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Sample records for canals mexico city

  1. 1985 Mexico City, Mexico Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The magnitude 8.1 earthquake occurred off the Pacific coast of Mexico. The damage was concentrated in a 25 square km area of Mexico City, 350 km from the epicenter....

  2. Microbiological indicators of water quality in the Xochimilco canals, Mexico City Indicadores microbiológicos de la calidad del agua de los canales de Xochimilco de la Ciudad de México

    OpenAIRE

    Luis Alfredo Juárez-Figueroa; Jesús Silva-Sánchez; Felipe Javier Uribe-Salas; Enrique Cifuentes-García

    2003-01-01

    OBJECTIVE: To quantify microbiology indicators of fecal contamination in the effluents of two waste water treatment plants and in samples collected in several canals in Xochimilco. MATERIAL AND METHODS: A cross sectional study was performed. Ten sites, 5 from plant effluents and 5 from canals, were selected for sampling during November and December 2001. Fecal coliforms and enterococci were quantified by membrane filtration, male specific (F+) and somatic coliphages by double agar layer techn...

  3. Structural Damage in Mexico City

    OpenAIRE

    Hall, John F; Beck, James L.

    1986-01-01

    This paper describes the structural damage in Mexico City caused by the September 19, 1985 earthquake. Photographs which illustrate various features of structural behavior are included. One explanation is presented as to why buildings with fundamental periods of elastic vibration considerably below the predominant two‐second period of the ground motion were most vulnerable to damage.

  4. Sister Cities along US/Mexico Border

    Data.gov (United States)

    U.S. Environmental Protection Agency — Locations of 29 cities referred to as US and Mexico "Sister Cities." The locations of the cities were pulled from the Digital Chart of the World database, 1994. The...

  5. Microbiological indicators of water quality in the Xochimilco canals, Mexico City Indicadores microbiológicos de la calidad del agua de los canales de Xochimilco de la Ciudad de México

    Directory of Open Access Journals (Sweden)

    Luis Alfredo Juárez-Figueroa

    2003-10-01

    Full Text Available OBJECTIVE: To quantify microbiology indicators of fecal contamination in the effluents of two waste water treatment plants and in samples collected in several canals in Xochimilco. MATERIAL AND METHODS: A cross sectional study was performed. Ten sites, 5 from plant effluents and 5 from canals, were selected for sampling during November and December 2001. Fecal coliforms and enterococci were quantified by membrane filtration, male specific (F+ and somatic coliphages by double agar layer technique, and Cryptosporidium oocysts and Giardia cysts by concentration with Envirocheck filter followed by immunofluorescence microscopy quantification.The average of organisms counts from effluents and canal water were compared with t Student test. RESULTS: Treated water discharge in canals showed a low count of Fecal Coliforms (average 40.4/100 ml, enterococci (average 58.8/100 ml and Cryptosporidium oocysts (average 13.2/100 l, while coliphages and Giardia cyst rendered higher counts (average 1467.5/100 ml and 1199.8/100 l, respectively suggesting the water treatment methods could fail to remove these agents. A significant lower count of Giardia cysts (average 45/100 l and no Cryptosporidium oocysts were found in irrigation canals, which suggests a natural clearance of these pathogens. Strains of Escherichia coli isolated in one of the canals contaminated with sewage had antimicrobial multi-resistance that was transferred by conjugation suggesting that resistance is encoded in a plasmid potentially transferable to other pathogenic bacteria. CONCLUSIONS: Cost effective and culturally acceptable waste treatment methods will require careful planning and consultation if they are to be adopted and mantained by local populations.OBJETIVO: Cuantificar diversos indicadores de contaminación fecal en los efluentes de dos plantas de tratamiento de aguas residuales y en muestras recogidas en varios canales de Xochimilco. MATERIAL Y MÉTODOS: Estudio transversal

  6. LCA of road infrastructure in Mexico City.

    OpenAIRE

    Rosales Carreon, Jesus

    2007-01-01

    Vehicular traffic is a major problem in metropolitan areas and Mexico City is no exception. Located in a pollutant-trapping valley, Mexico City (one of the largest cities in the world) is famous for its size, its history, and the warmth of its people. Nev

  7. Pollution of Lahore canal water in the city premises

    International Nuclear Information System (INIS)

    Water contamination is one of the major environmental pollution problems facing Pakistan because it has a direct impact on the health of human beings and crops. Lahore Canal water is being used both for irrigation and a source of ground water recharge. For the best use of this water, extent of pollution and its effect on soil hydraulic properties needs to be studied. For this purpose, water samples from twenty three sites and soil samples from three sites were collected along the Canal within the city limits of Lahore. The survey of the area from Jallo Park to Mall Road, show that all the abadies/colonies and industries situated on both sides of the canal dump their waste water and garbage in to canal. This result in increase of salinity as well as BOD and COD values which were found maximum at the locations of Herbuns Pura, Mughal Pura Dharam Pura, and Thoker Niaz Baig. (authors)

  8. Earthquake Damage in Mexico City, Mexico, September 19, 1985

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — On September 19, 1985, a magnitude 8.1 earthquake occurred off the Pacific coast of Mexico. The damage was concentrated in a 25 km2 area of Mexico City, 350 km from...

  9. Global politics in Mexico City.

    Science.gov (United States)

    Wulf, D; Willson, P D

    1984-01-01

    At the 1984 United Nations International Conference on Population held in August, delegates from 149 countries affirmed that population dynamics are an intrinsic part of development and that all people, including adolescents, have a right to family planning information and services. Despite concern for continued US support for population activities, the US delegation in Mexico City clearly emphasized its government's commitment to increased funding. The conference also accepted by acclamation the Mexico City Declaration on Population and Development drafted by 29 countries which stresses the importance of increased funding for population policy, the urgent need to improve women's status and the concern for the effects of the deepening economic crisis, Legal abortion and voluntary sterilization as fertility determinants were ignored. The meeting put to rest any notion that population and development activities are competing spheres of action. In contrast to its 1974 position, the US emphasized entrepreneurial initiative within a free-market system as a stimulus to economic development. The status of women was a major issue brought up by the delegations of Zimbabwe and Australia. The crucial but uncertain issue of funding was addressed by most country represehntatives and most developed countries pledged at least continued if not increased funding for development programs. Most discussion on the abortion issue was almost universally based on repudiation of the procedure as a family planning method. The role of the US in the abortion issue is discussed. The US criticized 2 international agencies that provide most of family planning services to which the US provides funding but which are promoting abortion through affiliates. The US affirmed it would not participate in or assist abortion promotion as a birth control method. The nature and scope of the current economic world crisis caused profound differences between the US and most developing countries' delegations

  10. 75 FR 28555 - Executive Green ICT & Energy Efficiency Trade Mission to Mexico City, Mexico

    Science.gov (United States)

    2010-05-21

    ... International Trade Administration Executive Green ICT & Energy Efficiency Trade Mission to Mexico City, Mexico... Commercial Service are organizing an Executive Green ICT & Energy Efficiency Trade Mission to Mexico City... conference will take place at the World Trade Center in Mexico City. Relevant issues on energy efficiency...

  11. 76 FR 58772 - Safety & Security Trade Mission; Mexico City and Monterrey, Mexico

    Science.gov (United States)

    2011-09-22

    ... International Trade Administration Safety & Security Trade Mission; Mexico City and Monterrey, Mexico AGENCY... Safety and Security trade mission to Mexico City and Monterrey, Mexico, for January 30-February 2, 2012... traveling to Mexico independently, will enhance the companies' ability to secure meetings with...

  12. [Typhus in Mexico City in 1915].

    Science.gov (United States)

    Rodríguez, Martha Eugenia

    2016-01-01

    The year 1915 was particularly difficult; it was characterized by droughts, famines, and outbreaks of diseases including typhus.This text exposes its spread in Mexico City as well as the measures implemented to combat it, carried out before knowing the etiology of the illness, focused on cleaning up the environment and the measures undertaken afterwards with the aim of delousing people. PMID:27160626

  13. The heat spells of Mexico City

    OpenAIRE

    Ernesto Jáuregui

    2009-01-01

    The warning of urban air has been documented to increase in intensity and area as cities grow (Oke, 1982). As the cities grow the so called heat island tends to increase the risk of more frequent heat waves as well as their impacts (IPCC, 2001). Threshold values to define a heat wave vary geographically. For the case of Mexico City located in a high inland valley in the tropics, values above 30° C (daily maximum observed for three or more consecutive days and 25° C or more as mean temperatu...

  14. Microbiological Implications of Periurban Agriculture and Water Reuse in Mexico City

    OpenAIRE

    Mazari-Hiriart, Marisa; Ponce-de-León, Sergio; López-Vidal, Yolanda; Islas-Macías, Pilar; Amieva-Fernández, Rosa Isabel; Quiñones-Falconi, Francisco

    2008-01-01

    Background Recycled treated or untreated wastewater represents an important health challenge in developing countries due to potential water related microbiological exposure. Our aim was to assess water quality and health implications in a Mexico City periurban agricultural area. Methodology/Principal Findings A longitudinal study in the Xochimilco wetland area was conducted, and 42 sites were randomly selected from 211, including irrigation water canals and effluents of treatment plants. Samp...

  15. Mexico City Air Quality Research Initiative

    International Nuclear Information System (INIS)

    The Mexico City Air Quality Research Initiative is one project that is examining the complex relationship between air pollution, economic growth, societal values, and air quality policies. This paper describes the programs that are being used to fulfill the three tasks of the project: air pollution modeling and simulation, air pollution monitoring, and strategic evaluation. The two lead institutions for this project are the Mexican Petroleum Institute and Los Alamos National Laboratory

  16. Urban air pollution, study of Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, M. [PUE-UNAM (Mexico); Guzman, F. [Inst. Mexicano del Petroleo (Mexico); Navarro, B. [Univ. Autonoma Metropolitana (Mexico)

    1996-12-01

    The Metropolitan Area of Mexico City (MAMC) is an outstanding case of a fast urban development with lagging, and thus insufficient, massive transportation facilities. This has given rise to a distorted transportation system that accounts for most of the air pollution problem of the city and constitutes a drag on economic development. In this paper, we first describe the MAMC geographical conditions, its growth in physical and economic terms, its transportation system, the ensuring air pollution problems together with some of the mitigation actions undertaken. Afterwards the results of a survey of the displacements of individuals within the city and the time spent on these are presented, to then draw some considerations on the negative economic impact it represents. (EG)

  17. MEXICO CITY'S MUNICIPAL SOLID WASTE CHARACTERISTICS AND COMPOSITION ANALYSIS

    OpenAIRE

    Alfonso DURÁN MORENO; Manuel GARCÉS RODRÍGUEZ; Adriana Rocío VELASCO; Juan Carlos MARÍN ENRIQUEZ; Rafaela GUTIÉRREZ LARA; Abril MORENO GUTIÉRREZ; Norma Angélica DELGADILLO HERNÁNDEZ

    2013-01-01

    Mexico City generates approximately 12 500 000 kg of municipal solid wastes (MSW) a day. Nowadays, waste management of the refuse material is of high concern since the local landfill has reached its limit capacity and its closure is imminent, thereby alternative disposal methods must be evaluated. The objective of this paper is to analyze the composition of MSW produced in Mexico City through a sampling campaign. In comparison to previous official reports of Mexico Citys MSW characterization,...

  18. Metals in aerosols of the Mexico City

    International Nuclear Information System (INIS)

    The general purpose and scope of this work was to have a data base that includes enough information about the heavy metals which are disseminated in the atmospheric air in Mexico City, like it is what refers to its elements, its concentration and its particle size. For this were collected samples through collectors types: of the filters unit and the cascade impactor. Through the PIXE analysis for filters and films it was identified the presence of 20 elements in the majority of samples studied of the four seasons during the years 1993-1994. The metals were classified in two groups: those of natural origin and those of anthropogenic origin. (Author)

  19. Determination of radon levels in Mexico City

    International Nuclear Information System (INIS)

    The study of the determination of radon levels in the houses room in Mexico City is part of the project Emanometry of the radon. To carry out this study, the passive method was used, which consists of: thin film dosemeter of cellulose nitrate, container of the same one and spark accountant. The method is based on the mensurations of exhibition of the number of marks of alpha track is of the open type and it allows to average the radon activity along several weeks and it presents low concentrations. This study was carried out in 4 periods of exhibition of 3 months each one. (Author)

  20. Seismic Hazard Management in Mexico City

    Science.gov (United States)

    Wintergerst, L.

    2007-05-01

    Mexico City is one of the largest cities in the world. More than 8.5 million residents and 4.5 million floating population are in the city itself, but with the surrounding suburbs the number of people that could be affected by natural and man-made hazards rises to approximately 20 million. The main risk to the city as a whole is a large magnitude earthquake. Since there is reason to prepare for a credible seismic scenario of Mw = 8.2, which would exceed the damages caused during the 1985 earthquake (Mw = 8.1), we founded the Metropolitan Geologic Service (MGS) in 1998. The MGS has developed geologic and seismic hazard maps for the city (http:www.proteccioncivil.df.gob.mx). The maps include three separate risk maps for low height (3 stories), medium height (10 stories) and tall buildings (10 stories). The maps were prepared by using the maximum horizontal accelerations documented during the 1985 earthquake, and wave propagation modeling for buildings of different resonant periods (T = 0.0, 1.0 and 2.0 sec). In all cases, the risk zones were adjusted to include documented damage during the 1957, 1979 and 1985 earthquakes. All three maps show a high risk zone in the north-central portion of the city, elongated in a N-S direction, which corresponds with a narrow graben where the thickness of alluvial sediments is particularly large, and where wave amplification is accentuated. Preparation of these maps, and others used for planning, has been facilitated by the ongoing elaboration of a Dynamic Geographical Information System, which is based on geo-scientific information, includes all types of risks, and incorporates vulnerability models. From the risk management standpoint, we have elaborated the Permanent Contingency Plan for Mexico City, which in its Earthquakes chapter includes plans for coordination and for organizing attention to the population in the event of a seismic disaster. This Permanent Plan follows the philosophy of Descartes' Method, has 11 processes (6

  1. 76 FR 73595 - Healthcare Technology, Policy & Trade Mission: Mexico City, Mexico, May 13-16, 2012

    Science.gov (United States)

    2011-11-29

    ... applicants will be evaluated on their ability to meet certain conditions and to satisfy the selection... arrival in Mexico City on May 13, participants will check into the hotel and participate in a commercial...; Preferential hotel rates in Mexico City. Optional Gold Key Service not included in the trade...

  2. Winter Dew Harvest in Mexico City

    Directory of Open Access Journals (Sweden)

    Arias-Torres Jorge Ernesto

    2015-12-01

    Full Text Available This study presents experimental and theoretical results of winter dew harvest in México City in terms of condensation rate. A simplified theoretical model based on a steady-state energy balance on a radiator-condenser was fitted, as a function of the ambient temperature, the relative humidity and the wind velocity. A glass sheet and aluminum sheet white-painted were used as samples over the outdoor experiments. A good correlation was obtained between the theoretical and experimental data. The experimental results show that there was condensation in 68% of the winter nights on both condensers. The total winter condensed mass was 2977 g/m2 and 2888 g/m2 on the glass sheet and aluminum sheet white-painted, respectively. Thus, the condensed mass on the glass was only 3% higher than that on the painted surface. The maximum nightly dew harvests occurred during December, which linearly reduced from 50 g/m2 night to 22 g/m2 night as the winter months went by. The condensation occurred from 1:00 a.m. to 9:00 a.m., with maximum condensation rates between 6:00 a.m. and 7:00 a.m. The dew harvest can provide a partial alternative to the winter water shortage in certain locations with similar climates to the winter in Mexico City, as long as pollution is not significant.

  3. A Grand Session with the World in Name of Canals——Retrospect on China Yangzhou World Canal Cities Expo

    Institute of Scientific and Technical Information of China (English)

    Xu; Pei

    2013-01-01

    <正>The Grand Canal of China,an important record of the Chinese civilization,has been making significant contributions to the country’s economic development,national unity,social progress,and cultural exchange between the north and the south.As the only city that was born and grew along with a canal in China,Yangzhou gains its prosperity through this canal and in return enhances the beauty of the canal.People in Yangzhou call the

  4. Lead exposure in students in Mexico City.

    Science.gov (United States)

    Alvear Galindo, M G; Carreón García, J; Moreno Altamirano, A; Cuéllar López, J A; Kimura, L Y

    1994-10-01

    The present study was done between 1989 and 1991 and performed on 263 children 7 to 9 years of age who lived in Mexico City. The goal was to determine the association between risk factors entering the body through the respiratory or digestive path and lead concentration in deciduous teeth. Exposure to risk factors was surveyed through a questionnaire; lead was determined by atomic absorption spectrophotometry with a graphite oven and reported in microgram Pb/g tooth. Statistical significance was found for the habit of sucking toys OR 4.98 (IC 95% 1.23-28.67), the use of glazed earthenware utensils for the preparation and serving of food and drinks OR 2.47 (IC 0.80-8.47), and the ingestion of tinned food, particularly juices OR 3.31 (IC 1.03-12.50). No positive results were found for risk factors involving the respiratory path. A possible explanation for these results is a different risk level for each of the two paths of access. PMID:7529159

  5. Mexico City's Water Management: In Search of Sustainability

    OpenAIRE

    Carrera-Hernandez, J.J.

    2006-01-01

    Mexico City is facing water supply problems as its population increases and aquifer overexploitation needs to be stopped. Because of its geographic location the City has continuously faced water related problems such as floods and lack of the resource. Currently the closest water sources have been already tapped and more water will be needed in the near future in order to satisfy the ever increasing demand as the aquifer systems located under the City provide nearly 75% of the total water sup...

  6. Light Absorbing Aerosols in Mexico City

    Science.gov (United States)

    Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

    2008-12-01

    The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

  7. Measurements of VOCs in Mexico City during the MILAGRO Campaign

    Science.gov (United States)

    Baker, A. K.; Beyersdorf, A. J.; Blake, N. J.; Meinardi, S.; Atlas, E.; Rowland, F.; Blake, D. R.

    2006-12-01

    During March of 2006 we participated in MILAGRO (Megacities Initiative: Local and Global Research Observations), a multi-platform campaign to measure pollutants in and in outflow from the Mexico City metropolitan area. As part of MILAGRO we collected whole air canister samples at two Mexico City ground sites: the Instituto Mexicano del Petroleo, located in the city, northeast of the center, and the Universidad Technologica de Tecamac, a suburban site approximately 50 km northeast of the city center. Samples were also collected in various other locations throughout Mexico City. Over 300 whole air samples were collected and analyzed for a wide range of volatile organic compounds (VOCs) including methane, carbon monoxide, nonmethane hydrocarbons (NMHCs) and halocarbons. Propane was the most abundant NMHC at both the urban and suburban locations, with mixing ratios frequently in excess of 10 parts per billion at both locations. This is likely the result of the widespread use of liquefied petroleum gas (LPG) of which propane is the major component. For most species, median mixing ratios at the urban sites were significantly greater than at the suburban site. Here we compare results from both urban and suburban locations and also examine the influence of transport on the composition of outflow from Mexico City.

  8. Emissions from Forest Fires near Mexico City

    Science.gov (United States)

    Yokelson, R.; Urbanski, S.; Atlas, E.; Toohey, D.; Alvarado, E.; Crounse, J.; Wennberg, P.; Fisher, M.; Wold, C.; Campos, T.; Adachi, K.; Buseck, P. R.; Hao, W. M.

    2007-01-01

    The emissions of NOx (defined as NO (nitric oxide) + NO2 (nitrogen dioxide)) and hydrogen cyanide (HCN), per unit amount of fuel burned, from fires in the pine forests that dominate the mountains surrounding Mexico City (MC) are about 2 times higher than normally observed for forest burning. The ammonia (NH3) emissions are about average for forest burning. The upper limit for the mass ratio of NOX to volatile organic compounds (VOC) for these MC-area mountain fires was approximately 0.38, which is similar to the NOx/VOC ratio in the MC urban area emissions inventory of 0.34, but much larger than the NOx/VOC ratio for tropical forest fires in Brazil (approximately 0.068). The nitrogen enrichment in the fire emissions may be due to deposition of nitrogen-containing pollutants in the outflow from the MC urban area. This effect may occur worldwide wherever biomass burning coexists with large urban areas (e.g. the tropics, southeastern US, Los Angeles Basin). The molar emission ratio of HCN to carbon monoxide (CO) for the mountain fires was 0.012 +/- 0.007, which is 2-9 times higher than widely used literature values for biomass burning. The ambient molar ratio HCN/CO in the MC-area outflow is about 0.003 +/- 0.0003. Thus, if only mountain fires emit significant amounts of HCN, these fires may be contributing about 25% of the CO production in the MCarea (approximately 98-100 W and 19-20 N). Comparing the PM10/CO and PM2.5/CO mass ratios in the MC Metropolitan Area emission inventory (0.01 15 and 0.0037) to the PM1/CO mass ratio for the mountain fires (0.133) then suggests that these fires could produce as much as approximately 79-92% of the primary fine particle mass generated in the MC-area. Considering both the uncertainty in the HCN/CO ratios and secondary aerosol formation in the urban and fire emissions implies that about 50 +/- 30% of the "aged" fine particle mass in the March 2006 MC-area outflow could be from these fires.

  9. Emissions from forest fires near Mexico City

    Directory of Open Access Journals (Sweden)

    R. J. Yokelson

    2007-11-01

    Full Text Available The emissions of NOx (defined as NO (nitric oxide + NO2 (nitrogen dioxide and hydrogen cyanide (HCN, per unit amount of fuel burned, from fires in the pine forests that dominate the mountains surrounding Mexico City (MC are about 2 times higher than normally observed for forest burning. The ammonia (NH3 emissions are about average for forest burning. The upper limit for the mass ratio of NOx to volatile organic compounds (VOC for these MC-area mountain fires was ~0.38, which is similar to the NOx/VOC ratio in the MC urban area emissions inventory of 0.34, but much larger than the NOx/VOC ratio for tropical forest fires in Brazil (~0.068. The nitrogen enrichment in the fire emissions may be due to deposition of nitrogen-containing pollutants in the outflow from the MC urban area. This effect may occur worldwide wherever biomass burning coexists with large urban areas (e.g. the tropics, southeastern US, Los Angeles Basin. The molar emission ratio of HCN to carbon monoxide (CO for the mountain fires was 0.012±0.007, which is 2–9 times higher than widely used literature values for biomass burning. The ambient molar ratio HCN/CO in the MC-area outflow is about 0.003±0.0003. Thus, if only mountain fires emit significant amounts of HCN, these fires may be contributing about 25% of the CO production in the MC-area (~98–100 W and 19–20 N. Comparing the PM10/CO and PM2.5/CO mass ratios in the MC Metropolitan Area emission inventory (0.0115 and 0.0037 to the PM1/CO mass ratio for the mountain fires (0.133 then suggests that these fires could produce as much as ~79–92% of the primary fine particle mass generated in the MC-area. Considering both the uncertainty in the HCN/CO ratios and secondary aerosol formation in the urban and fire emissions implies that about 50±30% of the "aged" fine particle mass in the March 2006 MC-area outflow could be from these fires.

  10. Urban agriculture in the metropolitan area of Mexico city

    OpenAIRE

    H. Losada; Rivera, J.; Cortes, J; Vieyra, J.

    2011-01-01

    Mexico City and the rest of the country do not escape from the social and economic inequalities of the present economic model applied worldwide.  Agriculture is a traditional activity in Mexico. This urban productive process has particular features: the predominance of smallholding, the restricted use of physical space, and the use of recycled materials and organic wastes. The population engaged in agriculture is heterogeneous, and includes women and children. There are a couple of production...

  11. 78 FR 7670 - Safety Zone; Indian Street Bridge Construction, St. Lucie Canal, Palm City, FL

    Science.gov (United States)

    2013-02-04

    ...The Coast Guard is establishing a temporary safety zone on the St. Lucie Canal, Palm City, Florida to provide for the safety of life and vessels on a narrow waterway during bridge construction for the Indian Street Bridge. Persons and vessels are prohibited from entering, transiting through, anchoring in, or remaining within the safety zone unless authorized by the Captain of the Port Miami or......

  12. Community Policing in Latin America: Lessons from Mexico City

    OpenAIRE

    Markus-Michael Müller

    2010-01-01

    Community policing programmes are widely perceived and promoted as an important solution for the pressing problems of insecurity in contemporary Latin American cities, and for improving citizen-police relationships. By drawing on the results of empirical fieldwork conducted in Mexico City, the article presents a critical analysis of the local community policing effort. The article demonstrates that this policing effort is overly determined by a local context, characterized by clientelism, pol...

  13. Producing Globalization in the Public Space of Mexico City

    OpenAIRE

    Moreno-Carranco, Maria

    2006-01-01

    According to Davies (2000) the distopian “‘cold’ frozen geometries” of US cities are being countered by Latino populations offering “a ‘hotter’, more exuberant urbanism” that is “tropicalizing” the city with colors, smells and new public spaces. Complimentary hopes, with fewer romantic and ethnic overtones, are being expressed for a resurgent civics as Latinos recast the discursive content of the public sphere (Valle & Torres, 2000). Yet, in Mexico, debates about public space draw deeply pess...

  14. Biodiesel from waste cooking oil in Mexico City.

    Science.gov (United States)

    Sheinbaum, Claudia; Balam, Marco V; Robles, Guillermo; Lelo de Larrea, Sebastian; Mendoza, Roberto

    2015-08-01

    The aim of this article is to evaluate the potential use of biodiesel produced from waste cooking oil in Mexico City. The study is divided in two main areas: the analysis of a waste cooking oil collection pilot project conducted in food markets of a Mexico City region; and the exhaust emissions performance of biodiesel blends measured in buses of the Mexico City public bus transportation network (RTP). Results from the waste cooking oil collection pilot project show that oil quantities disposed depend upon the type of food served and the operational practices in a cuisine establishment. Food markets' waste cooking oil disposal rate from fresh oil is around 10%, but with a very high standard deviation. Emission tests were conducted using the Ride-Along-Vehicle-Emissions-Measuring System in two different types of buses while travelling a regular route. Results shows that the use of biodiesel blends reduces emissions only for buses that have exhaust gas recirculation systems, as analysed by repeated measure analysis of variance. The potential use in Mexico City of waste cooking oil for biodiesel is estimated to cover 2175 buses using a B10 blend. PMID:26142425

  15. Short-Term Water Dynamics in Chihuahua City, Mexico

    OpenAIRE

    Thomas M Fullerton Jr; Ana Cecilia Nava

    2004-01-01

    Linear transfer ARIMA analysis of monthly per meter water consumption is conducted for Chihuahua City, Mexico. Sample data from January 1988 to December 2000 are analyzed. Time series utilized include water system revenue, climate, and industrial production data. Out-of-sample simulations are used to confirm the reliability of the in-sample estimation results.

  16. INAA of aerosol samples in Mexico City

    International Nuclear Information System (INIS)

    Total solid particles (TSP), respirable particles (RP) PM10 and 17 metallic pollutants were measured in dwellings in the Metropolitan Zone of Mexico Valley (MZMV) by gravimetry and instrumental neutron activation analysis (INAA). Monitoring was performed in Northeast, Center, Southeast and Southwest Zones in the winter and spring seasons. In general, the average concentration of contaminants (derived from industrial activities) that we have determined have increased with time. TSP and RP PM10 are often above the US and Mexican norms. (author)

  17. 33 CFR 165.556 - Regulated Navigation Area; Chesapeake and Delaware Canal, Chesapeake City Anchorage Basin, MD.

    Science.gov (United States)

    2010-07-01

    ... areas, found in 33 CFR 165.13, apply to the regulated navigation area described in paragraph (a) of this...; Chesapeake and Delaware Canal, Chesapeake City Anchorage Basin, MD. 165.556 Section 165.556 Navigation and..., Chesapeake City Anchorage Basin, MD. (a) Location. The following area is a regulated navigation area:...

  18. Alkyl nitrate production and persistence in the Mexico City Plume

    Directory of Open Access Journals (Sweden)

    G. Sachse

    2009-11-01

    Full Text Available Alkyl and multifunctional nitrates (ΣANs have been observed to be a significant fraction of NOy in a number of different chemical regimes. Their formation is an important free radical chain termination step ending production of ozone and possibly affecting formation of secondary organic aerosol. ΣANs also represent a potentially large, unmeasured contribution to OH reactivity and are a major pathway for the removal of nitrogen oxides from the atmosphere. Numerous studies have investigated the role of nitrate formation from biogenic compounds. Less attention has been paid to the role ΣANs may play in the complex mixtures of hydrocarbons typical of urban settings. Measurements of ΣANs, NO2, total peroxy nitrates (ΣPNs, HNO3 and a wide suite of hydrocarbons were obtained from the NASA DC-8 aircraft during spring of 2006 in and around Mexico City and the Gulf of Mexico. ΣANs were observed to be 10–20% of NOy in the Mexico City plume and to increase in importance with increased photochemical age. We describe three conclusions: 1 Correlations of ΣANs with odd-oxygen (Ox indicate a stronger role for ΣANs in the photochemistry of Mexico City than is expected based on currently accepted photochemical mechanisms, 2 ΣAN formation suppresses peak ozone production rates by as much as 30% in the near-field of Mexico City and 3 ΣANs play a comparable role to ΣPNs in the export of NOy to the Gulf Region.

  19. Urbanisation and flood vulnerability in the peri-urban interface of Mexico City.

    Science.gov (United States)

    Aragón-Durand, Fernando

    2007-12-01

    Chronic flooding in the Chalco valley, state of Mexico, Mexico, is the outcome of past and present socio-environmental changes which have taken place in Mexico City's south-eastern peri-urban interface. This flooding is the result of a complex interaction between urbanisation in an ex-lacustrine area, permanent ecological deterioration and ground subsidence, poor sanitation and inadequate policy responses. Far from solving the flooding problem, short-term policy responses have created increasingly unsafe conditions for current residents. A socio-historical analysis of disasters reveals the importance of taking into consideration particular social actors and institutions in hazard generation and flood vulnerability over time. This paper analyses three aspects of this flooding: first, the importance of approaching floods from a socio-historical perspective; second, the relation between urbanisation, former policies and flood risk generation; and third, current policy responses to and the failure in the risk management of La Compañía Canal. PMID:18028165

  20. Mexico City Air Quality Research Initiative; Volume 5, Strategic evaluation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-03-01

    Members of the Task HI (Strategic Evaluation) team were responsible for the development of a methodology to evaluate policies designed to alleviate air pollution in Mexico City. This methodology utilizes information from various reports that examined ways to reduce pollutant emissions, results from models that calculate the improvement in air quality due to a reduction in pollutant emissions, and the opinions of experts as to the requirements and trade-offs that are involved in developing a program to address the air pollution problem in Mexico City. The methodology combines these data to produce comparisons between different approaches to improving Mexico City`s air quality. These comparisons take into account not only objective factors such as the air quality improvement or cost of the different approaches, but also subjective factors such as public acceptance or political attractiveness of the different approaches. The end result of the process is a ranking of the different approaches and, more importantly, the process provides insights into the implications of implementing a particular approach or policy.

  1. Formaldehyde Surface Distributions and Variability in the Mexico City Basin

    Science.gov (United States)

    Junkermann, W.; Mohr, C.; Steinbrecher, R.; Ruiz Suarez, L.

    2007-05-01

    Formaldehyde ambient air mole fractions were measured throughout the dry season in March at three different locations in the Mexico City basin. The continuously running instruments were operated at Tenago del Aire, a site located in the Chalco valley in the southern venting area of the basin, at the Intituto Mexicano del Petroleo (IMP) in the northern part of the city and about 30 km north of the city at the campus of the Universidad Tecnològica de Tecamac (UTTEC). The technique used is the Hantzsch technology with a time resolution of 2 minutes and a detection limit of 100 ppt. Daily maxima peaked at 35 ppb formaldehyde in the city and about 15 to 20 ppb at the other sites. During night formaldehyde levels dropped to about 5 ppb or less. It is evident that the observed spatial and temporal variability in near surface formaldehyde distributions is strongly affected by local and regional advection processes.

  2. 3 CFR - Mexico City Policy and Assistance for Voluntary Population Planning

    Science.gov (United States)

    2010-01-01

    ... 3 The President 1 2010-01-01 2010-01-01 false Mexico City Policy and Assistance for Voluntary Population Planning Presidential Documents Other Presidential Documents Memorandum of January 23, 2009 Mexico... what has become known as the “Mexico City Policy” directed the United States Agency for...

  3. Selection Among Investment Alternatives for Transportation Infrastructure in Mexico City

    Directory of Open Access Journals (Sweden)

    Palomas–Molina X

    2010-10-01

    Full Text Available A systematic method is proposed to analyze, over a given set of high occupancy Mexico City traffic network nodes, the feasibility of different types of infrastructure modifications. This method al lows obtaining, based on statistical information and in te ger programming, the best combination of infrastructure modifications under a scenario of restricted bud get. The final choice is based, on one hand, on the savings implied by the reduction of traveling time and pollutants not emitted to the environment and, on the other, on the cost of the specific type of construction involved. The method can be easily adapted to other cities with adjustments to the statistical information.

  4. EDXRF determination of Pb in aerosol samples from Mexico City

    International Nuclear Information System (INIS)

    The indiscriminate use of automobile transport in high populated cities is one of the major causes of atmospheric pollution. The uncontrolled emissions from automobile engines in the past have made Mexico city one of the most polluted world capitals. Since 1989 the Government started a set of actions as part of the Program to improve the quality of the air in the Mexico valley. A method for the determination of Pb contents in air particulate matter was developed in the Laboratory of Bacteriology and Physical Chemistry, analyzing high volume aerosol filters by Energy Dispersive X-ray Fluorescence (EDXRF) using a 30 mCi 238 Pu excitation source. The performance of the analytical procedure is discussed

  5. Childhood acute leukemias are frequent in Mexico City: descriptive epidemiology

    Directory of Open Access Journals (Sweden)

    Bekker-Méndez Vilma

    2011-08-01

    Full Text Available Abstract Background Worldwide, acute leukemia is the most common type of childhood cancer. It is particularly common in the Hispanic populations residing in the United States, Costa Rica, and Mexico City. The objective of this study was to determine the incidence of acute leukemia in children who were diagnosed and treated in public hospitals in Mexico City. Methods Included in this study were those children, under 15 years of age and residents of Mexico City, who were diagnosed in 2006 and 2007 with leukemia, as determined by using the International Classification of Childhood Cancer. The average annual incidence rates (AAIR, and the standardized average annual incidence rates (SAAIR per million children were calculated. We calculated crude, age- and sex-specific incidence rates and adjusted for age by the direct method with the world population as standard. We determined if there were a correlation between the incidence of acute leukemias in the various boroughs of Mexico City and either the number of agricultural hectares, the average number of persons per household, or the municipal human development index for Mexico (used as a reference of socio-economic level. Results Although a total of 610 new cases of leukemia were registered during 2006-2007, only 228 fit the criteria for inclusion in this study. The overall SAAIR was 57.6 per million children (95% CI, 46.9-68.3; acute lymphoblastic leukemia (ALL was the most frequent type of leukemia, constituting 85.1% of the cases (SAAIR: 49.5 per million, followed by acute myeloblastic leukemia at 12.3% (SAAIR: 6.9 per million, and chronic myeloid leukemia at 1.7% (SAAIR: 0.9 per million. The 1-4 years age group had the highest SAAIR for ALL (77.7 per million. For cases of ALL, 73.2% had precursor B-cell immunophenotype (SAAIR: 35.8 per million and 12.4% had T-cell immunophenotype (SAAIR 6.3 per million. The peak ages for ALL were 2-6 years and 8-10 years. More than half the children (58.8% were

  6. Survey of aflatoxins in maize tortillas from Mexico City.

    Science.gov (United States)

    Castillo-Urueta, Pável; Carvajal, Magda; Méndez, Ignacio; Meza, Florencia; Gálvez, Amanda

    2011-01-01

    In Mexico, maize tortillas are consumed on a daily basis, leading to possible aflatoxin exposure. In a survey of 396 2-kg samples, taken over four sampling days in 2006 and 2007 from tortilla shops and supermarkets in Mexico City, aflatoxin levels were quantified by HPLC. In Mexico, the regulatory limit is 12 µg kg⁻¹ total aflatoxins for maize tortillas. In this survey, 17% of tortillas contained aflatoxins at levels of 3-385 µg kg⁻¹ or values below the limit of quantification (12 µg kg⁻¹ and 87% were below the regulatory limit. Average aflatoxin concentrations in 56 contaminated samples were: AFB1 (12.1 µg kg⁻¹); AFB2 (2.7 µg kg⁻¹); AFG1 (64.1 µg kg⁻¹) and AFG2 (3.7 µg kg⁻¹), and total AF (20.3 µg kg⁻¹). PMID:24779661

  7. Air pollution and unleaded gasoline in Mexico City

    OpenAIRE

    Bríd Gleeson Hanna; Alethia Jimenez Garcia

    2008-01-01

    Using a spline regression model and a monthly time series from January 1989 to December 2004 for Mexico City, we test for changes in the time trend for air pollution that coincide with the introduction of a new and relatively expensive unleaded gasoline in September 1990. At this time, new cars were required to have catalytic converters and leaded gasoline was significantly cheaper than unleaded gasoline. The price difference provided an incentive to use leaded gasoline in automobiles that we...

  8. Solar absorption infrared spectroscopic measurements over Mexico City: Methane enhancements

    OpenAIRE

    ALEJANDRO BEZANILLA; ARNE KRÜGER; WOLFGANG STREMME; MICHEL GRUTTER

    2014-01-01

    In this work, the experiment for performing solar-absorption infrared measurements from the atmospheric observatory of the Universidad Nacional Aut ó noma de M é xico (UNAM) located at the university campus in Mexico City is described. The Fourier transform infrared (FTIR) spectrometer and solar-tracking system have been operating since June 2010, and from the recorded spectra the total column amounts of several atmospheric gases can be derived. The current study presents the results obtained...

  9. Rapid ethnographic assessment of breastfeeding practices in periurban Mexico City.

    OpenAIRE

    Guerrero, M. L.; Morrow, R C; Calva, J. J.; Ortega-Gallegos, H.; Weller, S C; Ruiz-Palacios, G M; Morrow, A L

    1999-01-01

    Before carrying out a breastfeeding promotion programme in a periurban area of Mexico City, we conducted a rapid ethnographic study to determine the factors associated with absence of exclusive breastfeeding. The responses to pilot interviews were used to develop a standardized questionnaire regarding reasons for infant feeding choice, sources of advice, and barriers to breastfeeding. We interviewed a random sample of 150 mothers with a child < 5 years of age; 136 (91%) of them had initiated ...

  10. Selection Among Investment Alternatives for Transportation Infrastructure in Mexico City

    OpenAIRE

    Palomas–Molina X; Álvarez–Icaza L.

    2010-01-01

    A systematic method is proposed to analyze, over a given set of high occupancy Mexico City traffic network nodes, the feasibility of different types of infrastructure modifications. This method al lows obtaining, based on statistical information and in te ger programming, the best combination of infrastructure modifications under a scenario of restricted bud get. The final choice is based, on one hand, on the savings implied by the reduction of traveling time and pollutants not emitted to the...

  11. Using Aerial Photography to Study Mexico City: The El Caballito

    Directory of Open Access Journals (Sweden)

    Lourdes Roca

    2015-03-01

    Full Text Available This article describes potential lines of research using aerial photographs, focusing particularly on the study of urban areas. The specific case considered is that of Mexico City. After presenting an overview of aerial photography in Mexico, we review the potential of this type of record as a primary source for research. The visual corpus analyzed is composed of about 30 aerial photographs taken between 1932 and 1978. They portray the urban space that is our object of investigation: a downtown intersection in Mexico City, known as el crucero de El Caballito (“the little horse intersection” because an equestrian statue of Carlos IV stood there for nearly 150 years. We examine the collection of photographs taken at this site in order to demonstrate the methodological implications of working with aerial photographs of cities. The backdrop to this proposal is work on documentation, cataloguing and dissemination undertaken at the Laboratorio Audiovisual de Investigación Social (Audiovisual Laboratory for Social Research at the Instituto Mora.

  12. Irrigation water quality in southern Mexico City based on bacterial and heavy metal analyses

    Energy Technology Data Exchange (ETDEWEB)

    Solis, C. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo Postal 20-364, 01000 Mexico, DF (Mexico)]. E-mail: corina@fisica.unam.mx; Sandoval, J. [Instituto de Ecologia, Universidad Nacional Autonoma de Mexico, Apdo Postal 70-275, 04510 Mexico, DF (Mexico); Perez-Vega, H. [Ciencias Agropecuarias, Universidad Juarez Autonoma de Tabasco, Ave. Universidad S/N. Zona de la Cultura, 86040 Villa Hermosa, Tabasco (Mexico); Mazari-Hiriart, M. [Instituto de Ecologia, Universidad Nacional Autonoma de Mexico, Apdo Postal 70-275, 04510 Mexico, DF (Mexico)

    2006-08-15

    Xochimilco is located in southern Mexico City and represents the reminiscence of the pre-Columbian farming system, the 'chinampa' agriculture. 'Chinampas' are island plots surrounded by a canal network. At present the area is densely urbanized and populated, with various contaminant sources contributing to the water quality degradation. The canal system is recharged by a combination of treated-untreated wastewater, and precipitation during the rainy season. Over 40 agricultural species, including vegetables, cereals and flowers, are produced in the 'chinampas'. In order to characterize the quality of Xochimilcos' water used for irrigation, spatial and temporal contaminant indicators such as microorganisms and heavy metals were investigated. Bacterial indicators (fecal coliforms, fecal enterococcus) were analyzed by standard analytical procedures, and heavy metals (such as Fe, Cu, Zn and Pb) were analyzed by particle induced X-ray emission (PIXE). The more contaminated sites coincide with the heavily populated areas. Seasonal variation of contaminants was observed, with the higher bacterial counts and heavy metal concentrations reported during the rainy season.

  13. Irrigation water quality in southern Mexico City based on bacterial and heavy metal analyses

    International Nuclear Information System (INIS)

    Xochimilco is located in southern Mexico City and represents the reminiscence of the pre-Columbian farming system, the 'chinampa' agriculture. 'Chinampas' are island plots surrounded by a canal network. At present the area is densely urbanized and populated, with various contaminant sources contributing to the water quality degradation. The canal system is recharged by a combination of treated-untreated wastewater, and precipitation during the rainy season. Over 40 agricultural species, including vegetables, cereals and flowers, are produced in the 'chinampas'. In order to characterize the quality of Xochimilcos' water used for irrigation, spatial and temporal contaminant indicators such as microorganisms and heavy metals were investigated. Bacterial indicators (fecal coliforms, fecal enterococcus) were analyzed by standard analytical procedures, and heavy metals (such as Fe, Cu, Zn and Pb) were analyzed by particle induced X-ray emission (PIXE). The more contaminated sites coincide with the heavily populated areas. Seasonal variation of contaminants was observed, with the higher bacterial counts and heavy metal concentrations reported during the rainy season

  14. Physical Exposure to Seismic Hazards of Health Facilities in Mexico City, Mexico

    Science.gov (United States)

    Rodriguez, S. M.; Novelo Casanova, D.

    2010-12-01

    Although health facilities are essential infrastructure during disasters and emergencies, they are also usually highly vulnerable installations in the case of the occurrence of large and major earthquakes. Hospitals are one of the most complex critical facilities in modern cities and they are used as first response in emergency situations. The operability of a hospital must be maintained after the occurrence of a local strong earthquake in order to satisfy the need for medical care of the affected population. If a health facility is seriously damaged, it cannot fulfill its function when most is needed. In this case, hospitals become a casualty of the disaster. To identify the level of physical exposure of hospitals to seismic hazards in Mexico City, we analyzed their geographic location with respect to the seismic response of the different type of soils of the city from past earthquakes, mainly from the events that occurred on September 1985 (Ms= 8.0) and April 1989 (Ms= 6.9). Seismic wave amplification in this city is the result of the interaction of the incoming seismic waves with the soft and water saturated clay soils, on which a large part of Mexico City is built. The clay soils are remnants of the lake that existed in the Valley of Mexico and which has been drained gradually to accommodate the growing urban sprawl. Hospital facilities were converted from a simple database of names and locations into a map layer of resources. This resource layer was combined with other map layers showing areas of seismic microzonation in Mexico City. This overlay was then used to identify those hospitals that may be threatened by the occurrence of a large or major seismic event. We analyzed the public and private hospitals considered as main health facilities. Our results indicate that more than 50% of the hospitals are highly exposed to seismic hazards. Besides, in most of these health facilities we identified the lack of preventive measures and preparedness to reduce their

  15. Impact of trash burning on air quality in Mexico City.

    Science.gov (United States)

    Hodzic, A; Wiedinmyer, C; Salcedo, D; Jimenez, J L

    2012-05-01

    Air pollution experienced by expanding urban areas is responsible for serious health effects and death for millions of people every year. Trash burning is a common disposal method in poor areas, yet it is uncontrolled in many countries, and its contribution to air pollution is unclear due to uncertainties in its emissions. Here we develop a new trash burning emission inventory for Mexico City based on inverse socioeconomic levels and recently measured emission factors, and apply a chemistry-transport model to analyze the effects on pollutant concentrations. Trash burning is estimated to emit 25 tons of primary organic aerosols (POA) per day, which is comparable to fossil fuel POA emissions in Mexico City, and causes an increase in average organic aerosol concentrations of ∼0.3 μg m(-3) downtown and up to 2 μg m(-3) in highly populated suburbs near the sources of emission. An evaluation using submicrometer antimony suggests that our emission estimates are reasonable. Mitigation of trash burning could reduce the levels of organic aerosols by 2-40% and those of PM(2.5) by 1-15% over the metropolitan area. The trash burning contributions to carbon monoxide, nitrogen oxides, and volatile organic compounds were found to be very small (organic aerosols are also very small. PMID:22458823

  16. 14C content in aerosols in Mexico City

    Science.gov (United States)

    Gómez, V.; Solís, C.; Chávez, E.; Andrade, E.; Ortiz, M. E.; Huerta, A.; Aragón, J.; Rodríguez-Ceja, M.; Martínez, M. A.; Ortiz, E.

    2016-03-01

    14C-AMS of total carbon was determined in aerosols (PM10 fraction), collected in Mexico City during two weeks from 21 November to 3 December 2012. Other tracers such as total carbon (TC), organic carbon (OC), elemental carbon (EC) and trace element contents were also determined. F14C values varied from 0.39 to 0.48 with an average of 0.43. These values are slightly lower than those previously obtained for PM2.5 in 2003 and 2006 and reflect a high contribution of fossil CO2 to the carbonaceous matter in aerosols from Mexico City. In contrast, from 2006 to 2012 PM10 increased; EC, Ca, Ti and Fe concentrations remained constant, while OC, TC and K concentrations decreased. The use of potassium as an indicator of biomass burning showed that this source was negligible during this campaign. Combined analytical approaches allowed us to distinguish temporal variations of anthropogenic and natural inputs to the F14C.

  17. Challenges and Opportunities of Air Quality Management in Mexico City

    Science.gov (United States)

    Paramo, V.

    2013-05-01

    The Mexico City Metropolitan Area (MCMA) is located in the central plateau of Mexico and is the capital of the country. Its natural characteristics present favorable conditions for air pollution formation and accumulation: mountains surrounding the city, frequent thermal inversions, high isolation all around the year and weak winds. To these natural conditions, a population of more than 20 million inhabitants, a fleet of 4.5 million vehicles and more than 4 thousands industries, make air quality management a real challenge for governments of the region. Intensive air quality improvement actions and programs began at the end of the 1980's and continued nowadays. Since then criteria air pollutants concentrations have decreased in such a way that currently most of pollutants meet the Mexican air quality standards, except for ozone and particulate matter. Applied measures comprised of fuel quality improvements, fuel replacements, regulations for combustion processes, closing of high polluting refineries and industries, regulations of emissions for new and on road vehicles, mandatory I/M programs for vehicles, circulation restrictions for vehicles (Day without car program), alert program for elevated air pollution episodes, improvement of public transportation, among others. Recent researches (MILAGRO 2006 campaign) found that currently it is necessary to implement emissions reduction actions for Volatile Organic Compounds, particulate matter with a diameter of less than 2.5 micrometers PM2.5 and Nitrogen Oxides, in order to reduce concentrations of ozone and fine particulate matter. Among the new measures to be implemented are: regulations for VOCs emissions in the industry and commercial sectors; regulation of the diesel fleet that includes fleets renewal, filters and particulate traps for in use vehicles and regulation of the cargo fleet; new schemes for reducing the number of vehicles circulating in the city; implementation of non-motorized mobility programs; among

  18. Microbiological implications of periurban agriculture and water reuse in Mexico City.

    Directory of Open Access Journals (Sweden)

    Marisa Mazari-Hiriart

    Full Text Available BACKGROUND: Recycled treated or untreated wastewater represents an important health challenge in developing countries due to potential water related microbiological exposure. Our aim was to assess water quality and health implications in a Mexico City periurban agricultural area. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal study in the Xochimilco wetland area was conducted, and 42 sites were randomly selected from 211, including irrigation water canals and effluents of treatment plants. Sample collection took place during rainy and dry seasons (2000-2001. Microbiological parameters (total coliforms, fecal coliforms, streptococci/enterococci, and bacteria other than Vibrio grown on TCBS, Helicobacter pylori, and physicochemical parameters including trihalomethanes (THM were determined. Fecal coliforms and fecal streptococci are appropriate indicators of human or animal fecal contamination. Fecal coliform counts surpass Mexican and World Health Organization irrigation water guidelines. Identified microorganisms associated with various pathologies in humans and domestic animals comprise Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp., Enterococcus spp., and Pseudomonas spp; H. pylori was also present in the water. An environmental characteristic of the canal system showed high Total Organic Carbon content and relatively low dissolved oxygen concentration; residual chlorine as a disinfection control is not efficient, but THMs do not represent a problem. During the rainy season, temperature and conductivity were higher; in contrast, pH, dissolved oxygen, ammonia, and residual chlorine were lower. This is related with the continuous load of feces from human and animal sources, and to the aquatic systems, which vary seasonally and exhibit evidence of lower water quality in effluents from treatment plants. CONCLUSIONS/SIGNIFICANCE: There is a need for improvement of wastewater treatment systems, as well as more efficient

  19. Effects on soil properties of future settlements in downtown Mexico City due to ground water extraction

    OpenAIRE

    E. Ovando Shelley; M. P. Romo; Contreras, N.; Giralt, A. (Albert)

    2003-01-01

    Water pumping from shallow aquifers under Mexico City causes large differential settlements. Consolidation modifies the mechanical properties of the subsoil, both static and dynamic. Approximate expressions to predict soil properties are proposed. A scenario for the distribution of settlements in downtown Mexico City suggests that the city’s architectural heritage could be partly lost in a few decades. Seismic response analyses considering future soil properties show that seismic hazard distr...

  20. Metals in aerosols of the Mexico City; Metales en aerosoles de la Ciudad de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Reyes L, J. [Instituto Nacional de Investigaciones Nucleares, Salazar, Estado de Mexico C.P. 52045 (Mexico)

    1998-07-01

    The general purpose and scope of this work was to have a data base that includes enough information about the heavy metals which are disseminated in the atmospheric air in Mexico City, like it is what refers to its elements, its concentration and its particle size. For this were collected samples through collectors types: of the filters unit and the cascade impactor. Through the PIXE analysis for filters and films it was identified the presence of 20 elements in the majority of samples studied of the four seasons during the years 1993-1994. The metals were classified in two groups: those of natural origin and those of anthropogenic origin. (Author)

  1. Bank erosion of navigation canals in the western and central Gulf of Mexico

    Science.gov (United States)

    Thatcher, Cindy A.; Hartley, Stephen B.; Wilson, Scott A.

    2011-01-01

    Erosion of navigation canal banks is a direct cause of land loss, but there has been little quantitative analysis to determine why certain major canals exhibit faster widening rates (indicative of erosion) than others in the coastal zones of Texas, Louisiana, Mississippi, and Alabama. We hypothesize that navigation canals exhibit varying rates of erosion based on soil properties of the embankment substrate, vegetation type, geologic region (derived from digital versions of state geologic maps), and the presence or absence of canal bank armaments (that is, rock rip-rap, concrete bulkheads, or other shoreline protection structures). The first objective of this project was to map the shoreline position and substrate along both banks of the navigation canals, which were digitized from 3 different time periods of aerial photography spanning the years of 1978/79 to 2005/06. The second objective was to quantify the erosion rates of the navigation canals in the study area and to determine whether differences in erosion rates are related to embankment substrate, vegetation type, geologic region, or soil type. To measure changes in shoreline position over time, transects spaced at 50-m (164-ft) intervals were intersected with shorelines from all three time periods, and an annual rate of change was calculated for each transect. Mean annual rates of shoreline change ranged from 1.75 m/year (5.74 ft/year) on the west side of the Atchafalaya River, La., where there was shoreline advancement or canal narrowing, to -3.29 m/year (-10.79 ft/year) on the south side of the Theodore Ship Channel, Ala., where there was shoreline retreat or erosion. Statistical analysis indicated that there were significant differences in shoreline retreat rates according to geologic region and marsh vegetation type, and a weak relationship with soil organic content. This information can be used to better estimate future land loss rates associated with navigation canals and to prioritize the location of

  2. U.S.-Mexico Integration and Regional Economies: Evidence from Border- City Pairs

    OpenAIRE

    Gordon H. Hanson

    1996-01-01

    In this paper, I examine whether U.S.-Mexico economic integration is causing economic activity in the United States to relocate to the U.S.-Mexico border region. The approach I take is to study U.S.- Mexico border-city pairs. Border cities are natural laboratories in which to study the effects of trade policy. To the extent transport costs are the main non-trade policy barriers to trade, we expect regional economic integration to cause economic activity in border cities to expand. I exploit t...

  3. Volatile organic compounds in the atmosphere of Mexico City

    Science.gov (United States)

    Garzón, Jessica P.; Huertas, José I.; Magaña, Miguel; Huertas, María E.; Cárdenas, Beatriz; Watanabe, Takuro; Maeda, Tsuneaki; Wakamatsu, Shinji; Blanco, Salvador

    2015-10-01

    The Mexico City Metropolitan Area (MCMA) is one of the most polluted megacities in North America. Therefore, it is an excellent benchmark city to understand atmospheric chemistry and to implement pilot countermeasures. Air quality in the MCMA is not within acceptable levels, mainly due to high ground levels of ozone (O3). Tropospheric O3 is a secondary pollutant formed from the oxidation of volatile organic compounds (VOCs) in the presence of nitrogen oxides and sunlight. To gain a better understanding of O3 formation in megacities, evaluate the effectiveness of already-implemented countermeasures, and identify new cost-effective alternatives to reduce tropospheric O3 concentrations, researchers and environmental authorities require updated concentrations for a broader range of VOCs. Moreover, in an effort to protect human health and the environment, it is important to understand which VOCs exceed reference safe values or most contribute to O3 formation, as well as to identify the most probable emission sources of those VOCs. In this work, 64 VOCs, including 36 toxic VOCs, were measured at four sites in the MCMA during 2011-2012. VOCs related to liquefied petroleum gas leakages exhibited the highest concentrations. Toxic VOCs with the highest average concentrations were acetone and ethanol. The toxic VOC benzene represented the highest risk to Mexican citizens, and toluene contributed the most to O3 formation. Correlation analysis indicated that the measured VOCs come from vehicular emissions and solvent-related industrial sources.

  4. Shifting corporate geographies in global cities of the South: Mexico City and Johannesburg as case studie

    Directory of Open Access Journals (Sweden)

    Parnreiter, Christof

    2013-09-01

    Full Text Available Global city research links the expansion of advanced producer services in major cities to the internationalisation of real estate markets as well as to the spread of (mainly high-rise office complexes. This research, however, has based its findings mainly on cases of the Global North. This paper examines, based on Grant and Nijman’s (2002 suggestion that the “internal spatial organisation of gateway cities in the less-developed world” reflects “the city’s role in the global political economy”, which patterns occur in two metropoles of the Global South. In addition to this, the analysis focuses especially on the driving forces behind the changes in corporate geographies. The analysis is placed in Mexico City and Johannesburg and based on real estate market data (offices as well as background documents on urban development. The outcome shows that in these cities, local transformation processes of the real estate market and office space location are indeed considerably shaped by global market dynamics. However, the findings also indicate that there is no clear scale dependence of the territorial form. In order to comprehensively understand the changes in the corporate geographies therefore, it is necessary to direct more attention to local and national dynamics. The restructuring of the built environment in both cities can only be grasped fully by considering the particular role of local and national governments. This additional entry point to an understanding of shifting corporate geographies helps to put recent dynamics of global capitalism and politics of urban neoliberalism in perspective.

  5. Measurements of Natural Radioactivity in Submicron Aerosols in Mexico City.

    Science.gov (United States)

    Gaffney, J. S.; Marley, N. A.; Sterling, K.; Sturchio, N. C.

    2003-12-01

    Natural radionuclides can be useful in evaluating the transport of ozone and aerosols in the troposphere. Beryllium-7, which is produced by cosmic ray interactions in the upper troposphere and lower stratosphere and becomes adsorbed on fine aerosols, can be a useful indicator of upper air transport into a region. Lead-210 is produced by the decay of radon-222 out-gassed into the lower atmosphere from ground-based uranium deposits. Potassium-40, found in soils, can act as a measure of wind-blown dust and also comes from burning of wood and other biomass that is enriched in this natural radioisotope. Thus, both lead-210 and potassium-40 can aid in identification of aerosols sourced in the lower atmosphere. As part of our continuing interest in the lifetimes and sources of aerosols and their radiative effects, we report here measurements of fine aerosol radioactivity in Mexico City, one of the largest megacities in the world. Samples were collected on quartz fiber filters by using cascade impactors (Sierra type, Anderson Instruments) and high-volume air samplers from the rooftop of the main laboratory of El Centro Nacional de Investigacion y Capacitacion Ambiental (CENICA). By using stage 4 of the impactor and timers, we were able to collect integrated samples of sizes > 1 micrometer and < 1 micrometer over 12-hr time periods daily for approximately one month in April 2003. Samples were counted at the University of Illinois at Chicago by using state-of-the-art gamma counting (beryllium-7, 477.6 keV; potassium-40, 1460.8 keV; lead-210, 46.5 keV). The beryllium-7 data indicate one possible upper-air transport event during April 2003. As expected, the lead-210 data indicate very little soil contribution to the fine aerosol. The potassium-40 data showed an increase in fine aerosol potassium during Holy Week that might be attributed to local combustion of biomass fuels. The data will be presented and discussed in light of future data analysis and comparison with other

  6. Abusive Head Trauma at a Tertiary Care Children's Hospital in Mexico City. A Preliminary Study

    Science.gov (United States)

    Diaz-Olavarrieta, Claudia; Garcia-Pina, Corina A.; Loredo-Abdala, Arturo; Paz, Francisco; Garcia, Sandra G.; Schilmann, Astrid

    2011-01-01

    Objectives: Determine the prevalence, clinical signs and symptoms, and demographic and family characteristics of children attending a tertiary care hospital in Mexico City, Mexico, to illustrate the characteristics of abusive head trauma among this population. Methods: This is a cross-sectional descriptive study of infants and children under 5,…

  7. Seroprevalence of Toxoplasma gondii infection in captive mammals in three zoos in Mexico City, Mexico.

    Science.gov (United States)

    Alvarado-Esquivel, Cosme; Gayosso-Dominguez, Edgar Arturo; Villena, Isabelle; Dubey, J P

    2013-09-01

    Antibodies to Toxoplasma gondii were determined in 167 mammals in three zoos in Mexico City, Mexico, using the modified agglutination test (MAT). Overall, antibodies to T. gondii were found in 89 (53.3%) of the 167 animals tested. Antibodies were found in 35 of 43 wild Felidae: 2 of 2 bobcats (Lynx rufus); 4 of 4 cougars (Puma concolor); 10 of 13 jaguars (Panthera onca); 5 of 5 leopards (Panthera pardus); 7 of 7 lions (Panthera leo); 2 of 3 tigers (Panthera tigris); 2 of 3 ocelots (Leopardus pardalis); 2 of 2 Sumatran tigers (Panthera tigris sumatrae); lof 2 Jaguarundi (Herpailurus jagouaroundi); but not in 0 of 2 oncillas (Leopardus tigrinus). Such high seroprevalence in wild felids is of public health significance because of the potential of oocyst shedding. Four of 6 New World primates (2 of 2 Geoffroy's spider monkeys [Ateles geoffroyi], 1 of 3 Patas monkeys [Erythrocebus patas], and 1 of 1 white-headed capuchin [Cebus capucinus]) had high MAT titers of 3,200, suggesting recently acquired infection; these animals are highly susceptible to clinical toxoplasmosis. However, none of these animals were ill. Seropositivity to T. gondii was found for the first time in a number of species. PMID:24063119

  8. Effect of Canal Bank Filtration on Quality of Water Long Hyderabad City

    Directory of Open Access Journals (Sweden)

    IMDAD ALI KANDHAR

    2016-07-01

    Full Text Available The focus of the present study was to examine the effect of canal bank filtration on the quality of water and the geological settings along the banks of canals at the shallow depth aquifers. The four Model wells were drilled at different locations of the Line channel, Pinyari and phulali canals in the study area. The samples of soil were collected throughout drilling of the model wells for the analysis of grain size distribution .In addition to this, canal water and model well water samples were collected and analyzed for the water quality characteristics during winter and summer seasons. The analysis of soil and water samples reveals that the ground water is influenced by the grain size distribution, hydraulic conductivity and the location of the model Wells. The model well that has higher percentage of 0.075 mm of grain size distribution(hydraulic conductivity between 10-25 ft/day was more suitable for the filtration of the canal water through its banks, followed by 0.15 mm of grain size distribution (hydraulic conductivity > 25ft/ day. Moreover, the present study also shows that the canal water filtration is suitable in terms of total alkalinity, nitrate-nitrogen, total iron and pH to get the potable water at the location near upstream of the canal, especially in the summer season.

