPAHs), might have a highlighted role in determining the toxicity of PM2.5 [3]. The occurrence of quinones in PM2.5 , a class of oxygenated PAHs, is of concern because of their genotoxic effects. The presence of ROS can cause severe oxidative stress within cells [7] and lead to the development of diseases and pathological conditions such as asthma, cardiovascular diseases, Alzheimer, diabetes, or cancer [8].
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