Effects of meteorology on diurnal and nocturnal levels of priority polycyclic aromatic hydrocarbons and elemental and organic carbon in PM10 at a source and a receptor area in Mexico City |
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Authors: | Diana Guzmán-Torres Arantza Eiguren-Fernández Pablo Cicero-Fernández Marisela Maubert-Franco Armando Retama-Hernández Rafael Ramos Villegas Antonio H Miguel |
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Institution: | 1. Department of Physics, Sree Krishna College Guruvayur, Kerala 680102, India;2. Department of Physics, Sir Syed College, Taliparamba, Kannur, Kerala, India;3. Department of Physics, Govt. Brennen College, Thalassery, Kerala, India;4. Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA |
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Abstract: | PM10 levels of the 16 US-EPA Priority Pollutant polycyclic aromatic hydrocarbons (PAHs) were measured from March 17 to 31, 2003, in 8-h time bins (morning, afternoon and nighttime) at Merced, a source site dominated by vehicular traffic emissions near the center of Mexico City, and at Pedregal, a receptor area located downwind in a residential area of low traffic. Along with PAH, elemental (EC) and organic carbon (OC), mass, and prevailing meteorological parameters were measured. At the source location, measured concentrations of benzoa]pyrene (BAP), an agent suspected of being carcinogenic to humans and of causing oxidative DNA damage, reached concentrations as high as 2.04 and 2.11 ng m?3 during the morning of a weekday and the night period of a holiday. Compared with source dominated areas in Central Los Angeles, the BAP levels found in Central Mexico City are approximately 6 times higher. Benzoghi]perylene (BGP) levels were, in general, the highest among the target PAH, both at the source (7.2 ng m?3) and the receptor site (2.8 ng m?3), suggesting that, at both locations, exhaust emission by light-duty (LD) vehicles is an important contributor to the atmospheric PAH burden. Higher PAH concentrations were observed during the morning period (5:00–13:00 h) at the source and the receptor site. The concentrations of PAHs found predominantly in the particle-phase (MW > 202) correlated well (r = 0.57–0.71) with the occurrence of surface thermal inversions and with mixing heights (r = ?0.57 to ?0.72). Organic and elemental carbon ratios also indicated that Pedregal is impacted by secondary aerosols during the afternoon hours. |
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