Atmospheric levels of benzene, toluene, ethylbenzene, and xylenes (BTEX) were measured in an urban site located in Nuevo Leon, Mexico, during summer and autumn 2013. A total of 60 samples were collected using carbon-packed cartridges at 0900, 1200, and 1500 h and then analyzed using gas chromatography with flame ionization detector. Meterological parameters and criteria air pollutants were measured 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 55.24 μg m−3, 22.24 μg m−3, 6.94 μg m−3, and 4.17 μg m−3, respectively, during summer. Mean concentrations during autumn were 21.079 μg m−3 for benzene, 3.648 μg m−3 for toluene, 2.521 μg m−3 for ethylbenzene, and 2.115 μg m−3 for p-xylene. All measured BTEX showed clear diurnal and seasonal patterns. The highest mean levels for benzene were obtained during the midday. Toluene, ethylbenzene, and p-xylene showed the highest levels during afternoon period. BTEX levels were higher when wind blew from NE and ESE during summer and from ESE during autumn. The municipalities of Apodaca and Guadalupe are located in these directions where important industries, high traffic volume, many oil and gas service stations, and the biggest airport in this region are found. These sources could contribute to the BTEX concentrations measured during the sampling period

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The Mexican coastal zone of the Gulf of Mexico and Caribbean (CZGMC) is an important source of ecosystem services related to biodiversity, biological productivity, and nutrient balance. This region contains more than 50% of national wetlands, near 6,000 km 2 of coastal lagoons, 24 estuaries, and the most extensive areas of coral reef in Mesoamerica. These habitats holds more than 8,500 species of marine invertebrates and fishes, 328 species of birds, 29 species of marine mammals, and share 5 out of the 11 species of current marine turtles. Its biological productivity ranges 100-2000 mg C m 2 d-1. Biodiversity and natural productivity in the CZGMC are connected to the integrity and health of coastal habitats. This paper analysed the main ecological features and the socioeconomic indicators for this region. Using GIS tools, census data, and geographic databases we compiled information from the last 30 years to assess anthropogenic impact sources, and determine trends on levels of pollution in coastal environments. Oil industry, tourism, fisheries, marine transportation, cattle ranching, and agriculture are the main economic activities on the CZGMC, which contribute more than 16% of the Mexican GDP. The current population on the six Mexican estates that border the Gulf is more than 17 10 6. One third of this population live within a narrow corridor of three km from the coastline. Within this area, human activities have cleared 65% of natural vegetation, causing the direct loss of habitats, which leads to a reduction of biodiversity. Also, the coastal population in this area produce near 1 10 6 t y-1 of solid waste and about 1,500 10 6 m 3 of wastewater, which have led to water quality deterioration.

The chemistry of rainwater has been subject to numerous investigations during the last two decades due to the increase of environmental problems caused by the acid deposition. The present study focuses on one aspect of air pollution, the chemical composition of wet deposition of an industrial zone. The sampling period was from March to December 2009. The station was located on the roof of the Chemistry School at the University of Nuevo León, an area in the north of Monterrey where the majority of pollution is generated. Twenty-five wet precipitation samples were collected with an automatic sampler and analyzed for pH, ions ( 2 4 SO − , 3 NO − , Cl − , Ca 2+ , Mg 2+ , Na + , K + ) and conductivity. The results show that the average pH is higher than 5.6; the characteristics of the rainwater studied are of alkaline nature due to the values of pH found; there is an evident anthropogenic source contributing to the alkaline of rain water. In order to find possible association between ions and consequently the possible sources of pollutants correlation study was applied using the program SPSS v.12. Good correlations were found between ions 2 4 SO − and 3 NO − along with Ca 2+ and Mg 2+ . The local extraction industry and surrounding aerosols might be causing of alkaline rain which may be due to the neutralization effect of particulate matter. This study represents a continuation of the studies of rainwater chemistry in the Northeast of Mexico.

An integral analysis of Air Pollution in the Gulf of Mexico was made considering pollutants emissions assessment and diagnosis; air pollution monitoring; and modeling of air pollution dispersion. Combustion sources considered in this work were: thermoelectric power plants and open flares; and pollutants considered were sulfur dioxide, nitrogen dioxides, particulate matter (PM 10 and PM 2.5 ), Total suspended particles (TSP) and carbon monoxide (CO). This study made evident a lack of more recent information and a homogenization in emissions factors in order to know the conditions of air pollution in the Gulf of Mexico in a more reliable way.

How to cite this paper: Ramírez-Elías, M.A., Córdova-Quiroz, A.V., Cerón-Bretón, J.G., Cerón-Bretón, R.M., Rendón-von

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