  9. Surface albedo measurements in Mexico City metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Castro, T; Mar, B; Longoria, R; Ruiz Suarez, L. G [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico); Morales, L [Instituto de Geografia, UNAM, Mexico, D.F. (Mexico)

    2001-04-01

    Optical and thermal properties of soils are important input data for the meteorological and photochemical modules of air quality models. As development of these models increase on spatial resolution good albedo data become more important. In this paper measurements of surface albedo of UV (295-385 nm) and visible (450-550 nm) radiation are reported for different urban and rural surfaces in the vicinity of Mexico City. It was found for the downtown zone and average albedo value of 0.05 which is in very good agreement with reported values for urban surfaces. Our albedo values measured in UV region for grey cement and green grass are of 0.10 and 0.009, respectively, and quite similar to those found at the literature of 0.11 and 0.008 for those type of surfaces. [Spanish] Las propiedades opticas y termicas de suelos son datos importantes para los modulos meteorologicos y fotoquimicos de los modelos de calidad del aire. Conforme aumenta la resolucion espacial del modelo se vuelve mas importante contar con buenos datos de albedo. En este articulo se presentan mediciones de albedo superficial de radiacion Ultravioleta (295-385 nm) y visible (450-550 nm) para diferentes superficies urbanas. Los valores medidos de albedo en la region UV para cemento gris y pasto verde son de 0.10 y 0.009, respectivamente, y son muy similares a los reportados en la literatura, 0.11 y 0.008 para este tipo de superficies.

  10. Characterization of fine particle components in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, K. [Akita Prefectural Institute of Environmental Science, Yabase-Shimoyabase, Akita (Japan); Sera, K. [Iwate Medical Univ., Cyclotron Research Center, Takizawa, Iwate (Japan); Perales, J.G.; Garcia, F.A. [Centro Nacional de Investigacion y Capacitacion Ambiental (CENICA), Av. Michoacan y la Purisima Col. Vicentina C.P. 09340 Mexico (Mexico); Suzuki, H. [Environmental Data Analysis Laboratory, System Design, Inc., Shinagawa, Tokyo (Japan)

    1999-07-01

    Particulate matter (PM-3.9 and PM-15.8) samples were collected in the three zones at the Northeast, Southwest and Southeast suburbs of Mexico City, from July to August 1998, for one week for each sampling site. The concentrations of several elements in the PM-3.9 and PM-15.8 samples were determined by Particle Induced X-ray Emission (PIXE). In the PM-3.9 samples, 21 elements were determined for each zone, and Na, Mg, Al, Si, S, K, Ca, Ti, Fe, Cu, Zn and Pb are found to be the major elemental components. On the other hand, 22 elements including P were determined on the PM-15.8 samples, and the dominant elements were the same as in the PM-3.9. Factor analysis is applied to the 28 variables (14 elements for each PM-3.9 and PM-15.8 groups) and for 21 samples (seven days for three zones) in order to identify possible sources of the particles. The result of factor analysis allows to identify five major sources, being soil the major contributor. (author)

  11. Reformulated gasolines: The experience of Mexico City Metropolitan Zone

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, H.B.; Jardon, R.T.; Echeverria, R.S. [Centro de la Atmosfera (Mexico). Seccion de Contaminacion Ambiental

    1997-12-31

    The introduction of several reformulated gasolines into the Mexico City Metropolitan Zone (MCMZ) in the middle 1986 is an example of using fuel composition to improve, in theory, the air quality. However, although these changes have resulted in an important reduction of lead airborne concentrations, a worsened situation has been created. Ozone levels in the atmosphere MCMZ have presented a sudden rise since the introduction of the first reformulated gasoline, reaching in the 1990`s an annual average of 1,700 exceedances to the Mexican Ozone Air Quality Standard (0.11 ppm not to be exceeded 1 hr. a day one day a year). The authors examine the tendency on ozone air quality in MCMZ in relation with the changes in gasoline composition since 1986. The authors also discuss the importance to perform an air quality impact analysis before the introduction of reformulated gasolines in countries where the local economy do not allow to change the old car fleet not fitted with exhaust treatment devices.

  12. Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

    Directory of Open Access Journals (Sweden)

    C. Fountoukis

    2009-03-01

    Full Text Available Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1μm diameter, semi-volatile partitioning requires 15–30 min to equilibrate; longer time is typically required during the night and early morning hours. Aerosol and gas-phase speciation always exhibits substantial temporal variability, so that aerosol composition measurements (bulk or size-resolved obtained over large integration periods are not reflective of its true state. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as "equivalent sodium" (rather than explicitly in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramatically. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.

  13. Thermodynamic Characterization of Mexico City Aerosol during MILAGRO 2006

    Energy Technology Data Exchange (ETDEWEB)

    Fountoukis, C.; Nenes, A.; Sullivan, A.; Weber, R.; VanReken, T.; Fischer, M.; Matias, E.; Moya, M.; Farmer, D.; Cohen, R.C.

    2008-12-05

    Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM{sub 2.5} is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1 {micro}m diameter, semi-volatile partitioning requires 30-60 min to equilibrate; longer time is typically required during the night and early morning hours. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as 'equivalent sodium' (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramatically. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.

  14. Mexico

    Science.gov (United States)

    2002-01-01

    This true-color image of Mexico was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra spacecraft. In areal extent, Mexico is the third largest country on the continent of North America (not counting Greenland, which is a province of Denmark), comprised of almost 2 million square kilometers (756,000 square miles) of land. Home to roughly 100 million people, Mexico is second only to the United States in population, making it the world's largest Spanish-speaking nation. To the north, Mexico shares its border with the United States-a line that runs some 3,100 kilometers (1,900 miles) east to west. About half of this border is defined by the Rio Grande River, which runs southeast to the Gulf of Mexico (partially obscured by clouds in this image) and marks the dividing line between Texas and Mexico. Toward the upper left (northwest) corner of this image is the Baja California peninsula, which provides the western land boundary for the Gulf of California. Toward the northwestern side of the Mexican mainland, you can see the Sierra Madre Occidental Mountains (brownish pixels) running southeast toward Lake Chapala and the city of Guadalajara. About 400 km (250 miles) east and slightly south of Lake Chapala is the capital, Mexico City. Extending northward from Mexico City is the Sierra Madre Oriental Mountains, the irregular line of brownish pixels that seem to frame the western edges of the bright white cumulus clouds in this image. Between these two large mountain ranges is a large, relatively dry highland region. To the south, Mexico shares borders with Guatemala and Belize, both of which are located south of Mexico's Yucatan Peninsula. Image courtesy Reto Stockli, Brian Montgomery, and Robert Simmon, based on data from the MODIS Science Team

  15. Infrared Absorption by Atmospheric Aerosols in Mexico City during MILAGRO.

    Science.gov (United States)

    Kelley, K. L.; Mangu, A.; Gaffney, J. S.; Marley, N. A.

    2007-12-01

    Past research in our group using cylindrical internal reflectance spectroscopy has indicated that aqueous aerosols could contribute to the radiative warming as greenhouse species (1,2). Although aerosol radiative effects have been known for sometime and are considered one of the major uncertainties in climate change modeling, most of the studies have focused on the forcing due to scattering and absorption of radiation in the uv- visible region (3). Infrared spectral information also allows the confirmation of key functional groups that are responsible for enhanced absorption observations from secondary organics in the uv-visible region. This work extends our efforts to evaluate the infrared absorption by aerosols, particularly organics, that are now found to be a major fraction of urban and regional aerosols in the 0.1 to 1.0 micron size range and to help identify key types of organics that can contribute to aerosol absorption. During the MILAGRO campaign, quartz filter samples were taken at 12-hour intervals from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. These samples were taken at the two super-sites, T-0 (Instituto Mexicano de Petroleo in Mexico City) and T-1 (Universidad Technologica de Tecamac, State of Mexico). The samples have been characterized for total carbon content (stable isotope mass spectroscopy) and natural radionuclide tracers, as well as for their UV-visible spectroscopic properties by using integrating sphere diffuse reflectance spectroscopy (Beckman DU with a Labsphere accessory). These same samples have been characterized in the mid and near infrared spectral ranges using diffuse reflection spectroscopy (Nicolet 6700 FTIR with a Smart Collector accessory). Aerosol samples were removed from the surfaces of the aerosol filters by using Si-Carb sampler. The samples clearly indicate the presence of carbonyl organic constituents and the spectra are quite similar to those observed for humic and fulvic acids

  16. Mexico City air quality: Progress of an international collaborative project to define air quality management options

    International Nuclear Information System (INIS)

    Mexico City, faces a severe air pollution problem due to a combination of circumstances. The city is in a high mountain basin at a subtropical latitude. The basin setting inhibits dispersion of pollution and contributes to frequent wintertime thermal inversions which further trap pollutants near the surface. The elevation and latitude combine to provide plentiful sunshine which, in comparison to more northern latitudes, is enhanced in the UV radiation which drives atmospheric photochemistry to produce secondary pollutants such as ozone. The Area Metropolitana de la Ciudad de Mexico AMCW is defined to include the 16 delegations of the Federal District (D.F.) and 17 highly urbanized municipalities in the State of Mexico which border the D.F. The 1990 census (XI Censo General de Poblacion y Vivienda de 1990) records that slightly over 15 million people live in the AMCM. There are numerous other nearby communities which are in the airshed region of Mexico City, but which are not included in the definition and population of the AMCM. The Mexico City Air Quality Research Initiative is one project that is examining the complex relationship between air pollution, economic growth, societal values, and air quality management policies. The project utilizes a systems approach including computer modeling, comprehensive measurement studies of Mexico City's air pollutants, environmental chemical reaction studies and socioeconomic analysis. Los Alamos National Laboratory (USA) and the Mexican Petroleum Institute are the designated lead institutions

  17. Surface energy balance measurements in the Mexico City: a review

    Energy Technology Data Exchange (ETDEWEB)

    Tejeda Martinez, A. [Universidad Veracruzana, Xalapa, Veracruz (Mexico); Jauregui Ostos, E. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, UNAM, Mexico, D.F. (Mexico)

    2005-01-01

    During the last decade of the 20th Century, diverse campaigns for measuring the atmospheric energy balance were performed in downtown Mexico City (School of Mines and Preparatory School No. 7), in the southern suburbs (University Reserve) and in the surrounding rural areas (Plan Texcoco), in addition to a campaign carried out in 1985 in the Tacubaya district, a suburban western peripheral site. The objective was to obtain data for a better understanding of the climatic alterations due to urbanization, particularly to describe the role that the modification of the natural ground cover has played as a result of paving and the construction of urban canyons. In this paper, a review of these campaigns is presented. Energy partitioning in some areas (Tacubaya and Preparatory School No.7) is similar to that observed in urban centers of middle latitudes, whereas the major contrast was observed between Texcoco, with maximum energy consumption through evaporation, and School of Mines, where the latent heat is as low as in a desert. From the values of the correlations among the different components of energy balance, it may be possible to attempt the modeling of the diverse components of energy balance by means of regression equations starting from the net radiation. Those same coefficients distinguish the type of environment: urban, suburban or rural. [Spanish] Las primeras mediciones de balance energetico en la Ciudad de Mexico se realizaron en 1985 en un suburbio al poniente de la ciudad (el observatorio de Tacubaya). Ya en la decada de los anos noventa del siglo XX, dichas observaciones se multiplicaron tanto en el centro historico (antigua Escuela de Minas y en el edificio de la Preparatoria No. 7), como en otros sitios al sur (en terrenos de Ciudad Universitaria) y en la periferia rural (Plan Texcoco). El proposito de estas mediciones ha sido tener un mejor entendimiento de las alteraciones climaticas debidas a la urbanizacion. En este trabajo se presenta una revision

  18. PM composition and source reconciliation in Mexico City

    Science.gov (United States)

    Mugica, V.; Ortiz, E.; Molina, L.; De Vizcaya-Ruiz, A.; Nebot, A.; Quintana, R.; Aguilar, J.; Alcántara, E.

    PM 2.5 and PM 10 were collected during 24-h sampling intervals from March 1st to 31st, 2006 during the MILAGRO campaign carried out in Mexico City's northern region, in order to determine their chemical composition, oxidative activity and the estimation of the source contributions during the sampling period by means of the chemical mass balance (CMB) receptor model. PM 2.5 concentrations ranged from 32 to 70 μg m -3 while that of PM10 did so from 51 to 132 μg m -3. The most abundant chemical species for both PM fractions were: OC, EC, SO 42-, NO 3-, NH 4+, Si, Fe and Ca. The majority of the PM mass was comprised of carbon, up to about 52% and 30% of the PM2.5 and PM10, respectively. PM2.5 constituted more than 50% of PM10. The redox activity, assessed by the dithiothreitol (DTT) assay, was greater for PM 2.5 than for PM 10, and did not display significant differences during the sampling period. The PM 2.5 source reconciliation showed that in average, vehicle exhaust emissions were its most important source in an urban site with a 42% contribution, followed by re-suspended dust with 26%, secondary inorganic aerosols with 11%, and industrial emissions and food cooking with 10% each. These results had a good agreement with the Emission Inventory. In average, the greater mass concentration occurred during O 3S that corresponds to a wind shift initially with transport to the South but moving back to the North. Taken together these results show that PM chemical composition, oxidative potential, and source contribution is influenced by the meteorological conditions.

  19. Receptor Model Source Apportionment of Nonmethane Hydrocarbons in Mexico City

    Directory of Open Access Journals (Sweden)

    V. Mugica

    2002-01-01

    Full Text Available With the purpose of estimating the source contributions of nonmethane hydrocarbons (NMHC to the atmosphere at three different sites in the Mexico City Metropolitan Area, 92 ambient air samples were measured from February 23 to March 22 of 1997. Light- and heavy-duty vehicular profiles were determined to differentiate the NMHC contribution of diesel and gasoline to the atmosphere. Food cooking source profiles were also determined for chemical mass balance receptor model application. Initial source contribution estimates were carried out to determine the adequate combination of source profiles and fitting species. Ambient samples of NMHC were apportioned to motor vehicle exhaust, gasoline vapor, handling and distribution of liquefied petroleum gas (LP gas, asphalt operations, painting operations, landfills, and food cooking. Both gasoline and diesel motor vehicle exhaust were the major NMHC contributors for all sites and times, with a percentage of up to 75%. The average motor vehicle exhaust contributions increased during the day. In contrast, LP gas contribution was higher during the morning than in the afternoon. Apportionment for the most abundant individual NMHC showed that the vehicular source is the major contributor to acetylene, ethylene, pentanes, n-hexane, toluene, and xylenes, while handling and distribution of LP gas was the major source contributor to propane and butanes. Comparison between CMB estimates of NMHC and the emission inventory showed a good agreement for vehicles, handling and distribution of LP gas, and painting operations; nevertheless, emissions from diesel exhaust and asphalt operations showed differences, and the results suggest that these emissions could be underestimated.

  20. Mexico City's Petroleos Mexicanos explosion: disaster management and air medical transport.

    Science.gov (United States)

    Urquieta, Emmanuel; Varon, Joseph

    2014-01-01

    Mexico City is the largest metropolitan area in the Americas and 1 of the largest in the world; its geographic location and uncontrolled population and industrial growth make this metropolis prone to natural and human-made disasters. Mass casualty disaster responses in Mexico City tend to have complications from multiple logistical and operational challenges. This article focuses on the experiences and lessons learned from an explosion that occurred in a government building in Mexico City and the current status of mass casualty disaster risks and response strategies in Mexico City as well as air medical evacuation, which is a critical component and was shown to be extremely useful in the evacuation of 15 critically ill and polytraumatized patients (Injury Severity Score > 15). Several components of the public and privately owned emergency medical services and health care systems among Mexico City pose serious logistical and operational complications, which finally will be addressed by a joint emergency preparedness council to unify criteria in communications, triage, and incident/disaster command post establishment. PMID:25441528

  1. On the vertical distribution of pollutants in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Perez Vidal, H. [Universidad Juarez Autonoma de Tabasco, Division Academica de Ciencias Basicas, Tabasco (Mexico); Raga, G. B. [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico)

    1998-04-01

    The problem of air pollution in Mexico City is studied through the analysis of a large dataset obtained by an instrumented aircraft during February 1991. These data constitute a unique set in Mexico and provide insight into the vertical structure of the boundary layer and the pollutant species which has not been previously discussed. The results obtained on the evolution and structure of the mixed layer indicate that its height rises from 100 meters during the morning (8 am) to over 2000 meters al 5 pm. results consistently show that the maximum in ozone concentration is not observed al the surface, but al about 700 m on average about it near midday. The peak, with an average concentration over the observational period of 167 ppb, appears to be a transient feature, with concentrations becoming more uniform with height in the afternoon. The vertical profiles of nitrogen oxides and sulphur dioxide indicate that concentrations are highest during the morning and steadily decrease with height, suggesting that sources for these species are located near the surface, as was expected. There appears to be no correlation between the amount of nitrogen oxides observed during the take-off and the ozone concentrations observed during landing (2-3 hours later). When the variables are normalized by the mixed layer height the results indicate that the ozone observed is fairly independent of the nitrogen oxide concentrations observed earlier. A reduced range of values of the ratio of ozone accumulated in the mixed layer and the layer height is consistently day found during the observational period. Aerosol particles near the surface show maximum concentration during the morning hours, but in contrast, during the course of the day, there is a marked increase in their concentrations at higher levels in the boundary layer suggesting that possibly gas to particle conversion is responsible for the observed increase. [Spanish] El problema de la contaminacion del aire en la Ciudad de

  2. Mexico City Air quality: Progress of an international collaborative project to define air quality management options

    Science.gov (United States)

    Streit, Gerald E.; Guzmán, Francisco

    The Mexico City Air Quality Research Initiative was a 3-yr international collaborative project to develop or adapt a set of air quality management decision analysis tools for Mexico City and make them available to Mexican policy makers. The project comprised three tasks: modeling and simulation, characterization and measurement, and strategic evaluation. A prognostic, mesoscale meteorological model was adapted to the region of Mexico City and linked to a 3-D airshed model. These were extensively tested against data from the air quality monitoring network and from three intensive field campaigns. The interaction between policy and science was promoted through the development of a formal multiattribute decision analysis model to evaluate alternative control strategies. The project benefited by having researchers from both nations working side by side as peers, by having both nations investing resources and having an interest in the success of the project, and by having an objective, not of advocacy, but of the application of science to problem solving.

  3. O-MIF signature in sulfate aerosols from Mexico City

    Science.gov (United States)

    Erwann, Legendre; Erwan, Martin; Slimane, Bekki; Armando, Retama; Pierre, Cartigny; Becky, Alexander; Aurora, Armienta Maria; Claus, Siebe

    2016-04-01

    Since the discovery of mass independent fractionation of sulfur and oxygen isotopes (S- and O-MIF) on Earth, the study of sulfate isotopic composition opened a new and wide field of investigation on the evolution of the atmospheric composition and its consequences for the climate. Sulfate aerosols that have a negative forcing on the climate can therefore be studied via their isotopic composition and leads to better constraints on their formation, fate and sinks, which is essential for our understanding of the sulfur cycle on Earth. In this study we focus on the interaction between anthropogenic and volcanic emissions that is necessary to figure out the climatic impact of volcanoes in large urban area. For the first time the O- composition of sulfate aerosols was monitored over the past 25 years in one of the world's largest megacities: Mexico City (MC). Sulfate aerosols from the megalopolis were sampled from 1989 to 2013 in different stations by high volume pumps and collected on glass filters. Additionally, fresh volcanic ash samples were collected during recent eruptions (from 1997 to 2013) of the Popocatepetl, which is only 70km from MC. After extraction and purification of sulfate from filters and volcanic ash, the isotopic composition is measured. The sulfate aerosols from MC show O-MIF composition with Δ17O of about 0.7‰ during the wet season and around 1.2‰ during the dry season and δ18O from -0.4‰ to 17.5‰. However, the volcanic sulfate aerosols from the Popocatepetl do not show O-MIF and δ18O vary from 7.0‰ to 12.2‰. The dataset allows us to discuss the seasonal variations in the SO2 oxidation pathways that lead to sulfate aerosol formation in the troposphere above MC during the last 25 years. Furthermore, since 1997 we are able to trace and quantify the influence of volcanic sulfate aerosols on the megalopolis, which is important for the sulfur budget in the region.

  4. Longitudinal Study of Microbial Diversity and Seasonality in the Mexico City Metropolitan Area Water Supply System

    OpenAIRE

    Mazari-Hiriart, Marisa; López-Vidal, Yolanda; Ponce-de-León, Sergio; Calva, Juan José; Rojo-Callejas, Francisco; Castillo-Rojas, Gonzalo

    2005-01-01

    In the Mexico City metropolitan area (MCMA), 70% of the water for 18 million inhabitants is derived from the Basin of Mexico regional aquifer. To provide an overview of the quality of the groundwater, a longitudinal study was conducted, in which 30 sites were randomly selected from 1,575 registered extraction wells. Samples were taken before and after chlorine disinfection during both the rainy and dry seasons (2000-2001). Microbiological parameters (total coliforms, fecal coliforms, streptoc...

  5. Mexico.

    Science.gov (United States)

    1984-09-01

    Although Mexico has serious economic and population growth problems, the country is making progress toward solving both of these problems. Mexico has a population of 77.7 million and a population density of 102 persons/square mile. The country has a birth rate of 32/1000, a death rate of 6/1000, and an annual growth rate of 2.6%. The estimated infant mortality rate is 55/1000. The median age of the population is 17.4. Mexico City, with a population of 15 million, is the 3rd largest city in the world, and by 1995, it is expected to be the largest city in the world, with a projected population of 25.2 million. The government vigorously promotes family planning, and the annual population growth rate slowed down from a high of 3.2% in 1970-75 to the current rate of 2.6%. Mexico hopes to achieve replacement level fertility by the year 2000. Other government policies promote income equality, agricultural development, and regional equalization of population growth. In 1982 Mexico's per capita income was US$2270, exports totaled US$21 billion, and imports totaled US$15 billion. By 1976, Mexico's international debt was US$30.2 billion, and inflation was rampant. Recently, the newly elected president, Miguel de la Madrid of the Partido Revolucionario Institutional, obtained a grant of US$39 million from the International Monetary Fund and removed price controls. These efforts should help stabilize Mexico's economy. The country will also need to expand its exports and increase its cultivatable acreage. PMID:12339665

  6. Cluster Analysis of the Wind Events and Seasonal Wind Circulation Patterns in the Mexico City Region

    OpenAIRE

    Susana Carreón-Sierra; Alejandro Salcido; Telma Castro; Ana-Teresa Celada-Murillo

    2015-01-01

    The residents of Mexico City face serious problems of air pollution. Identifying the most representative scenarios for the transport and dispersion of air pollutants requires the knowledge of the main wind circulation patterns. In this paper, a simple method to recognize and characterize the wind circulation patterns in a given region is proposed and applied to the Mexico City winds (2001–2006). This method uses a lattice wind approach to model the local wind events at the meso-β scale, and h...

  7. Containing a contagion : crime and homosexuality in post-revolutionary Mexico City

    OpenAIRE

    Cook, Stephen Sherrard

    2008-01-01

    Primarily based upon archival resources at the Archivo Histórico del Distrito Federal (AHDF) and the Archivo General de la Nación (AGN) in Mexico City, this thesis is a social and cultural history of the criminalization and punishment of homosexuality during the 1920s and 1930s in Mexico City. The bulk of the primary historical research is based upon two separate spheres of homosexual-related criminal cases, adult and juvenile homosexual 'criminal' cases. The Archivo Histórico houses adult cr...

  8. Mexico City air quality research initiative. Volume 2, Problem definition, background, and summary of prior research

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    Air pollution in Mexico City has increased along with the growth of the city, the movement of its population, and the growth of employment created by industry. The main cause of pollution in the city is energy consumption. Therefore, it is necessary to take into account the city`s economic development and its prospects when considering the technological relationships between well-being and energy consumption. Air pollution in the city from dust and other particles suspended in the air is an old problem. However, pollution as we know it today began about 50 years ago with the growth of industry, transportation, and population. The level of well-being attained in Mexico City implies a high energy use that necessarily affects the valley`s natural air quality. However, the pollution has grown so fast that the City must act urgently on three fronts: first, following a comprehensive strategy, transform the economic foundation of the city with nonpolluting activities to replace the old industries, second, halt pollution growth through the development of better technologies; and third, use better fuels, emission controls, and protection of wooded areas.

  9. A study of indoor radon in greenhouses in Mexico City, Mexico

    International Nuclear Information System (INIS)

    Enclosed spaces in contact with soil, the main source of radon, like greenhouses have potentially high radon (222Rn) concentrations. Greenhouses are frequented by visitors and also are workplaces. The study of radon concentrations in greenhouses is, thus, a relevant concern for public health and environmental radiation authorities. For this study, the radon concentrations in 12 greenhouses in different locations within Mexico City were measured using nuclear track methodology. The detectors used for the study consisted of the well-known closed-end cup device, with CR-39 LantrackR as detector material. The measurements were carried out over a period of one year, divided into four three-month sub-periods. The lowest and highest annual mean radon concentrations found in individual greenhouses were 17.0 and 45.1 Bq/m3, respectively. The annual mean averaged over all 12 greenhouses was 27.3 Bq/m3. No significant seasonal variation was observed. Using the highest annual mean radon concentration found in an individual greenhouse, and an equilibrium factor of 0.4, the effective dose from 222Rn and its progenies was calculated to be 339.9 nSv/h. This corresponds to an annual dose rate of 679.8 μSv/y (0.057 WLM/y) for a worker spending 4 h a day, 5 days a week, 50 weeks a year, inside the greenhouse. For a visitor spending 12 h a year inside the greenhouse the annual dose is 2.469 μSv/y. The study of indoor radon concentrations in closed buildings such as greenhouses, which are both workplaces and open to visitors, is an important public health consideration. (author)

  10. Seasonal trends in black carbon properties and co-pollutants in Mexico City

    OpenAIRE

    A. Retama; Baumgardner, D; Raga, G. B.; G. R. McMeeking; Walker, J. W.

    2015-01-01

    The Mexico City Metropolitan Area (MCMA) is a region that continues to grow in population and vehicular traffic as well as being the largest source of short lived climate pollutants (SLCP) in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e. ozone (O3) and carbon monoxide (CO), but particulate matter (PM2.5 and PM10) and black carbon (BC) have shown little response to mitigation strategies th...

  11. 33 CFR 334.763 - Naval Support Activity Panama City; Gulf of Mexico; restricted area.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Naval Support Activity Panama City; Gulf of Mexico; restricted area. 334.763 Section 334.763 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.763 Naval Support Activity Panama...

  12. Cluster Analysis of the Wind Events and Seasonal Wind Circulation Patterns in the Mexico City Region

    Directory of Open Access Journals (Sweden)

    Susana Carreón-Sierra

    2015-07-01

    Full Text Available The residents of Mexico City face serious problems of air pollution. Identifying the most representative scenarios for the transport and dispersion of air pollutants requires the knowledge of the main wind circulation patterns. In this paper, a simple method to recognize and characterize the wind circulation patterns in a given region is proposed and applied to the Mexico City winds (2001–2006. This method uses a lattice wind approach to model the local wind events at the meso-β scale, and hierarchical cluster analysis to recognize their agglomerations in their phase space. Data of the meteorological network of Mexico City was used as input for the lattice wind model. The Ward’s clustering algorithm with Euclidean distance was applied to organize the model wind events in seasonal clusters for each year of the period. Comparison of the hourly population trends of these clusters permitted the recognition and detailed description of seven circulation patterns. These patterns resemble the qualitative descriptions of the Mexico City wind circulation modes reported by other authors. Our method, however, permitted also their quantitative characterization in terms of the wind attributes of velocity, divergence and vorticity, and an estimation of their seasonal and annual occurrence probabilities, which never before were quantified.

  13. Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry

    Directory of Open Access Journals (Sweden)

    R. C. Moffet

    2007-05-01

    Full Text Available Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS were carried out in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area – 2006 campaign (MCMA-2006 between 7–27 March, 2006. Biomass and organic carbon (OC particle types were found to dominate the accumulation mode both day and night. The concentrations of both organic carbon and biomass particles were roughly equal early in the morning, but biomass became the largest contributor to the accumulation mode mass from the late morning until early evening. The diurnal pattern can be attributed to aging and/or a change in meteorology. Fresh elemental carbon (EC particles were observed during rush hour. The majority of the EC particles were mixed with nitrate, sulfate, organic carbon and potassium. Submicron particles from industrial sources in the northeast were composed of an internal mixture of Pb, Zn, EC and Cl and peaked early in the morning. A unique nitrogen-containing organic (NOC particle type was observed, and is hypothesized to be from industrial emissions based on the temporal profile and back trajectory analysis. This study provides unique insights into the real-time changes in single particle mixing state as a function of size and time for aerosols in Mexico City. These new findings indicate that biomass burning and industrial operations make significant contributions to particles in Mexico City. These sources have received relatively little attention in previous intensive field campaigns.

  14. Spatial Analysis of the Level of Exposure to Seismic Hazards of Health Facilities in Mexico City, Mexico

    Science.gov (United States)

    Moran, S.; Novelo-Casanova, D. A.

    2011-12-01

    Although health facilities are essential infrastructure during disasters and emergencies, they are also usually highly vulnerable installations in the case of the occurrence of large and major earthquakes. Hospitals are one of the most complex critical facilities in modern cities and they are used as first response in emergency situations. The operability of a hospital must be maintained after the occurrence of a local strong earthquake in order to satisfy the need for medical care of the affected population. If a health facility is seriously damaged, it cannot fulfill its function when most is needed. In this case, hospitals become a casualty of the disaster. To identify the level of physical exposure of hospitals to seismic hazards in Mexico City, we analyzed their geographic location with respect to the seismic response of the different type of soils of the city from past earthquakes, mainly from the events that occurred on September 1985 (Ms= 8.0) and April 1989 (Ms= 6.9). Seismic wave amplification in this city is the result of the interaction of the incoming seismic waves with the soft and water saturated clay soils, on which a large part of Mexico City is built. The clay soils are remnants of the lake that existed in the Valley of Mexico and which has been drained gradually to accommodate the growing urban sprawl. Hospital facilities were converted from a simple database of names and locations into a map layer of resources. This resource layer was combined with other map layers showing areas of seismic microzonation in Mexico City. This overlay was then used to identify those hospitals that may be threatened by the occurrence of a large or major seismic event. We analyzed the public and private hospitals considered as main health facilities. Our results indicate that more than 50% of the hospitals are highly exposed to seismic hazards. Besides, in most of these health facilities we identified the lack of preventive measures and preparedness to reduce their

  15. Gross alpha and gross beta radioactivity in drinking water from Zacatecas and Guadalupe cities, Mexico

    International Nuclear Information System (INIS)

    The conditions to measure the gross alpha and gross beta radioactivity in water samples from Zacatecas and Guadalupe cities in the State of Zacatecas, Mexico were established. The gross alpha and beta radioactivity of water samples were measured using a liquid scintillation detector. The results show that the gross beta radioactivity in all cases is lower than the maximum contaminant level and the gros alpha radioactivity is higher in the samples collected from Guadalupe City and in the samples collected from the Southwest of Zacatecas City. (author)

  16. The Psychosocial Meaning of Pregnancy among Adolescents in Mexico City.

    Science.gov (United States)

    Atkin, Lucille C.; Alatorre-Rico, Javier

    Adolescent childbearing has historically been a relatively frequent phenomenon in Mexico and has only recently begun to decline. This study was designed to identify to what extent urban Mexican adolescents, who became pregnant out-of-wedlock and who carried their pregnancy to term, received social support during pregnancy and their emotional…

  17. Methanol-CO correlations in Mexico City pollution outflow from aircraft and satellite during MILAGRO

    Science.gov (United States)

    Xiao, Y.; Cady-Pereira, K. E.; Payne, V. H.; Millet, D. B.; Shephard, M. W.; Luo, M.; Alvarado, M.; Wells, K. C.; Apel, E. C.; Campos, T. L.; Singh, H. B.; Sachse, G. W.

    2012-02-01

    The correlation between methanol (CH3OH) and carbon monoxide (CO) is of particular interest for characterizing biogenic and anthropogenic emission sources of CH3OH and other chemical species. Here, the CH3OH/CO enhancement ratio (ΔCH3OH/ΔCO) in the lower to middle troposphere is examined using coincident CH3OH and CO observations from aircraft (NCAR C-130 and NASA DC-8) and from the Tropospheric Emission Spectrometer (TES) satellite during the MegaCity Initiative: Local and Global Research Observations (MILAGRO) in the Mexico City region in March 2006. ΔCH3OH/ΔCO ratios from the two in-situ aircraft measurements are far higher than previously reported CH3OH emission ratios relative to CO from US cities. This may reflect combustion of different fuel types in this area, and possibly photochemical production of CH3OH in Mexico City outflow. TES CH3OH and CO retrievals over the MILAGRO domain show relatively high sensitivity in the 600-800 hPa range, associated with Mexico City pollution outflow. The TES derived ΔCH3OH/ΔCO ratios during MILAGRO are 18-24 ppt ppb-1, which are similar to those observed from the DC-8 (26-39 ppt ppb-1), but lower than the C-130 observations (41-55 ppt ppb-1). Differences between the ΔCH3OH/ΔCO ratios measured aboard the two aircraft preclude an absolute validation of the TES-derived ratios for this dataset. The ΔCH3OH/ΔCO ratios observed from TES over this domain reflect bulk enhancements of CH3OH and CO in Mexico City outflow. Although the TES measurements are not expected to resolve small-scale variability in the ΔCH3OH/ΔCO ratio downwind of the strong source region of Mexico City, it is demonstrated that TES can clearly distinguish differences in the ΔCH3OH/ΔCO ratio due to different source categories of CH3OH. An example of this is shown by contrasting measurements over Mexico City (strong anthropogenic emissions) with those over the Amazon Basin (strong biogenic emissions). The results from this case study show the

  18. NO2 and HCHO variability in Mexico City from MAX-DOAS measurements

    Science.gov (United States)

    Grutter, M.; Friedrich, M. M.; Rivera, C. I.; Arellano, E. J.; Stremme, W.

    2015-12-01

    Atmospheric studies in large cities are of great relevance since pollution affects air quality and human health. A network of Multi Axis Differential Optical Absorption Spectrometers (MAX-DOAS) has been established in strategic sites within the Mexico City metropolitan area. Four instruments are now in operation with the aim to study the variability and spatial distribution of key pollutants, providing results of O4, NO2 and HCHO slant column densities (SCD). A numerical code has been written to retrieve gas profiles of NO2 and HCHO using radiative transfer simulations. We present the first results of the variability of these trace gases which will bring new insight in the current knowledge of transport patterns, emissions as well as frequency and origin of extraordinary events. Results of the vertical column densities (VCD) valiability of NO2 and HCHO in Mexico City are presented. These studies are useful to validate current and future satellite observatopns such as OMI, TROPOMI and TEMPO.

  19. Detection of mumps virus genotype H in two previously vaccinated patients from Mexico City.

    Science.gov (United States)

    Del Valle, Alberto; García, Alí A; Barrón, Blanca L

    2016-06-01

    Infections caused by mumps virus (MuV) have been successfully prevented through vaccination; however, in recent years, an increasing number of mumps outbreaks have been reported within vaccinated populations. In this study, MuV was genotyped for the first time in Mexico. Saliva samples were obtained from two previously vaccinated patients in Mexico City who had developed parotitis. Viral isolation was carried out in Vero cells, and the SH and HN genes were amplified by RT-PCR. Amplicons were sequenced and compared to a set of reference sequences to identify the MuV genotype. PMID:26935913

  20. Determination of radon levels in Mexico City; Determinacion de niveles de radon en la Ciudad de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Pena G, P

    1992-01-15

    The study of the determination of radon levels in the houses room in Mexico City is part of the project Emanometry of the radon. To carry out this study, the passive method was used, which consists of: thin film dosemeter of cellulose nitrate, container of the same one and spark accountant. The method is based on the mensurations of exhibition of the number of marks of alpha track is of the open type and it allows to average the radon activity along several weeks and it presents low concentrations. This study was carried out in 4 periods of exhibition of 3 months each one. (Author)

  1. A scenario of human thermal comfort in Mexico City for 2CO{sub 2} conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jauregui, Ernesto [Centro de Ciencias de la Atmosfera de la UNAM, Mexico, D.F. (Mexico); Tejeda, Adalberto [Universidad Veracruzana, Xalapa, Veracruz (Mexico)

    2001-07-01

    Applying the concept of effective temperature (ET), a scenario of human bioclimatic conditions for Mexico City is presented by using results from both GCM regional predictions for CO{sub 2} doubling and temperature trend projections from an urban station. Current and future bioclimatic maps for Mexico City and their conurbation are presented. Current environmental conditions will likely change toward a warmer atmosphere due to both the urbanization process and global greenhouse effect. The impact on the population will be more important during the warm season (March- May) when the bioclimate of the city will likely shift away from current neutrality to the next comfort scale category (ET 24-27 Celsius degrees) of warm conditions covering most of the capital city. [Spanish] A partir de la aplicacion del concepto de temperatura efectiva (ET) se presenta un escenario de las condiciones de bioclima humano para la Ciudad de Mexico y zona conurbada para la segunda mitad del proximo siglo. Se usaron resultados de predicciones regionales de modelos de circulacion general (GCM) para una duplicacion del CO{sub 2} y tambien las tendencias de temperatura de una estacion urbana. Se muestran mapas de las condiciones actuales y futuras de confort termico. La combinacion del efecto invernadero y la urbanizacion, muy probablemente impacten en la poblacion principalmente en la estacion calida (marzo a mayo), cuando se pase de la categoria de confort actual a la inmediata superior (ET 24-27 Celsius degrees) en la mayor parte de la capital del pais.

  2. Continuous measurement of carbon black in a densely populated area of Mexico City

    Science.gov (United States)

    Peralta, Oscar; Ortinez, Abraham; Castro, Telma; Espinosa, Maria; Saavedra, Isabel; Alvarez, Harry; Basaldud, Roberto; Paramo, Víctor; Martínez, Amparo

    2015-04-01

    The black carbon (BC) is a byproduct of burning fossil fuels and is an important short-lived climate forcer because it absorbs solar radiation altering the Earth's radiative budget and climate. It is also an atmospheric pollutant that promotes reactions of other compounds in the atmosphere. Despite its importance for health and climate, in Mexico there are very few studies on ambient concentrations of BC in urban areas and virtually no information of continuous measurements over long periods (more than a month of measurements). So, in order to develop more efficient local and regional mitigation strategies and policies that allow reducing ambient concentrations of BC, it is necessary to know BC seasonal evolution, contribution to radiative budget and impacts on health. This study shows continuous measurements (from July 2013 to July 2014) of BC to perform an analysis of seasonal variations. The selected monitoring site is located at Iztapalapa, a densely populated area with high traffic on the southeastern part of Mexico City. BC concentrations were obtained by two aethalometers (Magee Scientific Company, models AET31 and AET42) placed 15 meters above the ground. The aethalometers operate in the wavelength range of 370-950 nm and use a standard value of mass absorption coefficient MAC = 10.8 m2/g to calculate BC environmental concentration. To correct the aethalometers readings to the conditions of Mexico City, it was employed MAC = to 6.7 m2/g, which was determined for PM2.5 with a carbon analyzer (UIC, Inc.) and represents the mass absorption coefficient of soot emitted in Mexico City. The average value of the corrected concentration of BC in Mexico City during the period from July 2013 to July 2014 was 5.39 ± 1.89 μg/m3 (1.6 higher than readings recorded by aethalometers), which is greater than that measured in Shanghai in 2014 (annual average 2.33 μg/m3) and those reported for some U.S. cities; the value implies a potential danger to the health of

  3. The need for standards and codes to ensure an acoustically comfortable environment in multifamily housing buildings in Mexico City

    Science.gov (United States)

    Kotasek Gonzalez, Eduardo; Rodriguez Manzo, Fausto

    2002-11-01

    It is clear that almost all kinds of buildings require protection against noise and undesirable sounds, however, there are some countries where this is not yet regulated, such is the case of Mexico. Mexico City, the biggest city in the world could also be the noisiest. This is a problem which is today being debated; in fact there is no doubt that this has an important influence on the acoustic comfort conditions of dwellings, besides the habits and culture of the inhabitants, which are very different from those in the Anglo-Saxon countries. These are all details that must be taken into account in the design of an acoustic comfort standard for buildings in cities like Mexico. In this paper we deal with this problem and it suggests some recommendations to consider in a proposed acoustic comfort standard or code to be applied in the design of multifamily housing buildings in Mexico City.

  4. Particulate polycyclic aromatic hydrocarbon spatial variability and aging in Mexico City

    Directory of Open Access Journals (Sweden)

    D. A. Thornhill

    2007-11-01

    Full Text Available As part of the Megacities Initiative: Local and Global Research Observations (MILAGRO study in the Mexico City Metropolitan Area in March 2006, we measured particulate polycyclic aromatic hydrocarbons (PAHs and other gaseous species and particulate properties at six locations throughout the city. The measurements were intended to support the following objectives: to describe spatial and temporal patterns in PAH concentrations, to gain insight into sources and transformations of PAHs, and to quantify the relationships between PAHs and other pollutants. Total particulate PAHs at the Instituto Mexicano del Petróleo (T0 supersite located near downtown averaged 50 ng m−3, and aerosol active surface area averaged 80 mm2 m−3. PAHs were also measured on board the Aerodyne Mobile Laboratory, which visited six sites encompassing a mixture of different land uses and a range of ages of air parcels transported from the city core. Weak intersite correlations suggest that local sources are important and variable and that exposure to PAHs cannot be represented by a single regional-scale value. The relationships between PAHs and other pollutants suggest that a variety of sources and ages of particles are present. Among carbon monoxide, nitrogen oxides (NOx, and carbon dioxide, particulate PAHs are most strongly correlated with NOx. Mexico City's PAH-to-black carbon mass ratio of 0.01 is similar to that found on a freeway loop in the Los Angeles area and approximately 8–30 times higher than that found in other cities. Ratios also indicate that primary combustion particles are rapidly coated by secondary aerosol in Mexico City. If so, the lifetime of PAHs may be prolonged if the coating protects them against photodegradation or heterogeneous reactions.

  5. Particulate polycyclic aromatic hydrocarbon spatial variability and aging in Mexico City

    Science.gov (United States)

    Thornhill, D. A.; Herndon, S. C.; Onasch, T. B.; Wood, E. C.; Zavala, M.; Molina, L. T.; Gaffney, J. S.; Marley, N. A.; Marr, L. C.

    2007-11-01

    As part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) study in the Mexico City Metropolitan Area in March 2006, we measured particulate polycyclic aromatic hydrocarbons (PAHs) and other gaseous species and particulate properties at six locations throughout the city. The measurements were intended to support the following objectives: to describe spatial and temporal patterns in PAH concentrations, to gain insight into sources and transformations of PAHs, and to quantify the relationships between PAHs and other pollutants. Total particulate PAHs at the Instituto Mexicano del Petróleo (T0 supersite) located near downtown averaged 50 ng m-3, and aerosol active surface area averaged 80 mm2 m-3. PAHs were also measured on board the Aerodyne Mobile Laboratory, which visited six sites encompassing a mixture of different land uses and a range of ages of air parcels transported from the city core. Weak intersite correlations suggest that local sources are important and variable and that exposure to PAHs cannot be represented by a single regional-scale value. The relationships between PAHs and other pollutants suggest that a variety of sources and ages of particles are present. Among carbon monoxide, nitrogen oxides (NOx), and carbon dioxide, particulate PAHs are most strongly correlated with NOx. Mexico City's PAH-to-black carbon mass ratio of 0.01 is similar to that found on a freeway loop in the Los Angeles area and approximately 8-30 times higher than that found in other cities. Ratios also indicate that primary combustion particles are rapidly coated by secondary aerosol in Mexico City. If so, the lifetime of PAHs may be prolonged if the coating protects them against photodegradation or heterogeneous reactions.

  6. Seasonal and diurnal trends in black carbon properties and co-pollutants in Mexico City

    OpenAIRE

    A. Retama; Baumgardner, D; Raga, G. B.; G. R. McMeeking; Walker, J. W.

    2015-01-01

    The Mexico City metropolitan area (MCMA) is a region that continues to grow in population and vehicular traffic as well as being the largest source of short-lived climate pollutants (SLCP) in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e., ozone (O3) and carbon monoxide (CO), but particulate matter (PM2.5 and PM10) and black carbon (BC) have shown a less positive response to mitigation strategies that have...

  7. Heterogeneous nucleation of ice on anthropogenic organic particles collected in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Knopf, D.A.; Wang, B.; Laskin, A.; Moffet, R.C.; Gilles, M.K.

    2010-06-20

    This study reports on heterogeneous ice nucleation activity of predominantly organic (or coated with organic material) anthropogenic particles sampled within and around the polluted environment of Mexico City. The onset of heterogeneous ice nucleation was observed as a function of particle temperature (Tp), relative humidity (RH), nucleation mode, and particle chemical composition which is influenced by photochemical atmospheric aging. Particle analyses included computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). In contrast to most laboratory studies employing proxies of organic aerosol, we show that anthropogenic organic particles collected in Mexico City can potentially induce ice nucleation at experimental conditions relevant to cirrus formation. The results suggest a new precedent for the potential impact of organic particles on ice cloud formation and climate.

  8. An analysis of a low-energy, low-water use community in Mexico City

    Science.gov (United States)

    Bermudez Alcocer, Jose Luis

    This study investigated how to determine a potential scenario to reduce energy, water and transportation use in Mexico City by implementing low-energy, low-water use communities. The proposed mixed-use community has multi-family apartments and a small grocery store. The research included the analysis of: case studies, energy simulation, and hand calculations for water, transportation and cost analysis. The previous case studies reviewed include: communities in Mexico City, Mexico, Austin, Texas, Phoenix, Arizona, New York City, New York and San Diego, California in terms of successful low-energy, low-water use projects. The analysis and comparison of these centers showed that the Multifamiliar Miguel Aleman is an excellent candidate to be examined for Mexico City. This technical potential study evaluated energy conserving measures such as low-energy appliances and efficient lighting that could be applied to the apartments in Mexico City to reduce energy-use. The use of the simulations and manual calculations showed that the application of the mixed-use concept was successful in reducing the energy and water use and the corresponding carbon footprint. Finally, this technical potential study showed taking people out of their cars as a result of the presence of the on-site grocery store, small recreation center and park on the ground floor also reduced their overall transportation energy-use. The improvement of the whole community (i.e., apartments plus grocery store) using energy-efficient measures provided a reduction of 70 percent of energy from the base-case. In addition a 69 percent reduction in water-use was achieved by using water-saving fixtures and greywater reuse technologies for the complex. The combination of high-efficiency automobiles and the presence of the on-site grocery store, small recreation center and park potentially reduced the transportation energy-use by 65 percent. The analysis showed an energy cost reduction of 82 percent reduction for

  9. Identification of Enteric Viruses in Foods from Mexico City.

    Science.gov (United States)

    Parada-Fabián, José Carlos; Juárez-García, Patricia; Natividad-Bonifacio, Iván; Vázquez-Salinas, Carlos; Quiñones-Ramírez, Elsa Irma

    2016-09-01

    Foodborne viruses are a common and, probably, the most under-recognized cause of outbreaks of gastroenteritis. Among the main foods involved in the transmission of human enteric viruses are mollusks, and fruits and vegetables irrigated with wastewater and/or washed with non-potable water or contaminated by contact with surfaces or hands of the infected personnel during its preparation. In this study, 134 food samples were analyzed for the detection of Norovirus, Rotavirus, and Hepatitis A virus (HAV) by amplification of conserved regions of these viruses. From the 134 analyzed samples, 14 were positive for HAV, 6 for Norovirus, and 11 for Rotavirus. This is the first report in Mexico where emphasis is given to the presence of HAV and Norovirus on perishable foods and food from fisheries, as well as Rotavirus on frozen vegetables, confirming the role of vegetables and bivalve mollusks as transmitting vehicles of enteric viruses. PMID:27221088

  10. Vehicular Diesel control emissions benefit assessment in Mexico City

    Science.gov (United States)

    Garcia-Reynoso, J.; Jazcilevich, A. D.; Ruiz-Suarez, L.; Cruz-Nuñez, X.; Rojas, A. R.; Tripp, M. R.

    2013-12-01

    Diesel vehicles contribute in an important proportion to the particle and black carbon (BC) ambient concentrations in urban areas. These pollutants can effect the climate and health. The average age of the Diesel fleet in Mexico is 15 year-old. An introduction of new technologies and retrofit systems can reduce emissions from this type of vehicles. A set of policies were selected and applied in order to identify their economic benefits in health. An air quality model was used to obtain ambient concentrations from the emissions and specific methodology for emissions inventory adjustment was developed for this project. Preliminary results show an important benefit due to the improvement of the emissions reduction from the Diesel fleet. PM2.5 differences for reduction scenario case 1 and base case. Output from WRF-chem using 2005 Naional Emissions Inventory Reductions obtained using data from the initial fleet, fleet temporal variation and substitution policies.

  11. A Mexico City-Based Immersion Education Program: Training Mental Health Clinicians for Practice with Latino Communities

    Science.gov (United States)

    Platt, Jason James

    2012-01-01

    This article describes the philosophical foundations and educational methods of a Spanish language and cultural immersion program based in Mexico City, Mexico. The program is designed to assist U.S. graduate students in marriage and family therapy and clinical psychology programs to improve clinical service delivery with Latino clients. Utilizing…

  12. SURVIVAL STRATEGIES OF MICROENTREPRENEURS IN SOUTHERN MEXICO CITY: INFLUENCE OF APPRECIATED LEARNING

    OpenAIRE

    Arcelia López-Cabello; María del Rosario Ayala-Carrillo; Emma Zapata-Martelo

    2015-01-01

    The strategies of family reproduction are various ways in which families cope with the problems of everyday life, where the preservation of life and development of essential economic practices is ensured to optimize the material and non-material conditions of the family unit and of each of its members. Through in-depth interviews it was learned how some microentrepreneurs in Mexico City, have used their knowledge appreciated to implement various business generates economic resources to surviv...

  13. Preschool and Educational Technology: Evaluating a Tablet-Based Math Curriculum in Mexico City

    OpenAIRE

    Garduno, Ana Eugenia

    2016-01-01

    This study examines the effect of an intervention called Native Numbers on the development of number sense and quantitative skills in low-SES preschool children (ages 5 to 6) in Mexico City, using a randomized control trial (RCT). Native Numbers (NN) is a math curriculum built as an application for iPads that includes activities on number concepts, relations, ordering and counting. The study was conducted in 2014, with eight participating schools and an analytic sample of 249 students. The in...

  14. Evaluation of new secondary organic aerosol models for a case study in Mexico City

    OpenAIRE

    Dzepina, K.; Volkamer, R. M.; S. Madronich; Tulet, P; Ulbrich, I. M; Q. Zhang; C. D. Cappa; P. J. Ziemann; Jimenez, J. L.

    2009-01-01

    Recent field studies have found large discrepancies in the measured vs. modeled SOA mass loadings in both urban and regional polluted atmospheres. The reasons for these large differences are unclear. Here we revisit a case study of SOA formation in Mexico City described by Volkamer et al. (2006), during a photochemically active period when the impact of regional biomass burning is minor or negligible, and show that the observed increase in OA/ΔCO is consistent with results from several groups...

  15. Modeling the impacts of biomass burning on air quality in and around Mexico City

    OpenAIRE

    W. Lei; G Li; L. T. Molina

    2013-01-01

    The local and regional impacts of open fires and trash burning on ground-level ozone (O3) and fine carbonaceous aerosols in the Mexico City Metropolitan Area (MCMA) and surrounding region during two high fire periods in March 2006 have been evaluated using WRF-CHEM model. The model captured reasonably well the measurement-derived magnitude and temporal variation of the biomass burning organic aerosol (BBOA), and the simulated impacts of open fires on organic aerosol (OA) wer...

  16. Modeling the impacts of biomass burning on air quality in and around Mexico City

    OpenAIRE

    W. Lei; G Li; L. T. Molina

    2012-01-01

    The local and regional impacts of open fires and trash burning on ground-level ozone (O[subscript 3]) and fine carbonaceous aerosols in the Mexico City Metropolitan Area (MCMA) and surrounding region during two high fire periods in March 2006 have been evaluated using WRF-CHEM model. The model captured reasonably well the measurement-derived magnitude and temporal variation of the biomass burning organic aerosol (BBOA), and the simulated impacts of open fires on organic aerosol (OA) were cons...

  17. Characteristics of specific reading disability in children from a neuropsychological clinic in Mexico City

    OpenAIRE

    Poblano Adrián; Borja Sonia; Elías Yolanda; García-Pedroza Felipe; Arias Ma de Lourdes

    2002-01-01

    Objective. This report describes the main clinical features associated with specific reading disability (RD) in a group of 778 school-age children studied in a Neuropsychological Clinic in Mexico City. Material and Methods. The study was performed retrospectively, using data abstracted from clinical records of subjects seen in 1995-1996. Children were mainly from low and middle economic strata and aged between 6 to 12 years. The following data were collected: age, gender, diagnosis, school gr...

  18. Seroprevalence of Toxoplasma Gondii antibodies in cats from Durango City, Mexico.

    Science.gov (United States)

    The prevalence of antibodies to Toxoplasma gondii was determined in sera from 105 domestic cats from Durango City, Mexico. Using a modified agglutination test, antibodies to this parasite were found in (21%) of the 105 cats with titers of 1:25 in 3, 1:50 in 4, 1:200 in 5, 1:400 in 2, 1:800 in 2, 1...

  19. Human Settlements and Planning for Ecological Sustainability: The Case for Mexico City by Keith Pezzoli

    OpenAIRE

    Eisenstein, William

    1999-01-01

    From 1 983 through 1 985, a group of several hundred destitute families living in a squatter settlement on the outskirts of Mexico City attempted to organize their self-built community into something that they called a colonia ecologica productiva, or productive ecological settlement. The goal of the colonia was to enable the community to derive its livelihood from the land on which they had settled through sustainable agriculture techniques, reforestation projects, and the use of inexpensive...

  20. The dark side of aeromobilities:Unplanned airport planning in Mexico City

    OpenAIRE

    Lassen, Claus C.; Galland, Daniel

    2014-01-01

    Land-use conflicts, noise and health problems, local air pollution, decreased urban quality and affected liveability are considered amongst the core impacts and consequences associated with global airports, all of which have largely been individually documented. Through a case study of Mexico City International Airport, this article argues that a more integrated focus that brings such various issues and perspectives together is needed in order to widen the understanding of the existing relati...

  1. A Historical Perspective on Crime in Twentieth-Century Mexico City

    OpenAIRE

    Piccato, Pablo

    2003-01-01

    This paper is an overview of perceptions of crime in Mexico City during the twentieth century. After a brief review of quantitative evidence and the main sources on crime, the paper surveys police and judicial corruption as the common denominator of public perceptions of crime, punishment, and the judiciary. The paper then discusses gender violence and juvenile delinquency as two criminal practices that have characterized the impact of crime in everyday life. Based on a review of evidence abo...

  2. Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

    OpenAIRE

    M. Zavala; W. Lei; M. J. Molina; L. T. Molina

    2009-01-01

    The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA) have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile ...

  3. Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City

    OpenAIRE

    M. Johansson; Rivera, C.; de Foy, B.; Lei, W.; Song, J.; Zhang, Y.; Galle, B.; Molina, L.

    2009-01-01

    We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA) on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of H...

  4. Global changes, national development and urban poverty: Political engagement among the poor in Mexico City

    OpenAIRE

    Vegelin, C.L.

    2016-01-01

    As the world approaches the point in which urban poverty is to become the primary characteristic of global poverty by 2030, understanding the drivers, contexts, and conditions for urban poverty is increasingly urgent. This dissertation contributes to such needed understandings by carrying out an historical, multi-scalar analysis of the politics of urban poverty within the context of urban and global restructuring. In Mexico City, where vast wealth has been generated in some sectors, poverty h...

  5. Crisis, Xenophobia and Repatriation. The Spanish Immigrants in the City of Mexico, 1910-1936

    OpenAIRE

    Gil Lázaro, Alicia

    2011-01-01

    The article deals with the influence of economic crisis in migrant groups. It starts with a reflection about the current situation, putting forward a comparative view with a study case in the past, that is, the circumstances around the Spanish immigrants in Mexico City at the time of Mexican Revolution until the crisis of the Great Depression (1910-1936). Three aspects are explored: first of all, the close relationship between the spreading of the economic crisis and the increase of restrains...

  6. Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

    OpenAIRE

    M. Zavala; Lei, W.; M. J. Molina; L. T. Molina

    2008-01-01

    The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA) have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on...

  7. Vertical distribution of ozone and VOCs in the low boundary layer of Mexico City

    OpenAIRE

    E. Velasco; Márquez, C.; Bueno, E.; Bernabé, R. M.; Sánchez, A; Fentanes, O.; H. Wöhrnschimmel; Cárdenas, B.; A. Kamilla; Wakamatsu, S; L. T. Molina

    2007-01-01

    The evolution of ozone (O3) and 13 volatile organic compounds (VOCs) in the boundary layer of Mexico City was investigated during 2000–2004 to improve our understanding of the complex interactions between those trace gases and meteorological variables, and their influence on the air quality of a polluted megacity. A tethered balloon, fitted with electrochemical and meteorological sondes, was used to obtain detailed vertical profiles of O3 and mete...

  8. QUALITY OF LIFE AND COPING STRATEGIES IN OLDER ADULTS WITH PROBLEMS AND DISEASES IN MEXICO CITY

    OpenAIRE

    ANA LUISA GONZÁLEZ-CELIS; ADRIANA PADILLA

    2006-01-01

    Research purpose was to describe quality-of-life (QoL) and coping process in a sample of 194 elderly people in MexicoCity, towards their problems and illnesses. Results showed that 63.9% presented some illness, mainly chronicdegenerative(53.9%). QoL among ill adults vs non-ill persons was significantly different (t = -4.38, d.f. = 184,p

  9. Determinants of foreign aid in family planning: How relevant is the Mexico City Policy?

    OpenAIRE

    Asiedu, Elizabeth; Nanivazo, Malokele; Nkusu, Mwanza

    2013-01-01

    The Mexico City Policy (MCP) prohibits the United States Agency for International Development from providing aid to international non-governmental organizations that provide abortion-related services. This paper employs a panel data of 151 developing countries over the period of 1988 - 2010, to examine the effect of the MCP on the allocation of family planning aid to developing countries. We find that the MCP has a negative and robust effect on family planning aid. We also find that family pl...

  10. Evaluation and Proposed Development of the Municipal Solid Waste Management System in Mexico City

    OpenAIRE

    Escamilla Garcia, Pablo Emilio

    2015-01-01

    The work reported involves the evaluation of technologies and management systems applied to Municipal Solid Waste (MSW). The study focuses on Mexico City, which with a population of approximately 9 million inhabitants and an estimated daily generation of 13,000 tonnes of waste, is encountering extreme waste management issues. The structures and public policies designed to provide waste management services have proved inadequate in relation to high rates of population growth and intensive busi...

  11. Groundwater Flow and Solute Transport in Fractured Lacustrine Clay Near Mexico City

    Science.gov (United States)

    Rudolph, D. L.; Cherry, J. A.; Farvolden, R. N.

    1991-09-01

    A network of piezometers was installed in a surficial lacustrine clay aquitard overlying a thin saline water aquifer of volcanoclastic origin at a study site near Mexico City in the Basin of Mexico. The aquifer is underlain by additional lacustrine sediments which in turn overlie a thick regional freshwater aquifer. The regional aquifer provides approximately 70% of the water supply for 20 million people in the Basin of Mexico. In the study area, major ions, oxygen 18, and deuterium in the pore water of the surficial aquitard exhibit large variations with depth. The nature of these variations suggests that the saline pore water is being displaced downward by infiltrating meteoric water. The infiltration has been induced by strong downward hydraulic gradients imposed two to three decades ago when heavy aquifer pumping of the thin saline water aquifer began. One-dimensional analytical models representing solute transport in both fractured and unfractured porous media were used to simulate the geochemical profiles in the surficial aquitard. The fractured porous medium model, using a realistic mean hydraulic gradient and fracture spacing (1.5 m) and small but significant fracture aperture (30 μm) provide nearly an exact match to the field data. From this we infer that, because of vertical fractures, there is a much greater potential for downward leakage of water and contaminants through the Mexico City clay into underlying aquifers than has been previously thought.

