Levels of Aromatic Hydrocarbons in the atmosphere of one urban site located at the northeast of Mexico during winter 2013

摘要

Atmospheric levels of aromatic hydrocarbons: benzene, toluene, ethylbenzene and p-xylene (BTEX), were measured in an urban site located in Monterrey Nuevo Leon, Mexico using an active sampling during winter 2013. 1.5 h-samples were collected using carbon packed cartridges at 09:00 h, 12:00 h and 15:00 h, and then analyzed using gas chromatography with flame ionization detector (GC-FID). Criteria pollutants (CO, O_3, NO, NO_2, NO_x, and SO_2) were measured by automatic analyzers and correlated with BTEX by a Principal Component Analysis (PCA). The relative abundance of BTEX followed the order: benzene> toluene> ethylbenzene>p-xylene with mean concentrations of 30.97 μg/m~3, 19.86 μg/m~3, 5.22 μg/m~3 and 4.52 μg/m~3, respectively. All measured BTEX showed a clear diurnal pattern. The highest mean levels for benzene were obtained during the afternoon, and toluene, ethylbenzene and p-xylene showed the highest levels during the morning sampling. Levels of BTEX were higher when wind blew from NE, N and SW, in these directions are located the municipalities of Apodaca, General Escobedo and Santa Catarina, respectively, where important industries, high traffic avenues and many oil and gas service stations are located. It can be suggested that all these sources could contributed to the BTEX concentrations found in this site during the sampling period.