Humberto Bravo Alvarez

Photochemical assessment monitoring stations program adapted for ozone precursors monitoring network in Mexico City

The purpose of this study is to select a number of stations from the existing Sistema de Monitoreo Atmosferico (Atmospheric Monitoring System, SIMAT) of Mexico City to serve as an equivalent to the Photochemical Assessment Monitoring Stations according to the US-EPA criteria, in order to improve the study of urban ozone occurrence. The results indicate that four existing SIMAT stations meet the criteria to form such network. The relevance of this study is to present an ozone precursors monitoring network with continuous measurements for future trustful studies on air quality for ozone, considering the atmospheric chemistry and photochemical modeling for the design control strategies appropriate for the particular conditions of Mexico City.

Spatial and temporal variability of atmospheric mercury concentrations emitted from a coal-fired power plant in Mexico

ABSTRACT Atmospheric mercury in the environment as a result of the consumption of fossil fuels, such as coal used in electricity generation, has gained increased attention worldwide because of its toxicity, atmospheric persistence, and bioaccumulation. Determining or predicting the concentration of this pollutant in ambient air is essential for determining sensitive areas requiring health protection. This study investigated the spatiotemporal variability of gaseous elemental mercury (GEM) concentrations and its dry deposition surrounding the Presidente Plutarco Elías Calles (CETEPEC) coal-fired power plant, located on Mexico’s Pacific coast. The CALPUFF dispersion model was applied on the basis of the daily consumption of coal during 2013 for each generating unit in the power plant and considering the local scale. The established 300-ng/m3 annual average risk factor considered by the U.S. Department of Health and Human Services (U.S. DHHS) and Integrated Risk Information System (IRIS) must not be exceeded to meet satisfactory air quality levels. An area of 65 × 60 km was evaluated, and the results show that the risk level for mercury vapor was not exceeded because the annual average concentration was 2.8 ng/m3. Although the predicted risk level was not exceeded, continuous monitoring studies of GEM and of particulates in the atmosphere, soil, and water may be necessary to identify the concentration of this pollutant, specifically that resulting from coal-fired power plants operated in environmental areas of interest in Mexico. The dry mercury deposition was low in the study area; according to the CALPUFF model, the annual average was 1.40E−2 ng/m2/sec. These results represent a starting point for Mexico’s government to implement the Minamata Convention on Mercury, which Mexico signed in 2013. Implications: The obtained concentrations of mercury from a bigger coal-fired plant in Mexico, through the application of the CALPUFF dispersion model by the mercury emissions, are below the level recommended according to the US Department of Health and Human Services and Integrated Risk Information System. These results provide evidence of important progress in the planning and installation to the future of monitoring mercury stations in the area of interest.

ESTIMACIÓN DE EMISIONES DE MERCURIO EN LAS PLANTAS CARBOELÉCTRICAS DE MÉXICO

To reduce mercury emissions in the atmosphere is one of the agreements reached at the International Convention of Minamata, held in Kumamoto, Japan in 2013. In view of this commitment the main objective of this study was estimating monthly temporal variation of mercury emissions per generation unit for each of the three coal-fired power plants in Mexico during the years 2012 and 2013. Emissions were estimated based on the method of the US Environmental Protection Agency (USEPA), from mercury content in coal and emission factors, knowing the actual fuel consumption. The results show that the greatest emission was presented in the coal-fired power plant located in Petacalco, Guerrero, with the generating unit number seven presenting the major emissions. Furthermore, in all cases it was during the summer when a major amount of mercury was emitted due to a large requirement of electricity. This study is important as a preliminary tool for decision making in the process of prevention, minimization and control of toxic pollutants, which contribute to international agreements for the protection of the environment and society.