  12. Rapid ventilation of the Mexico City basin and regional fate of the urban plume

    Directory of Open Access Journals (Sweden)

    B. de Foy

    2006-01-01

    Full Text Available Urban areas can be large emitters of air pollutants leading to negative health effects and environmental degradation. The rate of venting of these airsheds determines the pollutant loading for given emission levels, and also determines the regional impacts of the urban plume. Mexico City has approximately 20 million people living in a high altitude basin with air pollutant concentrations above the health limits most days of the year. A mesoscale meteorological model (MM5 and a particle trajectory model (FLEXPART are used to simulate air flow within the Mexico City basin and the fate of the urban plume during the MCMA-2003 field campaign. The simulated trajectories are validated against pilot balloon and radiosonde trajectories. The residence time of air within the basin and the impacted areas are identified by episode type. Three specific cases are analysed to identify the meteorological processes involved. For most days, residence times in the basin are less than 12 h with little carry-over from day to day and little recirculation of air back into the basin. Very efficient vertical mixing leads to a vertically diluted plume which, in April, is transported predominantly towards the Gulf of Mexico. Regional accumulation was found to take place for some days however, with urban emissions sometimes staying over Mexico for more than 6 days. Knowledge of the residence times, recirculation patterns and venting mechanisms will be useful in guiding policies for improving the air quality of the MCMA.

  13. Aerosol Light Absorption and Scattering in Mexico City: Comparison With Las Vegas, NV, and Los Angeles, CA.

    Science.gov (United States)

    Paredes-Miranda, G.; Arnott, W. P.; Gaffney, J. S.; Marley, N. A.; Campbell, D.; Fujita, E.

    2007-12-01

    Aerosol light scattering and absorption measurements were deployed in and near Mexico City in March 2006 as part of the Megacity Impacts on Regional and Global Environments (MIRAGE). The primary site in Mexico City was an urban site at Instituto Mexicano del Petroleo (Mexican Oil Institute, denoted by IMP). Similar campaigns were held in Las Vegas, NV in January-February, 2003; and Los Angeles, CA at numerous sites during all seasons from 2003 through 2007. The IMP site gave in-situ characterization of the Mexico City plume under favorable wind conditions. The photoacoustic instrument (PAS) used at IMP operates at 532 nm, and conveniently allowed for characterization of gaseous absorption at this wavelength as well. Light scattering measurements are accomplished within the PAS by the reciprocal nephelometery method. In Mexico City the aerosol absorption coefficient typically varies between 20 and 180 Mm-1 during the course of the day and significant diurnal variation of the aerosol single scattering albedo was observed probably as a consequence of secondary aerosol formation. We will present the diurnal variation of the scattering and absorption as well as the single scattering albedo and fraction of absorption due to gases at the IMP site and compare with Las Vegas diurnal variation. Mexico City 'breaths' more during the course of the day than Las Vegas, Nevada in part because the latitude of Mexico City resulted in more direct solar radiation. Further insight on the meteorological connections and population dynamics will be discussed.

  14. Estimation of strong ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap

    OpenAIRE

    Kanamori, Hiroo; Jennings, Paul C.; Singh, Shri Krishna; Astiz, Luciana

    1993-01-01

    We performed simulations of ground motions in Mexico City expected for large earthquakes in the Guerrero seismic gap in Mexico. The simulation method uses as empirical Green's functions the accelerograms recorded in Mexico City during four small to moderate earthquakes (8 Feb. 1988, M_s = 5.8; 25 April 1989, M_w = 6.9; 11 May 1990, M_w = 5.5; and 31 May 1990, M_w = 6.0) in the Guerrero gap. Because these events occurred in the Guerrero gap, and have typical thrust mechanisms, the propagation ...

  15. The T1-T2 study: evolution of aerosol properties downwind of Mexico City

    Directory of Open Access Journals (Sweden)

    J. C. Doran

    2007-01-01

    Full Text Available As part of a major atmospheric chemistry and aerosol field program carried out in March 2006, a study was conducted in the area to the north and northeast of Mexico City to investigate the evolution of aerosols and their associated optical properties in the first few hours after their emission. The focus of the T1-T2 aerosol study was to investigate changes in the specific absorption αABS (absorption per unit mass, with unit of m2 g−1 of black carbon as it aged and became coated with compounds such as sulfate and organic carbon, evolving from an external to an internal mixture. Such evolution has been reported in previous studies. The T1 site was located just to the north of the Mexico City metropolitan area; the T2 site was situated approximately 35 km farther to the northeast. Nephelometers, particle soot absorption photometers, photoacoustic absorption spectrometers, and organic and elemental carbon analyzers were used to measure the optical properties of the aerosols and the carbon concentrations at each of the sites. Radar wind profilers and radiosonde systems helped to characterize the meteorology and to identify periods when transport from Mexico City over T1 and T2 occurred. Organic and elemental carbon concentrations at T1 showed diurnal cycles reflecting the nocturnal and early morning buildup from nearby sources, while concentrations at T2 appeared to be more affected by transport from Mexico City. Specific absorption during transport periods was lower than during other times, consistent with the likelihood of fresher emissions being found when the winds blew from Mexico City over T1 and T2. The specific absorption at T2 was larger than at T1, which is also consistent with the expectation of more aged particles with encapsulated black carbon being found at the more distant location. In situ measurements of single scattering albedo with an aircraft and a ground station showed general agreement with column-averaged values derived

  16. The T1-T2 study: evolution of aerosol properties downwind of Mexico City

    Directory of Open Access Journals (Sweden)

    J. C. Doran

    2006-12-01

    Full Text Available As part of a major atmospheric chemistry and aerosol field program carried out in March of 2006, a study was conducted in the area to the north and northeast of Mexico City to investigate the evolution of aerosols and their associated optical properties in the first few hours after their emission. The focus of the T1-T2 aerosol study was to investigate changes in the specific absorption αABS (absorption per unit mass, with unit of m2 g−1 of black carbon as it aged and became coated with compounds such as sulfate and organic carbon, evolving from an external to an internal mixture. Such evolution has been reported in previous studies. The T1 site was located just to the north of the Mexico City metropolitan area; the T2 site was situated approximately 35 km farther to the northeast. Nephelometers, particle soot absorption photometers, photoacoustic absorption photometers, and organic and elemental carbon analyzers were used to measure the optical properties of the aerosols and the carbon concentrations at each of the sites. Radar wind profilers and radiosonde systems helped to characterize the meteorology and to identify periods when transport from Mexico City over T1 and T2 occurred. Organic and elemental carbon concentrations at T1 showed diurnal cycles reflecting the nocturnal and early morning buildup from nearby sources, while concentrations at T2 appeared to be more affected by transport from Mexico City. Specific absorption during transport periods was lower than during other times, consistent with the likelihood of fresher emissions being found when the winds blew from Mexico City over T1 and T2. The specific absorption at T2 was larger than at T1, which is also consistent with the expectation of more aged particles with encapsulated black carbon being found at the more distant location. In situ measurements of single scattering albedo with an aircraft and a ground station showed general agreement with

  17. Microscopic Characterization of Carbonaceous Aerosol Particle Aging in the Outflow from Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Moffet, R. C.; Henn, T. R.; Tivanski, A. V.; Hopkins, R. J.; Desyaterik, Y.; Kilcoyne, A. L. D.; Tyliszczak, T.; Fast, J.; Barnard, J.; Shutthanandan, V.; Cliff, S.S.; Perry, K. D.; Laskin, A.; Gilles, M. K.

    2009-09-16

    This study was part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) field campaign conducted in Mexico City Metropolitan Area during spring 2006. The physical and chemical transformations of particles aged in the outflow from Mexico City were investigated for the transport event of 22 March 2006. A detailed chemical analysis of individual particles was performed using a combination of complementary microscopy and micro-spectroscopy techniques. The applied techniques included scanning transmission X-ray microscopy (STXM) coupled with near edge X-ray absorption fine structure spectroscopy (NEXAFS) and computer controlled scanning electron microscopy with an energy dispersive X-ray analyzer (CCSEM/EDX). As the aerosol plume evolves from the city center, the organic mass per particle increases and the fraction of carbon-carbon double bonds (associated with elemental carbon) decreases. Organic functional groups enhanced with particle age include: carboxylic acids, alkyl groups, and oxygen bonded alkyl groups. At the city center (T0) the most prevalent aerosol type contained inorganic species (composed of sulfur, nitrogen, oxygen, and potassium) coated with organic material. At the T1 and T2 sites, located northeast of T0 (~;;29 km and ~;;65 km, respectively), the fraction of homogenously mixed organic particles increased in both size and number. These observations illustrate the evolution of the physical mixing state and organic bonding in individual particles in a photochemically active environment.

  18. Methanol-CO correlations in Mexico City pollution outflow from aircraft and satellite during MILAGRO

    Directory of Open Access Journals (Sweden)

    Y. Xiao

    2012-02-01

    Full Text Available The correlation between methanol (CH3OH and carbon monoxide (CO is of particular interest for characterizing biogenic and anthropogenic emission sources of CH3OH and other chemical species. Here, the CH3OH/CO enhancement ratio (ΔCH3OH/ΔCO in the lower to middle troposphere is examined using coincident CH3OH and CO observations from aircraft (NCAR C-130 and NASA DC-8 and from the Tropospheric Emission Spectrometer (TES satellite during the MegaCity Initiative: Local and Global Research Observations (MILAGRO in the Mexico City region in March 2006. ΔCH3OH/ΔCO ratios from the two in-situ aircraft measurements are far higher than previously reported CH3OH emission ratios relative to CO from US cities. This may reflect combustion of different fuel types in this area, and possibly photochemical production of CH3OH in Mexico City outflow. TES CH3OH and CO retrievals over the MILAGRO domain show relatively high sensitivity in the 600–800 hPa range, associated with Mexico City pollution outflow. The TES derived ΔCH3OH/ΔCO ratios during MILAGRO are 18–24 ppt ppb−1, which are similar to those observed from the DC-8 (26–39 ppt ppb−1, but lower than the C-130 observations (41–55 ppt ppb−1. Differences between the ΔCH3OH/ΔCO ratios measured aboard the two aircraft preclude an absolute validation of the TES-derived ratios for this dataset. The ΔCH3OH/ΔCO ratios observed from TES over this domain reflect bulk enhancements of CH3OH and CO in Mexico City outflow. Although the TES measurements are not expected to resolve small-scale variability in the ΔCH3OH/ΔCO ratio downwind of the strong source region of Mexico City, it is demonstrated that TES can clearly distinguish differences in the ΔCH3OH/ΔCO ratio due to different source categories

  19. Eddy covariance flux measurements of pollutant gases in urban Mexico City

    Science.gov (United States)

    Velasco, E.; Pressley, S.; Grivicke, R.; Allwine, E.; Coons, T.; Foster, W.; Jobson, B. T.; Westberg, H.; Ramos, R.; Hernández, F.; Molina, L. T.; Lamb, B.

    2009-10-01

    Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 from a residential district of Mexico City (Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 and olefins were measured by the conventional EC technique using an open path CO2 sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded local emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The results show that the emissions inventory is in reasonable agreement with measured olefin and CO2 fluxes, while C2-benzenes and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not reported in the mobile emissions inventory.

  20. The traffic crisis and a tale of two cities: Traffic and air quality in Bangkok and Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Pendakur, V.S.; Badami, M.G.

    1995-12-31

    This paper focuses on congestion management techniques, traffic congestion levels and air quality. By using data from Bangkok and Mexico City, it illustrates the need for drastic changes in transportation policy tools and techniques for congestion management and for improving environmental quality. New approaches to investment and regulatory policy analysis and implementation are suggested. This requires the inclusion of all costs and benefits (economic and ecological) in the policy matrix so that investment and regulatory policies act in unison. Megacities are dominant in social, political and economic terms. 30 to 60% of national GDP is typically produced in these cities. Their human and motor vehicle populations have been doubling every 15-20 and 6-10 years respectively. They also have the most severe traffic congestion and air quality problems. They have the nation`s highest incidence of poverty and absolute poverty. Large portions of their populations endure severely unhealthy housing and sanitation conditions. Following are important characteristics of urban transportation systems in the megacities: the city centres are heavily congested with motorized traffic; traffic crawl rates vary from 2 to 10 km/hr; car and motorcycle ownership are increasing at annual rates of 10-12% and 15-20% respectively; significant air pollution with no relief in sight; TDM strategies are primarily creating new supply of road capacity; fairly high transit trips with substantial transit investments; weak air pollution monitoring and enforcement; and fairly cheap fuel and high costs of vehicles.

  1. An indoor radon survey of the X-ray rooms of Mexico City hospitals

    Energy Technology Data Exchange (ETDEWEB)

    Juarez, Faustino [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario No. 100. Estado de Mexico, 50000, Mexico. Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Circuito (Mexico); Reyes, Pedro G. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico, Instituto Literario No. 100. Estado de Mexico, 50000 (Mexico); Espinosa, Guillermo [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Circuito Exterior Ciudad Universitaria, Mexico D.F. Cp.04510 (Mexico)

    2013-07-03

    This paper presents the results of measurements of indoor radon concentrations in the X-ray rooms of a selection of hospitals in the metropolitan area of Mexico City. The metropolitan area of Mexico City is Mexico's largest metropolitan area by population; the number of patients requiring the use of X-rays is also the highest. An understanding of indoor radon concentrations in X-ray rooms is necessary for the estimation of the radiological risk to which patients, radiologists and medical technicians are exposed. The indoor radon concentrations were monitored for a period of six months using nuclear track detectors (NTD) consisting of a closed-end cup system with CR-39 (Lantrack Registered-Sign ) polycarbonate as detector material. The indoor radon concentrations were found to be between 75 and 170 Bq m{sup -3}, below the USEPA-recommended indoor radon action level for working places of 400 Bq m{sup -3}. It is hoped that the results of this study will contribute to the establishment of recommended action levels by the Mexican regulatory authorities responsible for nuclear safety.

  2. Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry

    Directory of Open Access Journals (Sweden)

    R. C. Moffet

    2008-08-01

    Full Text Available Continuous ambient measurements with aerosol time-of-flight mass spectrometry (ATOFMS were made in an industrial/residential section in the northern part of Mexico City as part of the Mexico City Metropolitan Area-2006 campaign (MCMA-2006. Results are presented for the period of 15–27 March 2006. The submicron size mode contained both fresh and aged biomass burning, aged organic carbon (OC mixed with nitrate and sulfate, elemental carbon (EC, nitrogen-organic carbon, industrial metal, and inorganic NaK inorganic particles. Overall, biomass burning and aged OC particle types comprised 40% and 31%, respectively, of the submicron mode. In contrast, the supermicron mode was dominated by inorganic NaK particle types (42% which represented a mixture of dry lake bed dust and industrial NaK emissions mixed with soot. Additionally, aluminosilicate dust, transition metals, OC, and biomass burning contributed to the supermicron particles. Early morning periods (2–6 a.m. showed high fractions of inorganic particles from industrial sources in the northeast, composed of internal mixtures of Pb, Zn, EC and Cl, representing up to 73% of the particles in the 0.2–3μm size range. A unique nitrogen-containing organic carbon (NOC particle type, peaking in the early morning hours, was hypothesized to be amines from local industrial emissions based on the time series profile and back trajectory analysis. A strong dependence on wind speed and direction was observed in the single particle types that were present during different times of the day. The early morning (3:30–10 a.m. showed the greatest contributions from industrial emissions. During mid to late mornings (7–11 a.m., weak northerly winds were observed along with the most highly aged particles. Stronger winds from the south picked up in the late morning (after 11 a.m., resulting in a decrease in the concentrations of the major aged particle types and an increase in the number fraction of fresh

  3. Mexico.

    Science.gov (United States)

    1993-01-01

    The background notes on Mexico provide text and recent statistical information on the geography, population, government, economy, and foreign relations, specifically the North American Free Trade Agreement with US. The 1992 population is estimated at 89 million of which 60% are mestizo (Indian-Spanish), 30% are American Indian, 9% are Caucasian, and 1% are other. 90% are Roman Catholic. There are 8 years of compulsory education. Infant mortality is 30/1000 live births. Life expectancy for males is 68 years and 76 years for females. The labor force is comprised of 30% in services, 24% in agriculture and fishing, 19% in manufacturing, 13% in commerce, 7% in construction, 4% in transportation and communication, and .4% in mining. There are 31 states and a federal district. Gross domestic product (GDP) per capita was $3200 in 1991. Military expenditures were .5% of GDP in 1991. The average inflation rate is 19%. Mexico City with 20 million is the largest urban center in the world. In recent years, the economy has been restructured with market oriented reforms; the result has been a growth of GDP of 3.6% in 1991 from 2% in 1987. Dependence on oil exports has decreased. There has been privatization and deregulation of state-owned companies. Subsidies to inefficient companies have been stopped. Tariff rates were reduced. The financial debt has been reduced and turned into a surplus of .8% in 1992. Mexico's foreign debt has been reduced from its high in 1987 of $107 billion. Agricultural reforms have been ongoing for 50 years. Land was redistributed, but standards of living and productivity have improved only slightly. Rural land tenure regulations have been changed, and other economic reforms are expected. Mexico engages in ad hoc international groups and is selective about membership in international organizations. PMID:12178052

  4. The possible influence of volcanic emissions on atmospheric aerosols in the city of Colima, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Javier; Zepeda, Francisco; Galindo, Ignacio

    2004-01-01

    An elemental composition study of atmospheric aerosols from the City of Colima, in the Western Coast of Mexico, is presented. Samples of PM{sub 15}-PM{sub 2.5} and PM{sub 2.5} were collected with Stacked Filter Units (SFU) of the Davis design, in urban and rural sites, the latter located between the City of Colima and the Volcan de Colima, an active volcano. Elemental analyses were carried out using Particle Induced X-ray Emission (PIXE). The gravimetric mass concentrations for the fine fraction were slightly higher in the urban site, while the mean concentrations in the coarse fraction were equal within the uncertainties. High Cl contents were determined in the coarse fraction, a fact also observed in emissions from the Volcan de Colima by other authors. In addition to average elemental concentrations, cluster analysis based on elemental contents was performed, with wind speed and direction data, showing that there is an industrial contributor to aerosols North of the urban area. Moreover, a contribution from the volcanic emissions was identified from the grouping of S, Cl, Cu, and Zn, elements associated to particles emitted by the Volcan de Colima. - Elemental analyses of PM{sub 15} in the City of Colima, Mexico, were done to identify possible contributions from the Volcan de Colima, an active volcano.

  5. Contribution of garbage burning to chloride and PM2.5 in Mexico City

    Directory of Open Access Journals (Sweden)

    N. Bei

    2012-09-01

    Full Text Available The contribution of garbage burning (GB emissions to chloride and PM2.5 in the Mexico City Metropolitan Area (MCMA has been investigated for the period of 24 to 29 March during the MILAGRO-2006 campaign using the WRF-CHEM model. When the MCMA 2006 official emission inventory without biomass burning is used in the simulations, the WRF-CHEM model significantly underestimates the observed particulate chloride in the urban and the suburban areas. The inclusion of GB emissions substantially improves the simulations of particulate chloride; GB contributes more than 60% of the observation, indicating that it is a major source of particulate chloride in Mexico City. GB yields up to 3 pbb HCl at the ground level in the city, which is mainly caused by the burning of polyvinyl chloride (PVC in the garbage. GB is also an important source of PM2.5, contributing about 3–30% simulated PM2.5 mass on average. More modeling work is needed to evaluate the GB contribution to hazardous air toxics, such as dioxin, which is found to be released at high level from PVC burning in laboratory experiments.

  6. Mexico City air quality research initiative, volume 3, modeling and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Mauzy, A. [ed.] [Los Alamos National Lab., NM (United States)

    1994-06-01

    The objective of the modeling and simulation task was to develop, test, and apply an appropriate set of models that could translate emission changes into air quality changes. Specifically, we wanted to develop models that could describe how existing measurements of ozone (O{sub 3}), carbon monoxide (CO), and sulfur dioxide (SO{sub 2}) would be expected to change if their emissions were changed. The modeling must be able to address the effects of difference in weather conditions and changes in land use as well as the effects of changes in emission levels. It must also be able to address the effects of changes in the nature and distribution of the emissions as well as changes in the total emissions. A second objective was to provide an understanding of the conditions that lead to poor air quality in Mexico City. We know in a general sense that Mexico City`s poor air quality is the result of large quantities of emissions in a confined area that is subject to light winds, but we did not know much about many aspects of the problem. For example, is the air quality on a given day primarily the result of emissions on that day...or is there an important carryover from previous nights and days? With a good understanding of the important meteorological circumstances that lead to poor air quality, we learn what it take duce an accurate forecast of impending quality so that we can determine the advisability of emergency measures.

  7. An Overview of the MILAGRO 2006 Campaign: Mexico City Emissions and their Transport and Transformation

    Energy Technology Data Exchange (ETDEWEB)

    Molina, Luisa T.; Madronich, Sasha; Gaffney, Jeffrey; Apel, Eric; de Foy, B.; Fast, Jerome D.; Ferrare, R.; Herndon, Scott C.; Jimenez, Jose L.; Lamb, Brian K.; Orsonio-Vargas, A. R.; Russell, P. B.; Schauer, James J.; Stevens, P. S.; Volkamer, Rainer M.; Zavala, Miguel A.

    2010-03-25

    The world’s population is projected to increase 33% during the next three decades, to 8.1 billion. Nearly all of the projected growth is expected to be concentrated in urban centers. These rapidly expanding urban regions and surrounding suburban areas are leading to the phenomenon of megacities (metropolitan areas with populations exceeding 10 million inhabitants). Well governed, densely populated settlements can reduce the need for land conversion and provide proximity to infrastructure and services. However, many urban areas experience uncontrolled sprawl and their activities are the leading cause of environmental problems. These mega-centers of human population are tied directly to increasing demands for energy and associated industrial activities and motorization that lead to more emission of pollutants into the atmosphere. Air pollution is one of the most important environmental challenges of this century. This challenge is particularly acute in the developing world where the rapid growth of megacities is producing atmospheric pollution of unprecedented severity and extent. MILAGRO (Megacity Initiative: Local And Global Research Observations) is the first international collaborative project to examine the behavior and the export of atmospheric pollutants generated in megacities. The Mexico City Metropolitan Area (MCMA) - one of the world’s largest megacities and North America’s most populous city -- was selected as the initial case study to characterize the sources and processes of emissions from the urban center and to evaluate the regional and global impacts of the Mexico City air pollution plume

  8. Serenity: Violence, Inequality, and Recovery on the Edge of Mexico City.

    Science.gov (United States)

    Garcia, Angela

    2015-12-01

    Over the last decade, there has been a sharp increase in drug addiction in Mexico, especially among the urban poor. During the same period, unregulated residential treatment centers for addiction, known as anexos, have proliferated throughout the country. These centers are utilized and run by marginalized populations and are widely known to engage in physical violence. Based on long-term ethnographic research in Mexico City, this article describes why anexos emerged, how they work, and what their prevalence and practices reveal about the nature of recovery in a context where poverty, drugs, and violence are existential realities. Drawing attention to the dynamic relationship between violence and recovery, pain, and healing, it complicates categories of violence and care that are presumed to have exclusive meaning, illuminating the divergent meanings of, and opportunities for, recovery, and how these are socially configured and sustained. PMID:25808246

  9. Implementation of a radiological safety management system in a hospital of Mexico City

    International Nuclear Information System (INIS)

    Full text: The reflection of this work is based in some radiological accidents that its have happened in some hospital centers or of research. The over exposure of some people is due to the pursuit of the procedures, the lack of quality assurance of the equipment or the inappropriate actions of the technicians. In Mexico one has seen in several hospitals the lack of existence of a Quality Assurance Program to prevent the accidents, the execution of the same ones and those good practices and the lack of Safety Culture makes that the hospital radiological safety it is faulty. The objective of the present work is the implementation of a radiological safety management in a hospital of Mexico City. (Author)

  10. Identification of elements in polutants of Mexico City's atmosphere, using the pixe analysis

    International Nuclear Information System (INIS)

    A review of the fundamentals and actual state in Mexico of the pixe (particle induced X- ray emission) technique are done. Elemental identification in samples of Mexico City's atmosphere taken in two sites is performed using this technique. A 3 MeV proton beam is used to irradiate the samples. Factors (Bremsstrahlung and interference) that difficult the use of the technique are discussed. The sensitivity of the method is enhanced as a main characteristic. It is shown that tje pixe technique together with an appropriate sampling system can be used to study environmental aerosols. Identified elements are bromine, lead, copper, iron, zinc, titanium, vanadium, calcium, potassium, chlorine, sulfur and silicon. Temporal variations of these elements are discussed. (Author)

  11. Spatial and temporal variability of particulate polycyclic aromatic hydrocarbons in Mexico City

    Directory of Open Access Journals (Sweden)

    D. A. Thornhill

    2008-06-01

    Full Text Available As part of the Megacities Initiative: Local and Global Research Observations (MILAGRO study in the Mexico City Metropolitan Area in March 2006, we measured particulate polycyclic aromatic hydrocarbons (PAHs and other gaseous species and particulate properties, including light absorbing carbon or effective black carbon (BC, at six locations throughout the city. The measurements were intended to support the following objectives: to describe spatial and temporal patterns in PAH concentrations, to gain insight into sources and transformations of PAHs and BC, and to quantify the relationships between PAHs and other pollutants. Total particulate PAHs at the Instituto Mexicano del Petróleo (T0 supersite located near downtown averaged 50 ng m−3, and aerosol active surface area averaged 80 mm2 m−3. PAHs were also measured on board the Aerodyne Mobile Laboratory, which visited six sites encompassing a mixture of different land uses and a range of ages of air parcels transported from the city core. A combination of analyses of time series, back trajectories, concentration fields, pollutant ratios, and correlation coefficients supports the concept of T0 as an urban source site, T1 as a receptor site with strong local sources, Pedregal and PEMEX as intermediate sites, Pico Tres Padres as a vertical receptor site, and Santa Ana as a downwind receptor site. Weak intersite correlations suggest that local sources are important and variable and that exposure to PAHs and BC cannot be represented by a single regional-scale value. The relationships between PAHs and other pollutants suggest that a variety of sources and ages of particles are present. Among carbon monoxide, nitrogen oxides (NOx, and carbon dioxide, particulate PAHs are most strongly correlated with NOx. Mexico City's PAH/BC mass ratio of 0.01 is similar to that found on a freeway loop in the Los Angeles area and approximately 8–30

  12. Spatial and temporal variability of particulate polycyclic aromatic hydrocarbons in Mexico City

    Science.gov (United States)

    Thornhill, D. A.; de Foy, B.; Herndon, S. C.; Onasch, T. B.; Wood, E. C.; Zavala, M.; Molina, L. T.; Gaffney, J. S.; Marley, N. A.; Marr, L. C.

    2008-06-01

    As part of the Megacities Initiative: Local and Global Research Observations (MILAGRO) study in the Mexico City Metropolitan Area in March 2006, we measured particulate polycyclic aromatic hydrocarbons (PAHs) and other gaseous species and particulate properties, including light absorbing carbon or effective black carbon (BC), at six locations throughout the city. The measurements were intended to support the following objectives: to describe spatial and temporal patterns in PAH concentrations, to gain insight into sources and transformations of PAHs and BC, and to quantify the relationships between PAHs and other pollutants. Total particulate PAHs at the Instituto Mexicano del Petróleo (T0 supersite) located near downtown averaged 50 ng m-3, and aerosol active surface area averaged 80 mm2 m-3. PAHs were also measured on board the Aerodyne Mobile Laboratory, which visited six sites encompassing a mixture of different land uses and a range of ages of air parcels transported from the city core. A combination of analyses of time series, back trajectories, concentration fields, pollutant ratios, and correlation coefficients supports the concept of T0 as an urban source site, T1 as a receptor site with strong local sources, Pedregal and PEMEX as intermediate sites, Pico Tres Padres as a vertical receptor site, and Santa Ana as a downwind receptor site. Weak intersite correlations suggest that local sources are important and variable and that exposure to PAHs and BC cannot be represented by a single regional-scale value. The relationships between PAHs and other pollutants suggest that a variety of sources and ages of particles are present. Among carbon monoxide, nitrogen oxides (NOx), and carbon dioxide, particulate PAHs are most strongly correlated with NOx. Mexico City's PAH/BC mass ratio of 0.01 is similar to that found on a freeway loop in the Los Angeles area and approximately 8 30 times higher than that found in other cities. Evidence also suggests that primary

  13. Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City

    Directory of Open Access Journals (Sweden)

    L. C. Marr

    2005-12-01

    Full Text Available Understanding sources, concentrations, and transformation of polycyclic aromatic hydrocarbons (PAHs in the atmosphere is important because of their potent mutagenicity and carcinogenicity. The measurement of particle-bound PAHs by three different methods during the Mexico City Metropolitan Area field campaign in April 2003 presents a unique opportunity for characterization of these compounds and assessment of the methods. The three methods are (1 collection and analysis of bulk samples for time-integrated gas- and particle-phase speciation by gas chromatography/mass spectrometry; (2 aerosol photoionization for fast detection of PAHs on particles' surfaces; and (3 aerosol mass spectrometry for fast analysis of size and chemical composition. This research represents the first time aerosol mass spectrometry has been used to measure ambient PAH concentrations and the first time that fast, real-time methods have been used to quantify PAHs alongside traditional filter-based measurements in an extended field campaign. Speciated PAH measurements suggest that motor vehicles and garbage and wood burning are important sources in Mexico City. The diurnal concentration patterns captured by aerosol photoionization and aerosol mass spectrometry are generally consistent. Ambient concentrations typically peak at ~110 ng m−3 during the morning rush hour and rapidly decay due to changes in source activity patterns and dilution as the boundary layer rises, although surface-bound PAH concentrations decay faster. The more rapid decrease in surface versus bulk PAH concentrations during the late morning suggests that freshly emitted combustion-related particles are quickly coated by secondary aerosol material in Mexico City's atmosphere and may also be transformed by heterogeneous reactions.

  14. Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City

    Directory of Open Access Journals (Sweden)

    L. C. Marr

    2006-01-01

    Full Text Available Understanding sources, concentrations, and transformations of polycyclic aromatic hydrocarbons (PAHs in the atmosphere is important because of their potent mutagenicity and carcinogenicity. The measurement of particle-bound PAHs by three different methods during the Mexico City Metropolitan Area field campaign in April 2003 presents a unique opportunity for characterization of these compounds and intercomparison of the methods. The three methods are (1 collection and analysis of bulk samples for time-integrated gas- and particle-phase speciation by gas chromatography/mass spectrometry; (2 aerosol photoionization for fast detection of PAHs on particles' surfaces; and (3 aerosol mass spectrometry for fast analysis of size and chemical composition. This research represents the first time aerosol mass spectrometry has been used to measure ambient PAH concentrations and the first time that fast, real-time methods have been used to quantify PAHs alongside traditional filter-based measurements in an extended field campaign. Speciated PAH measurements suggest that motor vehicles and garbage and wood burning are important sources in Mexico City. The diurnal concentration patterns captured by aerosol photoionization and aerosol mass spectrometry are generally consistent. Ambient concentrations of particle-phase PAHs typically peak at ~110 ng m-3 during the morning rush hour and rapidly decay due to changes in source activity patterns and dilution as the boundary layer rises, although surface-bound PAH concentrations decay faster. The more rapid decrease in surface versus bulk PAH concentrations during the late morning suggests that freshly emitted combustion-related particles are quickly coated by secondary aerosol material in Mexico City's atmosphere and may also be transformed by heterogeneous reactions.

  15. The impact of biogenic carbon emissions on aerosol absorption inMexico City

    Energy Technology Data Exchange (ETDEWEB)

    Marley, N; Gaffney, J; Tackett, M J; Sturchio, N; Hearty, L; Martinez, N; Hardy, K D; Machany-Rivera, A; Guilderson, T P; MacMillan, A; Steelman, K

    2009-02-24

    In order to determine the wavelength dependence of atmospheric aerosol absorption in the Mexico City area, the absorption angstrom exponents (AAEs) were calculated from aerosol absorption measurements at seven wavelengths obtained with a seven-channel aethalometer during two field campaigns, the Mexico City Metropolitan Area study in April 2003 (MCMA 2003) and the Megacity Initiative: Local and Global Research Observations in March 2006 (MILAGRO). The AAEs varied from 0.76 to 1.56 in 2003 and from 0.54 to 1.52 in 2006. The AAE values determined in the afternoon were consistently higher than the corresponding morning values, suggesting the photochemical formation of absorbing secondary organic aerosols (SOA) in the afternoon. The AAE values were compared to stable and radiocarbon isotopic measurements of aerosol samples collected at the same time to determine the sources of the aerosol carbon. The fraction of modern carbon (fM) in the aerosol samples, as determined from {sup 14}C analysis, showed that 70% of the carbonaceous aerosols in Mexico City were from modern sources, indicating a significant impact from biomass burning during both field campaigns. The {sup 13}C/{sup 12}C ratios of the aerosol samples illustrate the significant impact of Yucatan forest fires (C-3 plants) in 2003 and local grass fires (C-4 plants) at site T1 in 2006. A direct comparison of the fM values, stable carbon isotope ratios, and calculated aerosol AAEs suggested that the wavelength dependence of the aerosol absorption was controlled by the biogenically derived aerosol components.

  16. Blood lead levels in pregnant women of high and low socioeconomic status in Mexico City.

    OpenAIRE

    Farias, P; Borja-Aburto, V H; Rios, C.(Universidad de Santiago de Compostela, Santiago de Compostela, Spain); Hertz-Picciotto, I; Rojas-Lopez, M; Chavez-Ayala, R

    1996-01-01

    This study examined the determinants of blood lead (BPb) in 513 pregnant women in Mexico City: 311 from public hospital prenatal clinics, representing primarily women of low socioeconomic status (SES), and 202 from private hospitals, primarily women of high SES. Overall, BPb levels ranged from 1.38 to 29 micrograms/dl, with geometric means of 6.7 and 11.12 micrograms/dl for women from private and public hospitals, respectively. The crude geometric means difference obtained by t-test was 4.42 ...

  17. Mexico City air quality research initiative. Volume IV. Characterization and measurement

    Energy Technology Data Exchange (ETDEWEB)

    Mauzy, A. [ed.

    1994-04-01

    This volume describes the methods and the data gathered in an attempt to measure and characterize the meteorological factors and the concentration of different pollutants in the Mexico City Metropolitan Area. The main objective of this document was to provide input for the simulation models and to obtain information that could be used to test and improve the models` performance. Four field campaigns were conducted, as well as routine monitoring, in order to obtain a database of atmospheric dynamics and air pollution characteristics. Sections include Airborne measurements, Remote sensing measurements, and Traditional (in situ) measurements.

  18. The T1-T2 study: evolution of aerosol properties downwind of Mexico City

    OpenAIRE

    Doran, J.C.; J. C. Barnard; Arnott, W.P.; R. Cary; Coulter, R.; J. D. Fast; Kassianov, E. I.; L. Kleinman; N. S. Laulainen; Martin, T.; G. Paredes-Miranda; M. S. Pekour; Shaw, W. J.; Smith, D.F.; S. R. Springston

    2006-01-01

    As part of a major atmospheric chemistry and aerosol field program carried out in March of 2006, a study was conducted in the area to the north and northeast of Mexico City to investigate the evolution of aerosols and their associated optical properties in the first few hours after their emission. The focus of the T1-T2 aerosol study was to investigate changes in the specific absorption αABS (absorption per unit mass, with unit of m2 g&l...

  19. Archaeomagnetic Investigation at Chapultepec, Mexico City: Case Study of Classical Settlers

    Science.gov (United States)

    Lopez, V.; Romero, E.; Soler-Arechalde, A. M.; Espinosa, G.

    2007-05-01

    During the restoration campaign at the Chapultepec Park in Mexico City downtown, a teotihuacan settlement was found at the south flank of Chapultepec Hill. Samples represent a kind of irregular home kilns with a hole in their central part bounded by andesite rocks. Alternating field demagnetization had been employed. Rock magnetic measurements which included: Hysteresis, continuous susceptibility and isothermal remanence experiments revealed that some spinels, most probably magnetite or Ti-poor Titanomagnetites are responsible for the remanence. An archeomagnetic date obtained here is of 525 AD which is in good agreement with other evidences of the Teotihuacan Classic Metepec period (450-600 AD).

  20. PCBs and PAHs in surficial sediments from aquatic environments of Mexico City and the coastal states of Sonora, Sinaloa, Oaxaca and Veracruz (Mexico)

    Science.gov (United States)

    Piazza, Rossano; Ruiz-Fernández, Ana Carolina; Frignani, Mauro; Zangrando, Roberta; Bellucci, Luca Giorgio; Moret, Ivo; Páez-Osuna, Federico

    2008-06-01

    Concentrations of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in 13 surficial sediment samples collected at three lacustrine locations in the surroundings of Mexico City and four coastal areas of the States of Sinaloa, Sonora, Oaxaca and Veracruz. Total PCB concentrations span the interval 3.18 621 ng g-1. The highest values (63.7 621 ng g-1) were found in Mexico City, which is a highly anthropogenically impacted area, whereas low concentrations (3.18 12.9 ng g-1) were characteristic of seven places, some of them subject to intense hydrodynamics. In these latter cases, values increase by 18 73 times if normalised against the fine fraction (silt plus clay) content in sediment. Two samples from Mexico City exceed the ERM (Effect Range Median) guidelines and are likely to cause adverse effects. Samples contain only lower chlorinated PCBs (mainly 2-, 3- and 4-CB), thus suggesting that the most used PCB commercial mixture was Aroclor 1242. The homologue composition of the sample taken close to the nuclear power plant of Laguna Verde is identical to this commercial mixture. PAHs in the same samples have relatively low concentrations (14.9 287 ng g-1), well below ERL (Effect Range Low) guidelines. The composition of PAH mixtures accounts for the influence of both petrogenic and pyrolitic sources, with these latter prevailing at some places in Mexico City.

  1. Vehicle Traffic as a Source of Particulate Polycyclic Aromatic Hydrocarbon Exposure in the Mexico City Metropolitan Area

    OpenAIRE

    Marr, Linsey C.; GROGAN, LISA A.; Wöhrnschimmel, Henry; MOLINA, LUISAT.; Molina, Mario J.; Smith, Thomas J.; Garshick, Eric

    2004-01-01

    Surface properties of aerosols in the Mexico City metropolitan area have been measured in a variety of exposure scenarios related to vehicle emissions in 2002, using continuous, real-time instruments. The objective of these experiments is to describe ambient and occupational particulate polycyclic aromatic hydrocarbon (PAH) concentrations associated with vehicular traffic and facilities using diesel vehicles. Median total particulate PAH concentrations along Mexico City’s roadways range from ...

  2. Teotihuacan: completion of map of giant ancient city in the valley of Mexico.

    Science.gov (United States)

    Millon, R

    1970-12-01

    The detailed archeological map of Teotihuacán, near Mexico City, demonstrates what the prehistoric city was like from its densely crowded center to its more sparsely settled peripheries. The city's population lived in crowded one-story apartment compounds, grouped into neighborhoods based at least partly on occupation. At its height the city had a minimum population of 75,000, a probable population of 125,000, and a possible population of more than 200,000. Those involved in craft production and associated activities may have numbered in the tens of thousands. The scope and intensity of urbanization at Teotihuacán is not paralleled in other contemporary New World centers. The growth potential of the obsidian and other industries, the rise of Teotihuacán as a market and trade center, and its attraction as a religious center may have combined in a self-generating process that led to the creation of Teotihuacán's unique urban society. PMID:17777825

  3. Development of pollution reduction strategies for Mexico City: Estimating cost and ozone reduction effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, G.R.; Hardie, R.W. [Los Alamos National Lab., NM (United States); Barrera-Roldan, A. [Instituto Mexicano de Petroleo, Mexico City (Mexico)

    1993-12-31

    This reports on the collection and preparation of data (costs and air quality improvement) for the strategic evaluation portion of the Mexico City Air Quality Research Initiative (MARI). Reports written for the Mexico City government by various international organizations were used to identify proposed options along with estimates of cost and emission reductions. Information from appropriate options identified by SCAQMD for Southem California were also used in the analysis. A linear optimization method was used to select a group of options or a strategy to be evaluated by decision analysis. However, the reduction of ozone levels is not a linear function of the reduction of hydrocarbon and NO{sub x} emissions. Therefore, a more detailed analysis was required for ozone. An equation for a plane on an isopleth calculated with a trajectory model was obtained using two endpoints that bracket the expected total ozone precursor reductions plus the starting concentrations for hydrocarbons and NO{sub x}. The relationship between ozone levels and the hydrocarbon and NO{sub x} concentrations was assumed to lie on this plane. This relationship was used in the linear optimization program to select the options comprising a strategy.

  4. Source apportionment of fine organic aerosol in Mexico City during the MILAGRO Experiment 2006

    Directory of Open Access Journals (Sweden)

    E. A. Stone

    2007-07-01

    Full Text Available Organic carbon (OC comprises a large fraction of fine particulate matter (PM2.5 in Mexico City. Daily and select 12-h PM2.5 samples were collected in urban and peripheral sites in Mexico City from 17–30 March 2006. Samples were analyzed for OC and elemental carbon (EC using thermal-optical filter-based methods. Real-time water-soluble organic carbon (WSOC was collected at the peripheral site. Organic compounds, particularly molecular markers, were quantified by soxhlet extraction with methanol and dichloromethane, derivitization, and gas chromatography with mass spectrometric detection (GCMS. A chemical mass balance model (CMB based on molecular marker species was used to determine the relative contribution of major sources to ambient OC. Motor vehicles, including diesel and gasoline, consistently accounted for 47% of OC in the urban area and 31% on the periphery. The daily contribution of biomass burning to OC was highly variable, and ranged from 5–30% at the urban site and 11–50% at the peripheral site. The remaining OC unapportioned to primary sources showed a strong correlation with WSOC and was considered to be secondary in nature. Comparison of temporally resolved OC showed that contributions from primary aerosol sources during daylight hours were not significantly different from nighttime. This study provides quantitative understanding of the important sources of OC during the MILAGRO 2006 field campaign.

  5. Source apportionment of fine organic aerosol in Mexico City during the MILAGRO experiment 2006

    Directory of Open Access Journals (Sweden)

    E. A. Stone

    2008-03-01

    Full Text Available Organic carbon (OC comprises a large fraction of fine particulate matter (PM2.5 in Mexico City. Daily and select 12-h PM2.5 samples were collected in urban and peripheral sites in Mexico City from 17–30 March 2006. Samples were analyzed for OC and elemental carbon (EC using thermal-optical filter-based methods. Real-time water-soluble organic carbon (WSOC was collected at the peripheral site. Organic compounds, particularly molecular markers, were quantified by soxhlet extraction with methanol and dichloromethane, derivitization, and gas chromatography with mass spectrometric detection (GCMS. A chemical mass balance model (CMB based on molecular marker species was used to determine the relative contribution of major sources to ambient OC. Motor vehicles, including diesel and gasoline, consistently accounted for 49% of OC in the urban area and 32% on the periphery. The daily contribution of biomass burning to OC was highly variable, and ranged from 5–26% at the urban site and 7–39% at the peripheral site. The remaining OC unapportioned to primary sources showed a strong correlation with WSOC and was considered to be secondary in nature. Comparison of temporally resolved OC showed that contributions from primary aerosol sources during daylight hours were not significantly different from nighttime. This study provides quantitative understanding of the important sources of OC during the MILAGRO 2006 field campaign.

  6. Magnetic Properties and Heavy Metals in topsoils from Mexico City: Implications for Pollution

    Science.gov (United States)

    Morton-Bermea, O.; Hernandez-Alvarez, E.; Acosta, T.; Martinez, E.; Soler-Arechalde, A. M.; Urrutia-Fucugauchi, J.

    2006-12-01

    Initial results of a long-term geochemical and magnetic mineralogy study of the heavy metal pollution as recorded in topsoils in Mexico City are reported. We concentrate on investigating the contents and distribution of heavy metals and magnetic minerals in sediments associated to atmospheric particulate pollutants. The geological setting, environmental characteristics and development history of Mexico City make this extensive urban and industrial area a natural laboratory to investigate air-, land- and water-pollution. Thirty-eight samples from surface soils were collected from localities within the metropolitan area, which represent different traffic conditions and heavy metal pollution levels. Elemental determinations are made with induced-coupled plasma mass spectrometry (ICP-MS). Magnetic mineralogy is investigated by low-field susceptibility, remanence intensity, magnetic hysteresis and coercivity spectra analyses on natural and laboratory-induced magnetizations. Soils show high pollution levels indicated by increase concentrations of heavy metals such as Pb, Zn, Cu and Cd, and by high contents of iron minerals (iron-titanium oxides). Urban soils close to dense slow traffic condition zones show the higher heavy metal concentrations, like it was to be expected, some of them exceeding the allowed limits.

  7. Levels and source apportionment of volatile organic compounds in southwestern area of Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Rodolfo Sosa, E. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510, D.F. (Mexico); Humberto Bravo, A. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510, D.F. (Mexico)], E-mail: hbravo@servidor.unam.mx; Violeta Mugica, A. [Universidad Autonoma Metropolitana, Azcapotzalco, D.F. (Mexico); Pablo Sanchez, A. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, C.P. 04510, D.F. (Mexico); Emma Bueno, L. [Centro Nacional de Investigacion y Capacitacion Ambiental, Instituto Nacional de Ecologia (Mexico); Krupa, Sagar [Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108 (United States)

    2009-03-15

    Thirteen volatile organic compounds (VOCs) were quantified at three sites in southwestern Mexico City from July 2000 to February 2001. High concentrations of different VOCs were found at a Gasoline refueling station (GS), a Condominium area (CA), and at University Center for Atmospheric Sciences (CAS). The most abundant VOCs at CA and CAS were propane, n-butane, toluene, acetylene and pentane. In comparison, at GS the most abundant were toluene, pentane, propane, n-butane, and acetylene. Benzene, a known carcinogenic compound had average levels of 28, 35 and 250 ppbC at CAS, CA, and GS respectively. The main contributing sources of the measured VOCs at CA and CAS were the handling and management of LP (Liquid Propane) gas, vehicle exhaust, asphalt works, and use of solvents. At GS almost all of the VOCs came from vehicle exhaust and fuel evaporation, although components of LP gas were also present. Based on the overall results possible abatement strategies are discussed. - Volatile organic compounds were quantified in order to perform their source apportionment in southwestern area of Mexico City.

  8. Do we need an Ad hoc chemical mechanism for Mexico City's photochemical smog?

    Science.gov (United States)

    Ruiz-Suárez, L. G.; Castro, T.; Mar, B.; Ruiz-Santoyo, M. E.; Cruz, X.

    Chemical mechanisms in mathematical models for air quality studies represent the synthesis of about 30 years of research in gas kinetics and atmospheric chemistry, and are able to represent, to a good extent, the chemistry of photochemical smog. However, due to the large amount of computer resources required by these models, different well-known approaches have been used in order to make them operative. In any of these approaches, a set of educated guesses is made, based upon the knowledge of the conditions under which the reactions occur and the competition between them, and upon the expected absolute and relative concentrations of the emitted reactive organic gases (ROG). Are those educated guesses applicable to Mexico City? Do we know enough how the prevalent conditions of temperature, total pressure, ultraviolet irradiation and water content in the atmosphere operate over the chemistry of photochemical smog? An answer to these questions has been attempted by performing variational analysis of selected hydrocarbons. Some results for n-butane, propene and trans-2-butene are shown; they show that under conditions of high reactivity, some assumptions may not be applicable to Mexico City. Also, the results serve to show the applicability of the method to preliminary reactivity studies.

  9. Development of pollution reduction strategies for Mexico City: Estimating cost and ozone reduction effectiveness

    International Nuclear Information System (INIS)

    This reports on the collection and preparation of data (costs and air quality improvement) for the strategic evaluation portion of the Mexico City Air Quality Research Initiative (MARI). Reports written for the Mexico City government by various international organizations were used to identify proposed options along with estimates of cost and emission reductions. Information from appropriate options identified by SCAQMD for Southem California were also used in the analysis. A linear optimization method was used to select a group of options or a strategy to be evaluated by decision analysis. However, the reduction of ozone levels is not a linear function of the reduction of hydrocarbon and NOx emissions. Therefore, a more detailed analysis was required for ozone. An equation for a plane on an isopleth calculated with a trajectory model was obtained using two endpoints that bracket the expected total ozone precursor reductions plus the starting concentrations for hydrocarbons and NOx. The relationship between ozone levels and the hydrocarbon and NOx concentrations was assumed to lie on this plane. This relationship was used in the linear optimization program to select the options comprising a strategy

  10. A Pathological Study of the Epidemiology of Atherosclerosis in Mexico City

    Directory of Open Access Journals (Sweden)

    Joel Rodríguez-Saldaña

    2014-01-01

    Full Text Available Objective. To examine the frequency and patterns of association of cardiovascular risk factors with atherosclerosis in five different arterial territories at post-mortem in Mexico City. Methods. We obtained five arterial territories arteries (circle of Willis, coronary, carotid, renal, and aorta of 185 men and women 0 to 90 years of age who underwent autopsy at the Medical Forensic Service of Mexico City. We determined the prevalence and extent of atherosclerotic lesions by histopathology according to the classification of the American Heart Association as early (types I–III and advanced (types IV–VI, and according to the degree of stenosis and correlated with cardiovascular risk factors. Results. Atherosclerotic lesions were identified in at least one arterial territory in 181 subjects (97.8%, with involvement of two ore more territories in 178 subjects (92.2%. Advanced lesions were observed in 36% and 67% of subjects under 15 and between 16 and 35 years, respectively. Any degree of atherosclerosis was associated with the presence of diabetes mellitus, hypertension, overweight, obesity, and smoking, and to a greater extent with the presence of two or more risk factors (P<0.001. However, emerging and advanced athersoclerosis was observed in 53% and 20% people with no risk factors. Conclusions. The study shows a high prevalence of atherosclerosis in all age groups and both sexes. There is considerable development of atherosclerotic disease in subjects without known risk factors.

  11. The commuters' exposure to volatile chemicals and carcinogenic risk in Mexico City

    Science.gov (United States)

    Shiohara, Naohide; Fernández-Bremauntz, Adrián A.; Blanco Jiménez, Salvador; Yanagisawa, Yukio

    The commuters' exposure levels to volatile organic compounds were investigated in the following public transport modes: private car, microbus, bus, and metro along three commuting routes in the Metropolitan Area of Mexico City. The target chemicals were benzene, toluene, ethylbenzene, m/ p-xylene, and formaldehyde. Integrated samples were taken while traveling during the morning rush hour (weekdays 7:00-9:00 a.m.) for six consecutive weeks in June and July, 2002. Scheffe test showed that the average concentrations of all chemicals inside cars and microbuses were statistically higher than in metro trains ( Pautomobiles were significantly higher than in metro trains and buses ( Pcar, bus, and metro ( Pcar and microbus passengers are exposed to higher levels of volatile organic compounds than bus and metro commuters. These findings are consistent with previous studies looking at exposure of commuters to carbon monoxide. The lifetime carcinogenic risk from commuting by car was 2.0×10 -5-3.1×10 -5, that by microbus was 3.1×10 -5-4.0×10 -5, that by bus was 2.0×10 -5-2.7×10 -5, and that by metro was 1.3×10 -5-1.7×10 -5 in Mexico City.

  12. Eddy covariance flux measurements of pollutant gases in urban Mexico City

    Directory of Open Access Journals (Sweden)

    E. Velasco

    2009-03-01

    Full Text Available Eddy covariance (EC flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs and CO2 from a residential district of Mexico City (Velasco et al., 2005a, b. During the MILAGRO/MCMA-2006 field campaign, a second flux measurement study was conducted in a different district of Mexico City to corroborate the 2003 flux measurements, to expand the number of species measured, and to obtain additional data for evaluation of the local emissions inventory. Fluxes of CO2 and olefins were measured by the conventional EC technique using an open path CO2 sensor and a Fast Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of toluene, benzene, methanol and C2-benzenes were measured using a virtual disjunct EC method with a Proton Transfer Reaction Mass Spectrometer. The flux measurements were analyzed in terms of diurnal patterns and vehicular activity and were compared with the most recent gridded emissions inventory. In both studies, the results showed that the urban surface of Mexico City is a net source of CO2 and VOCs with significant contributions from vehicular traffic. Evaporative emissions from commercial and other anthropogenic activities were significant sources of toluene and methanol. The data show that the emissions inventory is in reasonable agreement with measured olefin and CO2 fluxes, while C2-benzenes and toluene emissions from evaporative sources are overestimated in the inventory. It appears that methanol emissions from mobile sources occur, but are not present in

  13. An overview of the MILAGRO 2006 campaign: Mexico City emissions and their transport and transformation

    Directory of Open Access Journals (Sweden)

    L. T. Molina

    2010-03-01

    Full Text Available MILAGRO (Megacity Initiative: Local And Global Research Observations is an international collaborative project to examine the behavior and the export of atmospheric emissions from a megacity. The Mexico City Metropolitan Area (MCMA – one of the world's largest megacities and North America's most populous city – was selected as the case study to characterize the sources, concentrations, transport, and transformation processes of the pollutants emitted to the MCMA atmosphere and to evaluate the regional and global impacts of these emissions. The findings of this study are relevant to the evolution and impacts of pollution from many other megacities.

    The measurement phase consisted of a month-long series of carefully coordinated observations of the chemistry and physics of the atmosphere in and near Mexico City during March 2006, using a wide range of instruments at ground sites, on aircraft and satellites, and enlisting over 450 scientists from 150 institutions in 30 countries. Three ground supersites were set up to examine the evolution of the primary emitted gases and fine particles. Additional platforms in or near Mexico City included mobile vans containing scientific laboratories and mobile and stationary upward-looking lidars. Seven instrumented research aircraft provided information about the atmosphere over a large region and at various altitudes. Satellite-based instruments peered down into the atmosphere, providing even larger geographical coverage. The overall campaign was complemented by meteorological forecasting and numerical simulations, satellite observations and surface networks. Together, these research observations have provided the most comprehensive characterization of the MCMA's urban and regional atmospheric composition that will take years to analyze and evaluate fully.

    In this paper we review over 120 papers resulting from the MILAGRO/INTEX-B Campaign

  14. Uranium hydrogeochemical and stream sediment reconnaissance data release for the New Mexico portions of the Douglas, Silver City, Clifton, and Saint Johns NTMS quadrangles, New Mexico/Arizona

    International Nuclear Information System (INIS)

    This report describes work done in the Douglas, Silver City, Clifton, and Saint Johns, New Mexico/Arizona, National Topographic Map Series (NTMS) quadrangles (1:250,000 scale) by the Los Alamos Scientific Laboratory (LASL) as part of the nationwide Hydrogeochemical and Stream Sediment Reconnaissance (HSSR). The HSSR is designed to identify areas having higher-than-normal concentrations of uranium in ground waters, surface waters, and water-transported sediments. In 1976 three private contractors, under contract to the LASL, collected water and stream sediment samples in New Mexico from the Mexico border north to Interstate 40 (north of 350N latitude) and from 107030' W longitude west to the New Mexico/Arizona state line. This report presents only the data from these sampling programs for the locations west of 1080W longitude--the New Mexico portions of the Douglas, Silver City, Clifton, and Saint Johns NTMS quadrangles. The numbers of water samples and sediment samples, respectively, collected in each quadrangle were: Douglas, 181 and 237; Silver City, 474 and 755; Clifton, 469 and 913; and Saint Johns, 437 and 672. The standard field and analytical procedures used in this uranium reconnaissance are given in Appendix A. Listings of the field and uranium data for the water samples from the New Mexico portions of the four NTMS quadrangles are given in Appendixes B-I through B-IV. Listings of the field and uranium data for the sediment samples are given in Appendixes C-I through C-IV. Keys to the water and sediment sample types as well as codes to site data are given in Appendix D

  15. Aerosol effects on the photochemistry in Mexico City during MCMA-2006/MILAGRO campaign

    Directory of Open Access Journals (Sweden)

    G. Li

    2011-06-01

    Full Text Available In the present study, the impact of aerosols on the photochemistry in Mexico City is evaluated using the WRF-CHEM model for the period from 24 to 29 March during the MCMA-2006/MILAGRO campaign. An aerosol radiative module has been developed with detailed consideration of aerosol size, composition, and mixing. The module has been coupled into the WRF-CHEM model to calculate the aerosol optical properties, including optical depth, single scattering albedo, and asymmetry factor. Calculated aerosol optical properties are in good agreement with the surface observations and aircraft and satellite measurements during daytime. In general, the photolysis rates are reduced due to the absorption by carbonaceous aerosols, particularly in the early morning and late afternoon hours with a long aerosol optical path. However, with the growth of aerosol particles and the decrease of the solar zenith angle around noontime, aerosols can slightly enhance photolysis rates when ultraviolet (UV radiation scattering dominates UV absorption by aerosols at the lower-most model layer. The changes in photolysis rates due to aerosols lead to about 2–17 % surface ozone reduction during daytime in the urban area in Mexico City with generally larger reductions during early morning hours near the city center, resulting in a decrease of OH level by about 9 %, as well as a decrease in the daytime concentrations of nitrate and secondary organic aerosols by 5–6 % on average. In addition, the rapid aging of black carbon aerosols and the enhanced absorption of UV radiation by organic aerosols contribute substantially to the reduction of photolysis rates.

  16. The ditches of México City and implications on residential buildings of the XVIII century

    Directory of Open Access Journals (Sweden)

    Alejandro Jimenez Vaca

    2015-08-01

    Full Text Available Known for its canals or by its designation in the New Spain as ditches, the image of aquatic city of Mexico City was widespread in the world. It would seem that those romantic references of the city had been left alone in the lines written by the chroniclers, but when analyzing architectural plans and current cadastral can glimpse vestiges of this lakeside past. This research is done by analyzing eigh-teenth century plans, through identification of ex-isting ditches in Mexico City during this period, and its current trajectory in a plane, performing both an analysis of their influence on residential architecture, determining the characteristics of the houses in the path of the canals, by classifying canal houses, depending on the level of relationship between these two constructive general.

  17. Investigation of the correlation between odd oxygen and secondary organic aerosol in Mexico City and Houston

    Directory of Open Access Journals (Sweden)

    E. C. Wood

    2010-09-01

    Full Text Available Many recent models underpredict secondary organic aerosol (SOA particulate matter (PM concentrations in polluted regions, indicating serious deficiencies in the models' chemical mechanisms and/or missing SOA precursors. Since tropospheric photochemical ozone production is much better understood, we investigate the correlation of odd-oxygen ([Ox]≡[O3]+[NO2] and the oxygenated component of organic aerosol (OOA, which is interpreted as a surrogate for SOA. OOA and Ox measured in Mexico City in 2006 and Houston in 2000 were well correlated in air masses where both species were formed on similar timescales (less than 8 h and not well correlated when their formation timescales or location differed greatly. When correlated, the ratio of these two species ranged from 30 μg m−3/ppm (STP in Houston during time periods affected by large petrochemical plant emissions to as high as 160 μg m−3/ppm in Mexico City, where typical values were near 120 μg m−3/ppm. On several days in Mexico City, the [OOA]/[Ox] ratio decreased by a factor of ~2 between 08:00 and 13:00 local time. This decrease is only partially attributable to evaporation of the least oxidized and most volatile components of OOA; differences in the diurnal emission trends and timescales for photochemical processing of SOA precursors compared to ozone precursors also likely contribute to the observed decrease. The extent of OOA oxidation increased with photochemical aging. Calculations of the ratio of the SOA formation rate to the Ox production rate using ambient VOC measurements and traditional laboratory SOA yields are lower than the observed [OOA]/[Ox] ratios by factors of 5 to 15, consistent with several other models' underestimates of SOA. Calculations of this ratio using emission factors for organic compounds from gasoline and diesel exhaust do not reproduce the observed

  18. Investigation of the correlation between odd oxygen and secondary organic aerosol in Mexico City and Houston

    Directory of Open Access Journals (Sweden)

    E. C. Wood

    2010-02-01

    Full Text Available Many recent models underpredict secondary organic aerosol (SOA particulate matter (PM concentrations in polluted regions, indicating serious deficiencies in the models' chemical mechanisms and/or missing SOA precursors. Since tropospheric photochemical ozone production is much better understood, we investigate the correlation of odd-oxygen ([Ox]≡[O3]+[NO2] and the oxygenated component of organic aerosol (OOA, which is interpreted as a surrogate for SOA. OOA and Ox measured in Mexico City in 2006 and Houston in 2000 were well correlated in air masses where both species were formed on similar timescales (less than 8 h and not well correlated when their formation timescales or location differed greatly. When correlated, the ratio of these two species ranged from 30 μg m−3 ppm−1 (STP in Houston during time periods affected by large petrochemical plant emissions to as high as 160 μg m−3 ppm−1 in Mexico City, where typical values were near 120 μg m−3 ppm−1. On several days in Mexico City, the [OOA]/[Ox] ratio decreased by a factor of ~2 between 08:00 and 13:00 LT. This decrease is only partially attributable to evaporation of the least oxidized and most volatile components of OOA; differences in the diurnal emission trends and timescales for photochemical processing of SOA precursors compared to ozone precursors also likely contribute to the observed decrease. The extent of OOA oxidation increased with photochemical aging. Calculations of the ratio of the SOA formation rate to the Ox production rate using ambient VOC measurements and traditional laboratory SOA yields are lower than the observed [OOA]/[Ox] ratios by factors of 5 to 15, consistent with several other models' underestimates of SOA. Calculations of this ratio using emission factors for organic compounds from gasoline and diesel

  19. Miscarriage history and Toxoplasma gondii infection: A cross-sectional study in women in Durango City, Mexico

    OpenAIRE

    Alvarado-Esquivel, C.; Pacheco-Vega, S. J.; Hernández-Tinoco, J.; Centeno-Tinoco, M. M.; Beristain-García, I.; Sánchez-Anguiano, L. F.; Liesenfeld, O; Rábago-Sánchez, E.; Berumen-Segovia, L. O.

