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Purpose -The aim of this work is to study the corrosion and scaling factors, mechanisms and processes affecting the materials, equipment and installations of the Cerro Prieto geothermal field (GTF). Design/methodology/approach -The physicochemical characteristics of the geothermal well and fluids were analysed, recorded and related to the corrosion and scaling phenomena. Findings -The high temperature and salinity of the steam-brine mixture and the presence of hydrogen sulphide and carbon dioxide impart a severe level of corrosivity. Originality/value -Corrosion and scaling control assure an efficient production regime, provide for the durability of the GTF engineering materials and equipment and contribute to environmental quality.

The hydraulic infrastructure is constituted by the assets of two central elements: water supply and energy generation facilities. This study deals with the durability of the structures and their engineering materials. Four vital parts of this infrastructure were selected: dams, canals, aqueducts and hydroelectric stations, which are built of two basic materials; steel and concrete. The global climate change and warming and the greenhouse -gas emissions (all interrelated complex phenomena) affect these construction materials and structures, mainly by their extreme events such as torrential rains and flooding, dry and wet seasons, high and low humidity and solar radiation. This study presents a general global approach to the climate influence on the durability of those materials and structures and concludes with a description of a particular region: a section of the 'Great American Desert' on the Mexico-USA border.

*autor a quien debe ser dirigida la correspondencia.Recibido Jul. 06, 2009; Aceptado Ago. 11, 2009; Versión Final recibida Nov. 13, 2009 RESUMEN El objetivo de esta investigación es estimar los factores de emisión (FE) que permitan valorar la cantidad de material particulado de las vías pavimentadas y no pavimentadas de la ciudad de Mexicali, Baja California, México. Se empleó el modelo AP-42 de la US EPA, bajo un diseño estadístico al azar, correspondiente a 60 sitios de muestreo en un mapa georeferenciado con proyección UTM 11 Norte. Se obtuvieron los valores de carga y porcentaje de sedimento menor a 75 µm en laboratorio, velocidad y número de vehículos, en campo. La estimación de los FE corresponden a 0.92 Kg. PM 10 /VKT y 0.73 Kg. PM 2.5 /VKT en vías pavimentadas y 2.33 Kg. PM 10 /VKT y 0.58 Kg. PM 2.5 /VKT en vías no pavimentadas, respectivamente. El valor de FE propio determina la cantidad de material particulado a suspenderse y la relación de los factores de emisión (PM 10 y PM 2.5 ) en ambas vías indica que es necesario hacer mantenimiento y control de flujo de vehículos. Palabras clave: factor de emisión, vía urbana, sedimento en vía, material particuladoEstimation of PM 10 and PM 2.5 Emission Factors, in City Roadways of Mexicali, Baja California, Mexico ABSTRACTThe objective of this research was to estimate the emission factors (EF) for evaluating the amount of particulate matter from paved and unpaved roads in the city of Mexicali, Baja California, Mexico. The model used was AP-42 of the U.S. EPA, under a random statistical design, corresponding to 60 sampling sites in a georeferenced map UTM 11 North projection. Load values were obtained and percent of sediment less than 75 µm in the laboratory, speed and number of vehicles in the field. The estimated FE correspond to 0.92 kg PM 10 /VKT and 0.73 kg PM 2.5 / VKT on paved road and 2.33 kg PM 10 /VKT and 0.58 kg PM 2.5 / VKT on unpaved roads, respectively. The value of FE determines the amount of particulate matter to be suspended and the relation of the emission factors (PM 10 and PM 2.5 ) in both roadways indicate that maintenance and control of vehicle flux may be needed.

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