Impact of external industrial sources on the regional and local SO<sub>2</sub> and O<sub>3</sub> levels of the Mexico megacity

Abstract

The air quality of megacities can be influenced by external emission sources on both global and regional scales. At the same time their outflow emissions can exert an impact to the surrounding environment. The present study evaluates an SO 2 peak observed on 24 March 2006 at the suburban supersite T1 and at ambient air quality monitoring stations located in the northern region of the Mexico City Metropolitan Area (MCMA) during the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. We found that this peak could be related to an important episodic emission event coming from Tizayuca region, northeast of the MCMA. Back-trajectory analyses suggest that the emission event started in the early morning at 04:00 LST and lasted for about 9 h. The estimated emission rate is about 2 kg s −1 . To the best of our knowledge, sulfur dioxide emissions from the Tizayuca region have not been considered in previous studies. This finding suggests the possibility of "overlooked" emission sources in this region that could influence the air quality of the MCMA. This further motivated us to study the cement plants, including those in the state of Hidalgo and in the State of Mexico. It was found that they can contribute to the SO 2 levels in the northeast (NE) region of the basin (about 42 %), at the suburban supersite T1 (41 %) and that at some monitoring stations their contribution can be even higher than the contribution from the Tula Industrial Complex (TIC).The contribution of the Tula Industrial Complex to regional ozone levels is estimated. The model suggests low contribution to the MCMA (1 to 4 ppb) and slightly higher contribution at the suburban T1 (6 ppb) and rural T2 (5 ppb) supersites. However, the contribution could be as high as 10 ppb in the upper northwest region of the basin and in the southwest and south-southeast regions of the state of Hidalgo. In addition, the results indicated that the ozone plume could also be transported to northwest Tlaxcala, eastern Hidalgo, and farther northeast of the State of Mexico, but with rather low values. A first estimate of the potential contribution from flaring activities to regional ozone levels is presented. Results suggest that up to 30 % of the total regional ozone from TIC could be related to flaring activities.Finally, the influence on SO 2 levels from technological changes in the existing refinery is briefly discussed. These changes are due to the upcoming construction of a new refinery in Tula. The combination of emission reductions in the power plant, the refinery and in local sources in the MCMA could result in higher reductions on the average SO 2 concentration. Reductions in external sources tend to affect more the northern part of the basin (−16 to −46 %), while reductions of urban sources in the megacity tend to diminish SO 2 levels substantially in the central, southwest, and southeast regions (−31 to −50 %).

Analysis of remotely sensed and surface data of aerosols and meteorology for the Mexico Megalopolis Area between 2003 and 2015

“…Previous analysis of emissions from the Popocatépetl Volcano showed that the wind direction pointed northwest toward the MCMA for less than 20% of the analysis period [Grutter et al, 2008]. A previous analysis of SO 2 levels in the MCMA attributed a significant fraction of its emissions to local cement plants and industrial processes in the Tizayuca region [Almanza et al, 2014]. Other studies have demonstrated the impact of SO 2 emissions from the Tula Industrial Complex, located northwest of Mexico City [de Foy et al, 2007;Karydis et al, 2011;Ying et al, 2014].…”

Application of Tropospheric Sulfate Aerosol Emissions to Mitigate Meteorological Phenomena with Extremely High Daily Temperatures

“…In this work, we also considered other lower rates (30 and ____________________________________________________________________________ 2019 / 23 23 50 g s −1 ). The maximum emission rate was determined at 1000 g s −1 per km 2 , based on industrial emissions derived from mega cities such as Mexico [74].…”

MODELO DE DISTRIBUCIÓN ESPACIAL, TEMPORAL Y DE ESPECIACIÓN DEL INVENTARIO DE EMISIONES DE MÉXICO (AÑO BASE 2008) PARA SU USO EN MODELIZACIÓN DE CALIDAD DEL AIRE (DiETE)

“…Se han presentado diferentes trabajos de modelización de calidad del aire para la zona centro de México (García-Reynoso et al 2009, Mena-Carrasco et al 2009, Song et al 2010, Jazcilevich et al 2011, Almanza et al 2014, García-Escalante et al 2014, Ruiz-Suárez 2015 y para toda la República Mexicana (Tie et al 2007, Emmons et al 2010. En el desarrollo de dichas investigaciones se han empleado inventarios de emisiones.…”