    2014-01-01

    Through a cross-sectional study design, 326 women with a history of miscarriage were examined for anti-Toxoplasma gondii IgG and IgM antibodies in Durango City, Mexico. Prevalence association with sociodemographic, clinical, and behavioral characteristics in women with miscarriage was also investigated.

  20. Complete Genome Sequence of Paenibacillus larvae MEX14, Isolated from Honey Bee Larvae from the Xochimilco Quarter in Mexico City.

    Science.gov (United States)

    Peréz de la Rosa, D; Pérez de la Rosa, J J; Cossio-Bayugar, R; Miranda-Miranda, E; Lozano, L; Bravo-Díaz, M A; Rocha-Martínez, M K; Sachman-Ruiz, B

    2015-01-01

    Paenibacillus larvae strain MEX14 is a facultative anaerobic endospore-forming bacterium that infects Apis mellifera larvae. Strain MEX14 was isolated from domestic bee larvae collected in a backyard in Mexico City. The estimated genome size was determined to be 4.18 Mb, and it harbors 4,806 protein coding genes (CDSs). PMID:26316636

  1. A Tale of two Cities: Photoacoustic and Aethalometer Measurements Comparisons of Light Absorption in Mexico City and Las Vegas, NV, USA

    Science.gov (United States)

    Paredes-Miranda, G.; Arnott, W. P.; Marley, N. A.; Gaffney, J. S.

    2007-05-01

    As part of the Megacity Impacts on Regional and Global Environments, MIRAGE-Mex deployment to Mexico City in the period of 30 days, March 2006, a suite of photoacoustic spectrometers (PAS; W. Arnott & G. Paredes), nephelometer scattering, and aetholemeter absorption instruments (N. Marley & J.Gaffney) were installed to measure at ground level the light absorption and scattering by aerosols at the urban site at Instituto Mexicano del Petroleo (Mexican Oil Institute, denoted by IMP). This IMP site gave in-situ characterization of the Mexico City plume under favorable wind conditions. The PAS used at IMP operates at 532 nm, and conveniently allowed for characterization of gaseous absorption at this wavelength as well. Light scattering measurements are accomplished within the PAS by the reciprocal nephelometery method. In the urban site the aerosol absorption coefficient typically varies between 20 and 180 Mm-1 during the course of the day and significant diurnal variation of the aerosol single scattering albedo was observed. The Las Vegas, NV site was located at East Charleston Street on January-February, 2003. In east Las Vegas typical westerly winds carry the city plume across the site. Comparisons of PAS aerosol light absorption and aetholemeter absorption measurements at 521 nm at both Las Vegas NV and Mexico City sites will be presented. We will also present a broad overview of the diurnal variation of the scattering and absorption as well as the single scattering albedo and fraction of absorption due to gases at the sites in relation to secondary aerosol formation.

  2. SURVIVAL STRATEGIES OF MICROENTREPRENEURS IN SOUTHERN MEXICO CITY: INFLUENCE OF APPRECIATED LEARNING

    Directory of Open Access Journals (Sweden)

    Arcelia López-Cabello

    2015-07-01

    Full Text Available The strategies of family reproduction are various ways in which families cope with the problems of everyday life, where the preservation of life and development of essential economic practices is ensured to optimize the material and non-material conditions of the family unit and of each of its members. Through in-depth interviews it was learned how some microentrepreneurs in Mexico City, have used their knowledge appreciated to implement various business generates economic resources to survive, but also have inherited the children. Technical and family secrets on how to make some product knowledge are transmitted from generation to generation, and part of the heritage of a family, becoming livelihood strategies.

  3. Pollution effects on stone benches of the Eagle Warriors Precinct at the Major Temple, Mexico City

    International Nuclear Information System (INIS)

    During Major Temple archaeological site excavations in Downtown Mexico City, the precinct of one of the most important Mexica military caste, the Eagle Warriors, was discovered. The ceremonial enclosure is composed of three rooms surrounded by paintings on 11 stone benches placed against the walls. Nowadays, these paintings and the stones present the effects of different deterioration processes produced by the underground water level, high humidity, and the presence of soil, water, and air pollutants. Ion beam analysis of samples from the benches and wall paintings was performed using PIXE and RBS techniques. Using enrichment factors of elements relative to iron concentrations, possible contamination by sulfur and chlorine salts was found, as well as airborne zinc scavenged by rain

  4. The epidemiology of Entamoeba histolytica in Mexico City. A pilot survey I.

    Science.gov (United States)

    Sargeaunt, P G; Williams, J E; Kumate, J; Jimenez, E

    1980-01-01

    Stocks of intestinal amoebae isolated from hospital patients in Mexico City and grown in monoxenic culture were compared among themselves and with those already described (SARGEAUNT & WILLIAMS, 1979), using the electrophoretic patterns of four enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM), L-malate:NADP+ oxido-reductase (oxalacetate-decarboxylating) (ME) and hexokinase (HK). New isoenzyme groups (SARGEAUNT & WILLIAMS, 1979) of all the amoebae, including Entamoeba histolytica have been demonstrated. Amongst these have been found seven more groups of E. histolytica, two new groups of E. hartmanni, one new group of Dientamoeba fragilis and one new group of E. coli. Of the seven new groups of E. histolytica three are known to originate from patients with clinical amoebiasis whilst the remainder are from asymptomatic subjects. Only 11.2% of the 125 isolations were associated with clinical amoebiasis, and these are clearly distinguished from the isolations from asymptomatic patients by their electrophoretic isoenzyme pattern. PMID:6259779

  5. QUALITY OF LIFE AND COPING STRATEGIES IN OLDER ADULTS WITH PROBLEMS AND DISEASES IN MEXICO CITY

    Directory of Open Access Journals (Sweden)

    ANA LUISA GONZÁLEZ-CELIS

    2006-10-01

    Full Text Available Research purpose was to describe quality-of-life (QoL and coping process in a sample of 194 elderly people in MexicoCity, towards their problems and illnesses. Results showed that 63.9% presented some illness, mainly chronicdegenerative(53.9%. QoL among ill adults vs non-ill persons was significantly different (t = -4.38, d.f. = 184,p<0,000, however QoL resulted a non dependent variable of the problems presented by the subjects, nor the type ofillness, neither the coping process. The problem presented more frequently was with family members (33.7% and thecoping process was towards the behavior (54.2%. Factorial analysis of the coping questionnaire provided four factors(explained variance = 37.49%: active, confrontative, with positive re-appreciation and avoiding. It is concluded that QoL goeswith the coping process of illness.

  6. Effects of revegetation and new artificial water bodies on the climate of Northeast Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Jauregui, E. (Center for Atmospheric Sciences, National Univ. of Mexico (UNAM), Mexico City (Mexico))

    1991-01-01

    An area of 10000 ha of the ex-Lake Texcoco bed on the NE fringes of Mexico City has been protected since about 1975. At present, some 5500 ha of previously almost denuded, salty, semi-arid land have been covered with native grass. According to current thought, the changes in albedo and infrared emission caused by vegetating a previously bare region result in an increase in net radiation absorbed at the surface. This increase in available energy is used for evaporation and, depending on the type and cover of vegetation, to heat the air. The new vegetated cover would result in a moister lower atmosphere with higher equivalent potential temperature. The construction of lakes and ponds has augmented advection of moisture downwind at the airport, which is observed both as an increase of mean dew-joint temperatures as well as a higher occurrence of ground fog. (orig./BWI).

  7. Absorbance and color change of LLDPE samples exposed to natural weathering in Aguascalientes City, Mexico

    Science.gov (United States)

    González-Mota, R.; Soto-Bernal, J. J.; Rosales-Candelas, I.; Vega-Dúran, J. T.

    2007-03-01

    The degradation of weather exposed linear low density polyethylene (LLDPE) specimens, with and without pigments, in Aguascalientes City, Ags. Mexico, during 269 days, was studied. Spectroscopic methods, ultraviolet (UV) spectroscopy and colorimetry, were used to determine the degradation of the specimens. The material used is not pure since they are samples of finished product that contain additives such as anti-oxidants, stabilizers, catalysts. One of the samples contains orange color pigment and the other sample is colorless. The plots describing the absorption bands attributable to the polymeric material show a similar profile in both samples. The bands attributable to pigment do show a considerable decrease in absorbance. The results suggest that the orange pigment has been degrading, as it can also be observed in the color change, while the polymeric material doesn't show any degradation.

  8. Correlation of Secondary Organic Aerosol with Odd Oxygen in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Herndon, Scott C.; Onasch, Timothy B.; Wood, Ezra C.; Kroll, Jesse H.; Canagaratna, M. R.; Jayne, John T.; Zavala, Miguel A.; Knighton, W. Berk; Mazzoleni, Claudio; Dubey, Manvendra K.; Ulbrich, Ingrid M.; Jimenez, Jose L.; Seila, Robert; de Gouw, Joost A.; de Foy, B.; Fast, Jerome D.; Molina, Luisa T.; Kolb, C. E.; Worsnop, Douglas R.

    2008-08-05

    Data collected from a mountain location within the Mexico City limits are used to demonstrate a correlation between secondary organic aerosol and odd-oxygen (O3 + NO2). Positive matrix factorization techniques are employed to separate organic aerosol components: hydrocarbon-like organic aerosol; oxidized-organic aerosol; and biomass burning organic aerosol. The measured hydrocarbon-like organic aerosol is correlated with urban CO (8±1) µg m-3 ppmv-1. The measured oxidized-organic aerosol is associated with photochemical oxidation products and correlates with odd-oxygen with an apparent slope of (70-120) µg m-3 ppmv-1. The dependence of the oxidized-organic aerosol to odd-oxygen correlation on the nature of the gas-phase hydrocarbon profile is discussed.

  9. CO2 variability from in situ and vertical column measurements in Mexico City

    Science.gov (United States)

    Baylon, J. L.; Grutter, M.; Stremme, W.; Bezanilla, A.; Plaza, E.

    2014-12-01

    UNAM started a program to measure, among many other atmospheric parameters, greenhouse gas concentrations at six stations in the Mexican territory as part of the "Red Universitaria de Observatorios Atmosfericos", RUOA (www.ruoa.unam.mx). In this work we present recent time series of CO2 measured at the station located in the university campus in Mexico City, and compare them to total vertical columns of this gas measured at the same location. In situ measurements are continuously carried out with a cavity ring-down spectrometer (Picarro Inc., G2401) since July 2014 and the columns are retrieved from solar absorption measurements taken with a Fourier transform infrared spectrometer (Bruker, Vertex 80) when conditions allow. The retrieval method is described and results of the comparison of both techniques and a detailed analysis of the variability of this important greenhouse gas is presented. Simultaneous surface and column CO2 data are useful to constrain models and estimate emissions.

  10. Concentration levels of radon in air, indoors and outdoors in houses of Mexico City

    International Nuclear Information System (INIS)

    Concentration levels of radon in air, indoors and outdoors have been obtained in houses from Mexico City, with the purpose of relating them with the local environment. Measurements were performed both outdoors and indoors in 60 unifamiliar houses. Track detectors, LR-115, Type II, were used in several detection arrangements during four recording periods with times of exposure of three months each, with the purpose of analyzing the fluctuations due to seasonal changes. Data were obtained about the construction materials were the detection systems were located in order to establish a correlation of radon levels with the climatic parameters and the construction materials. The results of radon concentrations both indoors or outdoors were lower than the international recommendations (148 Bq/m3) (Author)

  11. An Approach to Litter Generation and Littering Practices in a Mexico City Neighborhood

    Directory of Open Access Journals (Sweden)

    Cecilia E. Muñoz-Cadena

    2012-08-01

    Full Text Available Urban litter is generated by human societies everywhere. Some litter is recyclable waste. In this study, the acronym RMSW is used to refer to recyclable municipal solid waste generated in streets. Public attitude towards RMSW generation, generators’ perceptions, and quantification of RMSW in streets were examined in a Mexico City neighborhood, where litter presence causes major environmental problems affecting the population year after year. Interviews with neighborhood residents and item counts were carried out from 2010 to 2011. In all, 58% of interviewees reported generating RMSW at variable frequencies while 42% said they did not generate this kind of waste. Laziness, lack of vigilance by municipal authorities, no litter bins in streets, and imitation were the main causes identified by interviewees as reasons for littering. Potential litter generators may be of any age, educational level or income. Interviewees’ perception of RMSW generation was compared with item counts in the neighborhood studied.

  12. An exploration of measures for comparing measurements with the results from meteorological models for Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Williams, M.D.; Brown, M.J.

    1995-12-31

    Los Alamos National Laboratory and Instituto Mexicano del Petroleo have completed a joint study of options for improving air quality in Mexico City. We used a three-dimensional, prognostic, higher-order turbulence model for atmospheric circulation (HOTMAC) to treat domains that include an urbanized area. We tested the model against routine measurements and those of a major field program. During the field program, measurements included: (1) lidar measurements of aerosol transport and dispersion, (2) aircraft measurements of winds, turbulence, and chemical species aloft, (3) aircraft measurements of skin temperatures, and (4) Tethersonde measurements of winds and ozone. We made both graphical and statistical comparisons and we have reported some of the comparisons to provide insight into the meaning of statistical parameters including the index of agreement.

  13. Diagnosis of type of Bullying in eight grade students from Mexico City

    Directory of Open Access Journals (Sweden)

    Minerva Ramírez Almaraz

    2015-07-01

    Full Text Available The purpose of this paper was to investigate the type of bullying among Mexican adolescents. 480 students (average 13.72 years with a standard deviation of .60 attended eight grade in 12 public schools in Mexico City responded an adaptation of the questionnaire of the Ombudsman of Spain (2007. Data from the survey indicated that in all participating schools exist the different types of abuse explored by the instrument, including those that occur through the use of ICT. The percentage of spectators (students who had observed abuse was higher compared to those who said they had received and performed some of the types of investigated school bullying. As for the differences between gender, women expressed more frequently perform indirect abuse, whereas males reported conduct most often both direct and indirect harassment.

  14. Retrival of the vertical columns of CH4 over Mexico City using Solar Absortion Infrared Spectroscopy.

    Science.gov (United States)

    Bezanilla, A.; Stremme, W.; Grutter, M.

    2012-04-01

    Although the concentration of CH4 in the atmosphere is well known and many studies show that the concentration of this gas has more than doubled since the industrial revolution, the emission sources are poorly identified and usually have large uncertainties. However, due to the importance of this green house gas in climate forcing, more studies on its concentration and distribution need to be made globally through satellite measurements and international networks, but also on the regional and local scales. In this work we present the first results of CH4 vertical columms measured from a station located in the university campus of UNAM in Mexico City. We describe the methodology based on solar absorption FTIR spectroscopy and present preliminary results from 2007 until present.

  15. Lead levels in human teeth from the inhabitants of Mexico City from three different historical periods

    International Nuclear Information System (INIS)

    Human teeth from pre-Columbian, colonial and contemporary population groups were analyzed by PIXE in order to evaluate the lead contents in the inhabitants of Mexico City through different historical periods. Lead contents showed significant differences among the three groups, in Pre-Columbian teeth no lead was found, colonial teeth showed higher lead levels than contemporary ones. This results suggest that the native americans had no exposure to this toxic metal. The lead-glaze pottery introduced by the Spaniards, utilized in pottery and lead pipes, was the main source of lead in the colonial period. In recent teeth the deposited lead is mainly due to the absorption from the contaminated atmosphere. (Author)

  16. Crisis, Xenophobia and Repatriation. The Spanish Immigrants in the City of Mexico, 1910-1936

    Directory of Open Access Journals (Sweden)

    Alicia GIL LÁZARO

    2011-05-01

    Full Text Available The article deals with the influence of economic crisis in migrant groups. It starts with a reflection about the current situation, putting forward a comparative view with a study case in the past, that is, the circumstances around the Spanish immigrants in Mexico City at the time of Mexican Revolution until the crisis of the Great Depression (1910-1936. Three aspects are explored: first of all, the close relationship between the spreading of the economic crisis and the increase of restrains in migratory public policies in host countries. Secondly, the concomitant growth of xenophobic attitudes in native populations and, finally, the return to the homeland as one of the essential strategies developed by immigrants to confront the crisis drawing upon the social and associative networks of migration movements.

  17. Comfort temperatures inside low-cost housing : case : six warm climate cities in Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Azpeitia, G. [Colima Univ., Colima (Mexico). Faculty of Architecture and Design; Bojorquez, G.; Romero, R. [Autonomic Univ. of Baja California, Mexicali (Mexico). Faculty of Architecture and Design; Ruiz, P. [Autonomic Univ. of Chiapas, Tuxtla Gutierrez (Mexico). Faculty of Architecture; Ochoa, J. [Sonora Univ., Hermosillo (Mexico). School of Architecture; Perez, M. [Autonomic Univ. of Yucatan, Merida (Mexico). Faculty of Engineering; Resendiz, O. [Autonomic Univ. of Baja California Sur, La Paz (Mexico). Dept. of Fishing Engineering; Llamas, A. [Autonomic Univ. of Sinaloa, Culiacan (Mexico). Faculty of Architecture

    2009-07-01

    Mexico's National Council for Housing and National Council for Science and Technology supported a research project on the thermal comfort and energy savings in low-cost housing in Mexico. The objective was to establish thermal comfort models and provide reliable diagnostic tools for architectural designers of low-cost housing. Another objective was to promote energy savings through the adjustment of operative temperatures in air conditioning equipment. The approach of the research was an adaptive one in order to evaluate the thermal sensation of individuals in their own habitat; allow the integral study of both physiological and psychological reactions; and consider the individuals as proactive occupants, in search of their thermal comfort. The results of a field study developed according to the adaptive approach principles were presented in this paper. The survey was carried out from 2006 to 2007 in low-cost housing units in 6 Mexican cities with warm climates. In all cases, the houses were naturally ventilated. The measuring periods were determined according to the climatic characteristics of each city. The results of the field study demonstrated the importance of having standards of thermal comfort specific to each location, which must be defined through the direct response of individuals and in the environment in which they perform their daily activities. The results also showed that in hot climates, acclimated people may find comfort in temperatures around 30 degrees C during the warmest seasons. Therefore, reducing the operating temperatures of air conditioning in such conditions represents a huge opportunity for saving electricity. 16 refs., 6 tabs., 6 figs.

  18. An evaluation of the hybrid car technology for the Mexico Mega City

    Science.gov (United States)

    Jazcilevich, Aron D.; Reynoso, Agustin Garcia; Grutter, Michel; Delgado, Javier; Ayala, Ulises Diego; Lastra, Manuel Suarez; Zuk, Miriam; Oropeza, Rogelio Gonzalez; Lents, Jim; Davis, Nicole

    The introduction of hybrid electric vehicle (HEV) technology in the private car fleet of Mexico City is evaluated in terms of private costs, energy, public health and CO 2 emission benefits. In addition to constructing plausible scenarios for urban expansion, emission, car fleet, and fuel consumption for year 2026 and comparing them with a 2004 base case, a time series is built to obtain accumulated economic benefits. Experimental techniques were used to build a vehicle library for a car simulator that included a Prius 2002, chosen as the HEV technology representative for this work. The simulator is used to estimate the emissions and fuel consumption of the car fleet scenarios. In the context of an urban scenario for year 2026, a complex air quality model obtains the concentrations of criterion pollutants corresponding to these scenarios. Using a technology penetration model, the hybridized fleet starts unfolding in year 2009 reaching to 20% in 2026. In this year, the hybridized fleet resulted in reductions of about 10% of CO 2 emissions, and yielded reductions in daytime mean concentrations of up to 7% in ozone and 3.4% in PM 2.5 compared to the 2004 base case. These reductions are concentrated in the densely populated areas of Mexico City. By building a time series of costs and benefits it is shown that, depending on fuel prices and using a 5% return rate, positive accumulated benefits (CO 2 benefits + energy benefits + public health benefits - private costs) will start generating in year 2015 reaching between 2.8 and 4.5 billion US Dlls in 2026. Another modernized private fleet consisting exclusively of Tier I and II cars did not yield appreciable results, signaling that a change in private car technology towards HEV's is needed to obtain significant accumulated benefits.

  19. Location and Mapping of an Ethyl Acetate Plume in Mexico City

    Science.gov (United States)

    Rogers, T.; Grimsrud, E.; Knighton, W.; Velasco, E.; Lamb, B.; Westberg, H.; Jobson, T.; Alexander, M.; Prazeller, P.; Herndon, S.; Kolb, C.

    2004-12-01

    A major goal of the 2003 Mexico City Metropolitan Area (MCMA) field campaign was to gain a better understanding of the dispersion and transport of volatile organic compounds (VOCs) in this urban airshed. Continuous monitoring of VOCs in the atmosphere and identification and quantification of their emission sources is complicated by two factors: first, there are hundreds of different VOC species released daily in the MCMA atmosphere, and second, few real time (1-10 second) measurement techniques have been available to provide the high resolution spatial and/or temporal data usually required to locate VOC emission sources and measure their flux strength. A relatively new technique, Proton Transfer Reaction Mass Spectometery (PTR-MS) provides this capability and was used to locate and quantify a significant source of ethyl acetate in the Iztapalapa region of Mexico City. Two PTR-MS systems were deployed during the 2003 MCMA campaign, the MSU PTR-MS was operated on-board the Aerodyne Mobile Laboratory while the PNNL instrument located on the roof at the National Center for Environmental Research and Training (Centro Nacional de Investigacion y Capacitacion Ambiental or CENICA). The uniqueness of the ethyl acetate signature allowed the MSU PTR-MS on-board the mobile lab to track the ethyl acetate plume back to its source. A short movie documenting the plume mapping and location of the source of the ethyl acetate emission will be shown. Knowing of the plume source location and the local meteorological conditions, the time resolved responses from the PNNL PTR-MS at the CENCIA location have been applied to a simple plume model to estimate the plume's emission flux strength.

  20. Developing intake fraction estimates with limited data: Comparison of methods in Mexico City

    Science.gov (United States)

    Stevens, Gretchen; de Foy, Benjamin; West, J. Jason; Levy, Jonathan I.

    In order to estimate the health benefits of reducing mobile source emissions, analysts typically use detailed atmospheric models to estimate the change in population exposure that results from a given change in emissions. However, this may not be feasible in settings where data are limited or policy decisions are needed in the short term. Intake fraction (iF), defined as the fraction of emissions of a pollutant or its precursor that is inhaled by the population, is a metric that can be used to compare exposure assessment methods in a health benefits analysis context. To clarify the utility of rapid-assessment methods, we calculate particulate matter iFs for the Mexico City Metropolitan Area using five methods, some more resource intensive than others. First, we create two simple box models to describe dispersion of primary fine particulate matter (PM 2.5) in the Mexico City basin. Second, we extrapolate iFs for primary PM 2.5, ammonium sulfate, and ammonium nitrate from US values using a regression model. Third, we calculate iFs by assuming a linear relationship between emissions and population-weighted concentrations of primary PM 2.5, ammonium nitrate, and ammonium sulfate (a particle composition method). Finally, we estimate PM iFs from detailed atmospheric dispersion and chemistry models run for only a short period of time. Intake fractions vary by up to a factor of five, from 23 to 120 per million for primary PM 2.5. Estimates of 60, 7, and 0.7 per million for primary PM, secondary ammonium sulfate, and secondary ammonium nitrate, respectively, represent credible central estimates, with an approximate factor of two uncertainty surrounding each estimate. Our results emphasize that multiple rapid-assessment methods can provide meaningful estimates of iFs in resource-limited environments, and that formal uncertainty analysis, with special attention to model biases and uncertainty, would be important for health benefits analyses.

  1. Measurements of volatile organic compounds in Southeastern Mexico City, 1998 - 2007

    Science.gov (United States)

    Wöhrnschimmel, H.; Magaña, M.; Bueno, E.; Pérez, J. M.; González, S.; Blanco, S.; Cárdenas, B.

    2009-04-01

    Air pollution is one of the principal environmental problems in Megacities. In Mexico City, very high ozone concentrations, a result of precursors like nitrogen oxides (NOx) and volatile organic compounds (VOCs), are thought to cause severe health effects on a population of about 20 million. In addition, there are several air toxics among VOCs that threaten public health. Therefore, measuring VOCs is crucial for the definition of air quality management control strategies. In this paper we report a time series of VOC measurements, carried out in Southeastern Mexico City from 1998 to 2007. Over 26,000 grab samples were taken at different hours of the day and stations of the year, which permits a detailed analysis of changes and tendencies of VOC species, in particular the air toxics benzene, toluene and xylene (BTX). Totally, 13 species have been quantified by GC-FID. A significant decreasing tendency has been observed in VOC species, especially in BTX. The reductions were 0.1 ppbV per year for benzene and toluene. o-xylene decreased with an average rate of 0.3 ppbV per year. For the morning hours, when emissions are strongest, the reductions were even more notable (0.2, 1.3 and 0.5 ppbV per year, respectively). With this, the annual average for benzene concentrations is below the standard of 1.5 ppbV established by the European Community. The observed reductions can be attributed to an improving vehicle technology, in spite of an increasing vehicular fleet. Furthermore, in this paper we discuss total VOC data in comparison with simultaneous NOx measurements, and its implications on photochemical air pollution and validation of the emissions inventory.

  2. Linear and regressive stochastic models for prediction of daily maximum ozone values at Mexico City atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Bravo, J. L [Instituto de Geofisica, UNAM, Mexico, D.F. (Mexico); Nava, M. M [Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico); Gay, C [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico)

    2001-07-01

    We developed a procedure to forecast, with 2 or 3 hours, the daily maximum of surface ozone concentrations. It involves the adjustment of Autoregressive Integrated and Moving Average (ARIMA) models to daily ozone maximum concentrations at 10 monitoring atmospheric stations in Mexico City during one-year period. A one-day forecast is made and it is adjusted with the meteorological and solar radiation information acquired during the first 3 hours before the occurrence of the maximum value. The relative importance for forecasting of the history of the process and of meteorological conditions is evaluated. Finally an estimate of the daily probability of exceeding a given ozone level is made. [Spanish] Se aplica un procedimiento basado en la metodologia conocida como ARIMA, para predecir, con 2 o 3 horas de anticipacion, el valor maximo de la concentracion diaria de ozono. Esta basado en el calculo de autorregresiones y promedios moviles aplicados a los valores maximos de ozono superficial provenientes de 10 estaciones de monitoreo atmosferico en la Ciudad de Mexico y obtenidos durante un ano de muestreo. El pronostico para un dia se ajusta con la informacion meteorologica y de radiacion solar correspondiente a un periodo que antecede con al menos tres horas la ocurrencia esperada del valor maximo. Se compara la importancia relativa de la historia del proceso y de las condiciones meteorologicas previas para el pronostico. Finalmente se estima la probabilidad diaria de que un nivel normativo o preestablecido para contingencias de ozono sea rebasado.

  3. Direct measurements of NO{sub 2} photolysis rates for Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Castro, T.; Ruiz-Suarez, L. G.; Gay, C. [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico); Helguera, M. [Centro Nacional de Investigacion y Desarrollo Tecnologico, SEP, Cuernavaca, Mor. (Mexico); Ruiz-Suarez, J. C. [Departamento de Fisica Aplicada, CINVESTAV del IPN, Unidad Merida, Merida, Yucatan, (Mexico)

    1995-07-01

    Direct measurements of the rate of NO{sub 2} photolysis to NO and O({sup 3}P) are reported as photolysis frequencies J (NO{sub 2}) for Mexico City. These frequencies were measured using a flow reactor, where a known concentration of NO{sub 2} was photolysed for different experimental exposure times. Ultraviolet (UV) radiation was measured with an Eppley UV radiometer. Comparisons with calculated values using a radiation transfer model, and Madronich's formula are shown. [Spanish] Se reportan medidas de las constantes de fotolisis del NO{sub 2} a NO y O({sup 3}P) como frecuencias de fotolisis J(NO{sub 2}) para la Ciudad de Mexico. Estas frecuencias se midieron usando un reactor, en donde una concentracion conocida de NO{sub 2} se fotodisocia para diferentes tiempos de exposicion. La radiacion ultravioleta (UV) se midio con un radiometro Eppley. Se muestra una comparacion con valores calculados usando un modelo de transferencia y la formula de Madronich.

  4. Dietary intake, lung function and airway inflammation in Mexico City school children exposed to air pollutants

    Directory of Open Access Journals (Sweden)

    Díaz-Sánchez David

    2009-12-01

    Full Text Available Abstract Introduction Air pollutant exposure has been associated with an increase in inflammatory markers and a decline in lung function in asthmatic children. Several studies suggest that dietary intake of fruits and vegetables might modify the adverse effect of air pollutants. Methods A total of 158 asthmatic children recruited at the Children's Hospital of Mexico and 50 non-asthmatic children were followed for 22 weeks. Pulmonary function was measured and nasal lavage collected and analyzed every 2 weeks. Dietary intake was evaluated using a 108-item food frequency questionnaire and a fruit and vegetable index (FVI and a Mediterranean diet index (MDI were constructed. The impact of these indices on lung function and interleukin-8 (IL-8 and their interaction with air pollutants were determined using mixed regression models with random intercept and random slope. Results FVI was inversely related to IL-8 levels in nasal lavage (p 1 (test for trend p 1 and FVC as was with MDI and ozone for FVC. No effect of diet was observed among healthy children. Conclusion Our results suggest that fruit and vegetable intake and close adherence to the Mediterranean diet have a beneficial effect on inflammatory response and lung function in asthmatic children living in Mexico City.

  5. The distribution of potential West Nile virus vectors, Culex pipiens pipiens and Culex pipiens quinquefasciatus (Diptera: Culicidae, in Mexico City

    Directory of Open Access Journals (Sweden)

    Diaz-Perez Alfonso

    2011-05-01

    Full Text Available Abstract Background Culex spp. mosquitoes are considered to be the most important vectors of West Nile virus (WNV detected in at least 34 species of mosquitoes in the United States. In North America, Culex pipiens pipiens, Culex pipiens quinquefasciatus, and Culex tarsalis are all competent vectors of WNV, which is considered to be enzootic in the United States and has also been detected in equines and birds in many states of Mexico and in humans in Nuevo Leon. There is potential for WNV to be introduced into Mexico City by various means including infected mosquitoes on airplanes, migrating birds, ground transportation and infected humans. Little is known of the geographic distribution of Culex pipiens complex mosquitoes and hybrids in Mexico City. Culex pipiens pipiens preferentially feed on avian hosts; Culex pipiens quinquefasciatus have historically been considered to prefer mammalian hosts; and hybrids of these two species could theoretically serve as bridge vectors to transmit WNV from avian hosts to humans and other mammalian hosts. In order to address the potential of WNV being introduced into Mexico City, we have determined the identity and spatial distribution of Culex pipiens complex mosquitoes and their hybrids. Results Mosquito larvae collected from 103 sites throughout Mexico City during 2004-2005 were identified as Culex, Culiseta or Ochlerotatus by morphological analysis. Within the genus Culex, specimens were further identified as Culex tarsalis or as belonging to the Culex pipiens complex. Members of the Culex pipiens complex were separated by measuring the ratio of the dorsal and ventral arms (DV/D ratio of the male genitalia and also by using diagnostic primers designed for the Ace.2 gene. Culex pipiens quinquefasciatus was the most abundant form collected. Conclusions Important WNV vectors species, Cx. p. pipiens, Cx. p. quinquefasciatus and Cx. tarsalis, are all present in Mexico City. Hybrids of Cx. p. pipiens and Cx. p

  6. The possible influence of volcanic emissions on atmospheric aerosols in the city of Colima, Mexico.

    Science.gov (United States)

    Miranda, Javier; Zepeda, Francisco; Galindo, Ignacio

    2004-01-01

    An elemental composition study of atmospheric aerosols from the City of Colima, in the Western Coast of Mexico, is presented. Samples of PM(15)-PM(2.5) and PM(2.5) were collected with Stacked Filter Units (SFU) of the Davis design, in urban and rural sites, the latter located between the City of Colima and the Volcán de Colima, an active volcano. Elemental analyses were carried out using Particle Induced X-ray Emission (PIXE). The gravimetric mass concentrations for the fine fraction were slightly higher in the urban site, while the mean concentrations in the coarse fraction were equal within the uncertainties. High Cl contents were determined in the coarse fraction, a fact also observed in emissions from the Volcán de Colima by other authors. In addition to average elemental concentrations, cluster analysis based on elemental contents was performed, with wind speed and direction data, showing that there is an industrial contributor to aerosols North of the urban area. Moreover, a contribution from the volcanic emissions was identified from the grouping of S, Cl, Cu, and Zn, elements associated to particles emitted by the Volcán de Colima. PMID:14568726

  7. On the Sound Environment of the City of Puerto Vallarta, Jalisco, Mexico

    Directory of Open Access Journals (Sweden)

    R. R. Boullosa

    2011-12-01

    Full Text Available An exploration of the sound environment in the city of Puerto Vallarta, Jalisco, Mexico, is presented. A series of interviews were held with 19 residents, of which 7 were undergraduate students, related to the perception of sound in or around places of different zones in the so-called “Viejo Vallarta” (“Old Vallarta”.The purpose was twofold, firstly, to explore the ideas people have relating to the sounds they hear in the city -and in general, the ideas they have relating to peace and tranquility and its possible relation with the sound environment-; secondly, to identify some zones or places that have a particular sound environment - positive or negative. Natural sounds emerged as an important part of the sound identity of the Vallarta region and they seem to be highlyappreciated even when the sound levels are high. Sounds related to nature emerged in all interviews: bird calls, sound of wind rustling through trees, sound of breaking sea waves, etc. The interviewees identified places or zones with a negative sonic identity due to disagreeable or high intensity sounds; traffic flow, and mostly the urban bus, is to be blamed for in the main (some mentioned radios at high volume. A series of sound levels (dBA re 20 μPa at threedifferent times of the year: February, April, and October, 2009 were measured in some locations mentioned by the interviewees. The average sound levels found on those locations considered as having a disagreeable identity were the highest.

  8. A representative survey of indoor radon in the sixteen regions in Mexico City

    International Nuclear Information System (INIS)

    Mexico City, also called Federal District, covers an area of 1504 km2, and has more than 8 million inhabitants. It is located more than 2200 m above sea level in a zone of high seismicactivity, and founded on an ancient lake. At present it is one of the most crowded and contaminated cities in the world with thermal inversions. Chemical contaminants and aerosol particles in the environmental air are high most of the year. Due to these geological, environmental and socioeconomic conditions, Federal District presents very peculiar characteristics, which are important for understanding the distribution and measurement zone of high seismic activity of indoor radon concentration. In this work the results of 3 year (1998-2000) measurements of indoor radon levels in the Federal District are presented. For the detector distribution and measurements, the actual political administrative divisions of the Federal District, consisting of 16 very well defined zones was used. Nuclear track detection methodology was selected for the measurement, with a passive device close-end-cup system with CR-39 (Lantrack(r)) polycarbonate as the detection material, with one step chemical etching, following a very well established protocol developed at the Instituto de Fisica, UNAM. Calibration was carried out at the Oak Ridge National Laboratory, and verification at the Instituto de Fisica chamber. The results show that the arithmetical mean values of the indoor radon concentration for each region of the Federal District follow a non-homogeneous distribution. (author)

  9. Fracture hydraulic conductivity in the Mexico City clayey aquitard: Field piezometer rising-head tests

    Science.gov (United States)

    Vargas, Carlos; Ortega-Guerrero, Adrián

    A regional lacustrine aquitard covers the main aquifer of the metropolitan area of Mexico City. The aquitard's hydraulic conductivity (K') is fundamental for evaluating the natural protection of the aquifer against a variety of contaminants present on the surface and its hydraulic response. This study analyzes the distribution and variation of K' in the plains of Chalco, Texcoco and Mexico City (three of the six former lakes that existed in the Basin of Mexico), on the basis of 225 field-permeability tests, in nests of existing piezometers located at depths of 2-85 m. Tests were interpreted using the Hvorslev method and some by the Bouwer-Rice method. Results indicate that the distribution of K' fits log-Gaussian regression models. Dominant frequencies for K' in the Chalco and Texcoco plains range between 1E-09 and 1E-08 m/s, with similar population means of 1.19E-09 and 1.7E-09 m/s, respectively, which are one to two orders of magnitude higher than the matrix conductivity. In the Mexico City Plain the population mean is near by one order of magnitude lower; K'=2.6E-10 m/s. The contrast between the measured K' and that of the matrix is attributed to the presence of fractures in the upper 25-40 m, which is consistent with the findings of previous studies on solute migration in the aquitard. Un imperméable régional d'origine lacustre recouvre le principal aquifère de la zone urbaine de la ville de Mexico. La conductivité hydraulique K' de cet imperméable est fondamentale pour évaluer la protection naturelle de l'aquifère, contre les différents contaminants présents en surface, et sa réponse hydraulique. Cette étude analyse et les variations de K' dans les plaines de Chalco, Texcoco et Mexico (trois des six anciens lacs qui existaient dans le Bassin de Mexico), sur la base de 225 essais de perméabilité sur le terrain, réalisés en grappes dans des piézomètres existants entre 2 et 85 m de profondeur. Les essais ont été interprétés avec la m

  10. Multi-Gas analysis of ambient air using FTIR spectroscopy over Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Grutter, Michel [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico (UNAM), Mexico, D.F. (Mexico)

    2003-01-01

    A Fourier Transform Infrared (FTIR) spectrometer was used to analyze the composition of ambient air at a specific site in Mexico City metropolitan area. A continuous flow of air was passed through a multi-pass cell and the absorption spectra were collected over a period of two weeks. Quantitative analysis was performed by means of the classical-least square (CLS) method using synthetically generated spectra as references and calibration sources. Ambient levels of CO, CO{sup 2}, CH{sub 4} and N{sub 2}O are reported with a time resolution of five minutes for September 2001, showing interesting results in their diurnal patterns. Comments on the precision, detection limits and signal to noise of the instrument are included for the evaluation of this technique. Water concentrations were estimated and compared with those obtained with a relative humidity sensor. The technique of extractive FTIR for ambient trace gas monitoring was utilized in Mexico for the fist time and some potential applications are given. [Spanish] Se utilizo un espectrometro en el infrarrojo por transformadas de Fourier (FTIR) para analizar la composicion de aire ambiente en un sitio de la zona metropolitana de la Ciudad de Mexico. Para ello se introdujo un flujo constante de aire a una celda de gases de paso multiple y se colectaron los espectros durante un periodo de dos semanas. Para el analisis cuantitativo, se aplico el metodo clasico de minimos cuadrados (CLS) utilizando espectros sinteticos como referencias y fuentes de calibracion. Se observaron patrones interesantes en los niveles ambientales de CO, CO{sup 2}, CH{sub 4} y N{sub 2}O, los cuales son reportados con una resolucion temporal de cinco minutos para el mes de septiembre del 2001. En la evaluacion de esta tecnica se incluyen comentarios sobre la precision, los limites de deteccion, asi como de la relacion senal/ruido del instrumento. Se estimaron concentraciones de vapor de agua a traves de sus absorciones en el infrarrojo y se

  11. Georadar Archaeological Prospection at the Historical Center of the Merida City, Yucatan, Mexico.

    Science.gov (United States)

    Barba, L.; Ortiz, A.; Blancas, J.; Ligorred, J.

    2007-05-01

    This paper shows the results of the georadar archaeological prospection carried out by the Laboratorio de Prospección Arqueologica from the Instituto de Investigaciones Antropologicas (IIA) of the Universidad Nacional Autonoma de Mexico (UNAM) verifing the archaeological and historical information recovered by the Departamento de Patrimonio Arqueologico y Natural del Municipio (DPANM) del Ayuntamiento de Merida en el Centro Histerico de la Ciudad de Merida under a joint project. The Historical Center of Merida has been classified as a "zone of high patrimonial value" after the topographic data and the historical documents recovered showed a long-term occupation, non interrupted since pre-Columbian times, when T Ho was the great capital of the northern region of the Maya area. For the rehabilitation program of the Historical Center of Merida has been a great priority to verify the existence of archaeological remains, pre-Columbian or colonial, under the present streets, gardens and plazas that could be damaged during the public infrastructure works. In order to prevent any damage to the patrimony a large georadar study was carried out pulling 200 and 400 MHz antennas of the GSSI SIR System 2 for 16500 m of the city streets, focusing in the areas where infrastructure works were imminent. After the analysis of the radar data it was possible to build up a map with the location of the most noticeable archaeological remains under the pavement of the streets that confirmed many of the topographic and documental proposed places. As a final result, by the first time a city government has available information to take present urban decisions, while preventing the damage to the archaeological patrimony of the same city.

  12. Population vulnerability due to the exposure to radon and airborne particulate matter (PM{sub 10}), in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa, G., E-mail: espinosa@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20364, 01000 Mexico, D.F. (Mexico); Golzarri, J.I. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20364, 01000 Mexico, D.F. (Mexico); Ponciano-Rodriguez, G. [Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico); Gaso, M.I. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, 11801 Mexico, D.F. (Mexico); Mena, M.; Segovia, N. [Instituto de Geofisica, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico, D.F. (Mexico); Vazquez-Lopez, C. [Departamento de Fisica, CINVESTAV (Mexico); Sajo-Bohus, L. [Departamento de Fisica, Universidad Simon Bolivar (Venezuela, Bolivarian Republic of)

    2009-10-15

    Exposure to indoor radon and suspended particulate matter (SPM) is considered a high risk in lung cancer aetiology. In this paper indoor radon and SPM concentration measurements and their correlations, associated with lung cancer cases are given. Mexico City suffers high concentration of SPM as well as other photochemical pollutants such as ozone. During the last decade in Mexico City, radon and SPM have been monitored. The indoor radon measurements were done using the Nuclear Track Methodology, basically the close-end-cup device with polyallyldiglycol carbonate as detector material, followed of an established chemical etching protocol, and automatic digital image analyzer system for counting. SPM size and concentration were obtained from monitoring stations located along the city. The results show that the central-north part of Mexico City has a large concentration of SPM and the vulnerable population (older than 65 years and younger than 14 years) is located essentially in the same region. In this area, a large number of lung cancer cases were found, even if indoor radon levels were below the recommended limits.

  13. Incidence of leukemias in children from El Salvador and Mexico City between 1996 and 2000: Population-based data

    Directory of Open Access Journals (Sweden)

    Bernáldez-Ríos Roberto

    2005-04-01

    Full Text Available Abstract Background There are very few studies that report the incidence of acute leukemias in children in Latin America. This work assesses the incidence of acute leukemias, between 1996 and 2000, in children from 0–14 years old who were attended at the Mexican Social Security Institute in Mexico City and in children from 0–11 years old in El Salvador. Methods Design: Population-based data. Hospitals: In San Salvador, El Salvador, Hospital Nacional de Niños "Benjamín Bloom", the only center in El Salvador which attends all children, younger than 12 years, with oncologic disease. The Pediatric Hospital and the General Hospital of the Mexican Social Security Institute in Mexico City, the only centers in Mexico City which attend all those children with acute leukemia who have a right to this service. Diagnosis: All patients were diagnosed by bone marrow smear and were divided into acute lymphoid leukemia (ALL, acute myeloid leukemia (AML, chronic myeloid leukemia (CML, and unspecified leukemias (UL. The annual incidence rate (AIR and average annual incidence rate (AAIR were calculated per million children. Cases were stratified by age and assigned to one of four age strata: 1 Results The number of cases was 375 and 238 in El Salvador and Mexico City, respectively. AAIRs in Mexico City were 44.9, 10.6, 2.5, 0.5, and 58.4 per million children for ALL, AML, CML, UL, and total leukemias, respectively. The AAIRs in El Salvador could not be calculated because the fourth age stratum in El Salvador included children only from 0–11 years old. The incidence rates for the Salvadoran group of 0–11 year olds were 34.2, 7.1, 0.6, 0.2, and 43.2 per million children for ALL, AML, CML, UL, and total leukemias, respectively. Conclusion Reported AIRs for each age group in El Salvador were similar to those from other American countries. The AAIR of ALL in Mexico City is one of the highest reported for North America.

  14. Formation of semivolatile inorganic aerosols in the Mexico City Metropolitan Area during the MILAGRO campaign

    Science.gov (United States)

    Karydis, V. A.; Tsimpidi, A. P.; Lei, W.; Molina, L. T.; Pandis, S. N.

    2011-12-01

    One of the most challenging tasks for chemical transport models (CTMs) is the prediction of the formation and partitioning of the major semi-volatile inorganic aerosol components (nitrate, chloride, ammonium) between the gas and particulate phases. In this work the PMCAMx-2008 CTM, which includes the recently developed aerosol thermodynamic model ISORROPIA-II, is applied in the Mexico City Metropolitan Area in order to simulate the formation of the major inorganic aerosol components. The main sources of SO2 (such as the Miguel Hidalgo Refinery and the Francisco Perez Rios Power Plant) in the Mexico City Metropolitan Area (MCMA) are located in Tula, resulting in high predicted PM1 (particulate matter with diameter less than 1 μm) sulfate concentrations (over 25 μg m-3) in that area. The average predicted PM1 nitrate concentrations are up to 3 μg m-3 (with maxima up to 11 μg m-3) in and around the urban center, mostly produced from local photochemistry. The presence of calcium coming from the Tolteca area (7 μg m-3) as well as the rest of the mineral cations (1 μg m-3 potassium, 1 μg m-3 magnesium, 2 μg m-3 sodium, and 3 μg m-3 calcium) from the Texcoco Lake resulted in the formation of a significant amount of aerosol nitrate in the coarse mode with concentrations up to 3 μg m-3 over these areas. PM1-10 (particulate matter with diameter between 1 and 10 μm) chloride is also high and its concentration exceeds 2 μg m-3 in Texcoco Lake. PM1 ammonium concentrations peak at the center of Mexico City (2 μg m-3) and the Tula vicinity (2.5 μg m-3). The performance of the model for the major inorganic PM components (sulfate, ammonium, nitrate, chloride, sodium, calcium, and magnesium) is encouraging. At the T0 measurement site, located in the Mexico City urban center, the average measured values of PM1 sulfate, nitrate, ammonium, and chloride are 3.5 μg m-3, 3.5 μg m-3, 2.1 μg m-3, and 0.36 μg m-3, respectively. The corresponding predicted values are 3.7

  15. Formation of semivolatile inorganic aerosols in the Mexico City Metropolitan Area during the MILAGRO campaign

    Directory of Open Access Journals (Sweden)

    V. A. Karydis

    2011-12-01

    Full Text Available One of the most challenging tasks for chemical transport models (CTMs is the prediction of the formation and partitioning of the major semi-volatile inorganic aerosol components (nitrate, chloride, ammonium between the gas and particulate phases. In this work the PMCAMx-2008 CTM, which includes the recently developed aerosol thermodynamic model ISORROPIA-II, is applied in the Mexico City Metropolitan Area in order to simulate the formation of the major inorganic aerosol components. The main sources of SO2 (such as the Miguel Hidalgo Refinery and the Francisco Perez Rios Power Plant in the Mexico City Metropolitan Area (MCMA are located in Tula, resulting in high predicted PM1 (particulate matter with diameter less than 1 μm sulfate concentrations (over 25 μg m-3 in that area. The average predicted PM1 nitrate concentrations are up to 3 μg m−3 (with maxima up to 11 μg m−3 in and around the urban center, mostly produced from local photochemistry. The presence of calcium coming from the Tolteca area (7 μg m−3 as well as the rest of the mineral cations (1 μg m−3 potassium, 1 μg m−3 magnesium, 2 μg m−3 sodium, and 3 μg m−3 calcium from the Texcoco Lake resulted in the formation of a significant amount of aerosol nitrate in the coarse mode with concentrations up to 3 μg m−3 over these areas. PM1−10 (particulate matter with diameter between 1 and 10 μm chloride is also high and its concentration exceeds 2 μg m−3 in Texcoco Lake. PM1 ammonium concentrations peak at the center of Mexico City (2 μg m−3 and the Tula vicinity (2.5 μg m−3. The performance of the model for the major inorganic PM components (sulfate, ammonium, nitrate, chloride, sodium, calcium, and magnesium is encouraging. At the T0 measurement site, located in the

  16. The contribution of the International Atomic Energy Agency to peace and development. Address at the conference of the Diplomatic Academy at the Institute of 'Matias Romero', Mexico City, Mexico, 13 October 1999

    International Nuclear Information System (INIS)

    In his address at the Conference of the Diplomatic Academy at the Institute of 'Matias Romero' (Mexico City, Mexico, 13 October 1999), the Director General of the IAEA described the role of the IAEA and its contribution to peace and development, focussing in four areas: technology transfer, nuclear power and sustainable energy development, nuclear safety, and the Agency's verification system

  17. Genetic polymorphism of GSTM1 and antioxidant supplementation influence lung function in relation to ozone exposure in asthmatic children in Mexico City

    OpenAIRE

    Romieu, I; Sienra-Monge, J; Ramirez-Aguilar, M; Moreno-Macias, H; Reyes-Ruiz, N; d Estela,; Hernandez-Avila, M.; London, S.

    2004-01-01

    Background: We recently reported that antioxidant supplementation with vitamins C and E mitigated ozone related decline in forced expiratory flow (FEF25–75) in 158 asthmatic children in an area with high ozone exposure in Mexico City.

  18. Contributors to ozone episodes in three US/Mexico border twin-cities.

    Science.gov (United States)

    Shi, Chune; Fernando, H J S; Yang, Jie

    2009-09-01

    The Process Analysis tools of the Community Multiscale Air Quality (CMAQ) modeling system together with back-trajectory analysis were used to assess potential contributors to ozone episodes that occurred during June 1-4, 2006, in three populated U.S.-Mexico border twin cities: San Diego/Tijuana, Imperial/Mexicali and El Paso/Ciudad Juárez. Validation of CMAQ output against surface ozone measurements indicates that the predictions are acceptable with regard to commonly recommended statistical standards and comparable to other reported studies. The mean normalized bias test (MNBT) and mean normalized gross error (MNGE) for hourly ozone fall well within the US EPA suggested range of +/-15% and 35%, respectively, except MNBT for El Paso. The MNBTs for maximum 8-h average ozone are larger than those for hourly ozone, but all the simulated maximum 8-h average ozone are within a factor of 2 of those measured in all three regions. The process and back-trajectory analyses indicate that the main sources of daytime ground-level ozone are the local photochemical production and regional transport. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it is found that in the San Diego area (SD), chemistry and vertical advection contributed about 36%/48% and 64%/52% for June 2 and 3, respectively. This confirms the previous finding that high-altitude regional transport followed by fumigation contributes significantly to ozone in SD. The back-trajectory analysis shows that this ozone was mostly transported from the coastal area of southern California. For the episodes in Imperial Valley and El Paso, respectively, ozone was transported from the coastal areas of southern California and Mexico and from northern Texas and Oklahoma. PMID:19559465

  19. A Cross-Sectional Study of Prisoners in Mexico City Comparing Prevalence of Transmissible Infections and Chronic Diseases with That in the General Population

    OpenAIRE

    Bautista-Arredondo, Sergio; González, Andrea; Servan-Mori, Edson; Beynon, Fenella; Juarez-Figueroa, Luis; Conde-Glez, Carlos J.; Gras, Nathalie; Sierra-Madero, Juan; Lopez-Ridaura, Ruy; Volkow, Patricia; Stefano M. Bertozzi

    2015-01-01

    Objectives To describe patterns of transmissible infections, chronic illnesses, socio-demographic characteristics and risk behaviors in Mexico City prisons, including in comparison to the general population, to identify those currently needing healthcare and inform policy. Materials and Methods A cross-sectional study among 17,000 prisoners at 4 Mexico City prisons (June to December 2010). Participation was voluntary, confidential and based on informed consent. Participants were tested for HI...

  20. Ozone forming potential and sulfur effects on in-use vehicles of the metropolitan area of Mexico City

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The largest urban areas of Mexico cities have witnessed high levels of air pollution in the past few decades. The most important air pollutants are ozone and particulate matter with levels that are still far above current air quality standard, In this work we studied exhaust and evaporative emissions of Mexico City metropolitan area (MAMC) vehicles using fuels in which sulfur content was varied from 89×10-6 to 817×10-6, and calculated the ozone forming potential of emissions as well as the specific reactivity of the exhaust for each average fleet-fuel combinations. Data on emission levels were compared to those obtained in 2000 for the same vintage of vehicles. The almost twofold increase in emissions found could be due to degradation of the exhaust emissions control systems.

  1. Aerosol Light Absorption and Scattering at Four Sites in and Near Mexico City: Comparison with Las Vegas, Nevada, USA

    Science.gov (United States)

    Arnott, W. P.; Miranda, G. P.; Gaffney, J. S.; Marley, N. A.

    2007-05-01

    Four photoacoustic spectrometers (PAS) for aerosol light scattering and absorption measurements were deployed in and near Mexico City in March 2006 as part of the Megacity Impacts on Regional and Global Environments (MIRAGE). The four sites included: an urban site at Instituto Mexicano del Petroleo (Mexican Oil Institute, denoted by IMP); a suburban site at the Technological University of Tecamac; a rural site at "La Biznaga" ranch; and a site at the Paseo de Cortes (altitude 3,810 meters ASL) in the rural area above Amecameca in the State of Mexico, on the saddle between the volcanoes Popocatepetl and Iztaccihuatl. A similar campaign was held in Las Vegas, Nevada, USA in January-February, 2003. The IMP site gave in-situ characterization of the Mexico City plume under favorable wind conditions while the other sites provided characterization of the plume, mixed in with any local sources. The second and third sites are north of Mexico City, and the fourth site is south. The PAS used at IMP operates at 532 nm, and conveniently allowed for characterization of gaseous absorption at this wavelength as well. Instruments at the second and third sites operate at 870 nm, and the one at the fourth site at 780 nm. Light scattering measurements are accomplished within the PAS by the reciprocal nephelometery method. In the urban site the aerosol absorption coefficient typically varies between 20 and 180 Mm-1 during the course of the day and significant diurnal variation of the aerosol single scattering albedo was observed probably as a consequence of secondary aerosol formation. Comparisons with TSI nephelometer scattering at the T0 site will be presented. We will present the diurnal variation of the scattering and absorption as well as the single scattering albedo and fraction of absorption due to gases at the IMP site and compare with Las Vegas diurnal variation. Mexico City 'breaths' more during the course of the day than Las Vegas, Nevada in part because the latitude of

  2. Air emissions scenarios from ethanol as a gasoline oxygenate in Mexico City Metropolitan Area

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Carlos A. [Posgrado en Ingenieria Energetica, Universidad Nacional Autonoma de Mexico, Priv. Xochicalco s/n, Col. Centro, Apartado Postal 34, 62580 Temixco, Morelos (Mexico); Manzini, Fabio; Islas, Jorge [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Priv. Xochicalco s/n, Col. Centro, Apartado Postal 34, 62580 Temixco, Morelos (Mexico)

    2010-12-15

    The Mexican Biofuel Introduction Program states that during year 2010 the three biggest Mexican cities will have a gasoline blending with 6% ethanol available for all gasoline on-road vehicle fleet. Also in 2010 Mexican government has programmed to start the substitution of Tier 1 - the adopted US emission standards - by Tier 2, which are more stringent emission standards for motor vehicles and gasoline sulfur control requirements. How will the air emissions in the Mexico City Metropolitan Area (MCMA) be modified by using this blending? Four scenarios up to year 2030 were constructed and simulated using the Long-Range Energy Alternatives Planning model. Beginning with a BAU or reference scenario, in this scenario the current available fuel is a blending composed by 5% methyl tertiary butyl ether and 95% gasoline (MTBE5). Then, three alternative scenarios that use ethanol as an oxygenate are considered, one with the already programmed E6 blending (6% anhydride ethanol, 94% gasoline), for the sake of comparison the E10 blending (10% anhydride ethanol, 90% gasoline), and the other alternative to compare, ETBE13.7 (13.7% ethyl tertiary butyl ether, 86.3% gasoline; where ETBE is an ether composed by 48% anhydride ethanol and 52% isobutene). Emissions of carbon dioxide (CO{sub 2}), carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (PM10), sulfur dioxide (SO{sub 2}), total hydrocarbons (THC), benzene, formaldehyde, acetaldehyde and 1,3-butadiene were calculated using emission factors previously calculated using the adapted US-EPA computer model called MOBILE6-Mexico. Results show that Tier 1 and Tier 2 standards effectively lowers all emissions in all studied scenarios with the exception of PM10 and CO{sub 2} emissions. The alternative scenario E10 has the most total avoided emissions by weight but it is not the best when considering some individual pollutants. The greatest environmental benefit of ethanol in its final use as a gasoline oxygenate is for

  3. In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area

    Directory of Open Access Journals (Sweden)

    A. P. Rutter

    2008-07-01

    Full Text Available In order to expand the currently limited understanding of atmospheric mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of atmospheric mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March, 2006.

    Numerous short-lived increases in particulate mercury (PHg and reactive gaseous mercury (RGM concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows:

    i Urban site: PHg=187±300 pg m−3, RGM=62±64 pg m−3, GEM=7.2±4.8 ng m−3.

    ii Rural site: GEM=5.0±2.8 ng m−3.

    Several source regions of atmospheric mercury to the urban and rural sites were determined using Concentration Field Analysis, in which atmospheric mercury measurements were combined with back trajectory data to determine source regions. Only some source regions correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM, and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg and RGM were not found to correlate with biomass burning at either of the measurement sites.

  4. In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area

    Directory of Open Access Journals (Sweden)

    A. P. Rutter

    2009-01-01

    Full Text Available In order to expand the currently limited understanding of atmospheric mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of atmospheric mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March 2006.

    Numerous short-lived increases in particulate mercury (PHg and reactive gaseous mercury (RGM concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows: i urban site; PHg=187±300 pg m−3, RGM=62±64 pg m−3, GEM=7.2±4.8 ng m−3, and; ii rural site; GEM=5.0±2.8 ng m−3.

    Several source regions of atmospheric mercury to the urban and rural sites were determined using Concentration Field Analysis, in which atmospheric mercury measurements were combined with back trajectory data to determine source regions. Only some source regions correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM, and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg+RGM were not found to correlate with biomass burning at either of the measurement sites.

  5. Family planning barriers in marginal contexts in Mexico City, Federal District: vision of the health care provider

    OpenAIRE

    Marcela Agudelo B

    2009-01-01

    Objective: To approach the barriers to providing services of family planning in marginal areas of Iztapalapa and Tlalpan in the Federal District of Mexico City, from the perspective of health providers. Methodology: Qualitative exploration involved through focus groups with healthcare providers, both public and private, further topics such as socio-environmental, unmet needs in sexual and reproductive health (including family planning), relations gender, among others. Results:We found that ...

  6. 410 Epidemiological and Clinical Characteristics of Allergic Conjunctivitis Patients in a Reference Center of Mexico City

    OpenAIRE

    Robles-Contreras, Atzin; Ayala-Balboa, Julio; Alonso-Sánchez, Miguel E.; ESTRADA-GARCIA, IRIS; Jiménez-Martínez, Maria C.

    2012-01-01

    Background In our country (Mexico) there are few reports about epidemiological characteristics of allergic conjunctivitis patients; despite these studies give us some information about patient profile, in most cases these studies are not always comparable due to the use of different methodologies, that is, Include only a portion of the population (elderly, infants) or there are limited to one region of the city. The purpose of this study was to know the epidemiological and clinical characteri...

  7. Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis

    OpenAIRE

    Johnson, K.S.; B. de Foy; B. Zuberi; L. T. Molina; M. J. Molina; Xie, Y; A. Laskin; Shutthanandan, V.

    2006-01-01

    Aerosols play an important role in the atmosphere but are poorly characterized, particularly in urban areas like the Mexico City Metropolitan Area (MCMA). The chemical composition of urban particles must be known to assess their effects on the environment, and specific particulate emissions sources should be identified to establish effective pollution control standards. For these reasons, samples of particulate matter ≤2.5 μm (PM2.5) were collected during the MCMA-2003 Field Campaign f...

  8. Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis

    OpenAIRE

    Johnson, K.S.; B. de Foy; B. Zuberi; L. T. Molina; M. J. Molina; Xie, Y; A. Laskin; Shutthanandan, V.

    2006-01-01

    Aerosols play an important role in the atmosphere but are poorly characterized, particularly in urban areas like the Mexico City Metropolitan Area (MCMA). The chemical composition of urban particles must be known to assess their effects on the environment, and specific particulate emissions sources should be identified to establish effective pollution control standards. For these reasons, samples of particulate matter ≤2.5 μm (PM2.5) were collected dur...

  9. Prevalence of dementia and Alzheimer's disease in elders of nursing homes and a senior center of Durango City, Mexico

    OpenAIRE

    Rodríguez-Corral Karina; Guerrero-Iturbe Ángel; Tapia-Rodríguez Rosa; Hernández-Alvarado Ana; Alvarado-Esquivel Cosme; Martínez Sergio

    2004-01-01

    Abstract Background Epidemiological reports about dementia and Alzheimer's disease (AD) in elderly people from developing countries are scarce. Therefore, we sought to determine the prevalences of dementia and AD in a population of nursing home residents and senior center attendees of Durango City, Mexico, and to determine whether any socio-demographic characteristics from the subjects associated with dementia or AD exist. Methods One hundred and fifty-five residents of two nursing homes and ...

  10. Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaign

    OpenAIRE

    G. Paredes-Miranda; W. P. Arnott; Jimenez, J. L.; Aiken, A. C.; J. S. Gaffney; Marley, N. A.

    2008-01-01

    A photoacoustic spectrometer, a nephelometer, an aetholemeter, and an aerosol mass spectrometer were used to measure at ground level real-time aerosol light absorption, scattering, and chemistry at an urban site located in north east Mexico City (Instituto Mexicano del Petroleo, Mexican Petroleum Institute, denoted by IMP), as part of the Megacity Impact on Regional and Global Environments field experiment, MILAGRO, in March 2006. Photoacoustic and reciprocal nephelometer measurements at 532 ...

  11. Mexican Seismic Alert System's SAS-I algorithm review considering strong earthquakes felt in Mexico City since 1985

    Science.gov (United States)

    Cuellar Martinez, A.; Espinosa Aranda, J.; Suarez, G.; Ibarrola Alvarez, G.; Ramos Perez, S.; Camarillo Barranco, L.

    2013-05-01

    The Seismic Alert System of Mexico (SASMEX) uses three algorithms for alert activation that involve the distance between the seismic sensing field station (FS) and the city to be alerted; and the forecast for earthquake early warning activation in the cities integrated to the system, for example in Mexico City, the earthquakes occurred with the highest accelerations, were originated in the Pacific Ocean coast, whose distance this seismic region and the city, favors the use of algorithm called Algorithm SAS-I. This algorithm, without significant changes since its beginning in 1991, employs the data that generate one or more FS during P wave detection until S wave detection plus a period equal to the time employed to detect these phases; that is the double S-P time, called 2*(S-P). In this interval, the algorithm performs an integration process of quadratic samples from FS which uses a triaxial accelerometer to get two parameters: amplitude and growth rate measured until 2*(S-P) time. The parameters in SAS-I are used in a Magnitude classifier model, which was made from Guerrero Coast earthquakes time series, with reference to Mb magnitude mainly. This algorithm activates a Public or Preventive Alert if the model predicts whether Strong or Moderate earthquake. The SAS-I algorithm has been operating for over 23 years in the subduction zone of the Pacific Coast of Mexico, initially in Guerrero and followed by Oaxaca; and since March 2012 in the seismic region of Pacific covering the coasts among Jalisco, Colima, Michoacan, Guerrero and Oaxaca, where this algorithm has issued 16 Public Alert and 62 Preventive Alerts to the Mexico City where its soil conditions increase damages by earthquake such as the occurred in September 1985. This work shows the review of the SAS-I algorithm and possible alerts that it could generate from major earthquakes recordings detected by FS or seismometers near the earthquakes, coming from Pacific Ocean Coast whose have been felt in Mexico

  12. Using Acceleration Records as Diffuse Fields for Tomography of the Valley of Mexico City: Synthetic Results

    Science.gov (United States)

    Baena, M.; Perton, M.; Molina-Villegas, J. C.; Sanchez-Sesma, F. J.

    2013-12-01

    In order to improve the understanding of the seismic response of Mexico City Valley, we have proposed to perform a tomography study of the seismic wave velocities. For that purpose, we used a collection of acceleration seismograms (corresponding to earthquakes with magnitudes ranging from 4.5 to 8.1 and various epicentral distances to the City) recorded since 1985 in 83 stations distributed across the Valley. The H/V spectral ratios (obtained from average autocorrelations) strongly suggest these movements belong to a 3D generalized diffuse field. Thus, we interpret that cross-correlations between the signals of station pairs are proportional to the imaginary part of the corresponding Green function. Finally, the dispersion curves are constructed from the Green function which lead to the tomography. Other tomographies have already been made around the world using either the seismic coda or seismic noise. We used instead the ensemble of many earthquakes from distant sources that have undergone multiple scattering by the heterogeneities of the Earth and assume the wave fields are equipartitioned. The purpose of the present study is to describe the different steps of the data processing by using synthetic models. The wave propagation within an alluvial basin is simulated using the Indirect Boundary Element Method (IBEM) in 2D configuration for the propagation of P and SV waves. The theoretical Green function for a station pair is obtained by placing a unit force at one station and a receiver at the other. The valley illumination is composed by incoming waves which are simulated using distant independent sources and several diffractors. Data process is validated by the correct retrieval the theoretical Green function. We present here the in-plane Green function for the P-SV case and show the dispersion curves constructed from the cross-correlations compared with analytic results for a layer over a half-space. ACKNOWLEDGEMENTS. This study is partially supported by AXA

  13. Seismic delineation of Algal Mound Reservoirs, Humble City South Field, Lea County, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Caughey, C.A.

    1988-01-01

    Pennsylvanian algal mounds near Lovington, New Mexico, typify the targets remaining for exploration in the Permian basin. The Strawn trend new Lovington comprises numerous small (200-800 ac) reservoirs of clean algal limestone encased in unfossiliferous carbonate mudrocks. Vuggy porosity occurs in algal micrites and sporadically in crinoidal or foraminiferal grainstones associated with the mound. Some of the Lovington area fields encountered downdip water, but difficulty in finding the mound facies remains the principal dry-hole hazard. Vague acoustical boundaries complicate seismic detection of relatively minor (50-150 ft) carbonate buildups at depths of 11,200-11,600 ft. Stratigraphic interpretation of high-resolution seismic data recently led to several new field discoveries and major extensions. Development drilling, however, can be an even greater challenge to reservoir prediction. Humble City South field illustrates the difficulty of developing a stratigraphic oil field in an area of poor seismic definition and sparse well control. A shooting program following the wildcat discovery only heightened confusion about the size and shape of the new reservoir. Two subsequent dry holes missed the mound entirely and provided only negative control. Seismic modeling, careful stratigraphic interpretation, and saturation coverage with a three-dimensional seismic project ultimately defined the existing reservoir and revealed the presence of a separate, nearby pool. Exact reservoir delineation remains difficult, but this program presented the first clear picture of overall mount geometry. The Humble City experience showed that three-dimensional seismic can be an important tool in the critical period following a wildcat discovery.

  14. Processing of soot in an urban environment: case study from the Mexico City Metropolitan Area

    Directory of Open Access Journals (Sweden)

    K. S. Johnson

    2005-01-01

    Full Text Available Chemical composition, size, and mixing state of atmospheric particles are critical in determining their effects on the environment. There is growing evidence that soot aerosols play a particularly important role in both climate and human health, but still relatively little is known of their physical and chemical nature. In addition, the atmospheric residence times and removal mechanisms for soot are neither well understood nor adequately represented in regional and global climate models. To investigate the effect of locality and residence time on properties of soot and mixing state in a polluted urban environment, particles of diameter 0.2–2.0 μm were collected in the Mexico City Metropolitan Area (MCMA during the MCMA-2003 Field Campaign from various sites within the city. Individual particle analysis by different electron microscopy methods coupled with energy dispersed x-ray spectroscopy, and secondary ionization mass spectrometry show that freshly-emitted soot particles become rapidly processed in the MCMA. Whereas fresh particulate emissions from mixed-traffic are almost entirely carbonaceous, consisting of soot aggregates with liquid coatings suggestive of unburned lubricating oil and water, ambient soot particles which have been processed for less than a few hours are heavily internally mixed, primarily with ammonium sulfate. Single particle analysis suggests that this mixing occurs through several mechanisms that require further investigation. In light of previously published results, the internally-mixed nature of processed soot particles is expected to affect heterogeneous chemistry on the soot surface, including interaction with water during wet-removal.

  15. Time series analyses for PM10 and ozone in the Mexico City metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Icaza del Rio, G. de; Choularton, T.W.

    1998-12-31

    The Mexico City Metropolitan Area (MCMA) is located in a U shape valley at the foothills of the Anahuac cordilleras. Although situated in the tropical latitudes it has the climate of a temperate urban agglomeration. The topography of the valley is dominated by its high altitude, on the average of 2400 m above the mean sea level (msl), and its surrounding mountains that reach to more than 5300 m above msl. Overall the climate on the valley floor is semiarid with an accumulated annual mean precipitation over the city dropping from about 900 to 400 mm as one travels from west to east while the wet and dry seasons are fairly well defined, April to September and October to March respectively. The annual variation of temperature is relatively small but the diurnal range is large. Because of its geographic location, among other factors, the MCMA suffers from severe pollution problems. The altitude of the valley provides abundant solar radiation and its shape reduces the dispersion capabilities of the basin. Ozone and PM10 have been characterized as two of the most dangerous pollutants, because of both their high concentrations and their inherent chemical composition. Trends of both pollutants are examined for the period 1994-96 and the relation with some of their associated pollutants is analyzed. The results from this study show that the concentration of PM10 has increased in the three years and that the ozone concentrations have decreased slightly over the same period. Furthermore, meteorological parameters are incorporated into the analyses to help explain some of the deviations within the time series.

  16. Statistical persistence of air pollutants (O3,SO2,NO2 and PM10) in Mexico City

    Science.gov (United States)

    Meraz, M.; Rodriguez, E.; Femat, R.; Echeverria, J. C.; Alvarez-Ramirez, J.

    2015-06-01

    The rescaled range (R / S) analysis was used for analyzing the statistical persistence of air pollutants in Mexico City. The air-pollution time series consisted of hourly observations of ozone, nitrogen dioxide, sulfur dioxide and particulate matter obtained at the Mexico City downtown monitoring station during 1999-2014. The results showed that long-range persistence is not a uniform property over a wide range of time scales, from days to months. In fact, although the air pollutant concentrations exhibit an average persistent behavior, environmental (e.g., daily and yearly) and socio-economic (e.g., daily and weekly) cycles are reflected in the dependence of the persistence strength as quantified in terms of the Hurst exponent. It was also found that the Hurst exponent exhibits time variations, with the ozone and nitrate oxide concentrations presenting some regularity, such as annual cycles. The persistence dynamics of the pollutant concentrations increased during the rainy season and decreased during the dry season. The time and scale dependences of the persistence properties provide some insights in the mechanisms involved in the internal dynamics of the Mexico City atmosphere for accumulating and dissipating dangerous air pollutants. While in the short-term individual pollutants dynamics seems to be governed by specific mechanisms, in the long-term (for monthly and higher scales) meteorological and seasonal mechanisms involved in atmospheric recirculation seem to dominate the dynamics of all air pollutant concentrations.

  17. Ozone causes needle injury and tree decline in Pinus hartwegii at high altitudes in the mountains around Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    de la l. Bauere, M.deL.; Tejeda, T.H.; Manning, W.J.

    1985-08-01

    Needles of P. hartwegii were examined for a two-year period at 22 plots at Ajusco, D.F., south of Mexico City, at 3000 m. Ozone injury symptoms, consisting of extensive yellow banding and mottling, were observed on mature needles. These also became evident on new needles as they matured. This resulted in premature needle loss, reduction in cone and seed production, loss of tree vigor, bark beetle infestations, and tree decline and death. P. montezumae var. lindleyi and a few P. hartwegii trees in the same area were less susceptible. The most severe ozone injury to P. hartwegii occurs west to southwest of Mexico City in the mountain forest reserve of Desierto de los Leones, at 3500 m. Based on observations, the authors feel that needle injury and decline of P. hartwegii at high elevations in the mountains around Mexico City is caused primarily by ozone and not acid rain. It resembles the ozone-caused decline of ponderosa pine in the San Bernardino Mountains in California.

  18. Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

    Science.gov (United States)

    Adachi, K.; Buseck, P. R.

    2008-05-01

    Soot particles are major aerosol constituents that result from emissions of burning of fossil fuel and biomass. Because they both absorb sunlight and contribute to cloud formation, they are an influence on climate on local, regional, and global scales. It is therefore important to evaluate their optical and hygroscopic properties and those effects on the radiation budget. Those properties commonly change through reaction with other particles or gases, resulting in complex internal mixtures. Using transmission electron microscopy, we measured ~8000 particles (25 samples) with aerodynamic diameters from 0.05 to 0.3 μm that were collected in March 2006 from aircraft over Mexico City (MC) and adjacent areas. More than 50% of the particles consist of internally mixed soot, organic matter, and sulfate. Imaging combined with chemical analysis of individual particles show that many are coated, consist of aggregates, or both. Coatings on soot particles can amplify their light absorption, and coagulation with sulfates changes their hygroscopic properties, resulting in shorter lifetime. Our results suggest that a mixture of materials from multiple sources such as vehicles, power plants, and biomass burning occurs in individual particles, thereby increasing their complexity. Through changes in their optical and hygroscopic properties, internally mixed soot particles have a greater effect on the regional climate than uncoated soot particles. Moreover, soot occurs in more than 60% of all particles in the MC plumes, suggesting its important role in the formation of secondary aerosol particles.

  19. National uranium resource evaluation: Silver City Quadrangle, New Mexico and Arizona

    International Nuclear Information System (INIS)

    Reconnaissance and detailed geologic, geochemical, and radiometric studies were conducted throughout the Silver City Quadrangle, New Mexico and Arizona, to identify environments and delineate areas favorable for the occurrence of uranium deposits using National Uranium Resource Evaluation criteria. Surface and limited subsurface studies were augmented by aerial radiometric and hydrogeochemical and stream-sediment reconnaissance surveys. Results of the investigations indicate several areas favorable for magmatic-hydrothermal uranium deposits. They include Precambrian granitic, gneissic, and diabasic rocks; the Cretaceous Beartooth Quartzite where it overlies Precambrian granite; certain Laramide to mid-Tertiary monzonitic rocks; and Tertiary volcanic rocks adjacent to a quartz monzonitic stock. Studies also indicate environments favorable for allogenic deposits in the Tyrone laccolith and for uranium deposits in upper Cenozoic volcaniclastic lacustrine rocks. Formations judged unfavorable for magmatic-hydrothermal uranium deposits include large areas of Precambrian granitic and metamorphic rocks, almost all Laramide and mid-Tertiary intrusive rocks, and intruded Paleozoic and Cretaceous carbonate rocks. Precambrian metamorphic rocks are also considered unfavorable for contact metasomatic as well as for unconformity-related and vein-type uranium deposits. The entire Paleozoic and Cretaceous sedimentary section is considered unfavorable for sandstone and marine-black-shale uranium deposits. Moreover, mid-Tertiary rocks were judged unfavorable for volcanogenic uranium deposits, and upper Cenozoic basin-fill and surficial deposits are unfavorable for sandstone-type deposits and for uranium deposits associated with volcaniclastic lacustrine environments

  20. Characteristics of specific reading disability in children from a neuropsychological clinic in Mexico City

    Directory of Open Access Journals (Sweden)

    Poblano Adrián

    2002-01-01

    Full Text Available Objective. This report describes the main clinical features associated with specific reading disability (RD in a group of 778 school-age children studied in a Neuropsychological Clinic in Mexico City. Material and Methods. The study was performed retrospectively, using data abstracted from clinical records of subjects seen in 1995-1996. Children were mainly from low and middle economic strata and aged between 6 to 12 years. The following data were collected: age, gender, diagnosis, school grade, food intake, maternal complications during pregnancy, perinatal and postnatal neurological risk factors, and neurological signs and handedness. Results. Subjects with RD had a mean age of 102.9 months, were predominantly male (male female ratio, 2:1. Among the study group, 49.1% of the children were diagnosed with RD of a visuo-sensory-motor type, and 75.1% were from early school years (1st to 3rd grades; 27.6% showed evidence of malnutrition. A previous history of language disorders (49.2%, and a high frequency of perinatal risk factors and neurological soft signs were also found. Conclusions. This study shows that variables such as gender, food intake, and genetic and neurological risk factors, were associated with reading disabilities in school children.

  1. Impacts of black carbon and co-pollutant emissions from transportation sector in Mexico City

    Science.gov (United States)

    Zavala, Miguel; Almanza, Victor; Garcia, Agustin; Jazcilevich, Aron; Lei, Wenfang; Molina, Luisa

    2016-04-01

    Black carbon is one of the most important short-lived climate-forcing agents, which is harmful to human health and also contributes significantly to climate change. Transportation is one of the largest sources of black carbon emissions in many megacities and urban complexes, with diesel vehicles leading the way. Both on-road and off-road vehicles can emit substantial amounts of harmful BC-containing particulate matter (PM) and are also responsible for large emissions of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and many other co-emitted volatile organic compounds (VOCs). Regionally, black carbon emissions contributions from mobile sources may vary widely depending on the technical characteristics of the vehicle fleet, the quality and chemical properties of the fuels consumed, and the degree of local development and economic activities that foster wider and more frequent or intensive use of vehicles. This presentation will review and assess the emissions of black carbon from the on-road and off-road transportation sector in the Mexico City Metropolitan Area. Viable mitigation strategies, including innovative technological alternatives to reduce black carbon and co-pollutants in diesel vehicles and their impacts on climate, human health and ecosystems will be described.

  2. Impact of primary formaldehyde on air pollution in the Mexico City Metropolitan Area

    Directory of Open Access Journals (Sweden)

    W. Lei

    2008-11-01

    Full Text Available Formaldehyde (HCHO is a radical source that plays an important role in urban atmospheric chemistry and ozone formation. The Mexico City Metropolitan Area (MCMA is characterized by high anthropogenic emissions of HCHO (primary HCHO, which together with photochemical production of HCHO from hydrocarbon oxidation (secondary HCHO, lead to high ambient HCHO levels. The CAMx chemical transport model was employed to evaluate the impact of primary HCHO on its ambient concentration, on the ROx radical budget, and on ozone (O3 formation in the MCMA. Important radical sources, including HCHO, HONO, and O3-olefin reactions, were constrained by measurements from routine observations of the local ambient air monitoring network and the MCMA-2003 field campaign. Primary HCHO was found not only contributing significantly to the ambient HCHO concentration, but also enhancing the radical budget and O3 production in the urban atmosphere of the MCMA. Overall in the urban area, total daytime radical production is enhanced by up to 10% and peak O3 concentration by up to 8%. While primary HCHO contributes predominantly to the ambient HCHO concentration between nighttime and morning rush hours, significant influence on the radical budget and O3 production starts early morning, culminates at mid-morning and is sustained until early afternoon.

  3. GPS and GIS study of the western slope of the Chiquihuite hill in Mexico City

    Directory of Open Access Journals (Sweden)

    M. Martínez–Yáñez

    2009-04-01

    Full Text Available The demographic explosion of the City of Mexico has forced the anarchical growth of urban development in its mountain slopes. The geologic risk conditions that prevail in such areas are rock falls and down slope creep. The topographic slope analysis shows that these some areas pose a high risk condition for the housing developments located down slope. A geodetic net work was thus developed for the establishment of a reference frame to detect medium and long term slope movement. The location of these benchmarks included rock out crops, structural containment civil structures and street sidewalks. This network was designed to be occupied using GPS fast static methods, with times of occupation no greater to 45 minutes per station. In order to keep short baselines to the reference station and its position errors within low levels we installed a reference GPS site (U CHI on the Southern part of Cerro del Chiquihuite. The Chiquihuite GPS network was monitored for 5 years. The GPS solutions were obtained by differential techniques with ambiguity solution and precise or bits, and using UCHI stations as a reference. The Chiquihuite GPS network does not show significant variations, except for the vertical component at station CH55. This site is likely to be affected by regional subsidence.

  4. Behaviour of the groundwater system in the Santa Catarina area, Mexico City

    International Nuclear Information System (INIS)

    In the southeast area of Mexico City a line of 14 wells exist and are used as a potable water supply for surrounding towns. The average distance between each well is approximately 400 m. Each well was drilled to an approximate depth of 400 m. The results of vertical electrical soundings, performed as part of another study, indicated the presence of mineralized water down to a depth of approximately 200 m with potable water beneath. The granular aquifer is bounded by basaltic flows related to the Sierras de Santa Catarina in the north and the Chichinautzin in the south. To aid in the determination of the age and origin of the different groundwaters indicated by the geophysics, a geochemical and isotopic monitoring program was completed. Geochemical analysis was limited to the major ions. Isotopic analysis included 18O, 2H, 3H, 34S and 14C. Geochemical and isotopic data was significantly varied within the well field. The geochemical, isotopic and geophysical data was combined to produce a hydrogeological and hydrogeochemical qualitative model for the aquifer that exists around the Santa Catarina well field. (author). 11 refs, 3 figs, 7 tabs

  5. Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

    Directory of Open Access Journals (Sweden)

    K. Adachi

    2008-05-01

    Full Text Available Soot particles are major aerosol constituents that result from emissions of burning of fossil fuel and biomass. Because they both absorb sunlight and contribute to cloud formation, they are an influence on climate on local, regional, and global scales. It is therefore important to evaluate their optical and hygroscopic properties and those effects on the radiation budget. Those properties commonly change through reaction with other particles or gases, resulting in complex internal mixtures. Using transmission electron microscopy, we measured ~8000 particles (25 samples with aerodynamic diameters from 0.05 to 0.3 μm that were collected in March 2006 from aircraft over Mexico City (MC and adjacent areas. More than 50% of the particles consist of internally mixed soot, organic matter, and sulfate. Imaging combined with chemical analysis of individual particles show that many are coated, consist of aggregates, or both. Coatings on soot particles can amplify their light absorption, and coagulation with sulfates changes their hygroscopic properties, resulting in shorter lifetime. Our results suggest that a mixture of materials from multiple sources such as vehicles, power plants, and biomass burning occurs in individual particles, thereby increasing their complexity. Through changes in their optical and hygroscopic properties, internally mixed soot particles have a greater effect on the regional climate than uncoated soot particles. Moreover, soot occurs in more than 60% of all particles in the MC plumes, suggesting its important role in the formation of secondary aerosol particles.

  6. Heavy metals in urban road sediments of the city of Mexicali, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Meza T, L. M.; Quintero N, M.; Valdez S, B., E-mail: montserrat.meza@uabc.edu.mx [Universidad Autonoma de Baja California, Facultad de Ingenieria, Unidad Mexicali, 21280 Mexicali, Baja California (Mexico)

    2014-07-01

    A chemical sediment characterization of urban streets in the city of Mexicali at Baja California, Mexico, was conducted to estimate the most important heavy metals along with PM{sub 10} and PM{sub 2.5} emission factors to evaluate the amount of particulate matter. Sampling was conducted from february to may 2008, following a random statistical design, in 60 sampling sites on a geo referenced map at UTM 11 North. Samples were identified and treated in the laboratory, after undergoing cracking, drying, sieving, and weighing to get less than 75 microns of sediment by using a dry method. Twelve representative samples were selected for chemical characterization using energy dispersive X-rays (EDX) and inductively coupled plasma (Icp). The most significant elements found were zinc (Zn) and lead (Pb) with concentrations ranging from 1 to 15 mg/kg and 11 to 25 mg/kg, respectively, corresponding to the third classification from a reference set of a study by US EPA in 1981-1997. The clay type known as illite was identified in four specific samples. (author)

  7. Years of life lost (Yll) attributable to alcohol consumption in Mexico City.

    Science.gov (United States)

    Pérez-Pérez, Eduardo; Cruz-López, Leonardo; Hernández-Llanes, Norberto Francisco; Gallegos-Cari, Andrea; Camacho-Solís, Rafael Edgardo; Mendoza-Meléndez, Miguel Ángel

    2016-01-01

    The aim of this study was to estimate the YLL attributable to alcohol consumption in Mexico City from 2006 - 2012. Vital statistics on mortality attributable to alcohol consumption from the INEGI (Instituto Nacional de Estadística y Geografía) were used to determine YLL as well as the average age of death in relation to different age ranges by sex. A total estimate of 168,607 YLL was obtained, with an average loss of 18.32 years being observed for men and 17.54 years for women. Men accounted for a higher proportion of the YLL than women. According to the ICD-10 (Tenth Revision of International Classification of Diseases), liver disease attributable to alcohol consumption was found to be responsible for more than 80% of the total YLL. There was a cyclical trend in YLL from 2006 to 2012. The YLL attributable to alcohol suggest that alcohol consumption is a public health problem that involves losses in productivity and economic costs, and the decline in YLL could be explained by the decrease in income caused by the economic crisis of 2008, just as the increase could be explained by economic improvement in 2012. PMID:26816161

  8. Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City

    Science.gov (United States)

    Johansson, M.; Rivera, C.; de Foy, B.; Lei, W.; Song, J.; Zhang, Y.; Galle, B.; Molina, L.

    2009-08-01

    We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS) instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA) on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5-2.2) kg/s of HCHO and 4.4 (4.0-5.0) kg/s of NO2 using the UV instrument and 3.66 (3.63-3.73) kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.

  9. Vertical distribution of ozone and VOCs in the low boundary layer of Mexico City

    Directory of Open Access Journals (Sweden)

    E. Velasco

    2007-08-01

    Full Text Available The evolution of ozone and 13 volatile organic compounds (VOCs in the boundary layer of Mexico City was investigated during 2000–2004 to improve our understanding of the complex interactions between those trace gases and meteorological variables, and their influence on the air quality of a polluted megacity. A tethered balloon, fitted with electrochemical and meteorological sondes, was used to obtain detailed vertical profiles of ozone and meteorological parameters up to 1000 m above ground during part of the diurnal cycle (02:00–18:00 h. VOCs samples were collected up to 200 m by pumping air to canisters with a Teflon tube attached to the tether line. Overall, features of these profiles were found to be consistent with a simple picture of nighttime trapping of ozone in an upper residual layer and of VOCs in a shallow unstable layer above the ground. After sunrise an ozone balance is determined by photochemical production, entrainment from the upper residual layer and destruction by titration with NO, delaying the ground-level ozone rise by 2 h. The subsequent evolution of the conductive boundary layer and vertical distribution of pollutants are discussed in terms of the energy balance, the presence of turbulence and the atmospheric stability.

  10. Airborne Bacterial Diversity from the Low Atmosphere of Greater Mexico City.

    Science.gov (United States)

    García-Mena, Jaime; Murugesan, Selvasankar; Pérez-Muñoz, Ashael Alfredo; García-Espitia, Matilde; Maya, Otoniel; Jacinto-Montiel, Monserrat; Monsalvo-Ponce, Giselle; Piña-Escobedo, Alberto; Domínguez-Malfavón, Lilianha; Gómez-Ramírez, Marlenne; Cervantes-González, Elsa; Núñez-Cardona, María Teresa

    2016-07-01

    Greater Mexico City is one of the largest urban centers in the world, with an estimated population by 2010 of more than 20 million inhabitants. In urban areas like this, biological material is present at all atmospheric levels including live bacteria. We sampled the low atmosphere in several surveys at different points by the gravity method on LB and blood agar media during winter, spring, summer, and autumn seasons in the years 2008, 2010, 2011, and 2012. The colonial phenotype on blood agar showed α, β, and γ hemolytic activities among the live collected bacteria. Genomic DNA was extracted and convenient V3 hypervariable region libraries of 16S rDNA gene were high-throughput sequenced. From the data analysis, Firmicutes, Proteobacteria, and Actinobacteria were the more abundant phyla in all surveys, while the genera from the family Enterobacteriaceae, in addition to Bacillus spp., Pseudomonas spp., Acinetobacter spp., Erwinia spp., Gluconacetobacter spp., Proteus spp., Exiguobacterium spp., and Staphylococcus spp. were also abundant. From this study, we conclude that it is possible to detect live airborne nonspore-forming bacteria in the low atmosphere of GMC, associated to the microbial cloud of its inhabitants. PMID:26944561

  11. Investigation of OxProduction Rates in the Mexico City Metropolitan Area during MILAGRO

    Science.gov (United States)

    Dusanter, S.; Molina, L. T.; Stevens, P. S.

    2009-12-01

    Understanding the oxidative capacity of the atmosphere and the formation of secondary pollutants are important issues in atmospheric chemistry. For instance, the photochemical production of tropospheric ozone (O3) is of particular interest due to its detrimental effects on both human health and agricultural ecosystems. A detailed characterization of tropospheric O3 production rates will help in the development of effective control strategies. The 2006 Mexico City Metropolitan Area field campaign (MCMA-2006) was one of four components of MILAGRO (Megacity Initiative: Local And Global Research Observations) intended to collect information on the impact of megacity emissions on local, regional and global scales. In this presentation, rates of production of Ox (Ox = O3 + NO2) species during MCMA-2006 at the supersite T0 (Instituto Mexicano del Petroleo) will be presented using different approaches based on measured and modeled concentrations of ROx (OH + HO2 + RO2) radicals. In addition, we will examine both the reactivity of OH and the contribution of specific peroxy radicals to the oxidation rate of NO to estimate the contribution of groups of VOCs (alkanes, alkenes, aromatics, oxygenated and biogenic VOCs) to the total production rate of Ox species.

  12. National uranium resource evaluation: Silver City Quadrangle, New Mexico and Arizona

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, A J; Thiede, D S

    1982-05-01

    Reconnaissance and detailed geologic, geochemical, and radiometric studies were conducted throughout the Silver City Quadrangle, New Mexico and Arizona, to identify environments and delineate areas favorable for the occurrence of uranium deposits using National Uranium Resource Evaluation criteria. Surface and limited subsurface studies were augmented by aerial radiometric and hydrogeochemical and stream-sediment reconnaissance surveys. Results of the investigations indicate several areas favorable for magmatic-hydrothermal uranium deposits. They include Precambrian granitic, gneissic, and diabasic rocks; the Cretaceous Beartooth Quartzite where it overlies Precambrian granite; certain Laramide to mid-Tertiary monzonitic rocks; and Tertiary volcanic rocks adjacent to a quartz monzonitic stock. Studies also indicate environments favorable for allogenic deposits in the Tyrone laccolith and for uranium deposits in upper Cenozoic volcaniclastic lacustrine rocks. Formations judged unfavorable for magmatic-hydrothermal uranium deposits include large areas of Precambrian granitic and metamorphic rocks, almost all Laramide and mid-Tertiary intrusive rocks, and intruded Paleozoic and Cretaceous carbonate rocks. Precambrian metamorphic rocks are also considered unfavorable for contact metasomatic as well as for unconformity-related and vein-type uranium deposits. The entire Paleozoic and Cretaceous sedimentary section is considered unfavorable for sandstone and marine-black-shale uranium deposits. Moreover, mid-Tertiary rocks were judged unfavorable for volcanogenic uranium deposits, and upper Cenozoic basin-fill and surficial deposits are unfavorable for sandstone-type deposits and for uranium deposits associated with volcaniclastic lacustrine environments.

  13. Impact air quality by wildfire and agricultural fire in Mexico city 2015

    Science.gov (United States)

    Mendoza Campos, Alejandra; Agustín García Reynoso, José; Castro Romero, Telma Gloria; Carbajal Pérez, José Noel; Mar Morales, Bertha Eugenia; Gerardo Ruiz Suárez, Luis

    2016-04-01

    A forest fire is a large-scale process natural combustion where different types of flora and fauna of different sizes and ages are consumed. Consequently, forest fires are a potential source of large amounts of air pollutants that must be considered when trying to relate emissions to the air quality in neighboring cities of forest areas as in the Valley of Mexico. The size, intensity and occurrence of a forest fire directly dependent variables such as weather conditions, topography, vegetation type and its moisture content and the mass of fuel per hectare. An agricultural fire is a controlled combustion, which occurred a negligence can get out of control and increase the burned area or the possibly become a wildfire. Once a fire starts, the dry combustible material is consumed first. If the energy release is large and of sufficient duration, drying green material occurs live, with subsequent burning it. Under proper fuel and environmental conditions, this process can start a chain reaction. These events occur mainly in the dry season. Forest fires and agriculture fires contribute directly in the increase of carbon dioxide (CO2) into the atmosphere; The main pollutants emitted to the atmosphere by a wildfire are the PM10, PM2.5, NOx and VOC's, the consequences have by fire are deforestation, soil erosion or change of structure and composition of forests (Villers, 2006), also it affects ecosystems and the health of the population. In this study the impact of air quality for the emissions of particulate matter less than ten microns PM10, by wildfire and agricultural fire occurred on the same day and same place, the study was evaluated in Mexico City the Delegation Milpa Alta in the community of San Lorenzo Tlacoyucan, the fire occurred on 3rd March, 2015, the wildfire duration 12 hours consuming 32 hectares of oak forest and the agricultural fire duration 6 hours consumed 16 hectares of corn. To evaluate the impact of air quality the WRF-Chem, WRF-Fire and METv3

  14. Chemical evolution of volatile organic compounds in the outflow of the Mexico City Metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Apel, E.; Springston, S.; Karl, T.; Emmons, L.; Flocke, F.; Hills, A. J.; Madronich, S.; Lee-Taylor, J.; Fried, A.; Weibring, P.; Walega, J.; Richter, D., Tie, X.; Mauldin, L.; Campos, T.; Sive, B.; Kleinman, L.; Springston, S., Zaveri, R.; deGouw, J.; Zheng, J.; Zhang, R.; Rudolph, J.; Junkermann, W.; Riemer, D. D.

    2009-11-01

    The volatile organic compound (VOC) distribution in the Mexico City Metropolitan Area (MCMA) and its evolution as it is uplifted and transported out of the MCMA basin was studied during the 2006 MILAGRO/MIRAGE-Mex field campaign. The results show that in the morning hours in the city center, the VOC distribution is dominated by non-methane hydrocarbons (NMHCs) but with a substantial contribution from oxygenated volatile organic compounds (OVOCs), predominantly from primary emissions. Alkanes account for a large part of the NMHC distribution in terms of mixing ratios. In terms of reactivity, NMHCs also dominate overall, especially in the morning hours. However, in the afternoon, as the boundary layer lifts and air is mixed and aged within the basin, the distribution changes as secondary products are formed. The WRF-Chem (Weather Research and Forecasting with Chemistry) model and MOZART (Model for Ozone and Related chemical Tracers) were able to reproduce the general features of the daytime cycle of the VOC OH reactivity distribution showing that NMHCs dominate the distribution except in the afternoon hours and that the VOC OH reactivity peaks in the early morning due to high morning emissions from the city into a shallow boundary layer. The WRF-Chem and MOZART models showed higher reactivity than the experimental data during the nighttime cycle, perhaps indicating problems with the modeled nighttime boundary layer height. In addition, a plume was studied in which air was advected out of the MCMA and intercepted downwind with the DOE G1 on 18 March and the NCAR C130 one day later on 19 March. A number of identical species measured aboard each aircraft gave insight into the chemical evolution of the plume as it aged and was transported as far as 1000 km downwind. Ozone and many OVOCs were photochemically produced in the plume. The WRF-Chem and MOZART models were used to examine the spatial and temporal extent of the 19 March plume and to help interpret the OH

  15. Chemical evolution of volatile organic compounds in the outflow of the Mexico City Metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Apel, Eric; Emmons, L.; Karl, Thomas G.; Flocke, Frank M.; Hills, A. J.; Madronich, Sasha; Lee-Taylor, J.; Fried, Alan; Weibring, P.; Walega, J.; Richter, Dirk; Tie, X.; Mauldin, L.; Campos, Teresa; Weinheimer, Andrew J.; Knapp, David; Sive, B.; Kleinman, Lawrence I.; Springston, S.; Zaveri, Rahul A.; Ortega, John V.; Voss, Paul B.; Blake, D. R.; Baker, Angela K.; Warneke, Carsten; Welsh-Bon, Daniel; de Gouw, Joost A.; Zheng, J.; Zhang, Renyi; Rudolph, Jochen; Junkermann, W.; Riemer, D.

    2010-01-01

    The volatile organic compound (VOC) distribution in the Mexico City Metropolitan Area (MCMA) and its evolution as it is uplifted and transported out of the MCMA basin was studied during the 2006 MILAGRO/MIRAGE-Mex field campaign. The results show that in the morning hours in the city center, the VOC distribution is dominated by non-methane hydrocarbons (NMHCs) but with a substantial contribution from oxygenated volatile organic compounds (OVOCs), predominantly from primary emissions. Alkanes account for a large part of the NMHC distribution in terms of mixing ratios. In terms of reactivity, NMHCs also dominate overall, especially in the morning hours. However, in the afternoon, as the boundary layer lifts and air is mixed and aged within the basin, the distribution changes as secondary products are formed. The WRF-Chem (Weather Research and Forecasting with Chemistry) model and MOZART (Model for Ozone and Related chemical Tracers) were able to reproduce the general features of the daytime cycle of the VOC OH reactivity distribution showing that NMHCs dominate the distribution except in the afternoon hours and that the VOC OH reactivity peaks in the early morning due to high morning emissions from the city into a shallow boundary layer. The WRF-Chem and MOZART models showed higher reactivity than the experimental data during the nighttime cycle, perhaps indicating problems with the modeled nighttime boundary layer height. In addition, a plume was studied in which air was advected out of the MCMA and intercepted downwind with the DOE G1 on March 18 and the NCAR C130 one day later on March 19. A number of identical species measured aboard each aircraft gave insight into the chemical evolution of the plume as it aged and was transported as far as 1000 km downwind. Ozone and many OVOCs were photochemically produced in the plume. The WRF-Chem and MOZART models were used to examine the spatial and temporal extent of the March 19 plume and to help interpret the OH

  16. Chemical evolution of volatile organic compounds in the outflow of the Mexico City Metropolitan area

    Directory of Open Access Journals (Sweden)

    W. Junkermann

    2009-11-01

    Full Text Available The volatile organic compound (VOC distribution in the Mexico City Metropolitan Area (MCMA and its evolution as it is uplifted and transported out of the MCMA basin was studied during the 2006 MILAGRO/MIRAGE-Mex field campaign. The results show that in the morning hours in the city center, the VOC distribution is dominated by non-methane hydrocarbons (NMHCs but with a substantial contribution from oxygenated volatile organic compounds (OVOCs, predominantly from primary emissions. Alkanes account for a large part of the NMHC distribution in terms of mixing ratios. In terms of reactivity, NMHCs also dominate overall, especially in the morning hours. However, in the afternoon, as the boundary layer lifts and air is mixed and aged within the basin, the distribution changes as secondary products are formed. The WRF-Chem (Weather Research and Forecasting with Chemistry model and MOZART (Model for Ozone and Related chemical Tracers were able to reproduce the general features of the daytime cycle of the VOC OH reactivity distribution showing that NMHCs dominate the distribution except in the afternoon hours and that the VOC OH reactivity peaks in the early morning due to high morning emissions from the city into a shallow boundary layer. The WRF-Chem and MOZART models showed higher reactivity than the experimental data during the nighttime cycle, perhaps indicating problems with the modeled nighttime boundary layer height. In addition, a plume was studied in which air was advected out of the MCMA and intercepted downwind with the DOE G1 on 18~March and the NCAR C130 one day later on 19~March. A number of identical species measured aboard each aircraft gave insight into the chemical evolution of the plume as it aged and was transported as far as 1000 km downwind. Ozone and many OVOCs were photochemically produced in the plume. The WRF-Chem and MOZART models were used to examine the spatial and temporal extent of the 19~March plume and to help interpret

  17. A tale of two epidemics: gender differences in socio-demographic characteristics and sexual behaviors among HIV positive individuals in Mexico City

    OpenAIRE

    Bautista-Arredondo, Sergio; Servan-Mori, Edson; Beynon, Fenella; González, Andrea; Volkow, Patricia

    2015-01-01

    Background To date, the HIV epidemic in Mexico has been concentrated mainly among men who have sex with men, butheterosexual transmission, particularly to women, is increasingly important. This study examine gender differences in socio-demographic characteristics and risk behaviors of HIV positive individuals in Mexico City. Methods We analyzed data from a cross-sectional survey of 1,490 clinic patients (male:female ratio 8:1) with HIV inMexico City in 2010. We examined socio-demographic char...

  18. Ozone concentrations at a selected high-elevation forest site downwind Mexico City

    Science.gov (United States)

    Torres-JArdon, R.

    2013-05-01

    Torres-Jardón, R.*, Rosas-Pérez, I., Granada-Macías, L. M., Ruiz-Suárez, L. G. Centro de Ciencias de la Atmósfera, UNAM, México D. F. México * rtorres@unam.mx For many years, the vegetation of forest species such as Abies religiosa in natural parks located in the southwest mountains of Mexico City has attracted much attention since these parks have been experiencing a severe decline of unclear etiology. The high ozone levels in the area and the observed naked eye macroscopic, histological and cytological injuries on these species, strongly suggest an important contribution of tropospheric ozone to this deterioration process. Apart of historical short monitoring campaigns for measuring ozone levels in these mountains, it is known just a little is known about the present exposure levels at which the local vegetation is exposed. A continuous ozone analyzer has been in operation since 2011 at a high-elevation forest site (Parque Nacional Miguel Hidalgo, PNMH; 3110 m above mean sea level) located downwind of Mexico City Metropolitan Area (MCMA), in order to characterize the local ozone diel amplitude and its seasonal trend, as well as the influence of MCMA on the local O3 concentrations. Hourly average ozone data in PNMH shows that in general, the diel of ozone concentrations in the forest site has a statistical significant correlation with the pattern of ozone levels observed in several monitoring sites (smog receptor sites) within the MCMA, although the high elevation O3 levels are relatively lower than those in the urban area (around 2200 m above mean sea level). It is possible that a part of the oxidants in the air masses are removed by sink deposition processes during the air mass transport across the hills. The diel amplitude of ozone concentrations is small in the cold season, increasing as the seasons advance to June. As in the city, the highest ozone concentrations occur in April or May and the lowest levels during the rainy season, which extends from

  19. Bio-climatic strategy for energy saving in corporative buildings. City Juarez, Chihuahua, Mexico; Estrategia bioclimatica para ahorro energetico en edificios corporativos. Ciudad Juarez, Chihuahua, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Staines Orozco, E. R.

    2008-07-01

    Ciudad Juarez Chihuahua in Mexico is located in of de biggest Desert of Arid America called Chihuahuan Desert, and is there in where this border city with United State of North America and one of the border cities of greater commercial importance (a million six hundred thousands pop. approx.) has been develop to great influence of wasteful constructive systems of nonrenewable resources as they are the gas and electricity. These building take back surpassed models. In this article presents a design of a model of corporative building of five floors that counts including all a strategy from the process of architectonic design to the applications of echo passive and active Technologies (hybrid) like one of a ventilation tower, strategy that applied guarantees the significant saving to use energy. (Author)

  20. View From a Megacity: Aerosol Light Absorption and Scattering at Four Sites in and Near Mexico City.

    Science.gov (United States)

    Paredes-Miranda, G.; Arnott, W. P.; Gaffney, J. S.; Marley, N. A.

    2006-12-01

    As part of the Megacity Impacts on Regional and Global Environments, MIRAGE-Mex deployment to Mexico City in the period of 30 days, March 2006, a suite of photoacoustic spectrometers (PAS) were installed to measure at ground level the light absorption and scattering by aerosols at four sites: an urban site at Instituto Mexicano del Petroleo (Mexican Oil Institute, denoted by IMP), a suburban site at the Technological University of Tecamac, a rural site at "La Biznaga" ranch, and a site at the Paseo de Cortes (altitude 3,810 meters ASL) in the rural area above Amecameca in the State of Mexico, on the saddle between the volcanoes Popocatepetl and Iztaccihuatl. The IMP site gave in-situ characterization of the Mexico City plume under favorable wind conditions while the other sites provided characterization of the plume, mixed in with any local sources. The second and third sites are north of Mexico City, and the fourth site is south. The PAS used at IMP operates at 532 nm, and conveniently allowed for characterization of gaseous absorption at this wavelength as well. Instruments at the second and third sites operate at 870 nm, and the one at the fourth site at 780 nm. Light scattering measurements are accomplished within the PAS by the reciprocal nephelometery method. In the urban site the aerosol absorption coefficient typically varies between 40 and 250 Mm-1 during the course of the day and significant diurnal variation of the aerosol single scattering albedo was observed. Comparisons with TSI nephelometer scattering and Aetholemeter absorption measurements at the T0 site will be presented. We will present a broad overview of the diurnal variation of the scattering and absorption as well as the single scattering albedo and fraction of absorption due to gases at the IMP site. Insight on the dynamical connections will be discussed.

  1. Ambient Particulate Matter during MILAGRO in Mexico City: Main Findings, Impacts (on AQ and Climate), and Future Research Needs

    Science.gov (United States)

    Jimenez, Jose-Luis; Schauer, James J.; Molina, Luisa T.; MILAGRO Pm Team

    2010-05-01

    The MILAGRO campaign was a large international field experiments conduced in Mexico City and Central Mexico during March 2006. We present an overview of the main findings related to particulate matter and aerosol radiative properties. PM levels inside Mexico City were similar or higher than those in the most polluted North American cities, but ~5 times lower than levels in the most polluted Asian megacities During the study, PM10 and PM2.5 concentrations in the urban area of were about double the concentrations in the rural areas surrounding Mexico City. PM2.5 made up about half of the PM10 concentrations, with small amounts of mass in the PM2.5-PM1.0 range. Mineral matter made up approximately 25% of the PM10 and on average 15% and 28% of the PM2.5 in the urban and rural areas, respectively. Approximately 25% of the PM2.5 was secondary inorganic ions with the remaining PM2.5 mass being comprised of largely carbonaceous aerosol. Except for surface measurements at the central sampling sites in Mexico city, the elemental carbon mass absorption efficiency was relatively constant for aircraft and surface measurements throughout the study, contrary to expectations. Although different organic aerosol (OA) source apportionment methods had some differences, there was agreement that the dominant sources of carbonaceous aerosol were secondary OA (SOA), biomass burning, and mobile sources. The impact of biomass burning to the aerosol outflow from the region was much larger than to the surface concentrations inside the city. SOA formation from primary semivolatile and intermediate volatility precursors has the potential to close the gap in predicted vs. measured SOA, while formation from glyoxal also makes an important contribution, especially to organic oxygen. Biogenic SOA advected from the coastal mountain ranges contributes about 1 μg m-3 to concentrations in the MCMA. Primary OA from anthropogenic and biomass burning sources was found to be semivolatile, while secondary

  2. Mexico.

    Science.gov (United States)

    1988-02-01

    Focus in this discussion of Mexico is on the following: geography; the people; history; political conditions; the economy; foreign relations; and relations between the US and Mexico. As of July 1987, the population of Mexico numbered 81.9 million with an estimated annual growth rate of 2.09%. 60% of the population is Indian-Spanish (mestizo), 30% American Indian, 9% white, and 1% other. Mexico is the most populous Spanish-speaking country in the world and the 2nd most populous country in Latin America. Education is decentralized and expanded. Mexico's topography ranges from low desert plains and jungle-like coastal strips to high plateaus and rugged mountains. Hernan Cortes conquered Mexico in 1919-21 and founded a Spanish colony that lasted for almost 300 years. Independence from Spain was proclaimed by Father Miguel Hidalgo on September 16, 1810; the republic was established on December 6, 1822. Mexico's constitution of 1917 provides for a federal republic with a separation of powers into independent executive, legislative, and judicial branches of government. Significant political themes of the administration of President Miguel de la Madrid Hurtado, who began his 6-year term in 1982, have been restructuring the economy, liberalizing trade practices, decentralizing government services, and eliminating corruption among public servants. In 1987, estimates put the real growth of the Mexican economy at 1.5%; the gross domestic product (GDP) had shrunk by 3.5% in 1986. Yet, on the positive side, Mexico's international reserves increased to record levels in 1987 (to about $15 billion), and its current account surplus reached more than $3 billion. Mexico has made considerable progress in moving to restructure its economy. It has substantially reduced impediments to international trade and has moved to reduce the number of parastatal firms. 1987 was the 2nd consecutive year in which Mexico recorded triple-digit inflation; inflation reached 158.8%. Other problems include

  3. Interferometric synthetic aperture radar observation of vertical land displacement in the vicinity of the All-American Canal at the United States and Mexico border

    Science.gov (United States)

    Han, Joo-Yup

    Interferometric Synthetic Aperture Radar (InSAR) provided a synoptic view of the status of groundwater levels in the vicinity of the All-American Canal (AAC) by measuring vertical land displacements. The European Remote Sensing satellite SAR images were used to produce surface deformation maps. The full time period (1992-2000) was divided to two shorter periods (early and late) (1992-97 and 1996-2000). For low coherence areas such as agricultural fields in the Mexicali Valley, Persistent Scatterers InSAR (PSInSAR) was used to detect any deformation signals. The surface deformation maps from InSAR indicated that there were insignificant vertical land displacements in the vicinity of the AAC. However, the surrounding areas of the East Mesa Geothermal Field (EMGF) were subsiding over the full observation period (-38 mm/year). The maximum subsidence rate at the EMGF was reduced by 21% between the early (-43 mm/year) and late (-34 mm/year) periods. The AAC was within the edges of the spatial extent of the EMGF subsidence, especially during the early period, which was associated with a high averaged net geothermal production. The maximum subsidence on the East Highline Canal was -9.5 +/- 0.5 cm and -2.4 +/- 0.8 cm for the early and late periods, respectively. Results from PSInSAR in Mexicali City and the Mexicali Valley showed insignificant displacements. This lack of deformation indicated that there was no measurable surface deformation in the areas, but validation data were not available. The most interesting phenomenon is the high density of persistent scatterers in the areas between the Andrade Mesa and the Mexicali Valley, and the Sand Hills dunes. Forward modeling was conducted to characterize the reservoir zone of the EMGF based on the InSAR displacement over the full time period. Inputs to the model were the maximum subsidence (-3.8 cm) and depth of the reservoir, the radius of the reservoir and Poisson's ratio. An interactive approach was conducted to find the

  4. Trinational Library Forum Proceedings = Memorias [del] Foro Trinacional de Bibliotecas (5th, Mexico City, Mexico, February 23-25, 1995).

    Science.gov (United States)

    Instituto Tecnologico de Monterrey (Mexico).

    At the fifth Trinational Library Forum in 1995, 165 librarians from the United States, Canada, and Mexico gathered to discuss topics of international librarianship and exchanges, copyright regulations, and professional accreditation in information science. Presentations, with the full text in both English and Spanish, include: (1) "International…

  5. Chemical evolution of volatile organic compounds in the outflow of the Mexico City Metropolitan area

    Directory of Open Access Journals (Sweden)

    E. C. Apel

    2010-03-01

    Full Text Available The volatile organic compound (VOC distribution in the Mexico City Metropolitan Area (MCMA and its evolution as it is uplifted and transported out of the MCMA basin was studied during the 2006 MILAGRO/MIRAGE-Mex field campaign. The results show that in the morning hours in the city center, the VOC distribution is dominated by non-methane hydrocarbons (NMHCs but with a substantial contribution from oxygenated volatile organic compounds (OVOCs, predominantly from primary emissions. Alkanes account for a large part of the NMHC distribution in terms of mixing ratios. In terms of reactivity, NMHCs also dominate overall, especially in the morning hours. However, in the afternoon, as the boundary layer lifts and air is mixed and aged within the basin, the distribution changes as secondary products are formed. The WRF-Chem (Weather Research and Forecasting with Chemistry model and MOZART (Model for Ozone and Related chemical Tracers were able to approximate the observed MCMA daytime patterns and absolute values of the VOC OH reactivity. The MOZART model is also in agreement with observations showing that NMHCs dominate the reactivity distribution except in the afternoon hours. The WRF-Chem and MOZART models showed higher reactivity than the experimental data during the nighttime cycle, perhaps indicating problems with the modeled nighttime boundary layer height.

    A northeast transport event was studied in which air originating in the MCMA was intercepted aloft with the Department of Energy (DOE G1 on 18 March and downwind with the National Center for Atmospheric Research (NCAR C130 one day later on 19 March. A number of identical species measured aboard each aircraft gave insight into the chemical evolution of the plume as it aged and was transported as far as 1000 km downwind; ozone was shown to be photochemically produced in the plume. The WRF-Chem and MOZART models were used to examine the spatial extent and temporal evolution of the plume

  6. Seasonal and diurnal trends in black carbon properties and co-pollutants in Mexico City

    Science.gov (United States)

    Retama, A.; Baumgardner, D.; Raga, G. B.; McMeeking, G. R.; Walker, J. W.

    2015-08-01

    The Mexico City metropolitan area (MCMA) is a region that continues to grow in population and vehicular traffic as well as being the largest source of short-lived climate pollutants (SLCP) in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e., ozone (O3) and carbon monoxide (CO), but particulate matter (PM2.5 and PM10) and black carbon (BC) have shown a less positive response to mitigation strategies that have been in place for almost 3 decades. For the first time, extended measurements of equivalent black carbon (eBC), derived from light absorption measurements, have been made using a Photoacoustic Extinctiometer (PAX) over a 13 month period from March 2013 through March 2014. The daily trends in workdays (Monday through Saturday) and Sunday eBC, PM2.5 and the co-pollutants CO, O3 and NOx are evaluated with respect to the three primary seasons in the MCMA: rainy, cold and dry and warm and dry. The maximum values in all of the particle and gas concentrations were significantly larger (Student's t test, P matter. A significant "weekend effect" was also identified, particularly the decrease in BC due to fewer large transport vehicles that are fueled by diesel, which produces a large fraction of the BC. The other co-pollutant concentrations are also significantly less on weekends except for O3 that shows no change in maximum values from workdays to Sundays. This lack of change is a result of the balancing effects of lower precursor gases, i.e., VOCs, offset by lower concentrations of NOx, that is an O3 inhibitor. A comparison of the average maximum value of eBC measured during the 1 year period of the current study, with maximum values measured in shorter field campaigns in 2000 and 2006, shows no significant change in the eBC emissions over a 14 year period. This suggests that new methods may need to be developed that can decrease potentially toxic levels of this particulate pollutant.

  7. Basic statistics of PM2.5 and PM10 in the atmosphere of Mexico City.

    Science.gov (United States)

    Vega, E; Reyes, E; Sánchez, G; Ortiz, E; Ruiz, M; Chow, J; Watson, J; Edgerton, S

    2002-03-27

    The high levels of fine particulate matter in Mexico City are of concern since they may induce severe public health effects as well as the attenuation of visible light. Sequential filter samplers were used at six different sites from 23 February to 22 March 1997. The sampling campaign was carried out as part of the project 'Investigación sobre Materia Particulada y Deterioro Atmosferico-Aerosol and Visibility Evaluation Research'. This research was a cooperative project sponsored by PEMEX and by the US Department of Energy. Sampling sites represent the different land uses along the city, the northwest station, Tlalnepantla, is located in a mixed medium income residential and industrial area. The northeast station, Xalostoc, is located in a highly industrialized area, Netzahualcoyotl is located in a mixed land use area, mainly commercial and residential. Station La Merced is located in the commercial and administrative district downtown. The southwest station is located in the Pedregal de San Angel, in a high-income neighborhood, and the southeast station located in Cerro de la Estrella is a mixed medium income residential and commercial area. Samples were collected four times a day in Cerro de la Estrella (CES), La Merced (MER) and Xalostoc (XAL) with sampling periods of 6 h. In Pedregal (PED), Tlalnepantla (TLA) and Netzahualcoyot1 (NEZ) sampling periods were every 24 h. In this paper the basic statistics of PM2.5 and PM10 mass concentrations are presented. The average results showed that 49, 61, 46, 57, 51 and 44% of the PM10 consisted of PM2.5 for CES, MER, XAL, PED, TLA and NEZ, respectively. The 24-h average highest concentrations of PM25 and PM10 were registered at NEZ (184 and 267 microg/m3) and the lowest at PED (22 and 39 microg/m3). The highest PM10 correlations were between XAL-CES (0.79), PED-TLA (0.80). In contrast, the highest PM2.5 correlations were between CES-PED (0.74), MER-CES (0.73) and TLA-PED (0.72), showing a lower correlation than the PM10

  8. Evaluation of a Three-Dimensional Chemical Transport Model (PMCAMx) in the Mexico City Metropolitan Area

    Science.gov (United States)

    Tsimpidi, A. P.; Karydis, V. A.; Zavala, M.; Lei, W.; Molina, L. T.; Pandis, S. N.

    2007-05-01

    Atmospheric aerosols have adverse effects on human health, contribute to the visibility reduction and influence the energy balance of the planet. A three-dimensional chemical transport model (PMCAMx) (Gaydos et al., 2007) is used to simulate the particular matter (PM) mass composition distribution in the Mexico City Metropolitan Area (MCMA). PMCAMx uses the framework of CAMx (ENVIRON, 2002) modelling the processes of horizontal and vertical advection, horizontal and vertical dispersion, wet and dry deposition, and gas-phase chemistry. In addition to the above, PMCAMx includes three detailed aerosol modules: inorganic aerosol growth (Gaydos et al., 2003; Koo et al., 2003a), aqueous-phase chemistry (Fahey and Pandis, 2001), and secondary organic aerosol formation and growth (Koo et al., 2004). The aerosol thermodynamic model ISORROPIA has been improved as it now simulates explicitly the chemistry of Ca, Mg, and K salts and is linked to PMCAMx. The hybrid approach (Koo et al., 2003b) for modelling aerosol dynamics is applied in order to accurately simulate the inorganic components in coarse mode. This approach assumes that the smallest particles are in equilibrium while the condensation/evaporation equation is solved for the larger ones. The new CMU organic aerosol model, which is based on the splitting of the organic aerosol volatility range in discrete bins, is also used. The model predictions are evaluated against the PM and vapour concentration measurements from the MCMA-2003 Campaign (Molina et al., 2007). References Gaydos, T., Pinder, R., Koo, B., Fahey, Κ., Yarwood, G., and Pandis, S. N., (2007). Development and application of a three-dimensional Chemical Transport Model, PMCAMx. Atmospheric Environment, in press. ENVIRON (2002). User's guide to the comprehensive air quality model with extensions (CAMx). Version 3.10. Report prepared by ENVIRON International corporation, Novato, CA Gaydos, T., Koo, B., and Pandis, S. N., (2003). Development and application of

  9. Frequency and risk factors associated with dry eye in patients attending a tertiary care ophthalmology center in Mexico City

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    Martinez JD

    2016-07-01

    Full Text Available Jaime D Martinez,1 Anat Galor,2,3 Nallely Ramos-Betancourt,1 Andrés Lisker-Cervantes,1 Francisco Beltrán,1 Jorge Ozorno-Zárate,1 Valeria Sánchez-Huerta,1 Marco-Antonio Torres-Vera,1 Everardo Hernández-Quintela1 1Cornea and External Diseases Service, Asociación Para Evitar la Ceguera en Mexico (Association to prevent blindness in Mexico, Universidad Nacional Autónoma de México, Mexico City, Mexico; 2Department of Ophthalmology, Miami Veterans Affairs Medical Center, 3Cornea and External Diseases Division, Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA Purpose: The purpose of this study was to ascertain the frequency and risk factors of dry eye (DE among patients attending a tertiary care ophthalmology center in Mexico.Methods: Approximately 338 consecutive new patients attending a tertiary care ophthalmology center in Mexico City underwent an ocular surface examination, which included tear film break-up time, fluorescein corneal staining, Schirmer’s test, and evaluation of meibum quality. Symptoms of DE were evaluated by the Ocular Surface Disease Index and Dry Eye Questionnaire-5. Information on demographics, exposures, past medical and ocular history, and medications was also collected.Results: The frequency of severe DE symptoms was found to be 43% based on the Ocular Surface Disease Index and 30% based on Dry Eye Questionnaire-5. Risk factors significantly associated with increased DE symptoms included dry mouth and gastrointestinal ulcer medications. With regard to signs, aqueous tear deficiency was a less-frequent finding (22% in our population than evaporative deficiency (94%. Risk factors associated with aqueous tear deficiency were dry mouth and diuretic use. No risk factors were associated with evaporative deficiency. Risk factors associated with meibomian gland dysfunction included old age, male sex, arthritis, and use of an antihypertensive. The only risk factor associated with corneal staining was dry

  10. Characterization and in vitro biological effects of concentrated particulate matter from Mexico City

    Science.gov (United States)

    De Vizcaya-Ruiz, A.; Gutiérrez-Castillo, M. E.; Uribe-Ramirez, M.; Cebrián, M. E.; Mugica-Alvarez, V.; Sepúlveda, J.; Rosas, I.; Salinas, E.; Garcia-Cuéllar, C.; Martínez, F.; Alfaro-Moreno, E.; Torres-Flores, V.; Osornio-Vargas, A.; Sioutas, C.; Fine, P. M.; Singh, M.; Geller, M. D.; Kuhn, T.; Miguel, A. H.; Eiguren-Fernandez, A.; Schiestl, R. H.; Reliene, R.; Froines, J.

    Coarse and fine particles were collected using an ambient particle concentrator (VACES system) in the north, center and south regions of Mexico City during May and November of 2003 with the aim of collecting enough particulate matter (PM) to examine their chemical and physical characteristics, biological content, and toxicity potential. The chemical, morphological and biological composition of PM was determined, together with the redox activity, induction of apoptosis and DNA damage. Carbonaceous species determined by thermal-optical transmittance (TOT) showed that the highest concentrations were found in PM 2.5 from the north and in PM 10 from the center. When analyzed by inductively coupling plasma (ICP), levels of metals were higher in the coarse fraction, mainly in the north. Morphological analysis by Scanning Electron Microscope & Energy Dispersive X-ray Spectrometer (SEM-EDX) is shown. Bacteria, fungi and endotoxin were present mostly in the coarse samples from the north. Fine PM had higher redox activity, than the coarse PM assessed by the dithiothreitol (DTT) assay. Early apoptotic cell death assessed by annexin V was observed in A549 cells exposed to PM from all regions, particularly with those collected in May. The fine fraction from the south induced higher apoptotic cell death compared to the coarse fraction, in contrast, the coarse fraction from the north induced significantly higher apoptosis than the fine fraction. All PM samples induced DNA damage assessed by the comet assay on THP-1 cells when exposed to a concentration of 10 μg/mL, the highest DNA damage was produced by both particle fractions collected in the north in May and November. In conclusion, PM from the north showed a higher metal and biological content, apoptotic cell death induction and more extensive DNA damage. Also, fine PM fractions from all sampled regions showed more redox activity than the coarse fraction. In summary, location, season and size of PM collection influenced their

  11. Characterization of Aerosols Containing Zn, Pb, and Cl from an Industrial Region of Mexico City

    International Nuclear Information System (INIS)

    During the March, 2006 MILAGRO campaign, measurements in the Northern Mexico City Metropolitan Area revealed the frequent appearance of particles with a characteristically high content of internally mixed Zn, Pb, Cl, and P. A comprehensive study of the chemical and physical properties of these particles was performed using a complementary combination of aerosol measurement techniques. Individual particles were analyzed using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) and Computer Controlled Scanning Electron Microscopy/Energy Dispersive X-Ray spectroscopy (CCSEM/EDX). Proton Induced X-Ray Emission (PIXE) analysis of bulk aerosol samples provided time-resolved mass concentrations of individual elements. The PIXE measurements indicated that Zn is more strongly correlated with Cl than with any other element and that Zn concentrations are higher than other non-ferrous transition metals. The Zn- and Pb-containing particles have both spherical and non-spherical morphologies. Many metal rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2 6H2O as indicated by scanning transmission x-ray microscopy/near edge X-ray absorption spectroscopy (STXM/NEXAFS). The Zn and Pb rich particles were primarily in the submicron size range and internally mixed with elemental carbon. The unique chemical associations most closely match signatures acquired for garbage incineration. This unique combination of complementary analytical techniques has allowed for a comprehensive evaluation of Zn- and Pb- containing particles in a complex urban environment, highlighting unique characteristics that give powerful insight into their origin

  12. Impact of primary formaldehyde on air pollution in the Mexico City Metropolitan Area

    Directory of Open Access Journals (Sweden)

    W. Lei

    2009-04-01

    Full Text Available Formaldehyde (HCHO is a radical source that plays an important role in urban atmospheric chemistry and ozone formation. The Mexico City Metropolitan Area (MCMA is characterized by high anthropogenic emissions of HCHO (primary HCHO, which together with photochemical production of HCHO from hydrocarbon oxidation (secondary HCHO, lead to high ambient HCHO levels. The CAMx chemical transport model was employed to evaluate the impact of primary HCHO on its ambient concentration, on the ROx radical budget, and on ozone (O3 formation in the MCMA. Important radical sources, including HCHO, HONO, and O3-olefin reactions, were constrained by measurements from routine observations of the local ambient air monitoring network and the MCMA-2003 field campaign. Primary HCHO was found not only to contribute significantly to the ambient HCHO concentration, but also to enhance the radical budget and O3 production in the urban atmosphere of the MCMA. Overall in the urban area, total daytime radical production is enhanced by up to 10% and peak O3 concentration by up to 8%; moreover primary HCHO tends to make O3 both production rates and ambient concentration peak half an hour earlier. While primary HCHO contributes predominantly to the ambient HCHO concentration between nighttime and morning rush hours, significant influence on the radical budget and O3 production starts early in the morning, peaks at mid-morning and is sustained until early afternoon.

  13. Aerosol Simulation in the Mexico City Metropolitan Area during MCMA2003 using CMAQ/Models3

    Science.gov (United States)

    Bei, N.; Zavala, M.; Lei, W.; de Foy, B.; Molina, L.

    2007-12-01

    CMAQ/Models3 has been employed to simulate the aerosol distribution and variation during the period from 13 to 16 April 2003 over the Mexico City Metropolitan Area as part of MCMA-2003 campaign. The meteorological fields are simulated using MM5, with three one-way nested grids with horizontal resolutions of 36, 12 and 3 km and 23 sigma levels in the vertical. MM5 3DVAR system has also been incorporated into the meteorological simulations. Chemical initial and boundary conditions are interpolated from the MOZART output. The SAPRC emission inventory is developed based on the official emission inventory for MCMA in 2004. The simulated mass concentrations of different aerosol compositions, such as elemental carbon (EC), primary organic aerosol (POA), secondary organic aerosol (SOA), nitrate, ammonium, and sulfate have been compared to the measurements taken at the National Center for Environmental Research and Training (Centro Nacional de Investigacion y Capacitacion Ambiental, CENICA) super-site. Hydrocarbon-like organic aerosol (HOA) and oxygenated organic aerosol (OOA) are used as observations of POA and SOA, respectively in this study. The preliminary model results show that the temporal evolutions of EC and POA are reasonable compared with measurements. The peak time of EC and POA are basically reproduced, thus validating the emission inventory and its processing through CMAQ/Models3. But the magnitude of EC and POA are underestimated over the entire episode. The modeled nitrate and ammonium concentrations are overestimated on most of the days. There is 1-2 hour difference between the simulated peak time of nitrate and ammonium aerosols compared to observations at CENICA. The simulated mass concentrations of SOA and sulfate are significantly underestimated. The reasons of the discrepancy between simulations and measurements are due to the uncertainties existing in the emission inventory, meteorological fields, and as well as aerosol formation mechanism in the case

  14. Modeling the impacts of biomass burning on air quality in and around Mexico City

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    W. Lei

    2012-09-01

    Full Text Available The local and regional impacts of open fires and trash burning on ground-level ozone (O3 and fine carbonaceous aerosols in the Mexico City Metropolitan Area (MCMA and surrounding region during two high fire periods in March 2006 have been evaluated using WRF-CHEM model. The model captured reasonably well the measurement-derived magnitude and temporal variation of the biomass burning organic aerosol (BBOA, and the simulated impacts of open fires on organic aerosol (OA were consistent with many observation-based estimates. We did not detect significant effects of open fires and trash burning on surface O3 concentrations in the MCMA and surrounding region. In contrast, they had important influences on OA and elemental carbon (EC, contributing about 60, 22, 33, and 22% to primary OA (POA, secondary OA (SOA, total OA (TOA, and EC, respectively, on both the local and regional scales. Although the emissions of trash burning are substantially lower than those from open fires, trash burning made slightly smaller but comparable contributions to OA as open fires did, and exerted an even higher influence on EC. SOA formation due to the open fires and trash burning enhanced the OA concentration by about 10 and 5% in the MCMA, respectively. On the annual basis and taking the biofuel use emissions into consideration, we estimated that biomass burning contributed about 60, 30, and 25%, respectively, to the loadings of POA, SOA and EC in both the MCMA and its surrounding region, with about 35, 18, and 15% from open fires and trash burning. The estimates of biomass burning impacts in this study may contain considerable uncertainties due to the uncertainties in their emission estimates, extrapolations and the nature of spot comparison. More observation and modeling studies are needed to accurately assess the impacts of biomass burning on tropospheric chemistry, regional and global air quality, and climate change.

  15. Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City

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    L. Molina

    2009-08-01

    Full Text Available We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2 kg/s of HCHO and 4.4 (4.0–5.0 kg/s of NO2 using the UV instrument and 3.66 (3.63–3.73 kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.

  16. Obesity, eating behaviour and mental health among university students in Mexico city

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    Irina Lazarevich

    2013-12-01

    Full Text Available Introduction: Psychological factors are important in the development of obesity; however these are frequently underestimated in intervention programs. Objective: To examine the association of mental health with altered eating behavior related to weigh gain, and with abdominal obesity among college students in order to provide more comprehensive guidelines for intervention programs. Methods: A cross-sectional study was performed with 1,122 university students (from a total population of 1,820 freshmen students at the Metropolitan Autonomous University, Mexico City. Body mass index and waist circumference (WC were recorded. A six items questionnaire was applied to assess altered eating behavior. Self-reported questionnaires for depression (Beck Depression Inventory, anxiety (General Anxiety Disorder Scale of Carrol and Davidson, and impulsiveness symptoms (Plutchik Impulsivity Scale were used. Multiple logistic regression models were performed. Results: An increased WC was associated with depression symptoms (OR = 1.4, female sex (OR = 1.5, and age (OR = 1.1. Students with altered eating behaviors showed elevated levels of impulsivity (e.g. have difficulties to stop eating, OR = 4.2 and depression (e.g. have problem to eat at regular times, OR=6.98. In addition, higher WC was associated with female sex, parents' obesity, and unhealthy eating behaviors (e.g. have difficulties to stop eating, OR = 1.42; and constantly feel hungry, and eat too much, OR = 2.25. Conclusions: Although preventive programs directed at development of adequate eating habits and physical activity are considered a key component of intervention programs, strategies for the management of emotions, the promotion of positive mood and impulsivity-reduction techniques are a necessary complement for a comprehensive approach to overweight and obesity.

  17. The occurrence and distribution of a group of organic micropollutants in Mexico City's water sources.

    Science.gov (United States)

    Félix-Cañedo, Thania E; Durán-Álvarez, Juan C; Jiménez-Cisneros, Blanca

    2013-06-01

    The occurrence and distribution of a group of 17 organic micropollutants in surface and groundwater sources from Mexico City was determined. Water samples were taken from 7 wells, 4 dams and 15 tanks where surface and groundwater are mixed and stored before distribution. Results evidenced the occurrence of seven of the target compounds in groundwater: salicylic acid, diclofenac, di-2-ethylhexylphthalate (DEHP), butylbenzylphthalate (BBP), triclosan, bisphenol A (BPA) and 4-nonylphenol (4-NP). In surface water, 11 target pollutants were detected: same found in groundwater as well as naproxen, ibuprofen, ketoprofen and gemfibrozil. In groundwater, concentration ranges of salicylic acid, 4-NP and DEHP, the most frequently found compounds, were 1-464, 1-47 and 19-232 ng/L, respectively; while in surface water, these ranges were 29-309, 89-655 and 75-2,282 ng/L, respectively. Eleven target compounds were detected in mixed water. Concentrations in mixed water were higher than those determined in groundwater but lower than the detected in surface water. Different to that found in ground and surface water, the pesticide 2,4-D was found in mixed water, indicating that some pollutants can reach areas where they are not originally present in the local water sources. Concentration of the organic micropollutants found in this study showed similar to lower to those reported in water sources from developed countries. This study provides information that enriches the state of the art on the occurrence of organic micropollutants in water sources worldwide, notably in megacities of developing countries. PMID:23542484

  18. Land subsidence in major cities of Central Mexico: Interpreting InSAR-derived land subsidence mapping with hydrogeological data

    Science.gov (United States)

    Castellazzi, Pascal; Arroyo-Domínguez, Norma; Martel, Richard; Calderhead, Angus I.; Normand, Jonathan C. L.; Gárfias, Jaime; Rivera, Alfonso

    2016-05-01

    Significant structural damages to urban infrastructures caused by compaction of over-exploited aquifers are an important problem in Central Mexico. While the case of Mexico City has been well-documented, insight into land subsidence problems in other cities of Central Mexico is still limited. Among the cities concerned, we present and discuss the cases of five of them, located within the Trans-Mexican Volcanic Belt (TMVB): Toluca, Celaya, Aguascalientes, Morelia, and Queretaro. Applying the SBAS-InSAR method to C-Band RADARSAT-2 data, five high resolution ground motion time-series were produced to monitor the spatio-temporal variations of displacements and fracturing from 2012 to 2014. The study presents recent changes of land subsidence rates along with concordant geological and water data. It aims to provide suggestions to mitigate future damages to infrastructure and to assist in groundwater resources management. Aguascalientes, Celaya, Morelia and Queretaro (respectively in order of decreasing subsidence rates) are typical cases of fault-limited land subsidence of Central Mexico. It occurs as a result of groundwater over-exploitation in lacustrine and alluvial deposits covering highly variable bedrock topography, typical of horst-graben geological settings. Aguascalientes and Toluca show high rates of land subsidence (up to 10 cm/yr), while Celaya and Morelia show lower rates (from 2 to 5 cm/yr). Comparing these results with previous studies, it is inferred that the spatial patterns of land subsidence have changed in the city of Toluca. This change appears to be mainly controlled by the spatial heterogeneity of compressible sediments since no noticeable change occurred in groundwater extraction and related drawdown rates. While land subsidence of up to 8 cm/yr has been reported in the Queretaro Valley before 2011, rates inferior to 1 cm/yr are measured in 2013-2014. The subsidence has been almost entirely mitigated by major changes in the water management

  19. Formation of semivolatile inorganic aerosols in the mexico city metropolitan area during the milagro campaign

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    V. A. Karydis

    2011-08-01

    Full Text Available One of the most challenging tasks for chemical transport models (CTMs is the prediction of the formation and partitioning of the major semi-volatile inorganic aerosol components (nitrate, chloride, ammonium between the gas and particulate phases. In this work the PMCAMx-2008 CTM, which includes the recently developed aerosol thermodynamic model ISORROPIA-II, is applied in the Mexico City Metropolitan Area in order to simulate the formation of the major inorganic aerosol components. The main sources of SO2 (such as the Miguel Hidalgo Refinery and the Francisco Perez Rios Power Plant in the Mexico City Metropolitan Area (MCMA are located in Tula, resulting in high predicted PM1 sulfate concentrations (over 25 μg m−3 in that area. The average predicted PM1 nitrate concentrations are up to 3 μg m−3 (with maxima up to 11 μg m−3 in and around the urban center, mostly produced from local photochemistry. The presence of calcium coming from the Tolteca area (7 μg m−3 as well as the rest of the mineral cations (1 μg m−3 potassium, 1 μg m−3 magnesium, 2 μg m−3 sodium, and 3 μg m−3 calcium from the Texcoco Lake resulted in the formation of a significant amount of aerosol nitrate in the coarse mode with concentrations up to 3 μg m−3 over these areas. PM1−10 chloride is also high and its concentration exceeds 2 μg m−3 in Texcoco Lake. PM ammonium concentrations peak at the center of Mexico City (2 μg m−3 and the Tula vicinity (2.5 μg m−3. The performance of the model for the major inorganic PM components (sulfate, ammonium, nitrate, chloride, sodium, calcium, and magnesium is encouraging. At T0, the average measured values of PM1 sulfate, nitrate, ammonium, and chloride are 3.6 μg m−3, 3.6 μg m−3, 2.1 μg m

  20. Lattice Wind Description and Characterization of Mexico City Local Wind Events in the 2001–2006 Period

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    Alejandro Salcido

    2015-07-01

    Full Text Available Urban transformation and expansion in Mexico City continuously affect its urban morphology, and therefore the modes of wind circulation inside it and their occurrence probabilities. Knowledge on these topics is an important issue for urban planning and for other urban studies, such as air quality assessment. In this paper, using a lattice wind model at a meso-β scale, we develop a simple description and characterization of Mexico City local wind events that occurred during the period 2001–2006, including an estimation of the occurrence probabilities. This region was modeled as a 2D lattice domain of identical cells, and wind conditions in each cell were described by four wind attributes: the horizontal velocity components, divergence, and vorticity. Models of one and four cells were applied to wind data furnished by the meteorological network of the city. Results include the following: Early morning: low intensity winds (75% from N, NW, W and SW (75%, convergent (93%, with a slight predominance of cyclonic vorticity (54%. Morning and early afternoon: winds from N, NE and E (72% with speeds from 0.5 to 3.5 m/s, slight prevailing of convergent winds (51%, and slight predominance of cyclonic vorticity (57%. Late afternoon and night: winds blowing from N, NW, and S (63% with speeds from 1.5 to 3.5 m/s (66%, convergent (90%, and cyclonic (72%.

  1. Simulation of Mexico City plumes during the MIRAGE-Mex field campaign using the WRF-Chem model

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    X. Tie

    2009-07-01

    Full Text Available The quantification of tropospheric O3 production in the downwind of the Mexico City plume is a major objective of the MIRAGE-Mex field campaign. We used a regional chemistry-transport model (WRF-Chem to predict the distribution of O3 and its precursors in Mexico City and the surrounding region during March 2006, and compared the model with in-situ aircraft measurements of O3, CO, VOCs, NOx, and NOy concentrations. The comparison shows that the model is capable of capturing the timing and location of the measured city plumes, and the calculated variability along the flights is generally consistent with the measured results, showing a rapid increase in O3 and its precursors when city plumes are detected. However, there are some notable differences between the calculated and measured values, suggesting that, during transport from the surface of the city to the outflow plume, ozone mixing ratios are underestimated by about 0–25% during different flights. The calculated O3-NOx, O3-CO, and O3-NOz correlations generally agree with the measured values, and the analyses of these correlations suggest that photochemical O3 production continues in the plume downwind of the city (aged plume, adding to the O3 already produced in the city and exported with the plume. The model is also used to quantify the contributions to OH reactivity from various compounds in the aged plume. This analysis suggests that oxygenated organics (OVOCs have the highest OH reactivity and play important roles for the O3 production in the aging plume. Furthermore, O3 production per NOx molecule consumed (O3 production efficiency is more efficient in the aged plume than in the young plume near the city. The major contributor to the high O3 production efficiency in the aged plume is the

  2. Simulation of Mexico City plumes during the MIRAGE-Mex field campaign using the WRF-Chem model

    Directory of Open Access Journals (Sweden)

    X. Tie

    2009-04-01

    Full Text Available The quantification of tropospheric O3 production in the Mexico City outflow is a major objective of the MIRAGE-Mex field campaign. We used a regional chemistry-transport model (WRF-Chem to predict the distribution of O3 and its precursors in Mexico City and the surrounding region during March 2006, and compared with in-situ aircraft measurement of O3, CO, VOCs, NOx, and NOy concentrations. The comparison shows that the model is capable of capturing the timing/location of the measured city plumes, and the calculated variability along the flights is generally consistent with the measured results, showing a rapid enhancement of O3 and its precursors when city plumes are detected. However, there are some notable differences between the calculated and measured values, suggesting that, during transport from the surface of the city to the outflow plume, pollution levels are underestimated by about 0–25% during different flights. The calculated O3-NOx, O3-CO, and O3-NOz correlations generally agree with the measured values, and the analysis of these correlations suggest that photochemical O3 production continues in the plume downwind of the city (aged plume, adding to the O3 already produced in the city and exported with the plume. The model is also used to quantify the contributions to OH reactivity from various compounds in the aged plume. This analysis suggests that oxygenated organics (OVOCs have the highest OH reactivity and play important roles for the O3 production in the aging plume. Furthermore, O3 production per NOx molecule consumed (O3 production efficiency is more efficient in the aged plume than in the young plume near the city. The major contributor to the high O3 production efficiency in the aged plume is the reaction RO2+NO. By

  3. Contribution of biomass burning to particles matter smaller than ten microns in Mexico City during April 2013.

    Science.gov (United States)

    Mendoza Campos, Alejandra; Agustin Garcia Reynoso, Jóse; Castro Romero, Telma; Carbajal Perez, Jóse Noel; Gerardo Ruiz Suarez, Luis; Peralta Rosales, Oscar Augusto

    2015-04-01

    A forest fire is a natural combustion process in a specific geographic area, it's depends on meteorological variables, topography and vegetation type, The wildfires are potential sources of large amounts of pollutants. The main air pollutants emitted in a forest fire are the particles (PM10 and PM2.5) Carbon Monoxide (CO), Nitrogen Oxides (NOx), Volatile Organic Compounds (VOCs) and a negligible amount of Sulfur Dioxide (SO2) (Chow 1995), The study of the impact of air quality in Mexico City for a forest fire occurred on April 14 of 2013 was conducted a duration of 26 hours of grassland burning and consuming an extension of 150 ha, the WRF-Chem, WRF-fire and METv3 models were used to perform the study, for the study two modeling were made, one including emissions from forest fires and the other one no emission-fire, when interpolation is made between the two modeling and obtained the impact of air quality in Mexico City, performing calculating emissions and modeling, the impact on air quality for PM10particles were observed arriving at a concentration of 350 mg/m3 due to wildfire occurred, this issue exceeds the maximum permissible limit of PM10particles governed by NOM-025-SSA1-1993 that establishes a maximum of 120 mg/m3 on average for 24 hours, the modeling results with measured data is corroborated weather Stations the environmental monitoring network of the Mexico City, that alerts an environmental contingency for particles for the post-wildfire day. Until now is review the rule which establishes a maximum of 75 mg/m3 on average for 24 hours, implying greater involvement in air quality.

  4. Urban agriculture in the metropolitan area of Mexico city L’agriculture urbaine dans la métropole de Mexico Agricultura urbana en el área metropolitana de la Ciudad de México

    OpenAIRE

    H. Losada; Rivera, J.; Cortes, J; Vieyra, J.

    2011-01-01

    Mexico City and the rest of the country do not escape from the social and economic inequalities of the present economic model applied worldwide.  Agriculture is a traditional activity in Mexico. This urban productive process has particular features: the predominance of smallholding, the restricted use of physical space, and the use of recycled materials and organic wastes. The population engaged in agriculture is heterogeneous, and includes women and children. There are a couple of production...

  5. Estimation of a "radiatively correct" black carbon specific absorption during the Mexico City Metropolitan Area (MCMA) 2003 field campaign

    OpenAIRE

    Barnard, J. C.; E. I. Kassianov; Ackerman, T. P.; K. Johnson; Zuberi, B.; L. T. Molina; M. J. Molina

    2007-01-01

    During the Mexico City Metropolitan Area (MCMA) field campaign of 2003, measurements of the shortwave radiation field allowed the inference of the black carbon (BC) specific absorption, αλ, defined as the monochromatic absorption cross section per unit mass (with units of m2/g). The averaged values of αλ derived from the method here are either 8.9 m2/g or 8.2 m2/g at 500 nm, depending upon the physical and optical parameters assumed for BC. These re...

  6. Estimation of a "radiatively correct" black carbon specific absorption during the Mexico City Metropolitan Area (MCMA) 2003 field campaign

    OpenAIRE

    Barnard, J. C.; E. I. Kassianov; Ackerman, T. P.; K. Johnson; Zuberi, B.; L. T. Molina; M. J. Molina

    2007-01-01

    During the Mexico City Metropolitan Area (MCMA) field campaign of 2003, measurements of the shortwave radiation field allowed the inference of the black carbon (BC) specific absorption, αλ, defined as the monochromatic absorption cross section per unit mass (with units of m2/g). The averaged values of αλ derived from the method here are either 8.9 m2/g or 8.2 m2/g at 500 nm, depending upon the physical and optical parameters assumed for BC. These results are reasonab...

  7. Incidence of leukemias in children from El Salvador and Mexico City between 1996 and 2000: Population-based data

    OpenAIRE

    Bernáldez-Ríos Roberto; González-Miranda Guadalupe; Pérez-Saldivar María; de Reyes Gladys; Juárez-Ocaña Servando; Lorenzana Rodolpho; Bonilla Miguel; Mejía-Aranguré Juan; Ortiz-Fernández Antonio; Ortega-Alvarez Manuel; Martínez-García María; Fajardo-Gutiérrez Arturo

    2005-01-01

    Abstract Background There are very few studies that report the incidence of acute leukemias in children in Latin America. This work assesses the incidence of acute leukemias, between 1996 and 2000, in children from 0–14 years old who were attended at the Mexican Social Security Institute in Mexico City and in children from 0–11 years old in El Salvador. Methods Design: Population-based data. Hospitals: In San Salvador, El Salvador, Hospital Nacional de Niños "Benjamín Bloom", the only center ...

  8. Elemental contents determination in two different zones of Mexico City on the 1987-88 and 1994-95 winters

    International Nuclear Information System (INIS)

    During the 1987-1988 and 1994-1995 winters, there were taken samples of aerosols in Mexico City, in two different places, using an integral type of sampler which determines the total amount of suspended particulates; these samples were analyzed by the multi-element analysis technique called PIXE (Proton Induced X-ray Emission). One of the sites corresponds to the Alvaro Obregon area and the other to the Azcapotzalco area (a place near to the18 de Marzo Refinery). There were determined 16 elements, heavy metals, whose concentrations show differences for both sites and periods, standing out for this study the behavior of S, V and Pb. (Author)

  9. Caries dental en escolares del Distrito Federal Dental caries in school children in Mexico City

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    MARÍA ESTHER IRIGOYEN-CAMACHO

    1997-03-01

    Full Text Available Objetivo. Presentar las estimaciones de la prevalencia y la severidad de caries dental, así como las necesidades de tratamiento de la población escolar del Distrito Federal examinada en la encuesta de caries dental que se llevó a cabo en 1988 con la finalidad de obtener datos basales sobre caries en los escolares al inicio del Programa Nacional de Fluoruración de la Sal en México. Material y métodos. La población de estudio fue seleccionada empleando un marco muestral basado en el listado de las escuelas primarias y los jardines de niños registrados por la Secretaría de Educación Pública en 1988. En el examen de la cavidad bucal de los escolares se utilizaron los criterios diagnósticos señalados por la Organización Mundial de la Salud. Resultados. Un total de 4 475 escolares de 5 a 12 años de edad participaron en el estudio. La prevalencia de caries dental en la población alcanzó 90.5%. El índice de necesidades de tratamiento fue elevado (79.6%. El promedio de los índices de caries en los escolares de 12 años de edad fue CPOD= 4.42 (desviación estándar –DE– 3.2 y CPOS= 6.53 (DE 4.8. Conclusiones. Los resultados de la encuesta subrayan la pertinencia de un programa preventivo de amplia cobertura, como el de fluoruración de la sal. Además, muestran que se requiere elaborar estrategias para mejorar el acceso de la población escolar a los servicios odontológicos del sistema de salud en México.Objective. To estimate the prevalence and severity of dental caries and the dental treatment necessities of school children in Mexico City. The studied population was surveyed for dental caries in 1988 to obtain data necessary for the National Program of Salt Fluoridation in Mexico. Material and methods. The population was selected with a sample frame based on a list of Kindergardens and primary schools registered at the Ministry of Public Education in 1988. The oral cavity examination was based on diagnostic criteria marked by the

  10. Determination of particle size and content of metals in the atmosphere of ZMCM (Metropolitan Zone of Mexico City)

    International Nuclear Information System (INIS)

    Inside the breathable fraction of the atmosphere of Mexico City, the presence of metals in suspended particles, is determined and quantified. The detection was carry out simultaneously in three places of the city, using collectors of the type stacking filter unit (SFU) which allow the separation of particles according to its size. The SFU detectors allow the separation in two size: 'Gross' mass from 2.5 to 1.5 μm and 'fine' mass for particles smallest than 2.5 μm. The analysis of the samples was fulfilled by means of PIXE method. Samples were irradiated with a proton beam, and based in the X-ray spectra the elements were identified and quantified, which allow to establish the temporal behavior of the concentrations per element for gross mass and fine mass in each one of the places of sampling. (Author)

  11. Non-methane hydrocarbons in the atmosphere of Mexico City: Results of the 2012 ozone-season campaign

    Science.gov (United States)

    Jaimes-Palomera, Mónica; Retama, Armando; Elias-Castro, Gabriel; Neria-Hernández, Angélica; Rivera-Hernández, Olivia; Velasco, Erik

    2016-05-01

    With the aim to strengthen the verification capabilities of the local air quality management, the air quality monitoring network of Mexico City has started the monitoring of selected non-methane hydrocarbons (NMHCs). Previous information on the NMHC characterization had been obtained through individual studies and comprehensive intensive field campaigns, in both cases restricted to sampling periods of short duration. This new initiative will address the NMHC pollution problem during longer monitoring periods and provide robust information to evaluate the effectiveness of new control measures. The article introduces the design of the monitoring network and presents results from the first campaign carried out during the first six months of 2012 covering the ozone-season (Mar-May). Using as reference data collected in 2003, results show reductions during the morning rush hour (6-9 h) in the mixing ratios of light alkanes associated with the consumption and distribution of liquefied petroleum gas and aromatic compounds related with the evaporation of fossil fuels and solvents, in contrast to olefins from vehicular traffic. The increase in mixing ratios of reactive olefins is of relevance to understand the moderate success in the ozone and fine aerosols abatement in recent years in comparison to other criteria pollutants. In the case of isoprene, the typical afternoon peak triggered by biogenic emissions was clearly observed for the first time within the city. The diurnal profiles of the monitored compounds are analyzed in terms of the energy balance throughout the day as a surrogate of the boundary layer evolution. Particular features of the diurnal profiles and correlation between individual NMHCs and carbon monoxide are used to investigate the influence of specific emission sources. The results discussed here highlight the importance of monitoring NMHCs to better understand the drivers and impacts of air pollution in large cities like Mexico City.

  12. Modeling the impacts of biomass burning on air quality in and around Mexico City

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    W. Lei

    2013-03-01

    Full Text Available The local and regional impacts of open fires and trash burning on ground-level ozone (O3 and fine carbonaceous aerosols in the Mexico City Metropolitan Area (MCMA and surrounding region during two high fire periods in March 2006 have been evaluated using WRF-CHEM model. The model captured reasonably well the measurement-derived magnitude and temporal variation of the biomass burning organic aerosol (BBOA, and the simulated impacts of open fires on organic aerosol (OA were consistent with many observation-based estimates. We did not detect significant effects of open fires and trash burning on surface O3 concentrations in the MCMA and surrounding region. In contrast, they had important influences on OA and elemental carbon (EC, increasing primary OA (POA by ~60%, secondary OA (SOA by ~22%, total OA (TOA = POA + SOA by ~33%, and EC by ~22%, on both the local (urban and regional scales. Although the emissions of trash burning are substantially lower than those from open fires, trash burning made slightly smaller but comparable contributions to OA as open fires did, and exerted an even higher influence on EC. Of the ~22% enhancement in SOA concentrations (equivalent to a ~15% increase in TOA simulated, about two third was attributed to the open fires and one-third to the trash burning. On the annual basis and taking the biofuel use emissions into consideration, we estimated that open fires, trash burning and biofuel use together contributed about 60% to the loading of POA, 30% to SOA, and 25% to EC in both the MCMA and its surrounding region, of which the open fires and trash burning contributed about 35% to POA, 18% to SOA, and 15% to EC. The estimates of biomass burning impacts in this study may contain considerable uncertainties due to the uncertainties in their emission estimates in magnitude, temporal and spatial distribution, extrapolations and the nature of spot comparison. More observation and modeling studies are needed to accurately assess

  13. Modeling the impacts of biomass burning on air quality in and around Mexico City

    Science.gov (United States)

    Lei, W.; Li, G.; Molina, L. T.

    2013-03-01

    The local and regional impacts of open fires and trash burning on ground-level ozone (O3) and fine carbonaceous aerosols in the Mexico City Metropolitan Area (MCMA) and surrounding region during two high fire periods in March 2006 have been evaluated using WRF-CHEM model. The model captured reasonably well the measurement-derived magnitude and temporal variation of the biomass burning organic aerosol (BBOA), and the simulated impacts of open fires on organic aerosol (OA) were consistent with many observation-based estimates. We did not detect significant effects of open fires and trash burning on surface O3 concentrations in the MCMA and surrounding region. In contrast, they had important influences on OA and elemental carbon (EC), increasing primary OA (POA) by ~60%, secondary OA (SOA) by ~22%, total OA (TOA = POA + SOA) by ~33%, and EC by ~22%, on both the local (urban) and regional scales. Although the emissions of trash burning are substantially lower than those from open fires, trash burning made slightly smaller but comparable contributions to OA as open fires did, and exerted an even higher influence on EC. Of the ~22% enhancement in SOA concentrations (equivalent to a ~15% increase in TOA) simulated, about two third was attributed to the open fires and one-third to the trash burning. On the annual basis and taking the biofuel use emissions into consideration, we estimated that open fires, trash burning and biofuel use together contributed about 60% to the loading of POA, 30% to SOA, and 25% to EC in both the MCMA and its surrounding region, of which the open fires and trash burning contributed about 35% to POA, 18% to SOA, and 15% to EC. The estimates of biomass burning impacts in this study may contain considerable uncertainties due to the uncertainties in their emission estimates in magnitude, temporal and spatial distribution, extrapolations and the nature of spot comparison. More observation and modeling studies are needed to accurately assess the

  14. Oxidative capacity of the Mexico City atmosphere – Part 1: A radical source perspective

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    M. J. Molina

    2007-04-01

    Full Text Available A detailed analysis of OH, HO2 and RO2 radical sources is presented for the near field photochemical regime inside the Mexico City Metropolitan Area (MCMA. During spring of 2003 (MCMA-2003 field campaign an extensive set of measurements was collected to quantify time resolved ROx (sum of OH, HO2, RO2 radical production rates from day- and nighttime radical sources. The Master Chemical Mechanism (MCMv3.1 was constrained by measurements of (1 concentration time-profiles of photosensitive radical precursors, i.e., nitrous acid (HONO, formaldehyde (HCHO, ozone (O3, glyoxal (CHOCHO, and other oxygenated volatile organic compounds (OVOCs; (2 respective photolysis-frequencies (J-values; (3 concentration time-profiles of alkanes, alkenes, and aromatic VOCs (103 compound are treated and oxidants, i.e., OH- and NO3 radicals, O3; and (4 NO, NO2, meteorological and other parameters. The ROx production rate was calculated directly from these observations; MCM was used to estimate further ROx production from unconstrained sources, and express overall ROx production as OH-equivalents (i.e., taking into account the propagation efficiencies of RO2 and HO2 radicals into OH radicals. Daytime radical production is found to be about 10-25 times higher than at night; it does not track the abundance of sunlight. 12-h average daytime contributions of individual sources are: HCHO and O3 photolysis, each about 20%; O3/alkene reactions and HONO photolysis, each about 15%; unmeasured sources about 30%. While the direct contribution of O3/alkene reactions appears to be moderately small, source-apportionment of ambient HCHO and HONO identifies O3/alkene reactions as being largely responsible for jump-starting photochemistry about one hour after sunrise. The peak radical production is found to be higher than in any other urban influenced environment studied to date; further, differences exist in the timing of radical production. Our measurements and analysis comprise a

  15. Atmospheric dry deposition fluxes of trace elements measured in Queretaro City, Mexico

    Science.gov (United States)

    Garcia, R.; Hernandez, R.; Solis, S.; Perez, R.; Hernandez, G.; Morton, O.; Hernandez, E.; Torres, M. C.; Baez, A.

    2012-04-01

    Sampling was made in the southern section of downtown Mexico City. Samples were collected with an Mini-Vol PM10 . Eight different sources were identified for PM10 aerosols: secondary sulfate, wood combustion, fireworks, road traffic, mineral dust, de-icing salt, industrial and local anthropogenic activities. The ions SO42-, NO3-, Cl-, Na+, K+, Ca2+, Mg2+ and NH4+,were analyzed by ion chromatography and the trace metals using an atomic absorption spectrometer. The result indicated that SO42- was the most abundant ion and with respect to trace metal. All the trace elements except Mn and V show statistically significant differences between monitoring sites. The Pearson's correlation applied to all data, showed a high correlation among SO42-, NO3- and NH4+, indicating a common anthropogenic origin. In addition the correlation found between Ca2+ and Al indicated a crustal origin. On the other hand, in considering the total sampling period for particles as well as for all the metals, it is appreciable the significant differences between sites and meteorological seasons. The cluster analysis of air back-trajectories employed in the paper is a technique widely used to identify transport patterns and potential sources of both anthropogenic pollution and natural constituents of the atmosphere, including atmospheric aerosols. It is also used to determine how aerosol optical properties observed over the station differ depending on source region and transport pathways In order to gain a better insight into the origin of trace metal and major inorganic ions, a Principal Component Analysis was applied to the results for 6 elements and 8 ions, from the years 2009 and 2010. Further, the statistical analysis demonstrated the adequate selection of the monitoring areas, confirming that main emission source of these atmospheric pollutants is anthropogenic origin. Evidence suggests that the organic and inorganic species are not always internally mixed, especially in the small modes. The

  16. Exposure of children to air pollution in the industrial zone of Metropolitan Area of Mexico City

    Science.gov (United States)

    Mugica-Alvarez, Violeta; Quintanilla-Vega, Betsabé; De Vizcaya-Ruiz, Andrea; Alvarado-Cruz, Isabel

    2016-04-01

    An air quality monitoring in three schools located in the most important industrial zone at the Northeast of the Metropolitan Area of Mexico City (MAMC) was conducted in order to determine the exposure of children to toxics contained in PM10. Particles were analyzed for metals, polycyclic aromatic hydrocarbons (PAH), organic and elemental carbon by ICP-AES, GC-MS and TOT (Sunset lab) respectively. Average concentration of PM10 was 108.4±11.6 μg/m3. Most abundant metals were Fe, Zn and Pb with concentrations ranged by 1.1-5.4 μg/m3, 0.3-2 μg/m3, and 0.18-0.63 μg/m3 respectively; the sum of the seventeen PAHs varied from 1.4 to 3.3 ng/m3 where most abundant PAH were indene[1,2,3-c,d]pyrene, benzo[b]fluoranthene, benzo[a]anthracene, chrysene, and benzo[a]pyrene. The sum of the seven carcinogenic PAH contributed in average with the 48% of the total mixture. Carcinogenic potential of PAH were obtained using toxic equivalent factors determined by Nisbet and La Goy which varied from 0.3 to 0.6 ng/ m3 of benzo[a]pyrene equivalent (BAPeq), this value is lower than the standard proposed for the European Community of 1 ng/ m3, but higher than the standard from the United Kingdom of 0.25 ng/ m3. Principal component analysis for source apportionment showed that vehicular and industrial emissions are the main sources of PM in the zone. In general, the concentrations of particles as well as concentration of metals and PAHs are lower than concentrations measured six year before, showing that the established measures have improved the air quality. Nevertheless these PM10 concentrations exceeded frequently the Mexican Standard and children are especially susceptible due to the higher risk to develop diseases if the exposure occurs at early age.

  17. Evaluation of new secondary organic aerosol models for a case study in Mexico City

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    K. Dzepina

    2009-02-01

    Full Text Available Recent field studies have found large discrepancies in the measured vs. modeled SOA mass loadings in both urban and regional polluted atmospheres. The reasons for these large differences are unclear. Here we revisit a case study of SOA formation in Mexico City described by Volkamer et al. (2006, during a photochemically active period when the impact of regional biomass burning is minor or negligible, and show that the observed increase in OA/ΔCO is consistent with results from several groups during MILAGRO 2006. Then we use the case study to evaluate three new SOA models: 1 the update of aromatic SOA yields from recent chamber experiments (Ng et al., 2007; 2 the formation of SOA from glyoxal (Volkamer et al., 2007a; and 3 the formation of SOA from primary semivolatile and intermediate volatility species (P-S/IVOC (Robinson et al., 2007. We also evaluate the effect of reduced partitioning of SOA into POA (Song et al., 2007. Traditional SOA precursors (mainly aromatics by themselves still fail to produce enough SOA to match the observations by a factor of 7. The new low-NOx aromatic pathways with very high SOA yields make a very small contribution in this high-NOx urban environment as the RO2.+NO reaction dominates the fate of the RO2. radicals. Glyoxal contributes several μg m−3 to SOA formation, with similar timing as the measurements. P-S/IVOC are estimated from equilibrium with emitted POA, and introduce a large amount of gas-phase oxidizable carbon that was not in models before. With the formulation in Robinson et al. (2007 these species have a high SOA yield, and this mechanism can close the gap in SOA mass between measurements and models in our case study. However the volatility of SOA produced in the model is too high and the O/C ratio is lower than observations. Glyoxal SOA helps to bring the O/C ratio of predicted and observed SOA into better agreement. The

  18. Risk of Giardia intestinalis infection in children from an artificially recharged groundwater area in Mexico City.

    Science.gov (United States)

    Cifuentes, Enrique; Suárez, Leticia; Espinosa, Martha; Juárez-Figueroa, Luis; Martínez-Palomo, Adolfo

    2004-07-01

    The objective of this study was to assess the risk of infection with Giardia intestinalis in children living in an area with artificial groundwater recharge and potable water reuse in Mexico City. Eligible wells and surrounding homesteads were defined by using a geographic information system. Five wells were tested for G. intestinalis cysts per 400 liters of water. A total of 750 eligible households were visited during two cross-sectional surveys. Stool samples were provided by 986 children in the rainy season study and 928 children during the dry season survey for parasitologic tests. Their guardians provided information on water, sanitation, hygiene, and socioeconomic variables. The prevalence rates of G. intestinalis infection were 9.4% in the rainy season and 4.4% in the dry season. Higher rates of infection were observed in older individuals (9.5% and 10.6%) and girls had a lower risk of infection than boys (odds ratio [OR] =0.55, 95% confidence interval [CI] = 0.34, 0.88 in the rainy season and OR = 0.47, 95% CI = 0.25, 0.90 in the dry season). During the wet season survey, a health risk was detected among those storing water in unprotected receptacles (OR = 4.00, 4.69, and 5.34 for those using uncovered jars, cisterns or tanks, and buckets, respectively), and bathing outside the dwelling, i.e., using a tap (OR = 1.93, 95% CI = 1.10, 3.39). A health risk was also detected among children from households with unsafe food hygiene practices (OR =2.41, 95% CI =1.10, 5.30) and those with no hand-washing habits (OR = 2.27, 95% CI = 1.00, 5.20). Groundwater reserves are at risk of fecal pollution, as indicated by the presence of G. intestinalis cysts. However, the endemic pattern of intestinal infection reflects low standards of personal hygiene and unsafe drinking water storage and food-related practices at household level. Prevention activities must address health education and environmental protection policies. PMID:15238691

  19. Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

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    M. Zavala

    2008-08-01

    Full Text Available The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on the photochemistry in the region using observational and modeling approaches. The observed historical trends of ozone (O3, carbon monoxide (CO and nitrogen oxides (NOx suggest that ozone production in the MCMA has changed from a low to a high VOC-sensitive regime over a period of 20 years. Comparison of the historical emission trends of CO, NOx and hydrocarbons derived from mobile-source emission studies in the MCMA from 1991 to 2006 with the trends of the concentrations of CO, NOx, and the CO/NOx ratio during peak traffic hours also indicates that fuel-based fleet average emission factors have significantly decreased for CO and VOCs during this period whereas NOx emission factors do not show any strong trend, effectively reducing the ambient VOC/NOx ratio.

    This study presents the results of model analyses on the sensitivity of the observed ozone levels to the estimated historical changes in its precursors. The model sensitivity analyses used a well-validated base case simulation of a high pollution episode in the MCMA with the mathematical Decoupled Direct Method (DDM and the standard Brute Force Method (BFM in the 3-D CAMx chemical transport model. The model reproduces adequately the observed historical trends and current photochemical levels. Comparison of the BFM and the DDM sensitivity techniques indicates that the model yields ozone values that increase linearly with

  20. Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

    Directory of Open Access Journals (Sweden)

    M. Zavala

    2009-01-01

    Full Text Available The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on the photochemistry in the region using observational and modeling approaches. The observed historical trends of ozone (O3, carbon monoxide (CO and nitrogen oxides (NOx suggest that ozone production in the MCMA has changed from a low to a high VOC-sensitive regime over a period of 20 years. Comparison of the historical emission trends of CO, NOx and hydrocarbons derived from mobile-source emission studies in the MCMA from 1991 to 2006 with the trends of the concentrations of CO, NOx, and the CO/NOx ratio during peak traffic hours also indicates that fuel-based fleet average emission factors have significantly decreased for CO and VOCs during this period whereas NOx emission factors do not show any strong trend, effectively reducing the ambient VOC/NOx ratio.

    This study presents the results of model analyses on the sensitivity of the observed ozone levels to the estimated historical changes in its precursors. The model sensitivity analyses used a well-validated base case simulation of a high pollution episode in the MCMA with the mathematical Decoupled Direct Method (DDM and the standard Brute Force Method (BFM in the 3-D CAMx chemical transport model. The model reproduces adequately the observed historical trends and current photochemical levels. Comparison of the BFM and the DDM sensitivity techniques indicates that the model yields ozone values that increase linearly with

  1. From "The Weak Sex" to "The Devout Sex": Women, Gender, and Official Church Discourses in Early Nineteenth-Century Mexico City

    OpenAIRE

    Witschorik, Charles A.

    2011-01-01

    This paper examines the evolution of the gendered discourses in published, officially sanctioned church sermons and other writings from the opening decades of the nineteenth century in Mexico City. In studying these discourses, I argue that they constitute a significant, as yet little studied dimension of the history of the Catholic Church in nineteenth-century Mexico, offering instructive clues about how the institution evolved and adapted itself to changing political and social contexts in ...

  2. Seasonal trends in black carbon properties and co-pollutants in Mexico City

    Directory of Open Access Journals (Sweden)

    A. Retama

    2015-04-01

    Full Text Available The Mexico City Metropolitan Area (MCMA is a region that continues to grow in population and vehicular traffic as well as being the largest source of short lived climate pollutants (SLCP in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e. ozone (O3 and carbon monoxide (CO, but particulate matter (PM2.5 and PM10 and black carbon (BC have shown little response to mitigation strategies that have been in place for more than two decades. For the first time, extended measurements have been made of equivalent black carbon (eBC, derived from light absorption measurements made with a Photoacoustic Extinctiometer (PAX, over a 13 month period from March 2013 through March 2014. The daily trends in workday (Monday through Saturday and Sunday eBC, PM2.5 and the co-pollutants CO, O3 and NOx are evaluated with respect to the three primary seasons in that region: rainy, cold-dry and warm-dry. The maximum values in all of the particle and gas concentrations were significantly larger (Student's t test, P2.5, CO, O3, and NOx were 8.8 to 13.1 μg m-3 (40%, 49 to 73 μg m-3 (40%, 2.5 to 3.8 ppm (40%, 73 to 100 ppb (30% and 144 to 252 ppb (53%, respectively. The primary factors that lead to these large changes between the wet and dry seasons are the accelerated vertical mixing of boundary layer and free tropospheric air by the formation of clouds that dilutes the concentration of the SLCPs and the decreased actinic flux that reduces the production of ozone by photochemical reactions. A significant "weekend effect" was also identified, particularly the decrease in BC due to fewer large transport vehicles that are fueled by diesel that produces a large fraction of the BC emissions. The other co-pollutant concentrations are also significantly less on weekends except for O3 that shows no change in maximum values from workday to Sunday. As has been noted in previous studies, this lack of change is a

  3. Seasonal trends in black carbon properties and co-pollutants in Mexico City

    Science.gov (United States)

    Retama, A.; Baumgardner, D.; Raga, G. B.; McMeeking, G. R.; Walker, J. W.

    2015-04-01

    The Mexico City Metropolitan Area (MCMA) is a region that continues to grow in population and vehicular traffic as well as being the largest source of short lived climate pollutants (SLCP) in Latin America. The local city government has made significant progress in controlling some of these pollutants, i.e. ozone (O3) and carbon monoxide (CO), but particulate matter (PM2.5 and PM10) and black carbon (BC) have shown little response to mitigation strategies that have been in place for more than two decades. For the first time, extended measurements have been made of equivalent black carbon (eBC), derived from light absorption measurements made with a Photoacoustic Extinctiometer (PAX), over a 13 month period from March 2013 through March 2014. The daily trends in workday (Monday through Saturday) and Sunday eBC, PM2.5 and the co-pollutants CO, O3 and NOx are evaluated with respect to the three primary seasons in that region: rainy, cold-dry and warm-dry. The maximum values in all of the particle and gas concentrations were significantly larger (Student's t test, P< 0.05) during the dry periods than in the rainy season. The changes from rainy to dry seasons for eBC, PM2.5, CO, O3, and NOx were 8.8 to 13.1 μg m-3 (40%), 49 to 73 μg m-3 (40%), 2.5 to 3.8 ppm (40%), 73 to 100 ppb (30%) and 144 to 252 ppb (53%), respectively. The primary factors that lead to these large changes between the wet and dry seasons are the accelerated vertical mixing of boundary layer and free tropospheric air by the formation of clouds that dilutes the concentration of the SLCPs and the decreased actinic flux that reduces the production of ozone by photochemical reactions. A significant "weekend effect" was also identified, particularly the decrease in BC due to fewer large transport vehicles that are fueled by diesel that produces a large fraction of the BC emissions. The other co-pollutant concentrations are also significantly less on weekends except for O3 that shows no change in maximum

  4. Seasonal variation of atmospheric lead levels in three sites in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Rosas, Irma; Belmont, Raul; Jauregui, Ernesto [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico)

    1995-10-01

    Atmospheric lead concentrations associated to particles smaller than 10 {mu}m were measured in Mexico City, to establish changes of levels of this pollutant in three sites (industrial, commercial and residential) for 1990-1991. Moreover, an attempt was made to establish a possible link between this airborne pollutant and blood lead levels reported in children and women living near the sampling sites. A marked gradient in atmospheric lead from North to South is observed with higher and more variable mean lead values in the northern site where industry is located. Lead concentrations and their corresponding variability gradually decrease (from about 1.2 to 0.5 {mu}g m-3) toward the southern suburbs. Moreover, these values are significantly higher during the dry season than in the wet season when a marked washout effect if observed. However, the quarterly averages recorded during the sampling time do not exceed the international standard (1.5 {mu}g m-3). Lead concentrations and corresponding PM{sub 1}0 values showed a significant correlation. This results shows that lead is associated to the fine fraction of airborne particles, with high proportion of them deposited in the respiratory tract. A substantial abatement in levels of atmospheric lead is observed in 1991 with respect to the previous year. This may be explained by the introduction of improved quality gasoline in the capital city. In spite of this measure more than 30% of the evaluated population in 1991 presented blood-lead levels> 10 {mu}g dL-1. [Spanish] Durante 1991 se evaluaron en tres sitios (industrial, comercial y residencial), las concentraciones de plomo atmosferico asociado a particulas menores de 10 {mu}m, con el objeto de establecer los cambios en los niveles de este contaminante. Ademas, se trato de establecer la posible relacion de este contaminante con los niveles de plomo en sangre citados para ninos y mujeres que viven en los alrededores de los sitios de muestreo. Se observo un marcado

  5. canal24

    Data.gov (United States)

    California Department of Resources — Canal system center lines in the Central Valley of California and adjacent areas captured from 1:24,000-scale USGS topographic maps. Updates and modifications made...

  6. A comparative simple method for human bioclimatic conditions applied to seasonally hot/warm cities of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Tejeda Martinez, A. [Universidad Veracruzana, Xalapa, Veracruz (Mexico); Garcia Cueto, O.R. [Universidad Autonoma de Baja California, Mexicali, B.C. (Mexico)

    2002-01-01

    The climate of a region is an environmental resource with important implications for things such as thermal comfort, health and productivity of the population. In this work, the bioclimatic comfort was evaluated for seven seasonally warm/hot cities of Mexico by means of the following current indexes: Discomfort Index, Enthalpy Index and Heat Strain Index. Also, the periods during which it is necessary to use air conditioning in the studied cities were calculated from estimated global radiation and hourly data of temperature and relative humidity which made it possible to establish them with high precision. Finally, the useful of the Heat Strain Index is shown. It is a simple index needing available meteorological data to compare bioclimatic conditions of similar sites. [Spanish] El clima regional tiene implicaciones en el confort, la salud y la productividad de la poblacion. En este articulo se presentan las evaluaciones bioclimaticas comparativas de siete ciudades calidas de Mexico. Se aplicaron los indices bioclimaticos de disconfort, entalpia y esfuerzo frente al calor. Se calcularon los periodos para los cuales es necesario el uso de aire acondicionado, a partir de estimaciones de radiacion solar global y de temperatura y humedad horarias medias mensuales. Finalmente se muestra la utilidad y calidad del Indice de esfuerzo frente al calor, el cual requiere solo de datos climatologicos comunes para poder comparar condiciones bioclimaticas de sitios similares.

  7. Analysis of Mexico City urban air pollution using nitrogen dioxide column density measurements from UV/Visible spectroscopy

    Science.gov (United States)

    Garcia Payne, D. G.; Grutter, M.; Melamed, M. L.

    2010-12-01

    The differential optical absorption spectroscopy method (DOAS) was used to get column densities of nitrogen dioxide (NO2) from the analysis of zenith sky UV/visible spectra. Since the optical path length provides critical information in interpreting NO2 column densities, in conjunction with NO2 column densities, the oxygen dimer (O4) column density was retrieved to give insight into the optical path length. We report observations of year round NO2 and O4 column densities (from august 2009 to september 2010) from which the mean seasonal levels and the daily evolution, as well as the occurrence of elevated pollution episodes are examined. Surface nitric oxide (NO) and NO2 from the local monitoring network, as well as wind data and the vertical aerosol density from continuous Lidar measurements are used in the analysis to investigate specific events in the context of local emissions from vehicular traffic, photochemical production and transport from industrial emissions. The NO2 column density measurements will enhance the understanding Mexico City urban air pollution. Recent research has begun to unravel the complexity of the air pollution problem in Mexico City and its effects not only locally but on a regional and global scale as well.

  8. Comparison of lead levels in human permanent teeth from Strasbourg, Mexico City, and rural zones of Alsace

    International Nuclear Information System (INIS)

    A comparative study of the mean lead concentrations in enamel and dentin of human premolars and permanent molars was conducted by means of a systematic sampling procedure with energy-dispersive x-ray fluorescence analysis. In a first series of analyses, no significant statistical differences in mean lead concentrations at various levels of enamel and dentin were noted between young patients of Strasbourg and those of small villages of Alsace, nor between elderly patients living in these two locations, despite the fact that motor traffic was significantly lower in the rural zones. However, in both locations, a significantly higher concentration of lead was observed in enamel and dentin in relation to age. In a second series of analyses, the mean lead concentrations of both dental hard tissues of premolars and permanent molars of young individuals from Strasbourg, rural Alsace, and Mexico City were compared. Significantly higher mean lead concentrations were found in enamel and dentin samples from Mexico City. This was most evident for inner coronal dentin (5.7 and 6.1 times greater than in teeth of Strasbourg and rural zones of Alsace, respectively) and for pulpal root dentin (6.9 and 8.9 times greater than in teeth of Strasbourg and rural zones of Alsace). It is proposed that the higher lead concentrations are related to the higher lead content of motor gasoline and to more intense traffic conditions. The dental hard tissues appear to be of value for the study of environmental lead pollution

  9. Characterization of Fine Particulate Matter (PM) and Secondary PM Precursor Gases in the Mexico City Metropolitan Area

    Science.gov (United States)

    Molina, Luisa T.; Volkamer, Rainer; de Foy, Benjamin; Lei, Wenfang; Zavala, Miguel; Velasco, Erik; Molina; Mario J.

    2008-10-31

    This project was one of three collaborating grants funded by DOE/ASP to characterize the fine particulate matter (PM) and secondary PM precursors in the Mexico City Metropolitan Area (MCMA) during the MILAGRO Campaign. The overall effort of MCMA-2006, one of the four components, focused on i) examination of the primary emissions of fine particles and precursor gases leading to photochemical production of atmospheric oxidants and secondary aerosol particles; ii) measurement and analysis of secondary oxidants and secondary fine PM production, with particular emphasis on secondary organic aerosol (SOA), and iii) evaluation of the photochemical and meteorological processes characteristic of the Mexico City Basin. The collaborative teams pursued the goals through three main tasks: i) analyses of fine PM and secondary PM precursor gaseous species data taken during the MCMA-2002/2003 campaigns and preparation of publications; ii) planning of the MILAGRO Campaign and deployment of the instrument around the MCMA; and iii) analysis of MCMA-2006 data and publication preparation.

  10. Potential prescription patterns and errors in elderly adult patients attending public primary health care centers in Mexico City

    Directory of Open Access Journals (Sweden)

    José Antonio Corona-Rojo

    2009-08-01

    Full Text Available José Antonio Corona-Rojo1, Marina Altagracia-Martínez1, Jaime Kravzov-Jinich1, Laura Vázquez-Cervantes1, Edilberto Pérez-Montoya2, Consuelo Rubio-Poo31Division of Biological Sciences and Health, Metropolitan Autonomous University, Campus Xochimilco (UAM-X, Xochimilco, México; 2National Polytechnical Institute (IPN, México DF; 3Faculty of Higher Studies – Zaragoza (FES-Zaragoza, National Autonomous University of México (UNAM, México City, MéxicoIntroduction: Six out of every 10 elderly persons live in developing countries.Objective: To analyze and assess the drug prescription patterns and errors in elderly outpatients attending public health care centers in Mexico City, Mexico.Materials and methods: A descriptive and retrospective study was conducted in 2007. Fourteen hundred prescriptions were analyzed. Prescriptions of ambulatory adults aged >70 years who were residents of Mexico City for at least two years were included. Prescription errors were divided into two groups: (1 administrative and legal, and (2 pharmacotherapeutic. In group 2, we analyzed drug dose strength, administration route, frequency of drug administration, treatment length, potential drug–drug interactions, and contraindications. Variables were classified as correct or incorrect based on clinical literature. Variables for each drug were dichotomized as correct (0 or incorrect (1. A Prescription Index (PI was calculated by considering each drug on the prescription. SPSS statistical software was used to process the collected data (95% confidence interval; p < 0.05.Results: The drug prescription pattern in elderly outpatients shows that 12 drugs account for 70.72% (2880 of prescribed drugs. The most prescribed drugs presented potential pharmacotherapeutic errors (as defined in the present study. Acetylsalicylic acid–captopril was the most common potential interaction (not clinically assessed. Potential prescription error was high (53% of total prescriptions. Most

  11. The role of a peri-urban forest on air quality improvement in the Mexico City megalopolis

    International Nuclear Information System (INIS)

    Air quality improvement by a forested, peri-urban national park was quantified by combining the Urban Forest Effects (UFORE) and the Weather Research and Forecasting coupled with Chemistry (WRF-Chem) models. We estimated the ecosystem-level annual pollution removal function of the park’s trees, shrub and grasses using pollution concentration data for carbon monoxide (CO), ozone (O3), and particulate matter less than 10 microns in diameter (PM10), modeled meteorological and pollution variables, and measured forest structure data. Ecosystem-level O3 and CO removal and formation were also analyzed for a representative month. Total annual air quality improvement of the park’s vegetation was approximately 0.02% for CO, 1% for O3, and 2% for PM10, of the annual concentrations for these three pollutants. Results can be used to understand the air quality regulation ecosystem services of peri-urban forests and regional dynamics of air pollution emissions from major urban areas. - Highlights: ► Air quality regulation functions and ecosystem structure of a peri-urban forest in Mexico were quantified. ► Air pollution removal-formation dynamics were estimated using the UFORE and WRF-Chem models. ► Peri-urban forests positively contributed to air qualtiy improvement in Mexico City. ► Results can be used to quantify the ecosystem services of peri-urban forests. - Coupled models estimated air quality improvement and pollution removal-formation by peri-urban forest ecosystems in the Mexico City airshed.

  12. Vehicle fleet emissions of black carbon, polycyclic aromatic hydrocarbons, and other pollutants measured by a mobile laboratory in Mexico City

    Directory of Open Access Journals (Sweden)

    M. Jiang

    2005-01-01

    Full Text Available Black carbon (BC and polycyclic aromatic hydrocarbons (PAHs are of concern due to their effects on climate and health. The main goal of this research is to provide the first estimate of emissions of BC and particle-phase PAHs (PPAHs from motor vehicles in Mexico City. The emissions of other pollutants including carbon monoxide (CO, oxides of nitrogen (NOx, volatile organic compounds (VOCs, and particulate matter of diameter 2.5 μm and less (PM2.5 are also estimated. As a part of the Mexico City Metropolitan Area field campaign in April 2003 (MCMA-2003, a mobile laboratory was driven throughout the city. The laboratory was equipped with a comprehensive suite of gas and particle analyzers, including an aethalometer that measured BC and a photoionization aerosol sensor that measured PPAHs. While driving through traffic, the mobile lab continuously sampled exhaust plumes from the vehicles around it. We have developed a method of automatically identifying exhaust plumes, which are then used as the basis for calculation of fleet-average emissions. In the approximately 75 h of on-road sampling during the field campaign, we have identified ~30 000 exhaust measurement points that represent a variety of vehicle types and driving conditions. The large sample provides a basis for estimating fleet-average emission factors and thus the emission inventory. Motor vehicles in the Mexico City area are estimated to emit 1700±200 metric tons BC, 57±6 tons PPAHs, 1 190 000±40 000 tons CO, 120 000±3000 tons NOx, 240 000±50 000 tons VOCs, and 4400±400 tons PM2.5 per year, not including cold start emissions. The estimates for CO, NOx, and PPAHs may be low by up to 10% due to the slower response time of analyzers used to measure these species. Compared to the government's official motor vehicle emission inventory for the year 2002, the estimates for CO, NOx, VOCs, and PM2.5 are 38% lower, 23% lower, 27% higher, and 25% higher, respectively. The

  13. Breast cancer quality of life evaluation in Mexican Women at La Raza Hospital, Mexico City: A preliminary approach

    Directory of Open Access Journals (Sweden)

    Jacobo Alejandro Gómez-Rico

    2008-11-01

    Full Text Available Jacobo Alejandro Gómez-Rico1, Marina Altagracia-Martínez1, Jaime Kravzov-Jinich1, Rosario Cárdenas-Elizalde1, Juan Carlos Hinojosa-Cruz2, Consuelo Rubio-Poo31Departments of Biological Systems and Healthcare, Biological and Health Sciences Division (DCBS, Universidad Autónoma Metropolitana–Xochimilco (UAM-X, Xochimilco, Mexico; 2La Raza Hospital of the Mexican Social Security Institute (IMSS, Mexico City, Mexico; 3Universidad Nacional Autónoma de México (UNAM, Faculty of Professional Studies, Zaragoza (FES-Zaragoza, MexicoAbstract: Breast cancer (BC is the second leading cause of death among Mexican women over 40 years of age. This study aimed to identify and examine the effects of cancer stage and surgical treatment on the quality of life (QOL of Mexican women with early stage breast cancer (ESBC treated with either modified radical mastectomy (MRM or breast conservative surgery (BCS, plus adjuvant chemotherapy. The QLQ-C30 and QLQ BR-23 questionnaires were used to assess QOL. Sociodemographic characteristics and clinical factors of 102 women with early BC were also evaluated; analysis of variance (ANOVA was performed and a statistical significance of p < 0.05 was assumed. Most women were of reproductive age. Meaningful differences in QOL as a result of surgical treatment, in women receiving BCS compared with those receiving MRM, were limited to body image. We conclude that MRM and BCS are essentially equivalent choices in terms of QOL, with the exception of the impact on body image. In general, women who received BCS had a better perceived QOL.Keywords: quality of life, breast cancer, Mexican women

  14. Characterization of Fine Particulate Matter (PM) and Secondary PM Precursor Gases in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Charles E. Kolb

    2008-03-31

    This project was one of three collaborating grants designed to understand the atmospheric chemistry and aerosol particle microphysics impacting air quality in the Mexico City Metropolitan Area (MCMA) and its urban plume. The overall effort, titled MCMA- 2006, focused on: 1) the primary emissions of fine particles and precursor gases leading to photochemical production of atmospheric oxidants and secondary aerosol particles and 2) the measurement and analysis of secondary oxidants and secondary fine particular matter (PM) production, with particular emphasis on secondary organic aerosol (SOA). MCAM-2006 pursued it goals through three main activities: 1) performance and publication of detailed analyses of extensive MCMA trace gas and fine PM measurements made by the collaborating groups and others during earlier MCMA field campaigns in 2002 and 2003; 2) deployment and utilization of extensive real-time trace gas and fine PM instrumentation at urban and downwind MCMA sites in support of the MAX-Mex/MILAGRO field measurements in March, 2006; and, 3) analyses of the 2006 MCMA data sets leading to further publications that are based on new data as well as insights from analysis and publication of the 2002/2003 field data. Thirteen archival publications were coauthored with other MCMA-2003 participants. Documented findings included a significantly improved speciated emissions inventory from on-road vehicles, a greatly enhanced understanding of the sources and atmospheric loadings of volatile organic compounds, a unique analysis of the high fraction of ambient formaldehyde from primary emission sources, a much more extensive knowledge of the composition, size distributions and atmospheric mass loadings of both primary and secondary fine PM, including the fact that the rate of MCMA SOA production greatly exceeded that predicted by current atmospheric models, and evaluations of significant errors that can arise from standard air quality monitors for ozone and nitrogen

  15. Application of neural networks to obtain the site response in Mexico City

    Directory of Open Access Journals (Sweden)

    Vargas J. Carlos A.

    2003-08-01

    Full Text Available

    We have implemented a neural network of three hidden layers with 40 neurons each layer to be used as soil/rock transfer functions for two stations in Mexico City. The net was trained with supervised learning through input and output vectors of accelerations (twelve records, from five seismic events from Guerrero and Puebla, 5.8 M 7.3, and tested with three records not taken in account in the training. The results in the frequency domain are good, finding a seismic amplification between 0.2 to 5 Hz for the Lake zone. In the time domain we obtain results that are not coincident. Due to the data and the complex of the phenomena, it is necessary to apply this tool using more records for the training net, so the phenomena can be learned better through reliable database.

    Hemos implementado una red neuronal de tres capas escondidas con 40 neuronas por capa para ser usada como funciones de trasferencia suelo/roca en dos estaciones acelerométricas en Ciudad de México. La red fue entrenada con entrenamiento supervisado por medio de vectores de aceleración de entrada y salida (doce registros de cinco eventos sísmicos localizados en la costa de Guerrero y uno al sur de Puebla, 5, 8 M 7, 3, y probada con tres registros no tornados en cuenta en el entrenamiento de la red. Los resultados obtenidos en el dominio de la frecuencia son bastante buenos, encontrándose una amplificación sísmica entre 0,2 a 5 Hz para la zona de Lago (estación RMCS. En el dominio del tiempo obtuvimos resultados que no son coincidentes.

    Oxidative capacity of the Mexico City atmosphere – Part 1: A radical source perspective

    Directory of Open Access Journals (Sweden)

    R. Volkamer

    2010-07-01

    Full Text Available A detailed analysis of OH, HO2 and RO2 radical sources is presented for the near field photochemical regime inside the Mexico City Metropolitan Area (MCMA. During spring of 2003 (MCMA-2003 field campaign an extensive set of measurements was collected to quantify time-resolved ROx (sum of OH, HO2, RO2 radical production rates from day- and nighttime radical sources. The Master Chemical Mechanism (MCMv3.1 was constrained by measurements of (1 concentration time-profiles of photosensitive radical precursors, i.e., nitrous acid (HONO, formaldehyde (HCHO, ozone (O3, glyoxal (CHOCHO, and other oxygenated volatile organic compounds (OVOCs; (2 respective photolysis-frequencies (J-values; (3 concentration time-profiles of alkanes, alkenes, and aromatic VOCs (103 compound are treated and oxidants, i.e., OH- and NO3 radicals, O3; and (4 NO, NO2, meteorological and other parameters. The ROx production rate was calculated directly from these observations; the MCM was used to estimate further ROx production from unconstrained sources, and express overall ROx production as OH-equivalents (i.e., taking into account the propagation efficiencies of RO2 and HO2 radicals into OH radicals.

    Daytime radical production is found to be about 10–25 times higher than at night; it does not track the abundance of sunlight. 12-h average daytime contributions of individual sources are: Oxygenated VOC other than HCHO about 33%; HCHO and O3 photolysis each about 20%; O3/alkene reactions and HONO photolysis each about 12%, other sources <3%. Nitryl chloride photolysis could potentially contribute ~15% additional radicals, while NO2* + water makes – if any – a very small contribution (~2%. The peak radical production of ~7.5 107 molec cm−3 s−1 is

  16. Effect of hydrocarbons and nitrogen oxides on ozone formation in smog chambers exposed to solar irradiance of Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval F, J; Marroquin de la R, O; Jaimes L, J. L; Zuniga L, V. A; Gonzalez O, E; Guzman Lopez-Figueroa, F [Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico)

    2001-01-01

    Outdoor smog chambers experiments were performed on air to determine the answer of maximum ozone levels, to changes in the initial hydrocarbons, HC, and nitrogen oxide NO{sub x}. These captive-air experiments under natural irradiation were carried out. Typically, eight chambers were filled with Mexico city air in the morning. In some of those chambers, the initial HC and/or Nox concentrations were varied by {+-}25% to {+-}50% by adding various combinations of a mixture of HC, clean air, or NO{sub x} (perturbed chambers). The O{sub 3} and NO{sub x} concentration in each chamber was monitored throughout the day to determine O{sub 3} (max). The initial HC and NO{sub x} concentration effects were determined by comparing the maximum ozone concentrations measured in the perturbed and unperturbed chambers. Ozone isopleths were constructed from the empirical model obtained of measurements of the eight chambers and plotted in a graph whose axe were the initial HC and NO{sub x} values. For the average initial conditions that were measured in Mexico City, it was found that the most efficient strategy to reduce the maximum concentration of O{sub 3} is the one that reduces NO{sub x}. [Spanish] Se realizaron experimentos de camaras de esmog con el aire de la ciudad de Mexico para determinar las respuestas de los niveles maximos de ozono a los cambios en las concentraciones iniciales de hidrocarburos, HC y oxido de nitrogeno, NO{sub x}. Por lo general, se llenaron 8 bolsas con aire matutino de la Ciudad de Mexico. En algunas camaras, las concentraciones iniciales fueron cambiadas de 25% a 50%, anadiendo varias concentraciones de una mezcla de HC, aire limpio y/o NO{sub x}. La concentracion de O{sub 3} y NO{sub x}, en cada camara, fueron monitoreadas a lo largo del dia para determinar el maximo de O{sub 3}. El efecto de los HC y el NO{sub x} fue determinado por comparacion del maximo de ozono formado en las camaras, que fueron perturbadas por adicion o reduccion de HC y/o Nox

  17. The use of the electric vehicle in the metropolitan area of Mexico city; Uso de vehiculos electricos en el area metropolitana de la ciudad de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Robles, G. [Centro de Intrumentos, UNAM, Mexico, D. F. (Mexico); Sheinbaum, C. [Instituto de Ingenieria, UNAM, Mexico, D. F. (Mexico)

    1997-12-31

    A study is performed on the impact that the introduction of the electric vehicle (EV) would have in the environmental pollution of the metropolitan area of Mexico City (MAMC) for different penetration scenarios of this technology and the costs of the electric vehicle is analyzed and compared with its counterpart, the gasoline vehicle. The associated emissions of a fleet formed of EV and internal combustion engine vehicles (ICEV) were determined and the emissions reduction of the contaminants considered in the period 1995-2010 produced was analyzed. It was found that the introduction of EV could importantly reduce the carbon monoxide, methane and carbon dioxide and marginally the nitrogen oxides. It was determined that if the EV is massively produced its total cost for its entire useful life would be comparable to the cost of the ICEV. [Espanol] Se realiza un estudio sobre el impacto que tendria la introduccion de vehiculos electricos (VE) en la contaminacion ambiental del area metropolitana de la ciudad de Mexico (AMCM) para diferentes escenarios de penetracion de esta tecnologia y se analiza el costo de los vehiculos electricos en comparacion con su contraparte de gasolina. Se determinaron las emisiones asociadas a una flota compuesta de VE y vehiculos con motor de combustion interna (VMCI) y se analizo la reduccion que producia en las emisiones de los diferentes contaminantes considerados en el periodo 1995-2010. Se encontro que la introduccion de VE podria reducir de manera importante las emisiones de monoxido de carbono, metano y dioxido de carbono y marginalmente las de oxido de nitrogeno. Se determino que si los VE son producidos masivamente su costo total para toda su vida util seria comparable al correspondiente al de los VMCI.

  18. Evaluation of radiological protection aspects in radiodiagnostic rooms in Mexico City

    International Nuclear Information System (INIS)

    The preliminary results of an evaluation of radiological protection carried out in radiology services of different hospitals of Mexico are shown. The evaluated points were: relative aspects of the room, operation parameters of operation of the equipment, work procedures and training about radiological protection for the equipment operators. (authors). 2 refs., 1 fig

  19. Use of resistivity measurements to detect urban caves in Mexico City and to assess the related hazard

    Directory of Open Access Journals (Sweden)

    R. G. Antonio-Carpio

    2004-01-01

    Full Text Available In the XIX century when Mexico City was much smaller than at present, there was non-regulated mining of building materials in a region of tuffs northwest of the city in an inhabited countryside. With the growth of the city during the XX century, this region was increasingly populated and in the 1970's many two-level bricks houses were built, without regard for underground caves created by the earlier extractions. Some ground sinkings in adjacent areas alarmed the residents who now are worried about this permanent hazard. An association of residents contracted a private company for a geophysical study in order to know the distribution of the caves. Resistivity measurements were taken in the area to detect the caves in order to alert city authorities. Resistivity data along most of the streets were collected with the array pole-dipole that consisted of three grounded electrodes. We performed 2-D dimensional inversions to the data in order to get a 2-D resistivity image of every street. This is similar to a resistivity cross-section of the ground but obtained from the inversion of pole-dipole and Schlumberger resistivity data simultaneously. Using the information of previous drills we modified our programming code in order to perform constrained inversion and to get more accurate resistivity models in agreement with the drills. From the resistivity models obtained for every street it was possible to produce a map which shows the horizontal distribution of the resistive bodies at a depth of 12m. These resistive bodies show coherent alignments that seem to correspond with a distributions of interconnected caves or tunnels used for extracting the sandy-tuffs. From these kind of interpretation method it was intended to get a more accurate horizontal distribution of the excavated areas in order to better know the urbanized area affected and lead the authorities to remedy the area with refill material.

  1. Acanthamoeba spp. in domestic tap water in houses of contact lens wearers in the metropolitan area of Mexico City.

    Science.gov (United States)

    Bonilla-Lemus, Patricia; Ramírez-Bautista, Gerardo A; Zamora-Muñoz, Claudia; Ibarra-Montes, María Del Rocío; Ramírez-Flores, Elizabeth; Hernández-Martínez, María Dolores

    2010-09-01

    A survey was carried out in the metropolitan area of Mexico City to determine the presence of Acanthamoeba in the tap water of houses of contact lens wearers. Water samples were taken from the mains water entry, bathroom sinks and storage containers (roof tanks, cisterns) of 27 houses; and from the solution contained in the contact lens cases. Samples were filtered and cultured onto NNE medium. The isolates were identified based on their morphological features and pathogenicity. Total and fecal coliforms, water temperature, pH, dissolved oxygen and residual free-chlorine were measured by standard methods. Forty five isolates of Acanthamoeba from 200 water samples were obtained. The highest number of amoebae was isolated from cisterns and roof tanks. Most Acanthamoeba isolates were non-pathogenic, however, their presence in tap water is a potential hazard since some species can cause Acanthamoeba keratitis and granulomatous amoebic encephalitis. PMID:19995560

  2. Mexico

    International Nuclear Information System (INIS)

    This document summarizes the key energy data for Mexico: 1 - energy organizations and policy: Ministry of energy (SENER), Comision Reguladora de Energia (CRE), Ministry of Finances, Ministry of trade and industrial development (SECOFI), national commission for energy savings (CONAE); 2 - companies: federal commission of electricity (CFE), Minera Carbonifera Rio Escondido (MICARE - coal), Pemex (petroleum); 3 - energy production: resources, electric power, petroleum, natural gas; 4 - energy consumption; 5 - stakes and perspectives. Some economic and energy indicators are summarized in a series of tables: general indicators, supply indicators (reserves, refining and electric capacity, energy production, foreign trade), demand indicators (consumption trends, end use, energy independence, energy efficiency, CO2 emissions), energy status per year and per energy source. (J.S.)

  3. A hybrid method for the estimation of ground motion in sedimentary basins: Quantitative modelling for Mexico City

    International Nuclear Information System (INIS)

    To estimate the ground motion in two-dimensional, laterally heterogeneous, anelastic media, a hybrid technique has been developed which combines modal summation and the finite difference method. In the calculation of the local wavefield due to a seismic event, both for small and large epicentral distances, it is possible to take into account the sources, path and local soil effects. As practical application we have simulated the ground motion in Mexico City caused by the Michoacan earthquake of September 19, 1985. By studying the one-dimensional response of the two sedimentary layers present in Mexico City, it is possible to explain the difference in amplitudes observed between records for receivers inside and outside the lake-bed zone. These simple models show that the sedimentary cover produces the concentration of high-frequency waves (0.2-0.5 Hz) on the horizontal components of motion. The large amplitude coda of ground motion observed inside the lake-bed zone, and the spectral ratios between signals observed inside and outside the lake-bed zone, can only be explained by two-dimensional models of the sedimentary basin. In such models, the ground motion is mainly controlled by the response of the uppermost clay layer. The synthetic signals explain the major characteristics (relative amplitudes, spectral ratios, and frequency content) of the observed ground motion. The large amplitude coda of the ground motion observed in the lake-bed zone can be explained as resonance effects and the excitation of local surface waves in the laterally heterogeneous clay layer. Also, for the 1985 Michoacan event, the energy contributions of the three subevents are important to explain the observed durations. (author). 39 refs, 15 figs, 1 tab

  4. The role of feral mammals on wildlife infectious disease prevalence in two nature reserves within Mexico City limits.

    Science.gov (United States)

    Suzán, Gerardo; Ceballos, Gerardo

    2005-09-01

    Wild and feral medium-sized mammals were live trapped at two natural protected areas within the Mexico City limits to determine antibody prevalence for the most common infectious diseases (rabies, toxoplasmosis, and canine parvovirus) in dogs and cats. Mammals were trapped during the dry (March-April) and rainy seasons (July-August) of 1996 and 1997. A total of 68 individuals were captured, representing 8 species: opossums (Didelphis virginiana), ringtails (Bassariscus astutus), spotted skunks (Spilogale gracilis), weasels (Mustela frenata), rock squirrels (Spermophilus variegatus), Mexican gray squirrels (Sciurus aureogaster), feral cats (Felis catus), and feral dogs (Canis familiaris). There was marked seroprevalence for parvovirus (86.6%) and lower seroprevalences for both toxoplasma (23.9%) and rabies (17.9%). There were no significant prevalence differences among mammals in both protected areas, which were of contrasting size and isolation (i.e., small and isolated versus large and nonisolated). We suggest that high seroprevalence of these three infectious agents in wild mammals is a result of the high densities of feral dogs and cats in the two areas sampled. Feral dogs are able to maintain the infectious agents in these localities regardless of the protected area size and isolation. However, the native mammals of the small and isolated reserve are more vulnerable to infectious diseases because of small population size and genetic bottlenecks. Our results indicate that natural areas in and around Mexico City are a refugium for latent infectious agents, several of which are zoonotic. These findings suggest that conservation measures, such as eradication of feral mammals and vaccination programs, in the protected areas and surrounding areas could be beneficial. PMID:17312768

  5. Understanding the Evolution of Organic Aerosols in the Mexico City Airshed in 2002, 2003 and 2006 using Positive Matrix Factorization

    Science.gov (United States)

    Ulbrich, I. M.; Dzepina, K.; Canagaratna, M.; Zhang, Q.; Decarlo, P.; Salcedo, D.; Aiken, A. C.; Onasch, T. B.; Allan, J.; Russell, L. M.; Grivicke, R.; Lamb, B.; Alexander, M. L.; Worsnop, D. R.; Jimenez, J.

    2008-12-01

    Aerosol mass spectrometric measurements yield spectra of ambient aerosols that are a mix of various primary and secondary sources. Organic aerosol (OA) datasets acquired using Aerodyne aerosol mass spectrometers (Q-AMS, C-ToF-AMS, and HR-ToF-AMS) deployed in 2002, 2003, and 2006 in the Mexico City Metropolitan Area (MCMA) at multiple ground locations and from aircraft flights are analyzed with Positive Matrix Factorization to deconvolve information about important sources and processes for organic aerosols. Several components are identified in each dataset. Most datasets resolve contributions from: reduced (oxidative state) hydrocarbon-like OA (HOA), which correlates well with primary combustion tracers such as CO, NOx, and BC; biomass burning OA (BBOA), which correlates with regional fire counts, potassium, levoglucosan, acetonitrile, and HCN; highly-oxidized OA (OOA-I) which shows more regional behavior; and less oxidized OA (OOA-II) which correlates with semivolatile inorganic species such as ammonium nitrate and gas-phase secondary species such as Ox (NO2 + O3) and glyoxal. These correlations are consistent across most datasets when run separately in PMF. Factor spectra are also compared to reference spectra, and ratios of factor concentrations to relevant tracers (e.g., HOA/CO, OOA/Ox) are presented. Factor spectra, time series, diurnal cycles, and ratios are compared at sampling locations across the MCMA and in different years in order to understand the evolution of OA across the airshed. The effect of running multiple datasets within a single PMF model (e.g., simultaneous measurements made at two locations in Mexico City), and the stability of PMF solutions will be described.

  6. Effect of aerosols and NO2 concentration on ultraviolet actinic flux near Mexico City during MILAGRO: Measurements and model calculations

    Energy Technology Data Exchange (ETDEWEB)

    Palancar, Gustavo G.; Lefer, Barry; Hall, Samual R.; Shaw, William J.; Corr, Chelsea A.; Herndon, Scott C.; Slusser, J. R.; Madronich, Sasha

    2013-01-24

    Ultraviolet (UV) actinic fluxes (AF) measured with three Scanning Actinic Flux Spectroradiometers (SAFS) are compared with the Tropospheric Ultraviolet-Visible (TUV) model v.5 in order to assess the effects of aerosols and NO2 concentrations on the radiation. Measurements were made during the MILAGRO campaign near Mexico City in March 2006, at a ground-based station near Mexico City (the T1 supersite) and from the NSF/NCAR C-130 aircraft. At the surface, measurements are typically smaller by up to 25 % in the morning, 10% at noon, and 40% in the afternoon, than actinic flux modeled for clean, cloud-free conditions. When measurements of PBL height, NO2 concentration and aerosols optical properties are included in the model, the agreement improves to within ±10% in the morning and afternoon, and ±3% at noon. Based on daily averages, aerosols account for 68%, NO2 for 25%, and residual uncertainties for 7% of these AF reductions observed at the surface. Several overpasses from the C-130 aircraft provided the opportunity to examine the actinic flux perturbations aloft, and also show better agreement with the model when aerosol and NO2 effects are included above and below the flight altitude. TUV model simulations show that the vertical structure of the actinic flux is sensitive to the choice of the aerosol single scattering albedo (SSA) at UV wavelengths. Typically, aerosols caused enhanced AF above the PBL and reduced AF near the surface. However, for highly scattering aerosols (SSA > 0.95), enhancements can penetrate well into the PBL, while for strongly absorbing aerosols (SSA<0.7) reductions in AF are computed in the free troposphere as well as in the PBL. Additional measurements of the SSA at these wavelengths are needed to better constrain the effect of aerosols on the vertical structure of the actinic flux.

  7. Effect of aerosols and NO2 concentration on ultraviolet actinic flux near Mexico City during MILAGRO: measurements and model calculations

    Directory of Open Access Journals (Sweden)

    C. A. Corr

    2013-01-01

    Full Text Available Urban air pollution absorbs and scatters solar ultraviolet (UV radiation, and thus has a potentially large effect on tropospheric photochemical rates. We present the first detailed comparison between actinic fluxes (AF in the wavelength range 330–420 nm measured in highly polluted conditions and simulated with the Tropospheric Ultraviolet-Visible (TUV model. Measurements were made during the MILAGRO campaign near Mexico City in March 2006, at a ground-based station near Mexico City (the T1 supersite and from the NSF/NCAR C-130 aircraft. At the surface, measured AF values are typically smaller than the model by up to 25% in the morning, 10% at noon, and 40% in the afternoon, for pollution-free and cloud-free conditions. When measurements of PBL height, NO2 concentration and aerosols optical properties are included in the model, the agreement improves to within ±10% in the morning and afternoon, and ±3% at noon. Based on daily averages, aerosols account for 68% and NO2 for 25% of AF reductions observed at the surface. Several overpasses from the C-130 aircraft provided the opportunity to examine the AF perturbations aloft, and also show better agreement with the model when aerosol and NO2 effects are included above and below the flight altitude. TUV model simulations show that the vertical structure of the actinic flux is sensitive to the choice of the aerosol single scattering albedo (SSA at UV wavelengths. Typically, aerosols enhance AF above the PBL and reduce AF near the surface. However, for highly scattering aerosols (SSA > 0.95, enhancements can penetrate well into the PBL, while for strongly absorbing aerosols (SSA < 0.6 reductions in AF are computed in the free troposphere as well as in the PBL. Additional measurements of the SSA at these wavelengths are needed to better constrain the effect of aerosols on the vertical structure of the AF.

  8. Detection of pollution transport events southeast of Mexico City using ground-based visible spectroscopy measurements of nitrogen dioxide

    Directory of Open Access Journals (Sweden)

    M. Grutter

    2009-07-01

    Full Text Available This work presents ground based differential optical absorption spectroscopy (DOAS measurements of nitrogen dioxide (NO2 during the MILAGRO field campaign in March 2006 at the Tenango del Aire research site located to the southeast of Mexico City. The DOAS NO2 column density measurements are used in conjunction with ceilometer, meteorological and surface nitric oxide (NO, nitrogen oxides (NOx and total reactive nitrogen (NOy measurements to analyze pollution transport events to the southeast of Mexico City during the MILARGO field campaign. The study divides the data set into three case study pollution transport events that occurred at the Tenango del Aire research site. The unique data set is then used to provide an in depth analysis of example days of each of the pollution transport events. An in depth analysis of 13 March 2006, a Case One day, shows the transport of several air pollution plumes during the morning through the Tenango del Aire research site when southerly winds are present and demonstrates how DOAS tropospheric NO2 vertical column densities (VCD, surface NO2 mixing ratios and ceilometer data are used to determine the vertical homogeneity of the pollution layer. The analysis of 18 March 2006, a Case Two day, shows that when northerly winds are present for the entire day, the air at the Tenango del Aire research site is relatively clean and no major pollution plumes are detected. Case 3 days are characterized by relatively clean air throughout the morning with large DOAS NO2 enhancements detected in the afternoon. The analysis of 28 March 2006 show the DOAS NO2 enhancements are likely due to lightning activity and demonstrate how suitable ground-based DOAS measruements are for monitoring anthropogenic and natural pollution sources that reside above the mixing layer.

  9. Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaign

    Directory of Open Access Journals (Sweden)

    G. Paredes-Miranda

    2008-09-01

    Full Text Available A photoacoustic spectrometer, a nephelometer, an aetholemeter, and an aerosol mass spectrometer were used to measure at ground level real-time aerosol light absorption, scattering, and chemistry at an urban site located in north east Mexico City (Instituto Mexicano del Petroleo, Mexican Petroleum Institute, denoted by IMP, as part of the Megacity Impact on Regional and Global Environments field experiment, MILAGRO, in March 2006. Photoacoustic and reciprocal nephelometer measurements at 532 nm accomplished with a single instrument compare favorably with conventional measurements made with an aethelometer and a TSI nephelometer. The diurnally averaged single scattering albedo at 532 nm was found to vary from 0.60 to 0.85 with the peak value at midday and the minimum value at 7 a.m. local time, indicating that the Mexico City plume is likely to have a net warming effect on local climate. The peak value is associated with strong photochemical generation of secondary aerosol. It is estimated that the same-day photochemical production of secondary aerosol (inorganic and organic is approximately 40 percent of the aerosol mass concentration and light scattering in association with the peak single scattering albedo. A strong correlation of aerosol scattering at 532 nm and total aerosol mass concentration was found, and an average mass scattering efficiency factor of 3.8 m2/g was determined. Comparisons of photoacoustic and aethalometer light absorption with oxygenated organic aerosol concentration (OOA indicate a very small systematic bias of the filter based measurement associated with OOA and the peak aerosol single scattering albedo.

  10. Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaign

    Directory of Open Access Journals (Sweden)

    G. Paredes-Miranda

    2009-06-01

    Full Text Available A photoacoustic spectrometer, a nephelometer, an aethalometer, and an aerosol mass spectrometer were used to measure at ground level real-time aerosol light absorption, scattering, and chemistry at an urban site located in North East Mexico City (Instituto Mexicano del Petroleo, Mexican Petroleum Institute, denoted by IMP, as part of the Megacity Impact on Regional and Global Environments field experiment, MILAGRO, in March 2006. Photoacoustic and reciprocal nephelometer measurements at 532 nm accomplished with a single instrument compare favorably with conventional measurements made with an aethalometer and a TSI nephelometer. The diurnally averaged single scattering albedo at 532 nm was found to vary from 0.60 to 0.85 with the peak value at midday and the minimum value at 07:00 a.m. local time, indicating that the Mexico City plume is likely to have a net warming effect on local climate. The peak value is associated with strong photochemical generation of secondary aerosol. It is estimated that the photochemical production of secondary aerosol (inorganic and organic is approximately 75% of the aerosol mass concentration and light scattering in association with the peak single scattering albedo. A strong correlation of aerosol scattering at 532 nm and total aerosol mass concentration was found, and an average mass scattering efficiency factor of 3.8 m2/g was determined. Comparisons of photoacoustic and aethalometer light absorption with oxygenated organic aerosol concentration (OOA indicate a very small systematic bias of the filter based measurement associated with OOA and the peak aerosol single scattering albedo.

  11. Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaign

    Science.gov (United States)

    Paredes-Miranda, G.; Arnott, W. P.; Jimenez, J. L.; Aiken, A. C.; Gaffney, J. S.; Marley, N. A.

    2009-06-01

    A photoacoustic spectrometer, a nephelometer, an aethalometer, and an aerosol mass spectrometer were used to measure at ground level real-time aerosol light absorption, scattering, and chemistry at an urban site located in North East Mexico City (Instituto Mexicano del Petroleo, Mexican Petroleum Institute, denoted by IMP), as part of the Megacity Impact on Regional and Global Environments field experiment, MILAGRO, in March 2006. Photoacoustic and reciprocal nephelometer measurements at 532 nm accomplished with a single instrument compare favorably with conventional measurements made with an aethalometer and a TSI nephelometer. The diurnally averaged single scattering albedo at 532 nm was found to vary from 0.60 to 0.85 with the peak value at midday and the minimum value at 07:00 a.m. local time, indicating that the Mexico City plume is likely to have a net warming effect on local climate. The peak value is associated with strong photochemical generation of secondary aerosol. It is estimated that the photochemical production of secondary aerosol (inorganic and organic) is approximately 75% of the aerosol mass concentration and light scattering in association with the peak single scattering albedo. A strong correlation of aerosol scattering at 532 nm and total aerosol mass concentration was found, and an average mass scattering efficiency factor of 3.8 m2/g was determined. Comparisons of photoacoustic and aethalometer light absorption with oxygenated organic aerosol concentration (OOA) indicate a very small systematic bias of the filter based measurement associated with OOA and the peak aerosol single scattering albedo.

  12. Emissions of black carbon and co-pollutants emitted from diesel vehicles in the Mexico City Metropolitan Area

    Science.gov (United States)

    Zavala, Miguel; Molina, Luisa T.; Fortner, Edward; Knighton, Berk; Herndon, Scott; Yacovitch, Tara; Floerchinger, Cody; Roscioli, Joseph; Kolb, Charles; Mejia, Jose Antonio; Sarmiento, Jorge; Paramo, Victor Hugo; Zirath, Sergio; Jazcilevich, Aron

    2014-05-01

    Black carbon emitted from freight, public transport, and heavy duty trucks sources is linked with adverse effects on human health. In addition, the control of emissions of black carbon, an important short-lived climate forcing agent (SLCF), has recently been considered as one of the key strategies for mitigating regional near-term climate change. Despite the availability of new emissions control technologies for reducing emissions from diesel-powered mobile sources, their introduction is still not widespread in many urban areas and there is a need to characterize real-world emission rates of black carbon from this key source. The emissions of black carbon, organic carbon, and other gaseous and particle pollutants from diesel-powered mobile sources in Mexico were characterized by deploying a mobile laboratory equipped with real-time instrumentation in Mexico City as part of the SLCFs-Mexico 2013 project. From February 25-28 of 2013 the emissions from selected diesel-powered vehicles were measured in both controlled experiments and real-world on-road driving conditions. Sampled vehicles had several emissions levels technologies, including: EPA98, EPA03, EPA04, EURO3-5, and Hybrid. All vehicles were sampled using diesel fuel and several vehicles were measured using both diesel and biodiesel fuels. Additional measurements included the use of a remote sensing unit for the co-sampling of all tested vehicles, and the installation and operation of a Portable Emissions Measurements System (PEMS) for the measurement of emissions from a test vehicle. We will present inter-comparisons of the emission factors obtained among the various vehicle technologies that were sampled during the experiment as well as the inter-comparison of results from the various sampling platforms. The results can be used to

  13. Frequency and risk factors associated with dry eye in patients attending a tertiary care ophthalmology center in Mexico City

    Science.gov (United States)

    Martinez, Jaime D; Galor, Anat; Ramos-Betancourt, Nallely; Lisker-Cervantes, Andrés; Beltrán, Francisco; Ozorno-Zárate, Jorge; Sánchez-Huerta, Valeria; Torres-Vera, Marco-Antonio; Hernández-Quintela, Everardo

    2016-01-01

    Purpose The purpose of this study was to ascertain the frequency and risk factors of dry eye (DE) among patients attending a tertiary care ophthalmology center in Mexico. Methods Approximately 338 consecutive new patients attending a tertiary care ophthalmology center in Mexico City underwent an ocular surface examination, which included tear film break-up time, fluorescein corneal staining, Schirmer’s test, and evaluation of meibum quality. Symptoms of DE were evaluated by the Ocular Surface Disease Index and Dry Eye Questionnaire-5. Information on demographics, exposures, past medical and ocular history, and medications was also collected. Results The frequency of severe DE symptoms was found to be 43% based on the Ocular Surface Disease Index and 30% based on Dry Eye Questionnaire-5. Risk factors significantly associated with increased DE symptoms included dry mouth and gastrointestinal ulcer medications. With regard to signs, aqueous tear deficiency was a less-frequent finding (22%) in our population than evaporative deficiency (94%). Risk factors associated with aqueous tear deficiency were dry mouth and diuretic use. No risk factors were associated with evaporative deficiency. Risk factors associated with meibomian gland dysfunction included old age, male sex, arthritis, and use of an antihypertensive. The only risk factor associated with corneal staining was dry mouth. Conclusion This is the first study to demonstrate the frequency of symptomatic and clinical DE in a tertiary care ophthalmology center in Mexico. The frequency of DE ranged from 30% using a symptomatic definition to 94% using objective measures. Different risk factors were found for different aspects of DE, suggesting differing underlying pathophysiologies behind different DE subtypes.

  14. Long-range pollution transport during the MILAGRO-2006 campaign: a case study of a major Mexico City outflow event using free-floating altitude-controlled balloons

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Paul B.; Zaveri, Rahul A.; Flocke, Frank M.; Mao, Huitimg; Hartley, Tom; DeAmicis, Pam; Deonandan, Indira; Contrerars-Jimenez, G.; Martinez-Antonio, O.; Figueroa Estrada, M.; Greenberg, David; Campos, Teresa; Weinheimer, Andrew J.; Knapp, David; Montzka, DeeDee; Crounse, J. D.; Wennberg, P. O.; Apel, Eric; Madronich, Sasha; de Foy, B.

    2010-08-04

    One of the major objectives of the Megacities Initiative: Local And Global Research 3 Observations (MILAGRO 2006) campaign was to investigate the long-range transport of 4 Mexico City Metropolitan Area (MCMA) pollution outflow and its downwind impacts on air 5 quality and climate. Four aircraft (DOE G-1, NSF/NCAR C-130, NASA-J31, and NASA 6 DC-8) made extensive chemical, aerosol, and radiation measurements above MCMA and over 7 1000 km downwind in order to characterize the evolution of MCMA pollution as it aged and 8 dispersed over the central Mexican plateau and the Gulf of Mexico. As part of this effort, 9 free-floating Controlled-Meteorological (CMET) balloons, capable of changing altitude on 10 command via satellite, characterized the MCMA outflow by performing repeated soundings 11 during the transit. In this paper, we present an analysis based on the data from two CMET 12 balloons that were launched near Mexico City on the afternoon of 18 March 2006 and floated 13 downwind with the outflow for nearly 30 hours. Continuous profile measurements made by 14 the balloons show the evolving structure of the MCMA outflow in considerable detail: its 15 stability and stratification, interaction with other air masses, mixing episodes, and dispersion 16 into the regional background. Air parcel trajectories, computed directly from the balloon 17 wind profiles, show three different transport pathways for Mexico City outflow on 18-19 18 March: (a) high-altitude advection of the top of the MCMA mixed layer, (b) low-altitude flow 19 over the Sierra Madre Oriental followed by decoupling and isolated transport over the Gulf, 20 and (c) the same decoupling scenario with entrainment into a cleaner westerly jet below the 21 plateau. The C-130 intercepted the balloon-based trajectories three times on 19 March, once 22 along each transport pathway. In all three cases, distinct peaks in the urban tracer signature 23 and LIDAR backscatter imagery provided evidence for Mexico City air

  15. At the Table with Hungry Ghosts: Intimate Borderwork in Mexico City

    Directory of Open Access Journals (Sweden)

    Jean Duruz

    2011-09-01

    Full Text Available This article focuses on the project of sustaining cultural diversity within global cities’ intimate spaces. Specifically, it sketches the culinary histories of an Anglo-Australian woman (who, in 1968, settled permanently in Mexico and her male partner (who grew up in Mexico; his mother Mexican, his father Cantonese. Drawing on the tools of ‘borderwork’ (Hodge and O’Carroll, the argument positions culturally diverse landscapes of ‘Sydney’, ‘China’ and ‘Mexico City’ as distinct yet overlapping geographies. Meanwhile, analysis of curious moments in the couple’s intersecting histories contributes much fluidity to this cartography. In the process, a company of hungry ghosts appears at the dinner table – ghosts of diversity, diaspora and cosmopolitanism; nostalgia and memory; gender and ethnicity; home and belonging. The article concludes that even when borderwork is conducted amiably behind closed doors, it relies on contradictions for cultural sustenance. At the same time, its tensions resonate with possibilities for creative practice.

  16. Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis

    Directory of Open Access Journals (Sweden)

    K. S. Johnson

    2006-01-01

    Full Text Available Aerosols play an important role in the atmosphere but are poorly characterized, particularly in urban areas like the Mexico City Metropolitan Area (MCMA. The chemical composition of urban particles must be known to assess their effects on the environment, and specific particulate emissions sources should be identified to establish effective pollution control standards. For these reasons, samples of particulate matter ≤2.5 μm (PM2.5 were collected during the MCMA-2003 Field Campaign for elemental and multivariate analyses. Proton-Induced X-ray Emission (PIXE, Proton-Elastic Scattering Analysis (PESA and Scanning Transmission Ion Microscopy (STIM measurements were done to determine concentrations of 19 elements from Na to Pb, hydrogen, and total mass, respectively. The most abundant elements from PIXE analysis were S, Si, K, Fe, Ca, and Al, while the major emissions sources associated with these elements were industry, wind-blown soil, and biomass burning. Wind trajectories suggest that metals associated with industrial emissions came from northern areas of the city whereas soil aerosols came from the southwest and increased in concentration during dry conditions. Elemental markers for fuel oil combustion, V and Ni, correlated with a large SO2 plume to suggest an anthropogenic, rather than volcanic, emissions source. By subtracting major components of soil and sulfates determined by PIXE analysis from STIM total mass measurements, we estimate that approximately 50% of non-volatile PM2.5 consisted of carbonaceous material.

  17. Aerosol composition and source apportionment in the Mexico City Metropolitan Area with PIXE/PESA/STIM and multivariate analysis

    Directory of Open Access Journals (Sweden)

    K. S. Johnson

    2006-05-01

    Full Text Available Aerosols play an important role in the atmosphere but are poorly characterized, particularly in urban areas like the Mexico City Metropolitan Area (MCMA. The chemical composition of urban particles must be known to assess their effects on the environment, and specific particulate emissions sources should be identified to establish effective pollution control standards. For these reasons, samples of particulate matter ≤2.5 μm (PM2.5 were collected during the MCMA-2003 Field Campaign for elemental and multivariate analyses. Proton-Induced X-ray Emission (PIXE, Proton-Elastic Scattering Analysis (PESA and Scanning Transmission Ion Microscopy (STIM techniques were done to determine concentrations of 19 elements from Na to Pb, hydrogen, and total mass, respectively. The most abundant elements from PIXE analysis were S, Si, K, Fe, Ca, and Al, while the major emissions sources associated with these elements were industry, wind-blown soil, and biomass burning. Wind trajectories suggest that metals associated with industrial emissions came from northern areas of the city whereas soil aerosols came from the southwest and increased in concentration during dry conditions. Elemental markers for fuel oil combustion V and Ni correlated with a large SO2 plume to suggest an anthropogenic, rather than volcanic, emissions source. By subtracting major components of soil and sulfate determined by PIXE analysis from STIM total mass measurements, we estimate that approximately 50% of non-volatile PM2.5 consisted of carbonaceous material.

  18. PIXE and XRF analysis of atmospheric aerosols from a site in the West area of Mexico City

    International Nuclear Information System (INIS)

    Due to geographical factors, most of the Metropolitan Area of Mexico City features, on average, similar heights above the sea level, climate, wind speed and direction, with very uniform pollution degrees in most of the frequently studied sites. A site with different characteristics, Cuajimalpa de Morelos, was studied. It is located to the West of the urban area at 2760 m above sea level, in contrast to other sites (2240 m). Here, the wind is mostly directed towards the center of the city. Then, the site should not be affected by pollutants from the Northern/Northeastern industrial zones, so lower aerosol concentrations are expected. In this work, the elemental composition of coarse (PM10-2.5) and fine (PM2.5) fractions of atmospheric aerosol samples collected in Cuajimalpa is studied. The sampling period covered the cold-dry season in 2004–2005 (December 1st, 2004 to March 31, 2005), exposing polycarbonate filters with a Stacked Filter Unit of the Gent design along 24 h, every two days. The samples were analyzed with Particle Induced X-ray Emission (PIXE) and X-ray Fluorescence (XRF), to obtain elemental concentrations. The EPA code UNMIX was used to determine the number of possible influencing polluting sources, which were then identified through back-trajectory simulations with the HYSPLIT modeling software. Four sources (mostly related to soil) were found in the coarse fraction, while the fine fraction presented three main sources (fuel oil, industry and biomass burning)

  19. PIXE and XRF analysis of atmospheric aerosols from a site in the West area of Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Díaz, R.V.; López-Monroy, J. [Instituto Nacional de Investigaciones Nucleares, Centro Nuclear “Nabor Carrillo”, Autopista México-Toluca, Salazar, Edo. Mex. (Mexico); Miranda, J., E-mail: miranda@fisica.unam.mx [Instituto Nacional de Investigaciones Nucleares, Centro Nuclear “Nabor Carrillo”, Autopista México-Toluca, Salazar, Edo. Mex. (Mexico); Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México, DF (Mexico); Espinosa, A.A. [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 México, DF (Mexico)

    2014-01-01

    Due to geographical factors, most of the Metropolitan Area of Mexico City features, on average, similar heights above the sea level, climate, wind speed and direction, with very uniform pollution degrees in most of the frequently studied sites. A site with different characteristics, Cuajimalpa de Morelos, was studied. It is located to the West of the urban area at 2760 m above sea level, in contrast to other sites (2240 m). Here, the wind is mostly directed towards the center of the city. Then, the site should not be affected by pollutants from the Northern/Northeastern industrial zones, so lower aerosol concentrations are expected. In this work, the elemental composition of coarse (PM{sub 10-2.5}) and fine (PM{sub 2.5}) fractions of atmospheric aerosol samples collected in Cuajimalpa is studied. The sampling period covered the cold-dry season in 2004–2005 (December 1st, 2004 to March 31, 2005), exposing polycarbonate filters with a Stacked Filter Unit of the Gent design along 24 h, every two days. The samples were analyzed with Particle Induced X-ray Emission (PIXE) and X-ray Fluorescence (XRF), to obtain elemental concentrations. The EPA code UNMIX was used to determine the number of possible influencing polluting sources, which were then identified through back-trajectory simulations with the HYSPLIT modeling software. Four sources (mostly related to soil) were found in the coarse fraction, while the fine fraction presented three main sources (fuel oil, industry and biomass burning)

  20. Committed dose assessment based on background outdoor gamma exposure in Chihuahua City, Mexico

    International Nuclear Information System (INIS)

    Full text: Determining ionizing radiation in a geographic area serves to assess its effects on populations health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the committed dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, annual effective dose, and the lifetime cancer risk, 48 sampling points were randomly selected along the Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Muller counter. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th, 40K and their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Outdoor gamma dose rates ranged from 56 to 193 n Gy h-1. Results indicated that lifetime effective dose to inhabitants of Chihuahua City is in average of 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of activity concentrations in soil were 51.8, 73.1, and 1096.5 Bq kg-1, of 226Ra, 232Th and 40K, respectively. From the analysis of the spatial distribution of 232Th, 226Ra, and 40K is to north, to north-center, and to south of city, respectively. In conclusion, natural background gamma dose received by inhabitants of Chihuahua City is high and mainly due to geological characteristics of the zone. (Author)

  1. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

    Directory of Open Access Journals (Sweden)

    Sergio Luevano-Gurrola

    2015-09-01

    Full Text Available Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

  2. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

    Science.gov (United States)

    Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

    2015-01-01

    Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. PMID:26437425

  3. Committed dose assessment based on background outdoor gamma exposure in Chihuahua City, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Luevano G, S.; Perez T, A.; Pinedo A, C.; Renteria V, M. [Universidad Autonoma de Chihuahua, Facultad de Zootecnia y Ecologia, Perif. Francisco R. Almada Km 1, 31415 Chihuahua, Chih. (Mexico); Carrillo F, J.; Montero C, M. E., E-mail: mrenteria@uach.mx [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes 120, 31136 Chihuahua, Chih. (Mexico)

    2015-10-15

    Full text: Determining ionizing radiation in a geographic area serves to assess its effects on populations health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the committed dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, annual effective dose, and the lifetime cancer risk, 48 sampling points were randomly selected along the Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Muller counter. At the same sites, 48 soil samples were taken to obtain the activity concentrations of {sup 226}Ra, {sup 232}Th, {sup 40}K and their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Outdoor gamma dose rates ranged from 56 to 193 n Gy h{sup -1}. Results indicated that lifetime effective dose to inhabitants of Chihuahua City is in average of 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of activity concentrations in soil were 51.8, 73.1, and 1096.5 Bq kg{sup -1}, of {sup 226}Ra, {sup 232}Th and {sup 40}K, respectively. From the analysis of the spatial distribution of {sup 232}Th, {sup 226}Ra, and {sup 40}K is to north, to north-center, and to south of city, respectively. In conclusion, natural background gamma dose received by inhabitants of Chihuahua City is high and mainly due to geological characteristics of the zone. (Author)

  4. Implications in the difference of anti-Mi-2 and -p155/140 autoantibody prevalence in two dermatomyositis cohorts from Mexico City and Guadalajara

    OpenAIRE

    Petri, Marcelo H.; Satoh, Minoru; Martin-Marquez, Beatriz T; Vargas-Ramírez, Raul; Jara, Luis J; Saavedra, Miguel A; Cruz-Gonzalez, Claudia; Andrade-Ortega, Lilia; Vera-Lastra, Olga; Salazar-Páramo, Mario; Prieto-Parra, Rosa E; Gonzalez-Lopez, Laura; Gamez-Nava, Jorge I; Hermes U. Ramírez-Sánchez; Chan, Jason YF

    2013-01-01

    Introduction Autoantibodies and clinical manifestations in polymyositis/dermatomyositis (PM/DM) are affected by both genetic and environmental factors. The high prevalence of DM and anti-Mi-2 in Central America is thought to be associated with the high UV index of the area. The prevalences of autoantibodies and the clinical manifestations of PM/DM were evaluated comparing two cohorts in Mexico. Methods Ninety-five Mexican patients with PM/DM (66 DM, 29 PM; 67 Mexico City, 28 Guadalajara) were...

  5. Seasonal characterization of municipal solid waste (MSW) in the city of Chihuahua, Mexico

    International Nuclear Information System (INIS)

    Management of municipal solid waste (MSW) has become a significant environmental problem, especially in fast-growing cities. The amount of waste generated increases each year and this makes it difficult to create solutions which due to the increase in waste generation year after year and having to identify a solution that will have minimum impact on the environment. To determine the most sustainable waste management strategy for Chihuahua, it is first necessary to identify the nature and composition of the city's urban waste. The MSW composition varied considerably depending on many factors, the time of year is one of them. Therefore, as part of our attempt to implement an integral waste management system in the city of Chihuahua, we conducted a study of the characteristics of MSW composition for the different seasons. This paper analyzes and compares the findings of the study of the characterization and the generation of solid waste from households at three different socio-economic levels in the city over three periods (April and August, 2006 and January, 2007). The average weight of waste generated in Chihuahua, taking into account all three seasons, was 0.592 kg capita-1 day-1. Our results show that the lowest income groups generated the least amount of waste. We also found that less waste was generated during the winter season. The breakdown for the composition of the waste shows that organic waste accounts for the largest proportion (45%), followed by paper (17%) and others (16%).

  6. Seasonal characterization of municipal solid waste (MSW) in the city of Chihuahua, Mexico.

    Science.gov (United States)

    Gómez, Guadalupe; Meneses, Montserrat; Ballinas, Lourdes; Castells, Francesc

    2009-07-01

    Management of municipal solid waste (MSW) has become a significant environmental problem, especially in fast-growing cities. The amount of waste generated increases each year and this makes it difficult to create solutions which due to the increase in waste generation year after year and having to identify a solution that will have minimum impact on the environment. To determine the most sustainable waste management strategy for Chihuahua, it is first necessary to identify the nature and composition of the city's urban waste. The MSW composition varied considerably depending on many factors, the time of year is one of them. Therefore, as part of our attempt to implement an integral waste management system in the city of Chihuahua, we conducted a study of the characteristics of MSW composition for the different seasons. This paper analyzes and compares the findings of the study of the characterization and the generation of solid waste from households at three different socio-economic levels in the city over three periods (April and August, 2006 and January, 2007). The average weight of waste generated in Chihuahua, taking into account all three seasons, was 0.592 kg capita(-1) day(-1). Our results show that the lowest income groups generated the least amount of waste. We also found that less waste was generated during the winter season. The breakdown for the composition of the waste shows that organic waste accounts for the largest proportion (45%), followed by paper (17%) and others (16%). PMID:19303762

  7. CANAL code

    International Nuclear Information System (INIS)

    The CANAL code presented here optimizes a realistic iron free extraction channel which has to provide a given transversal magnetic field law in the median plane: the current bars may be curved, have finite lengths and cooling ducts and move in a restricted transversal area; terminal connectors may be added, images of the bars in pole pieces may be included. A special option optimizes a real set of circular coils

  8. Ion beam analysis of ancient Mexican colored teeth from archaeological sites in Mexico City

    International Nuclear Information System (INIS)

    Infant teeth with extremely rare colored enamel regions white, blue-gray and brown, have been analyzed by Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS). The teeth were part of human being sacrifices to deities of the Mexica culture, Mexico, corresponding to the Late Post-classic period (1325-1521 A.D.). Comparisons to normal teeth from the same historical period indicate that the colored ones present larger mean amounts of Mn and Fe, while Zn and Sr do not differ too much. Possible inorganic compounds responsible for the different colorations are indicated

  9. Eddy covariance flux measurements of pollutant gases in urban Mexico City

    OpenAIRE

    Velasco, E; S. Pressley; Grivicke, R.; E. Allwine; T. Coons; Foster, W; B. T. Jobson; Westberg, H.; Ramos, R.; Hernández, F.; Molina, L. T.; Lamb, B.

    2009-01-01

    Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases over an urban area are a direct way to improve and evaluate emissions inventories, and, in turn, to better understand urban atmospheric chemistry and the role that cities play in regional and global chemical cycles. As part of the MCMA-2003 study, we demonstrated the feasibility of using eddy covariance techniques to measure fluxes of selected volatile organic compounds (VOCs) and CO2 fro...

  10. Stressors associated with hiperstress in undergraduate students in the city of Chilpancingo, Guerrero, Mexico

    OpenAIRE

    Mireya Maruris Reducindo; Pedro Cortés Genchi; Miguel Ángel Cabañas Guerrero; Flaviano Godínez Jaimes; Mónica González Ramírez; René Landero Hernández

    2013-01-01

    The objective was to determine the level of stress and associated factors in undergraduates students from all the Academic Units located in the University city in chilpancingo, gro. A cross-sectional study was conducted in a random sample of 500 students with ages ranging from 17-44 years, the average age was 21.29 ± 3.13 years. Stress levels were measured with an estresometer containing 96 questions related to lifestyle, environment, symptoms, employment/occupation, relationships and persona...

  11. Site response and seismic wavefield in Toluca city, Mexico, from strong motion records

    OpenAIRE

    Hugo Ferrer-Toledo; Martín Cárdenas-Soto; Francisco J. Chávez-García

    2006-01-01

    Since 1993 a network of 6 accelerographs has been operating in the city of Toluca. To date, only one seismic event has been recorded by all six stations. We analyse in detail those records with the purpose of measuring site response and analyzing the recorded wavefield. We compute spectral ratios of Fourier amplitude spectra relative to a reference station and of the horizontal components relative to the vertical recorded at each site. We compare the traces in different period bands, analyse ...

  12. Opposing seasonal trends for polycyclic aromatic hydrocarbons and PM10: Health risk and sources in southwest Mexico City

    Science.gov (United States)

    Amador-Muñoz, Omar; Bazán-Torija, S.; Villa-Ferreira, S. A.; Villalobos-Pietrini, Rafael; Bravo-Cabrera, José Luis; Munive-Colín, Zenaida; Hernández-Mena, Leonel; Saldarriaga-Noreña, H.; Murillo-Tovar, M. A.

    2013-03-01

    This study reports the measurement of polycyclic aromatic hydrocarbons (PAHs) in airborne particles ≤ 10 μm (PM10) during four years. Seasonal variation was observed for PM10 and PAH in southwest Mexico City, with major mass concentrations during the dry season (November-April). A non linear decreasing trend of PM10 was observed during this period, while a linear increase (in the four years) was obtained for benzo[a]pyrene (88 pg m- 3), phenanthrene (29 pg m- 3), fluoranthene (88 pg m- 3), and benzo[ghi]perylene (438 pg m- 3). Coronene also showed an increasing trend but it was nonlinear. This suggests that air control strategies implemented by the government contributed to maintaining PM10 under the 24 h maximum limit and resulted in a decreasing trend during this period. However, these strategies did not result in controlling some organic constituents with mutagenic and/or carcinogenic properties as it is the case of benzo[a]pyrene. The annual average of this PAH exceeded the UK recommendation. It was estimated a median (10th-90th) lifetime health risk of 7.6 (3.4-17.2) additional cases of cancer per 10 million people in this zone exists and the health risk of PAH is almost three times greater in dry seasons than it is in rainy seasons. Specific humidity, temperature and wind speed acted as cleaners for PM10 and PAH from the atmosphere. PAH diagnostic ratios and correlation and principal component analyses suggest incomplete combustion from gasoline and diesel engines as the main contributor to PAH found in southwest Mexico City, where factor 1 grouped all PAH emitted from gasoline engines during first three years. During last year, factor 1 only grouped PAH markers of diesel engines. This suggests a change of emission amounts between gasoline and diesel combustion sources or a contribution of other source(s) which changed the PAH profiles. During four years retene was always separated from factors which grouped the rest of PAH, due to its wood combustion

  13. Concentrations of benzene and toluene in the atmosphere of the southwestern area at the Mexico City Metropolitan Zone

    Energy Technology Data Exchange (ETDEWEB)

    Bravo, H.; Sosa, R.; Sanchez, P. [Universidad Autonoma de Mexico, Ciudad Universitaria (Mexico). Centro de Ciencias de la Atmosfera; Bueno, E.; Gonzalez, L. [Centro Nacional de Investigacion y Capacitacion Ambiental, Instituto Nacional de Ecologia, SEMARNAP, Mexico (Mexico)

    2002-08-01

    The Mexico City Metropolitan Zone (MCMZ) presents important emissions of hazardous air pollutants. It is well documented that the MCMZ suffers a critical air pollution problem due to high ozone and particulate matter concentrations. However, toxic air pollutants such as benzene and toluene have not been considered. Benzene has accumulated sufficient evidence as a human carcinogen, and the ratio benzene/toluene is an excellent indicator to evaluate control strategies efficiency. In order to evaluate the levels of these two air toxic pollutants in the MCMZ, ambient air samples were collected in canisters and analyzed with a gas chromatograph with a flame ionization detector, according to procedures described in the United States Environmental Protection Agency (USEPA) method TO-15. Quality assurance was performed collecting duplicate samples which were analyzed in replicate to quantify the precision of air-quality measurements. Three different sites located in the Southwestern area in the MCMZ were selected for the sampling: the University campus, a gas station, and a vertical condominium area, in the same neighborhood, which presents different activities. At these sites, grab air samples were collected during the morning hours (7-8 a.m.), while for the University area, 24 h integrated air samples were collected simultaneously, with grab samples. Benzene concentrations (24 h sampling) in the atmosphere around the University campus have similar present levels as in other cities of North America. Mean values in this site were about 1.7 ppb. A significant variation exists between the benzene and toluene concentrations in the studied sites, being the more critical values than those registered at the gas station (an average of 25.8 ppb and a maximum of 141 ppb of benzene). There is a fuel regulation for gasoline in Mexico, which allows a maximum of 1 percent of benzene. However, since more than 60 percent of vehicles do not have catalytic converters (models before 1991

  14. Isolation of Cryptococcus neoformans var. neoformans from bird droppings, fruits and vegetables in Mexico City.

    Science.gov (United States)

    López-Martínez, R; Castañón-Olivares, L R

    1995-01-01

    The presence of Cryptococcus neoformans in various natural sources, such as bird droppings, fruits and vegetables, was investigated. A total of 711 samples were analyzed; C. neoformans var. neoformans was isolated from seven out of 74 bird droppings (9.5%), with parrots as one of the most significant sources. Fruits were positive in 9.5% of the 169 samples studied, specially citrus fruits, particularly grapefruit, in which the highest frequency was found. From the 468 vegetable samples, only 20 were positive (4.2%). It is emphasized that five of the positive vegetables species are autochthonous to Mexico: avocado (Nectandra salicifolia), beet (Beta vulgaris var. quinopodiace), chayote (Sechium edule), stringbean (Cassia sp), and nopal (Opuntia ficus-indica). PMID:7617014

  15. Prescription patterns of antihypertensives in a community health centre in Mexico City: a drug utilization study.

    Science.gov (United States)

    Alba-Leonel, Adela; Carvajal, Alfonso; Fierro, Immaculada; Castillo-Nájera, Fernando; Campos-Ramos, Oscar; Villa-Romero, Antonio; Molina-Guarneros, Juan

    2016-06-01

    Hypertension is highly prevalent; in Mexico, the 2012 National Health and Nutrition Survey reported a prevalence of hypertension of 31.5% in the adult population. Pharmacological treatment is the commonest intervention and has been shown to reduce cardiovascular mortality and morbidity, and total mortality. Accordingly, the type and number of antihypertensives used and the outcome - in terms of blood pressure (BP) control - are important. Therefore, our purpose is to learn the pattern of antihypertensive drug prescription and explore the determinants of BP control in an urban population in Mexico. A retrospective cross-sectional drug utilization study was conducted. Medical records from a community health centre were searched to identify those corresponding to patients diagnosed with hypertension; information upon antihypertensives used and control of the disease was carefully retrieved. A logistic regression model was built to know the main determinants of BP control. A sample of 345 clinical records of interest was identified. Most patients received antihypertensives (86.4%); the leading medications used were angiotensin-converting enzyme inhibitors, 63.8%; beta-blockers (26.5%), diuretics (19.8%), angiotensin-receptor blockers (15.8%) and calcium-channel blockers (6.4%). Only the age (≥55 years) and BMI (>30) of the patients, and the age of the doctors (≥55 years), had an important influence on BP control. Obesity is a particular and important determinant of uncontrolled hypertension; it is worth to act on body weight, on an individual basis. As lack of control has been also tied to elderly doctors, an education programme could be envisaged. PMID:26787266

  16. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study

    Directory of Open Access Journals (Sweden)

    J. A. de Gouw

    2009-05-01

    Full Text Available Volatile organic compounds (VOCs and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives. Diurnal variations of hydrocarbons, elemental carbon (EC and hydrocarbon-like organic aerosol (HOA were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA and water-soluble organic carbon (WSOC stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the U.S., but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the U.S., due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the U.S. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC, and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps

  17. Factors influencing the large-scale distribution of Hg° in the Mexico City area and over the North Pacific

    OpenAIRE

    D. Blake; S. Vay; Sachse, G.; Browell, E.; Avery, M.; J. Dibb; E. Scheuer; H. Mao; Talbot, R.; Huey, G.; H. Fuelberg

    2007-01-01

    Gas-phase elemental mercury (Hg°) was measured aboard the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in spring 2006. Flights were conducted around Mexico City and on two subsequent deployments over the North Pacific based out of Honolulu, Hawaii and Anchorage, Alaska. Data obtained from 0.15–12 km altitude showed that Hg° exhibited a relatively constant vertical profile centered around 100 ppqv. Highly concentrated pol...

  18. Factors influencing the large-scale distribution of Hg° in the Mexico City area and over the North Pacific

    OpenAIRE

    Talbot, R.; H. Mao; E. Scheuer; J. Dibb; Avery, M.; Browell, E.; Sachse, G.; S. Vay; D. Blake; Huey, G.; H. Fuelberg

    2008-01-01

    Gas-phase elemental mercury (Hg°) was measured aboard the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in spring 2006. Flights were conducted around Mexico City and on two subsequent deployments over the North Pacific based out of Honolulu, Hawaii and Anchorage, Alaska. Data obtained from 0.15–12 km altitude showed that Hg° exhibited a relatively constant vertical profile centered around 100 ppqv. Highl...

  19. Factors influencing the large-scale distribution of Hg° in the Mexico City area and over the North Pacific

    OpenAIRE

    Talbot, R.; H. Mao; E. Scheuer; J. Dibb; Avery, M.; Browell, E.; Sachse, G.; S. Vay; D. Blake; Huey, G.; H. Fuelberg

    2008-01-01

    International audience Gas-phase elemental mercury (Hg°) was measured aboard the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in spring 2006. Flights were conducted around Mexico City and on two subsequent deployments over the North Pacific based out of Honolulu, Hawaii and Anchorage, Alaska. Data obtained from 0.15?12 km altitude showed that Hg° exhibited a relatively constant vertical profile centered around 100 ppqv. Highly conc...

  20. Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO2 retrievals during the MILAGRO field campaign

    OpenAIRE

    B. de Foy; Krotkov, N. A.; Bei, N.; S. C. Herndon; L. G. Huey; Martínez, A.-P.; L. G. Ruiz-Suárez; Wood, E. C.; Zavala, M; L. T. Molina

    2009-01-01

    Large sulfur dioxide plumes were measured in the Mexico City Metropolitan Area (MCMA) during the MILAGRO field campaign. This paper seeks to identify the sources of these plumes and the meteorological processes that affect their dispersion in a complex mountain basin. Surface measurements of SO2 and winds are analysed in combination with radar wind profiler data to identify transport directions. Satellite retrievals of vertical SO2 columns from the Ozone Monitoring Ins...

  1. Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO2 retrievals during the MILAGRO field campaign

    OpenAIRE

    Wood, E. C.; Zavala, M; L. G. Ruiz-Suárez; L. G. Huey; A.-P. Martínez; S. C. Herndon; B. de Foy; Bei, N.; L. T. Molina

    2009-01-01

    Large sulfur dioxide plumes were measured in the Mexico City Metropolitan Area (MCMA) during the MILAGRO field campaign. This paper seeks to identify the sources of these plumes and the meteorological processes that affect their dispersion in a complex mountain basin. Surface measurements of SO2 and winds are analysed in combination with radar wind profiler data to identify transport directions. Satellite retrievals of vertical SO2 columns from the Ozone Monitoring Instrument (OMI) reveal the...

  2. Emission and chemistry of organic carbon in the gas and aerosol phase at a sub-urban site near Mexico City in March 2006 during the MILAGRO study

    Directory of Open Access Journals (Sweden)

    J. A. de Gouw

    2008-12-01

    Full Text Available Volatile organic compounds (VOCs and carbonaceous aerosol were measured at a sub-urban site near Mexico City in March of 2006 during the MILAGRO study (Megacity Initiative: Local and Global Research Objectives. Diurnal variations of hydrocarbons, elemental carbon (EC and hydrocarbon-like organic aerosol (HOA were dominated by a high peak in the early morning when local emissions accumulated in a shallow boundary layer, and a minimum in the afternoon when the emissions were diluted in a significantly expanded boundary layer and, in case of the reactive gases, removed by OH. In comparison, diurnal variations of species with secondary sources such as the aldehydes, ketones, oxygenated organic aerosol (OOA and water-soluble organic carbon (WSOC stayed relatively high in the afternoon indicating strong photochemical formation. Emission ratios of many hydrocarbon species relative to CO were higher in Mexico City than in the US, but we found similar emission ratios for most oxygenated VOCs and organic aerosol. Secondary formation of acetone may be more efficient in Mexico City than in the US, due to higher emissions of alkane precursors from the use of liquefied petroleum gas. Secondary formation of organic aerosol was similar between Mexico City and the US. Combining the data for all measured gas and aerosol species, we describe the budget of total observed organic carbon (TOOC, and find that the enhancement ratio of TOOC relative to CO is conserved between the early morning and mid afternoon despite large compositional changes. Finally, the influence of biomass burning is investigated using the measurements of acetonitrile, which was found to correlate with levoglucosan in the particle phase. Diurnal variations of acetonitrile indicate a contribution from local burning sources. Scatter plots of acetonitrile versus CO suggest that the contribution of biomass burning to the enhancement of most gas and aerosol species was not dominant and perhaps not

  3. THE RELATIONSHIP BETWEEN SARCOPENIA,UNDERNUTRITION, PHYSICAL MOBILITY AND BASIC ACTIVITIES OF DAILY LIVING IN A GROUP OF ELDERLY WOMEN OF MEXICO CITY

    OpenAIRE

    María del Consuelo Velázquez Alva; María Esther Irigoyen Camacho; Jaime Delgadillo Velázquez; Irina Lazarevich

    2013-01-01

    Background: Sarcopenia is a geriatric syndrome, which affects the functional status and mobility of individuals. Objective: To identify the prevalence of sarcopenia and undernutrition, and to assess the association between sarcopenia and mobility, and sarcopenia and basic activities of daily living (ADL) in a group of elderly women. Subjects and methods: A cross-sectional study was performed in patients attending a geriatric service at a government hospital in Mexico City. Sarcopenia was iden...

  4. Eddy Covariance Flux Measurements of Pollutant Gases in the Mexico City Urban Area: a Useful Technique to Evaluate Emissions inventories

    Science.gov (United States)

    Velasco, E.; Grivicke, R.; Pressley, S.; Allwine, G.; Jobson, T.; Westberg, H.; Lamb, B.; Ramos, R.; Molina, L.

    2007-12-01

    Direct measurements of emissions of pollutant gases that include all major and minor emissions sources in urban areas are a missing requirement to improve and evaluate emissions inventories. The quality of an urban emissions inventory relies on the accuracy of the information of anthropogenic activities, which in many cases is not available, in particular in urban areas of developing countries. As part of the MCMA-2003 field campaign, we demonstrated the feasibility of using eddy covariance (EC) techniques coupled with fast-response sensors to measure fluxes of volatile organic compounds (VOCs) and CO2 from a residential district of Mexico City. Those flux measurements demonstrated to be also a valuable tool to evaluate the emissions inventory used for air quality modeling. With the objective to confirm the representativeness of the 2003 flux measurements in terms of magnitude, composition and diurnal distribution, as well to evaluate the most recent emissions inventory, a second flux system was deployed in a different district of Mexico City during the 2006 MILAGRO field campaign. This system was located in a busy district surrounded by congested avenues close to the center of the city. In 2003 and 2006 fluxes of olefins and CO2 were measured by the EC technique using a Fast Isoprene Sensor calibrated with a propylene standard and an open path Infrared Gas Analyzer (IRGA), respectively. Fluxes of aromatic and oxygenated VOCs were analyzed by Proton Transfer Reaction-Mass Spectroscopy (PTR-MS) and the disjunct eddy covariance (DEC) technique. In 2006 the number of VOCs was extended using a disjunct eddy accumulation (DEA) system. This system collected whole air samples as function of the direction of the vertical wind component, and the samples were analyzed on site by gas chromatography / flame ionization detection (GC-FID). In both studies we found that the urban surface is a net source of CO2 and VOCs. The diurnal patterns were similar, but the 2006 fluxes

  5. Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

    Directory of Open Access Journals (Sweden)

    J. Lee-Taylor

    2011-06-01

    Full Text Available The evolution of organic aerosols (OA in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere, wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3–10 alkanes, alkenes, and light aromatics, as well as larger n-alkanes (up to C25 not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO. The model successfully reproduces the magnitude and diurnal shape for both primary (POA and secondary (SOA organic aerosols, with POA peaking in the early morning at 15–20 μg m−3, and SOA peaking at 10–15 μg m−3 during mid-day. The majority (≥75 % of the model SOA stems from the large n-alkanes, with the remainder mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by δ-hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative impacts of SOA.

  6. Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

    Directory of Open Access Journals (Sweden)

    J. Lee-Taylor

    2011-12-01

    Full Text Available The evolution of organic aerosols (OA in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere, wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3-10 alkanes, alkenes, and light aromatics, as well as larger n-alkanes (up to C25 not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO. The model successfully reproduces the magnitude and diurnal shape for both primary (POA and secondary (SOA organic aerosols, with POA peaking in the early morning at 15–20 μg m−3, and SOA peaking at 10–15 μg m−3 during mid-day. The majority (≥75% of the model SOA stems from reaction products of the large n-alkanes, used here as surrogates for all emitted hydrocarbons of similar volatility, with the remaining SOA originating mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by δ-hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative

  7. Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

    Energy Technology Data Exchange (ETDEWEB)

    Lee-Taylor, J.; Madronich, Sasha; Aumont, B.; Baker, A.; Camredon, M.; Hodzic, Alma; Tyndall, G. S.; Apel, Eric; Zaveri, Rahul A.

    2011-12-21

    The evolution of organic aerosols (OA) in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3-10 alkanes, alkenes, and light aromatics, as well as larger n-alkanes (up to C25) not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO). The model successfully reproduces the magnitude and diurnal shape for both primary (POA) and secondary (SOA) organic aerosols, with POA peaking in the early morning at 15-20 ug m-3, and SOA peaking at 10-15 μg m-3 during mid-day. The majority (> 75%) of the model SOA stems from the large n-alkanes, with the remainder mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by *- hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative impacts of SOA.

  8. Structural Determinants of Client Perpetrated Violence Among Female Sex Workers in Two Mexico-U.S. Border Cities.

    Science.gov (United States)

    Conners, Erin E; Silverman, Jay G; Ulibarri, Monica; Magis-Rodriguez, Carlos; Strathdee, Steffanie A; Staines-Orozco, Hugo; Patterson, Thomas L; Brouwer, Kimberly C

    2016-01-01

    Female sex workers (FSWs) are disproportionately affected by both HIV and gender-based violence, such as that perpetrated by clients (CPV). We used a structural determinants framework to assess correlates of physical or sexual CPV in the past 6 months among FSWs in the Mexico/U.S. border cities of Ciudad Juárez and Tijuana. Bivariate and multivariate logistic regression analysis identified individual, client, interpersonal, work environment and macrostructural factors associated with recent CPV. Among 496 FSWs, 5 % experienced recent CPV. Witnessing violence towards other FSWs in one's neighborhood (aOR 5.6, 95 % CI 1.8-17.2), having a majority of foreign (aOR 3.5, 95 % CI 1.4-8.4) or substance using (aOR 4.0, 95 % CI 1.5-10.4) clients, and being a street worker (aOR 3.0, 95 % CI 1.1-7.7) were independently associated with recent CPV. Our findings underscore the vulnerability of FSWs and the need to design policies and interventions addressing macro-level influences on CPV rather than exclusively targeting individual behaviors. PMID:26111732

  9. Family planning barriers in marginal contexts in Mexico City, Federal District: vision of the health care provider

    Directory of Open Access Journals (Sweden)

    Marcela Agudelo B

    2009-08-01

    Full Text Available Objective: To approach the barriers to providing services of family planning in marginal areas of Iztapalapa and Tlalpan in the Federal District of Mexico City, from the perspective of health providers. Methodology: Qualitative exploration involved through focus groups with healthcare providers, both public and private, further topics such as socio-environmental, unmet needs in sexual and reproductive health (including family planning, relations gender, among others. Results:We found that among the main obstacles to access to family planning services are misinformation, culture and population beliefs, the inadequate training of health professionals in related areas, the shortage methods o f contraception, the deficiency infrastructure and resources. The barriers perceived by providers are coming from the people, and seldom alluded to the barriers arising from service of their own profession and/or personal convictions. Conclusion: Although the study focused on a specific social environment, this could reflect a reality in other contexts with similar characteristics, so this work constitutes a contribution to both practical and methodological analysis of the phenomenon.

  10. Comparative analysis of the street generation of inorganic urban solid waste (IUSW) in two neighborhoods of Mexico City.

    Science.gov (United States)

    Muñoz-Cadena, C E; Arenas-Huertero, F J; Ramón-Gallegos, E

    2009-03-01

    Inorganic urban solid waste (IUSW) is a serious problem in developing countries, and IUSW in the street that does not have adequate final disposal is responsible for serious environmental effects. The aim of this work was to determine the dynamics of the generation of IUSW in the streets of two neighborhoods of different socioeconomic strata in Mexico City during 5 weeks in 2006. The amount of IUSW was recorded every day from 9:00 to 12:00 h, separated, classified, and registered. It was found that plastic (50%) and paper (44.5%) wastes were found most frequently, whereas, textiles (0.4%) and glass (0.5%) wastes were present less frequently in all samples. The IUSWs without commercial brands were more abundant. Branded plastic wrappers of PepsiCo and Bimbo, as well as polyethylene terephthalate (PET) containers of Coca Cola, registered the highest values, while Gatorade, Barrilitos, and Peñafiel registered the lowest. The neighborhood with a higher income and more vegetation on sidewalks or in jardinières, which are used to hide solid waste, had more IUSW than the neighborhood with lower income, where IUSW was thrown out directly into the street. The knowledge of the real generation and composition of IUSW will contribute to the prevention of its negative environmental and social impacts, as well as guarantee the efficiency of its sustainable management. PMID:18845430

  11. Estimation of a "radiatively correct" black carbon specific absorption during the Mexico City Metropolitan Area (MCMA 2003 field campaign

    Directory of Open Access Journals (Sweden)

    J. C. Barnard

    2007-01-01

    Full Text Available During the Mexico City Metropolitan Area (MCMA field campaign of 2003, measurements of the shortwave radiation field allowed the inference of the black carbon (BC specific absorption, αλ, defined as the monochromatic absorption cross section per unit mass (with units of m2/g. The averaged values of αλ derived from the method here are either 8.9 m2/g or 8.2 m2/g at 500 nm, depending upon the physical and optical parameters assumed for BC. These results are reasonably consistent with those of Schuster et al. (2005, 9.5 m2/g, and Baumgartner et al. (2002, 7.0 m2/g, both measured at 550 nm. The αλ values reported in this paper should only be considered effective, "radiatively correct" values because when used in radiative transfer calculations the calculated irradiances match the measured irradiances at 500 nm. The specific absorption so defined can assume a wide range of values, depending upon: (1 the assumptions made prior to the retrieval (e.g., shell/core aerosol configuration, and (2 values chosen for BC density and refractive index. The range of possible values is large, corresponding to a "worst case" uncertainty of about ±70%, assuming that all errors are additive and of the same sign so that no error cancellation occurs.

  12. Application of high resolution geophysical prospecting to assess the risk related to subsurface deformation in Mexico City

    Science.gov (United States)

    Centeno-Salas, F. A.; Carreón-Freyre, D.; Flores-García, W. A.; Gutiérrez-Calderón, R. I.

    2015-11-01

    In the eastern sector of Mexico City the sub soil consists of high contrasting sequences (lacustrine and volcanic inter bedded deposits) that favor the development of erratic fracturing in the surface causing damage to the urban infrastructure. The high-resolution geophysical prospecting are useful tools for the assessment of ground deformation and fracturing associated with land subsidence phenomena. The GPR method allowed to evaluate the fracture propagation and deformation of vulcano-sedimentary sequences at different depths, the main electrical parameters are directly related with the gravimetric and volumetric water content and therefore with the plasticity of the near surface prospected sequences. The active seismology prospection consisted in a combination of Seismic Refraction (SR) and Multichannel Analysis of Surface Waves (MASW) for the estimation of the velocity of the mechanical compressive (P) and the shear (S) waves. The integration of both methods allowed to estimate the geomechanical parameters characterizing the studied sequence, the Poisson Ratio and the volumetric compressibility. The obtained mechanical parameters were correlated with laboratory measured parameters such as plasticity index, density, shear strength and compressibility and, GPR and seismic profiles were correlated with the mapped fracture systems in the study area. Once calibrated, the profiles allowed to identify the lithological contact between lacustrine and volcanic sequences, their variations of thicknesses in depth and to assess the deformation area in the surface. An accurate determination of the geometry of fracturing was of the most importance for the assessment of the geological risk in the study area.

  13. Of Lady-killers and ‘Men Dressed As Women’: Soap Opera, Scapegoats and the Mexico City Police Department

    Directory of Open Access Journals (Sweden)

    Vek Lewis

    2008-02-01

    Full Text Available Over two days in October 2005, police in Mexico City conducted a series of raids on male-to-female transgender (travesti prostitutes working in the streets. The motive of the investigation was not related to sex work at all, but rather, the hunt for a serial killer responsible for the deaths of elderly women between 2003 and 2005. With few leads apart from reports by a couple of eyewitnesses that they had seen ‘a man dressed as a woman’ enter the houses of the victims, the Chief Public Prosecutor announced that the killer could be a travesti. On January 25, 2006, the ‘lady-killer’ was finally discovered to be neither a ‘man dressed as a woman’, nor a travesti. The suspect, a female former lucha libre wrestler, Juana Barraza, was taken into custody. In the period leading up to the October raids, Mexico’s chief television channel, Televisa, finished up the season of its popular soap, La Madrastra, with a plot line that features a man who dresses as a woman to disguise his usual male identity and kill his female victims. This paper examines the case, looking at the influence of the soap opera narrative in the profiling of travestis as suspect ‘men dressed as women’. It draws on studies of soap opera and mass media forms in Mexican society, as well as the work of transgender theory in understanding how crossgender identities are circumscribed by discourse.

  14. The social construction of real estate market risk. The case of a financial investments cluster in Mexico City

    Directory of Open Access Journals (Sweden)

    Louise David

    2012-11-01

    Full Text Available This article contributes to the study of the geographical concentration of financial investments in real estate markets. It demonstrates the social construction process at work in the evolution of real estate market risks. The objective is to highlight the conditions that allow or impede the implementation of ‘opportunistic’ and ‘conservative’ risk strategies. By analyzing the market entry of financial investors in the Cuautitlan industrial real estate market - an ‘emerging’ real estate market in Mexico City - this paper demonstrates that, due to the joint action of land developers, non-financial as well as financial real estate investors, this market moved from being ‘too risky’ to becoming an opportunistic market, and then a conservative one. There were two important phases in the transformation process. First, the contribution of land developers was fundamental to the transformation of the market from being too risky to being opportunistic from the perspective of financial investors. Two different types of land developers are evident: some are not willing to help financial investors’ entry in the market while others developed a business plan designed to facilitate financial investments. In the second phase of the market’s risks transformation, opportunistic financial investors enabled the conditions for the arrival of conservative financial investors, thanks to their presence in emerging markets and the diffusion of information.

  15. Emission factors for domestic use of L.P. gas in the metropolitan area of Mexico City

    International Nuclear Information System (INIS)

    One of the main problems found in air pollution in the Metropolitan Area of Mexico City (MAMC) is the presence of high concentrations of ozone at ground level in the atmosphere. The official Mexican standard for ozone concentration in the air (0.11 ppm, one hour, once every 3 years) has been exceeded more than 300 days per year. Ozone is formed due to the emissions of nitrogen oxides and hydrocarbons originated from either combustion processes or vapors emanating from fuel handling operations. The results of an evaluation of several domestic devices like stoves and water heaters with L.P. gas as fuel are presented. A method for the evaluation of hydrocarbon emission was developed. A prototype of domestic installation was constructed. The prototype includes L.P. gas tank, domestic stove, water heater, piping and instrumentation. Several combinations of stoves and water heaters were evaluated. The sampling and analysis of hydrocarbons were performed using laboratory equipment originally designed for the evaluation of combustion and evaporative emissions in automobiles: a SHED camera (sealed room equipped with an hydrocarbon analyzer) was used to measure leaks in the prototype of domestic installation and a Constant Volume Sampler (CVS) for the measurement of incomplete combustion emissions. Emission factors were developed for each domestic installation

  16. Modelling canopy radiation budget through multiple scattering approximation: a case study of coniferous forest in Mexico City Valley

    Science.gov (United States)

    Silván-Cárdenas, Jose L.; Corona-Romero, Nirani

    2015-10-01

    In this paper, we describe some results from a study on hyperspectral analysis of coniferous canopy scattering for the purpose of estimating forest biophysical and structural parameters. Georeferenced airborne hyperspectral measurements were taken from a flying helicopter over a coniferous forest dominated by Pinus hartweguii and Abies religiosa within the Federal District Conservation Land in Mexico City. Hyperspectral data was recorded in the optical range from 350 to 2500 nm at 1nm spectral resolution using the FieldSpec 4 (ASD Inc.). Spectral measurements were also carried out in the ground for vegetation and understory components, including leaf, bark, soil and grass. Measurements were then analyzed through a previously developed multiple scattering approximation (MSA) model, which represents above-canopy spectral reflectance through a non-linear combination of pure spectral components (endmembers), as well as through a set of photon recollision probabilities and interceptance fractions. In this paper we provide an expression for the canopy absorptance as the basis for estimating the components of canopy radiation budget using the MSA model. Furthermore, since MSA does not prescribe a priori the endmembers to incorporate in the model, a multiple endmember selection method (MESMSA) was developed and tested. Photon recollision probabilities and interceptance fractions were estimated by fitting the model to airborne spectral reflectance and selected endmembers where then used to estimate the canopy radiation budget at each measured location.

  17. The energy demand and the impact by fossil fuels use in the Mexico City Metropolitan Area, from 1988 to 2000

    International Nuclear Information System (INIS)

    Temporary variation for the demand of refining products which are used in the Mexico City Metropolitan Area (MCMA) is presented. Its consequent energy contribution is evaluated from 1988 to 2000. The annual estimation was integrated from a detailed inventory of fuels volume, so as the calculus of its respective energy equivalence. The fuel quality specifications, which have been required by regional Air Quality authority for controlling emissions to the atmosphere, are also presented for the same period. The evolution demand of fuels, in term of volume, quality and its energy contribution for this area, is compared with the national demand. On this regard, fuel pool differs in each bound and the demand along the same period has been increasing on both regions but at different rates, with 21% at MCMA and 31% countrywide. In 2000, the MCMA demanded 14% of the internal refining products volume sales, which represented 17% of the energy contribution to the country for those fuels. Likewise, the energy use coefficient (GJ per capita) was applied to compare this region with country trends. During 1996 and up to 2000, the MCMA presented slightly minor energy use per capita, than the rest of the country, and this period was distinguished also for using cleaner fuels and for obtaining improvements in air quality. On the other hand, MCMA and country greenhouse gases emissions will increase because of their fossil fuel dependence, so several mitigation measures must be implemented in the next decades

  18. What Explains Criminal Violence in Mexico City? A Test of Two Theories of Crime

    Directory of Open Access Journals (Sweden)

    Carlos Vilalta

    2016-02-01

    Full Text Available There are competing theories of what drives crime in cities and neighbourhoods. Two widely cited theoretical approaches focused on social disorganization and institutional anomie propose different explanations for the causes and dynamics of criminality. Yet these theories are seldom empirically tested, much less acknowledged, outside of North America and Western Europe. This article considers their applicability in Mexico’s capital, a sprawling metropolis of more than 20 million people. The authors administer spatial and general statistical tests to explain the geographical patterns of crime rates across multiple forms of criminality. The assessment demonstrates that both theories accurately predict the spatial distribution of crime. The article concludes with a host of policy conclusions, emphasizing social crime prevention over more traditional law and order measures. and consolidating families, parents and childcare.

  19. Stressors associated with hiperstress in undergraduate students in the city of Chilpancingo, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Mireya Maruris Reducindo

    2013-08-01

    Full Text Available The objective was to determine the level of stress and associated factors in undergraduates students from all the Academic Units located in the University city in chilpancingo, gro. A cross-sectional study was conducted in a random sample of 500 students with ages ranging from 17-44 years, the average age was 21.29 ± 3.13 years. Stress levels were measured with an estresometer containing 96 questions related to lifestyle, environment, symptoms, employment/occupation, relationships and personality. The prevalence of hiperestrés was 44.4%. The Academic Units with more prevalence of stress were chemistry Sciences (56% and philosophy and literature (52.54%. The women have more stress that the men. We found 17 factors associated with hiperstress, among which are: no exercise, alcohol consumption, feeling tired and without energy, among others.

  20. Panama Canal Watershed Experiment- Agua Salud Project

    Science.gov (United States)

    Stallard, Robert F.; Ogden, Fred L.; Elsenbeer, Helmut; Hall, Jefferson S.

    2010-01-01

    The Agua Salud Project utilizes the Panama Canal’s (Canal) central role in world commerce to focus global attention on the ecosystem services provided by tropical forests. The Canal was one of the great engineering projects in the world. Completed in 1914, after almost a decade of concerted effort, its 80 km length greatly shortened the voyage between the Atlantic and Pacific Oceans. An entire class of ships, the Panamax, has been constructed to maximize the amount of cargo that can be carried in a Canal passage. In today’s parlance, the Canal is a “green” operation, powered largely by water (Table 1). The locks, three pairs on each end with a net lift of 27 meters, are gravity fed. For each ton of cargo that is transferred from ocean to ocean, about 13 tons of water (m3) are used. Lake Gatún forms much of the waterway in the Canal transect. Hydroelectricity is generated at the Gatún dam, whenever there is surplus water, and at Madden Dam (completed in 1936) when water is transferred from Lake Alhajuela to Lake Gatún. The Canal watershed is the source of drinking water for Panama City and Colon City, at either end of the Canal, and numerous towns in between.

  1. Root canal irrigants

    OpenAIRE

    Kandaswamy Deivanayagam; Venkateshbabu Nagendrababu

    2010-01-01

    Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are...

  2. Discussion on Sustainable Water Technologies for Peri-Urban Areas of Mexico City: Balancing Urbanization and Environmental Conservation

    Directory of Open Access Journals (Sweden)

    Tiemen A. Nanninga

    2012-09-01

    Full Text Available Often centralized water supply, sanitation and solid waste services struggle to keep up with the rapid expansion of urban areas. The peri-urban areas are at the forefront of this expansion and it is here where decentralized technologies are increasingly being implemented. The introduction of decentralized technologies allows for the development of new opportunities that enable the recovery and reuse of resources in the form of water, nutrients and energy. This resource-oriented management of water, nutrients and energy requires a sustainable system aimed at low resource use and high recovery and reuse rates. Instead of investigating each sector separately, as has been traditionally done, this article proposes and discusses a concept that seeks to combine the in- and outflows of the different sectors, reusing water and other liberated resources where possible. This paper shows and demonstrates examples of different types of sustainable technologies that can be implemented in the peri-urban areas of Mexico City [rainwater harvesting, EcoSan and biofiltros (small constructed wetlands, and (vermi-composting]. An innovative participatory planning method, combining scenario development with a participatory planning workshop with key stakeholders, was applied and resulted in three concept scenarios. Specific technologies were then selected for each concept scenario that the technical feasibility and applicability was assessed. Following this, the resulting resource flows (nutrients, water and energy were determined and analyzed. The results show that decentralized technologies not only have the potential to deliver adequate water supply, sanitation and solid waste services in peri-urban areas and lessen environmental pollution, but also can recover significant amounts of resources thereby saving costs and providing valuable inputs in, for instance, the agricultural sector. Social acceptance of the technologies and institutional cooperation

  3. Discussion on Sustainable Water Technologies for Peri-Urban Areas of Mexico City: Balancing Urbanization and Environmental Conservation

    Directory of Open Access Journals (Sweden)

    Laura Essl

    2012-09-01

    Full Text Available Often centralized water supply, sanitation and solid waste services struggle to keep up with the rapid expansion of urban areas. The peri-urban areas are at the forefront of this expansion and it is here where decentralized technologies are increasingly being implemented. The introduction of decentralized technologies allows for the development of new opportunities that enable the recovery and reuse of resources in the form of water, nutrients and energy. This resource-oriented management of water, nutrients and energy requires a sustainable system aimed at low resource use and high recovery and reuse rates. Instead of investigating each sector separately, as has been traditionally done, this article proposes and discusses a concept that seeks to combine the in- and outflows of the different sectors, reusing water and other liberated resources where possible. This paper shows and demonstrates examples of different types of sustainable technologies that can be implemented in the peri-urban areas of Mexico City [rainwater harvesting, EcoSan and biofiltros (small constructed wetlands, and (vermi-composting]. An innovative participatory planning method, combining scenario development with a participatory planning workshop with key stakeholders, was applied and resulted in three concept scenarios. Specific technologies were then selected for each concept scenario that the technical feasibility and applicability was assessed. Following this, the resulting resource flows (nutrients, water and energy were determined and analyzed. The results show that decentralized technologies not only have the potential to deliver adequate water supply, sanitation and solid waste services in peri-urban areas and lessen environmental pollution, but also can recover significant amounts of resources thereby saving costs and providing valuable inputs in, for instance, the agricultural sector. Social acceptance of the technologies and institutional cooperation, however, is

  4. Educational impact of a clinical anatomy workshop on 1st-year orthopedic and rheumatology fellows in Mexico City.

    Science.gov (United States)

    Saavedra, M A; Villaseñor-Ovies, P; Harfush, L A; Navarro-Zarza, J E; Canoso, J J; Cruz-Domínguez, P; Vargas, A; Hernández-Díaz, C; Chiapas-Gasca, K; Camacho-Galindo, J; Alvarez-Nemegyei, J; Kalish, R A

    2016-05-01

    We aim to study the educational impact of a clinical anatomy workshop in 1st-year orthopedic and rheumatology fellows. First-year rheumatology fellows (N = 17) and a convenience sample of 1st-year orthopedic fellows (N = 14) from Mexico City in the 9th month of training participated in the study. The pre- and the post- workshop tests included the same 20 questions that had to be answered by identification or demonstration of relevant anatomical items. The questions, arranged by anatomical regions, were asked in five dynamic stations. Overall, the 31 participants showed an increase of correct answers, from a median of 6 (range 1 to 12) in the pre-workshop test, to a median of 14 (range 7 to 19) in the post-workshop test. In the pre-workshop test, the correct median answers were 7 (range 2 to 12) in the orthopedic fellows and 5 (range 1 to 10) in the rheumatology fellows (p = 0.297). Corresponding scores in the post-workshop were 15 (range 10 to 19) and 12 (range 7 to 18) (p = 0.026) showing a significant difference favoring the orthopedic group. Our clinical anatomy workshop was efficacious, in the short term, as a teaching instrument for 1st-year orthopedic and rheumatology fellows. The post-workshop scores, although significantly improved in both groups, particularly in the orthopedic fellows, were still suboptimal. Further refinements of our workshop might yield better results. PMID:26400643

  5. A remedy against delinquency: child labour in lock-up institutions in post-revolutionary Mexico City

    Directory of Open Access Journals (Sweden)

    Sosenski, Susana

    2008-12-01

    Full Text Available In post-revolutionary Mexico City, work therapy prevailed over other treatments used to correct what was considered a social disease: child delinquency. Thousands of children took up the fields of farm schools as well as workshops in reformatories and industrial schools. The manual labor carried out by children of the popular sectors was used in childhood establishments as a way to make up for what they received in those places. Based on the logic that work as regenerator of a sick body and an ill mind, the Mexican state tried to turn the young delinquents into the future workers.

    En la Ciudad de México, durante el periodo posrevolucionario la terapéutica del trabajo se impuso frente a otros tratamientos como forma de prevenir y corregir lo que se consideraba una enfermedad social: la delincuencia infantil. Mientras miles de niños ocuparon los campos de cultivo de las escuelas granjas y las decenas de talleres de las correccionales y escuelas industriales. La mano de obra de los niños de los sectores populares fue utilizada en establecimientos de «protección» a la infancia como retribución a lo que recibían en estos lugares. Bajo la lógica del trabajo como regenerador de un cuerpo y una mente enferma, se pretendió convertir a los niños infractores en los futuros trabajadores y de esa forma incorporarlos al proyecto económico del Estado mexicano.

  6. Measurements of Black Carbon Specific Absorption in the Mexico City Metropolitan Area during the MCMA 2003 Field Campaign

    Directory of Open Access Journals (Sweden)

    J. C. Barnard

    2005-06-01

    Full Text Available During the Mexico City Metropolitan Area (MCMA field campaign of 2003, measurements of the shortwave radiation field, lidar backscatter, and atmospheric concentrations of black carbon (BC permitted the inference of the BC carbon specific absorption, αλ, defined as the absorption cross section per unit mass (with units of m2/g. This diverse set of measurements allowed us to determine αλ in two ways. These methods – labeled I and II – are distinguished from one another in the manner that the columnar concentration of BC (with units of mg/m2 is determined. This concentration is found by using either surface measurements of BC concentration and lidar estimates of aerosol mixing heights, or a more rigorous method that relies on the columnar aerosol size distribution. The averaged values of αλ derived from these methods agree to about 20%, although we expect that the values obtained from method I are underestimated. These results, along with those of Schuster et al. (2005, suggest that in the MCMA, αλ is in a range of 8 to 10 m2/g at a wavelength of 550 nm. This range is somewhat lower than the commonly accepted value of 10 m2/g for a wavelength of 550 nm, but is consistent with the calculations of Fuller et al. (1999, who suggest that this value is too high.

  7. Loss of a lake system in a megacity: The impact of urban expansion on seasonal meteorology in Mexico City

    Science.gov (United States)

    Benson-Lira, V.; Georgescu, M.; Kaplan, S.; Vivoni, E. R.

    2016-04-01

    The Mexico City Metropolitan Area (MCMA) has undergone significant urban expansion in a closed basin that once supported a large lacustrine system. While urbanization has been mentioned as a factor in observed meteorological trends, a systematic study of the effects of land use-land cover change (LULCC) on seasonal meteorology is lacking. In this study, we utilize the Weather Research and Forecasting (WRF) system to determine the spatiotemporal changes in near-surface air temperature, precipitation, and boundary layer conditions induced by the modern-day urban landscape relative to presettlement conditions. We capture the MCMA extent through an improved Landsat-based multicategory urban classification and therefore account for intraurban spatial heterogeneity and further conduct additional experiments to examine the sensitivity to anthropogenic heating within WRF. We find that accounting for these factors produced the best simulations of thermal conditions, with RMSE values less than 1.5°C at all measurement stations, and an improved diurnal cycle of air temperature and precipitation. We then assessed the impacts of LULCC in the MCMA, finding that thermal changes were largest during daytime hours, with temperature increasing, on average, by more than 4°C. Furthermore, we utilize these simulations to mechanistically link the built environment-induced increase in air temperature to simulated increases in rainfall during the evening hours. To our knowledge, this study provides the first dynamical and thermodynamical evidence to support the rainfall enhancements documented through observations in the MCMA and link it quantitatively to the warming effects associated with urbanization. These results have important implications for understanding the meteorological conditions leading to widespread urban flooding in the MCMA.

  8. Daily respiratory mortality and PM{sub 10} pollution in Mexico City: importance of considering place of death

    Energy Technology Data Exchange (ETDEWEB)

    Tellez-Rojo, M.M.; Hernandez-Avila, M.M. [Inst. Nacional de Salud Publica, (Mexico); Romieu, I. [Pan American Health Organization (Mexico); Ruiz-Velasco, S. [Inst. de Investigacion en Matematicas Aplicadas y Sistemas. UNAM (Mexico); Lezana, M.-A. [Direccion General de Estadstica e Informatica. Secretara de Salud (Mexico)

    2000-07-01

    Significant associations have been reported between particles,with a 50% cut-off aerodynamic diameter of 10 mm (PM{sub 10}) and ozone ambient concentrations, and daily number of deaths from respiratory causes. The aim of the present study was to assess such associations among elderly ({>=}65 yrs) residents of Mexico City. Ambient air pollution data were provided by the Metropolitan Monitoring Network. During the study period, the average daily PM{sub 10} ranged 23.4-175.3 {mu}g.m{sup -3}, and ozone 1 h daily maximums ranged 39.4-216.7 ppb. Information was compiled on the primary and underlying causes of death. The analyses were conducted separately according to place of death (within or out of a hospital unit) using time-series methodology. The total number of deaths from all respiratory causes and mortality for chronic obstructive pulmonary diseases (COPD) were significantly related to PM{sub 10} over different lags: an increase of 10 {mu}g.m{sup -3} was related to a 2.9% (95% (CI): 0.9-4.9%) increase and to a 4.1% (95% CI: 1.3%-6.9%) increase with a 3-day lag when death occurred out of medical units, respectively. For deaths occurring in medical units, a longer lag and smaller risk estimate was observed. An interactive effect between PM{sub 10} and ozone was detected. This study confirms that there is an important impact of PM{sub 10} on respiratory morbidity among elderly subjects. It also indicates that accounting for primary and underlying causes of death, and considering place of death may reduce misclassification and provide more accurate estimates of the adverse impact of PM{sub 10} on mortality. (au)

  9. Sources and transport of Δ14C in CO2 within the Mexico City Basin and vicinity

    Directory of Open Access Journals (Sweden)

    H. B. Singh

    2009-07-01

    Full Text Available Radiocarbon samples taken over Mexico City and the surrounding region during the MILAGRO field campaign in March 2006 exhibited an unexpected distribution: (1 relatively few samples (23% were below the North American free tropospheric background value (57±2‰ despite the fossil fuel emissions from one of the world's most highly polluted environments; and (2 frequent enrichment well above the background value was observed. Correlate source tracer species and air transport characteristics were examined to elucidate influences on the radiocarbon distribution. Our analysis suggests that a combination of radiocarbon sources biased the "regional radiocarbon background" above the North American value thereby decreasing the apparent fossil fuel signature. Likely sources include the release of 14C-enhanced carbon from bomb 14C sequestered in plant carbon pools via the ubiquitous biomass burning in the region as well as the direct release of radiocarbon as CO2 from other "hot" sources. Plausible perturbations from local point "hot" sources include the burning of hazardous waste in cement kilns; medical waste incineration; and emissions from the Laguna Verde Nuclear Power Plant. These observations provide insight into the use of Δ14CO2 to constrain fossil fuel emissions in the megacity environment, indicating that underestimation of the fossil fuel contribution to the CO2 flux is likely wherever biomass burning coexists with urban emissions and is unaccounted for as a source of the elevated CO2 observed above local background. Our findings increase the complexity required to quantify fossil fuel-derived CO2 in source-rich environments characteristic of megacities, and have implications for the use of Δ14CO2 observations in evaluating bottom-up emission inventories and their reliability as a tool for validating national emission claims of CO2 within the framework of the Kyoto Protocol.

  10. Aerosol airmass type mapping over the urban Mexico City region from space-based multi-angle imaging

    Directory of Open Access Journals (Sweden)

    F. Patadia

    2013-03-01

    Full Text Available Using Multi-angle Imaging SpectroRadiometer (MISR and sub-orbital measurements from the 2006 INTEX-B/MILAGRO field campaign, in this study we demonstrate MISR's ability to map different aerosol air mass types over the Mexico City metropolitan area. The aerosol air mass distinctions are based on shape, size and single scattering albedo retrievals from the MISR Research Aerosol Retrieval algorithm. In this region, the research algorithm identifies dust-dominated aerosol mixtures based on non-spherical particle shape, whereas spherical biomass burning and urban pollution particles are distinguished by particle size. Four distinct aerosol air masses are identified in the MISR data on 6 March 2006; these results are supported by coincident, airborne high-spectral-resolution lidar (HSRL measurements. Aerosol optical depth (AOD gradients are also consistent between the MISR and sub-orbital measurements, but particles having SSA558≈0.7 must be included in the retrieval algorithm to produce good absolute AOD comparisons over pollution-dominated aerosol air masses. The MISR standard V22 AOD product, at 17.6 km resolution, captures the observed AOD gradients qualitatively, but retrievals at this coarse spatial scale and with limited spherical absorbing particle options underestimate AOD and do not retrieve particle properties adequately over this complex urban region. However, we demonstrate how AOD and aerosol type mapping can be accomplished with MISR data over urban regions, provided the retrieval is performed at sufficiently high spatial resolution, and with a rich enough set of aerosol components and mixtures.

  11. Sixty Years of Mogollon Archaeeology: Papers From the Ninth Mogollon Conference, Silver City, New Mexico, 1996, by Stephanie M Whittlesey, SRI Press, Tucson, 1999

    Directory of Open Access Journals (Sweden)

    Stephen E. Nash

    2000-11-01

    Full Text Available "The diverse papers that were presented at the 1996 Mogollon Conference reveal the geographic, intellectual, and temporal scope of contemporary Mogollon archaeology, and almost nothing of the historical controversy surrounding the Mogollon culture concept" (Whittlesey 1999:vii. With these words, Stephanie M. Whittlesey makes it clear in the preface that Sixty Years of Mogollon Archaeology: Papers From the Ninth Mogollon Conference, Silver City, New Mexico, 1996 (SRl Press 2000 contains few papers on the history of Mogollon archaeology. It might therefore be more appropri­ately titled "Current Research in Mogollon Archaeology." The volume was apparently named to honor the sixtieth anniversary of Emil Haury's 1936 publication The Mogollon Culture of Southwestern New Mexico, which described the Mogollon for the first time.

  12. On the usefulness of atmospheric measurements for air quality evaluation in the context of recent urban meteorology findings in Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Cruz Nunez, X.; Jazcilevich Diamant, A. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: xochitl@atmosfera.unam.mx

    2007-10-15

    In many cities, the main tool used to assess pollution abatement policies is the air quality information obtained from local monitoring network. However, in the context of a complex meteorology and land use such as those prevailing in Mexico City, the point-wise character and lack of detailed chemistry of this information may confer conflictive or biased information. The approach to understand the problem could be not based on solid ground. It is not until the measurement effort is complemented with detailed meteorological and air quality modeling that proper use of the information can be assured. In order to provide an example of this assertion, the usefulness of measured air quality data is gauged in a simplified manner, constructing three dimensional graphs containing local emission concentrations of nitrogen oxides (NO{sub x}), volatile organic compounds (VOC) and maximum ozone (O{sub 3}) concentrations, that we call ozone isopleths, for three sites in Mexico City. Together with corresponding wind rose data, an interpretation of the air pollution transport in the Valley of Mexico using only measured data is attempted. This interpretation, based on measured information subject to local influences, is compared with recent air quality modeling results showing that when measured data is used in conjunction with air quality modeling a better interpretation of air pollution problem can be obtained. A correct strategy to study the air quality problem, especially in the case of Mexico City where complex meteorology and land use is present, should be that both endeavors, measuring and modeling, are pursued with equal vigor. [Spanish] En muchas ciudades la herramienta principal en la evaluacion de las politicas para el control de la contaminacion es la informacion de calidad del aire proveniente de las redes locales de mediciones. Sin embargo, en el contexto de una meteorologia compleja y el uso de suelo de la Ciudad de Mexico, el caracter puntual y la carencia de

  13. Factors influencing the large-scale distribution of Hg° in the Mexico City area and over the North Pacific

    Directory of Open Access Journals (Sweden)

    D. Blake

    2007-11-01

    Full Text Available Gas-phase elemental mercury (Hg° was measured aboard the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment Phase B (INTEX-B campaign in spring 2006. Flights were conducted around Mexico City and on two subsequent deployments over the North Pacific based out of Honolulu, Hawaii and Anchorage, Alaska. Data obtained from 0.15–12 km altitude showed that Hg° exhibited a relatively constant vertical profile centered around 100 ppqv. Highly concentrated pollution plumes emanating from the Mexico City urban agglomeration revealed that mixing ratios of Hg° as large as 500 ppqv were related to combustion tracers such as CO, but not SO2 which is presumably released locally from coal burning, refineries, and volcanoes. Our analysis of Mexico City plumes indicated that widespread multi-source urban/industrial emissions may have a more important influence on Hg° than specific point sources. Over the Pacific, correlations with CO, CO2, CH4, and C2Cl4 were diffuse overall, but recognizable on flights out of Anchorage and Honolulu. In distinct plumes originating from the Asian continent the Hg°- CO relationship yielded an average value of ~0.56 ppqv/ppbv, in good agreement with previous findings. A prominent feature of the INTEX-B dataset was frequent total depletion of Hg° in the upper troposphere when stratospherically influenced air was encountered. Ozone data obtained with the differential absorption lidar (DIAL showed that the stratospheric impact on the tropospheric column was a common and pervasive feature on all flights out of Honolulu and Anchorage. We propose that this is likely a major factor driving large-scale seasonality in Hg° mixing ratios, especially at mid-latitudes, and an important process that should be incorporated into global chemical transport models.

  14. Factors influencing the large-scale distribution of Hg° in the Mexico City area and over the North Pacific

    Directory of Open Access Journals (Sweden)

    D. Blake

    2008-04-01

    Full Text Available Gas-phase elemental mercury (Hg° was measured aboard the NASA DC-8 aircraft during the Intercontinental Chemical Transport Experiment Phase B (INTEX-B campaign in spring 2006. Flights were conducted around Mexico City and on two subsequent deployments over the North Pacific based out of Honolulu, Hawaii and Anchorage, Alaska. Data obtained from 0.15–12 km altitude showed that Hg° exhibited a relatively constant vertical profile centered around 100 ppqv. Highly concentrated pollution plumes emanating from the Mexico City urban agglomeration revealed that mixing ratios of Hg° as large as 500 ppqv were related to combustion tracers such as CO, but not SO2 which is presumably released locally from coal burning, refineries, and volcanoes. Our analysis of Mexico City plumes indicated that widespread multi-source urban/industrial emissions may have a more important influence on Hg° than specific point sources. Over the Pacific, correlations with CO, CO2, CH4, and C2Cl4 were diffuse overall, but recognizable on flights out of Anchorage and Honolulu. In distinct plumes originating from the Asian continent the Hg°- CO relationship yielded an average value of ~0.56 ppqv/ppbv, in good agreement with previous findings. A prominent feature of the INTEX-B dataset was frequent total depletion of Hg° in the upper troposphere when stratospherically influenced air was encountered. Ozone data obtained with the differential absorption lidar (DIAL showed that the stratospheric impact on the tropospheric column was a common and pervasive feature on all flights out of Honolulu and Anchorage. We propose that this is likely a major factor driving large-scale seasonality in Hg° mixing ratios, especially at mid-latitudes, and an important process that should be incorporated into global chemical transport models.

  15. Sustainable passenger road transport scenarios to reduce fuel consumption, air pollutants and GHG (greenhouse gas) emissions in the Mexico City Metropolitan Area

    International Nuclear Information System (INIS)

    This paper presents passenger road transport scenarios that may assist the MCMA (Mexico City Metropolitan Area) in achieving lower emissions in both criteria air pollutants (CO, NOx, NMVOC (non-methane volatile organic compounds), and PM10) and GHG (greenhouse gas) (CH4, N2O and CO2), while also promoting better mobility and quality of life in this region. We developed a bottom-up model to estimate the historical trends of energy demand, criteria air pollutants and GHG emissions caused by passenger vehicles circulating in the Mexico City Metropolitan Area (MCMA) in order to construct a baseline scenario and two mitigation scenarios that project their impact to 2028. Mitigation scenario “eff” considers increasing fuel efficiencies and introducing new technologies for vehicle emission controls. Mitigation scenario “BRT” considers a modal shift from private car trips to a Bus Rapid Transport system. Our results show significant reductions in air pollutants and GHG emissions. Incentives and environmental regulations are needed to enable these scenarios. - Highlights: • More than 4.2 million passenger vehicles in the MCMA (Mexico City Metropolitan Area) that represent 61% of criteria pollutants and 44% of GHG (greenhouse gas) emissions. • Emissions of CO, NOx and NMVOC (non-methane volatile organic compounds) in baseline scenario decrease with respect to its 2008 value because emission standards. • Emissions of PM10 and GHG increase in baseline scenario. • Emissions of PM10 and GHG decrease in eff + BRT scenario from year 2020. • Additional reductions are possible with better standards for diesel vehicles and other technologies

  16. At the bottom of the Popocatepetl. Revitalisation of a former refinery in Mexico City; Am Fusse des Popocatepetl. Revitalisierung einer ehemaligen Raffinerie in Mexiko-Stadt

    Energy Technology Data Exchange (ETDEWEB)

    Meyer-Murlowsky, Thomas; Kleffel, Guido [Zueblin Umwelttechnik GmbH, Stuttgart (Germany); Kuellenberg, Jochen [ZUEBLIN Ambiental S.A. de C.V., Tlalnepantla (Mexico)

    2010-06-15

    The denotation of the revitalization of refuse dumps increasingly gains in importance also in Central America. An actual example is the current redevelopment of the area of the former refinery in Mexico City. In this area, a 65 hectare large recreation park is to be built. With the current decontamination activities, well-known redevelopment technologies such as ground air redevelopment, bio venting and air-sparging are used. Also a new procedure combinations of 'multi-fase extraction with gas torch' were used for combustion.

  17. Obesity and overweight in IMSS female workers in Mexico City Obesidad y sobrepeso en mujeres trabajadoras del IMSS, en la Ciudad de México

    OpenAIRE

    José Luis Vázquez-Martínez; Héctor Gómez-Dantés; Felipe Gómez-García; María de los Angeles Lara-Rodríguez; Joel Navarrete-Espinosa; Gabriela Pérez-Pérez

    2005-01-01

    OBJECTIVE: To estimate the prevalence and risk factors for overweight (OW) and obesity (OB) in women working at the Mexican Social Security Institute (IMSS, per its abbreviation in Spanish) in Mexico City, using two different classification criteria. MATERIAL AND METHODS: A cross-sectional study was performed from July 1999 to September 2000. It included 588 women 20 to 65 years of age and who were working at the IMSS. The criteria used to estimate the prevalence of OW and OB were the WHO cri...

  18. Metals in lung tissue from autopsy cases in Mexico City residents: comparison of cases from the 1950s and the 1980s.

    OpenAIRE

    Fortoul, T. I.; Osorio, L S; Tovar, A T; Salazar, D; Castilla, M E; Olaiz-Fernández, G

    1996-01-01

    In autopsies performed on residents of Mexico City during the 1950s and 1980s (45 males and 24 females and 42 males and 42 females, respectively), concentrations of cadmium, copper, cobalt, nickel, and lead in the lungs were studied by atomic absorption spectrometry. Sharp increases were noted in samples taken in the 1980s compared to those from the 1950s. In samples from both time periods, the concentrations were influenced by gender. Smoking was not associated with higher levels of the meta...

  19. Water quality of the Boca Raton canal system and effects of the Hillsboro Canal inflow, southeastern Florida, 1990-91

    Science.gov (United States)

    McKenzie, D.J.

    1995-01-01

    The City of Boca Raton in southeastern Palm Beach County, Florida, is an urban residential area that has sustained a constant population growth with subsequent increase in water use. The Boca Raton network of canals is controlled to provide for drainage of excess water, to maintain proper coastal ground-water levels to prevent saltwater intrusion, and to recharge the surficial aquifer system from which the city withdraws potable water. Most of the water supplied to the Boca Raton canal system and the surficial aquifer system, other than rainfall and runoff, is pumped from the Hillsboro Canal. The Biscayne aquifer, principal hydrogeologic unit of the surficial aquifer system, is highly permeable and there is a close relation between water levels in the canals and the aquifer. The amount of water supplied by seepage from the conservation areas is unknown. Because the Hillsboro Canal flows from Lake Okeechobee and Water Conservation Areas 1 and 2, which are places of more highly mineralized ground water and surface water, the canal is a possible source of contamination. Water samples were collected at 10 canal sites during wet and dry seasons and analyzed for major inorganic ions and related characteristics, nutrients, and trace elements. All concentrations were generally within or less than the drinking-water standards established by the Florida Department of Environmental Protection. The high concentrations of sodium and chloride that were detected in samples from the Boca Raton canal system are probably from the more mineralized water of the Hillsboro Canal. Other water-quality data, gathered from various sources from 1982 through 1991, did not indicate any significant changes nor trends. The effects of the Hillsboro Canal on the water quality of the Boca Raton canal system are indicated by increased concentrations of sodium, chloride, dissolved solids, and total organic carbon. Concentrations of the constituents in the canal water generally decrease with distance

  20. Subsidence hazard and risk assessments for Mexico City: An interdisciplinary analysis of satellite-derived subsidence map (PSInSAR) and census data.

    Science.gov (United States)

    Solano Rojas, D. E.; Cabral-Cano, E.; Wdowinski, S.; Hernaández Espriú, A.; Falorni, G.; Bohane, A.

    2014-12-01

    The Mexico City Metropolitan Area is the largest urban center in the American continent, with 20.4 millions of inhabitants, representing 17.8% of the total population of the country. Over the past several decades Mexico City has been experienced rapid subsidence, up to ~370 mm/yr, caused by groundwater extraction. The subsidence rate is inhomogeneous, as it controlled by the local geology. Unconsolidated sediments tend to compact and induce rapid subsidence, whereas subsurface volcanic rocks are less prone to subsidence. Intensive faulting in the city has been observed in areas of differential deformation; in these areas buildings and infrastructure are highly damaged. Quantification of subsidence-induce damage is needed for establishing the magnitude of the phenomenon. Our study uses three data sources: a satellite-derived subsidence map, census information of population distribution for 2010, and information on buildings and infrastructure. The subsidence map was calculated from 29 SAR scene acquired by the Envisat satellite during the years 2003-2010 using the Persistent Scatterers Interferometry (PSI) method with the SqueeSAR algorithm. The information of the census of population comes from the National Institute of Statistics and Geography (INEGI), which also provides the information about infrastructure. We intersected the information from the three maps using a geographic information system (GIS), which cover an area of 1, 640 km2. As subsidence-induced damage occurs mainly in areas of differential subsidence, we based the GIS analysis on the subsidence gradients, rather than subsidence rates. In order to evaluate subsidence-induced faulting risk, we generated a risk matrix that worked as the main parameter to create a risk map. We then reclassified the urban area into 5 zones according to the related risk, with R0 for the lowest risk and R4 for the highest. Our counting showed that 350 km2 of the city is located in an urban area of high to very high risk

  1. The Role and Style of Meetings in a Native Village in Mexico City: A Contribution towards the Analysis of Meetings

    Directory of Open Access Journals (Sweden)

    Turid Hagene

    2015-10-01

    Full Text Available This article explores the role of meetings and the style in which they are carried out in the local community of San Lorenzo Acopilco in Mexico City. The community predates the Spanish conquest, and thus forms part of this megacity’s 200 native villages (pueblos originarios, which to this day reproduce distinctive social, political and religious practices. Ethnographies of three meetings are presented and analysed with concepts and theories from a variety of disciplines; these may also be helpful in the analysis of meetings in other locations. The meetings are regulated by laws of either citizen participation or agrarian issues. The choice of meeting style influences the outcomes of meetings, and thus figures in the repertoire of elements which substantially influence the community’s capacity to preserve its distinctive way of life from the encroachment of the megacity.   Resumen: El papel y el estilo de reuniones en un pueblo originario de la Ciudad de México: Una contribución hacia el análisis de reuniones  Este artículo explora el papel de las reuniones y el estilo en el que éstas se llevan a cabo en la comunidad local de San Lorenzo Acopilco en Ciudad de México. Dicha comunidad antedata a la conquista española y por consiguiente forma parte de los 200 pueblos originarios de esta megaciudad, que hasta la fecha reproducen prácticas sociales, políticas y religiosas distintivas. Se presentan etnografías de tres reuniones y se analizan mediante conceptos y teorías de varias disciplinas; todo este material también puede ser útil para el análisis de reuniones de otros lugares. Las reuniones se rigen por la ley de participación ciudadana o por la ley agraria. La elección del estilo de las reuniones marca los resultados de las mismas y consecuentemente figura en el repertorio de elementos que influyen considerablemente en la capacidad comunitaria para preservar su modo de vida característico frente a la invasión de la

  2. Analysis of non-regulated vehicular emissions by extractive FTIR spectrometry: tests on a hybrid car in Mexico City

    Science.gov (United States)

    Reyes, F.; Grutter, M.; Jazcilevich, A.; González-Oropeza, R.

    2006-07-01

    A methodology to acquire valuable information on the chemical composition and evolution of vehicular emissions is presented. The analysis of the gases is performed by passing a constant flow of a sample gas from the tail-pipe into a 10 L multi-pass cell. The absorption spectra within the cell are obtained using an FTIR spectrometer at 0.5 cm-1 resolution along a 13.1 m optical path. Additionally, the total flow from the exhaust is continuously measured from a differential pressure sensor on a Pitot tube installed at the exit of the exhaust. This configuration aims to obtain a good speciation capability by coadding spectra during 30 s and reporting the emission (in g/km) of key and non-regulated pollutants, such as CO2, CO, NO, SO2, NH3, HCHO, NMHC, during predetermined driving routines. The advantages and disadvantages of increasing the acquisition frequency, as well as the effect of other parameters such as spectral resolution, cell volume and flow rate, are discussed. With the aim of testing and evaluating the proposed technique, experiments were performed on a dynamometer running FTP-75 and typical driving cycles of the Mexico City Metropolitan Area (MCMA) on a Toyota Prius hybrid vehicle. This car is an example of recent automotive technology to reach the market dedicated to reduce emissions and therefore pressing the need of low detection techniques. This study shows the potential of the proposed technique to measure and report in real time the emissions of a large variety of pollutants, even from a super ultra-low emission vehicle (SULEV). The emissions of HC's, NOx, CO and CO2 obtained here are similar to experiments performed in other locations with the same vehicle model. Some differences suggest that an inefficient combustion process and type of gasoline used in the MCMA may be partly responsible for lower CO2 and higher CO and NO emission factors. Also, a fast reduction of NO emission to very low values is observed after cold ignition, giving rise to

  3. The stable carbon isotope composition of PM 2.5 and PM 10 in Mexico City Metropolitan Area air

    Science.gov (United States)

    López-Veneroni, D.

    The sources and distribution of carbon in ambient suspended particles (PM 2.5 and PM 10) of Mexico City Metropolitan Area (MCMA) air were traced using stable carbon isotopes ( 13C/ 12C). Tested potential sources included rural and agricultural soils, gasoline and diesel, liquefied-petroleum gas, volcanic ash, and street dust. The complete combustion of LP gas, diesel and gasoline yielded the lightest δ13C values (-27 to -29‰ vs. PDB), while street dust (PM 10) represented the isotopically heaviest endmember (-17‰). The δ13C values of rural soils from four geographically separated sites were similar (-20.7 ± 1.5‰). δ13C values of particles and soot from diesel and gasoline vehicle emissions and agricultural soils varied between -23 and -26‰. Ambient PM samples collected in November of 2000, and March and December of 2001 at three representative receptor sites of industrial, commercial and residential activities had a δ13C value centered around -25.1‰ in both fractions, resulting from common carbon sources. The predominant carbon sources to MCMA atmospheric particles were hydrocarbon combustion (diesel and/or gasoline) and particles of geological origin. The significantly depleted δ13C values from the industrial site reflect the input of diesel combustion by mobile and point source emissions. Based on stable carbon isotope mass balance, the carbon contribution of geological sources at the commercial and residential sites was approximately 73% for the PM 10 fraction and 54% for PM 2.5. Although not measured in this study, biomass-burning emissions from nearby forests are an important carbon source characterized by isotopically lighter values (-29‰), and can become a significant contributor (67%) of particulate carbon to MCMA air under the prevalence of southwesterly winds. Alternative sources of these 13C-depleted particles, such as cooking fires and municipal waste incineration, need to be assessed. Results show that stable carbon isotope

  4. PIXE and XRF analysis of atmospheric aerosols from a site in the West area of Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, R.V.; López-Monroy, J., E-mail: raul.diaz@inin.gob.mx, E-mail: jose.lopezm@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Centro Nuclear Nabor Carrillo, Salazar, Edo. Mex. (Mexico); Miranda, J.; Espinosa, A.A., E-mail: miranda@fisica.unam.mx, E-mail: albertoe@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, México, D.F. (Mexico)

    2013-07-01

    Full text: The pollution by atmospheric aerosols in the Metropolitan Area of Mexico City (MAMC) is still presenting issues that require deeper studies. Because of geographical factors, most of the MAMC features, on average, very similar characteristics. These include height above the sea level, climate, wind speed and direction, resulting in very uniform pollution levels in most of the traditionally studied sites. A site with different characteristics with respect to them, Cuajimalpa de Morelos, was selected for the present work. It is located to the West of the MAMC at 2,760 m above sea level (a.s.l.), in contrast to other sites (2,240 m a.s.I); sub-humid area with lush vegetation, influenced by the forest of the 'Desierto de los Leones' National Park. Here, the wind for most part of the day is directed towards the center of the MAMC, joining flows that run from North to South. This prevents the site from receiving influence of pollutants generated in the Northern industrial zone, Xalostoc or Naucalpan. Thus, it is expected that this area should present lower concentration of pollutants than the rest of the MAMC. Therefore, the present work is aimed to study the elemental composition of coarse (PM{sub 10-}2{sub .5}) and fine (PM{sub 2.5}) fractions of atmospheric aerosol samples collected in Cuajimalpa. The sampling period covered the cold-dry season in 2004-2005 (December 1{sup st} , 2004, to March 31, 2005), exposing polycarbonate filters with a Stacked Filter Unit (SFU) of the Gent design along 24 h, every two days. The samples were then analyzed with PIXE and X-ray Fluorescence (XRF), to obtain elemental concentrations. The EPA code UNMIX was used to determine the number of possible influencing polluting sources, which were then identified through back-trajectory simulations with the HYSPLlT modeling software. Four sources (mostly related to soil) were found for the coarse fraction, while the fine fraction presented three main sources (fuel oil

  5. PIXE and XRF analysis of atmospheric aerosols from a site in the West area of Mexico City

    International Nuclear Information System (INIS)

    Full text: The pollution by atmospheric aerosols in the Metropolitan Area of Mexico City (MAMC) is still presenting issues that require deeper studies. Because of geographical factors, most of the MAMC features, on average, very similar characteristics. These include height above the sea level, climate, wind speed and direction, resulting in very uniform pollution levels in most of the traditionally studied sites. A site with different characteristics with respect to them, Cuajimalpa de Morelos, was selected for the present work. It is located to the West of the MAMC at 2,760 m above sea level (a.s.l.), in contrast to other sites (2,240 m a.s.I); sub-humid area with lush vegetation, influenced by the forest of the 'Desierto de los Leones' National Park. Here, the wind for most part of the day is directed towards the center of the MAMC, joining flows that run from North to South. This prevents the site from receiving influence of pollutants generated in the Northern industrial zone, Xalostoc or Naucalpan. Thus, it is expected that this area should present lower concentration of pollutants than the rest of the MAMC. Therefore, the present work is aimed to study the elemental composition of coarse (PM10-2.5) and fine (PM2.5) fractions of atmospheric aerosol samples collected in Cuajimalpa. The sampling period covered the cold-dry season in 2004-2005 (December 1st , 2004, to March 31, 2005), exposing polycarbonate filters with a Stacked Filter Unit (SFU) of the Gent design along 24 h, every two days. The samples were then analyzed with PIXE and X-ray Fluorescence (XRF), to obtain elemental concentrations. The EPA code UNMIX was used to determine the number of possible influencing polluting sources, which were then identified through back-trajectory simulations with the HYSPLlT modeling software. Four sources (mostly related to soil) were found for the coarse fraction, while the fine fraction presented three main sources (fuel oil, industry, and biomass

  6. Diurnal variations of airborne pollen concentration and the effect of ambient temperature in three sites of Mexico City

    Science.gov (United States)

    Ríos, B.; Torres-Jardón, R.; Ramírez-Arriaga, E.; Martínez-Bernal, A.; Rosas, I.

    2016-05-01

    Pollen is an important cause of allergic respiratory ailments in the Mexico City Metropolitan Area (MCMA). However, very little is known if ambient air temperature correlates with the early blooming of plants observed in other urban areas around the world. A research study was conducted during the dry season of 2012-2013 at three representative sites of the MCMA with different urban characteristics with the aim to understand the relationships between the profusion and diversity of pollen against temperature and other meteorological variables and degree of urbanization. Pollen samples were collected using a Hirst-type trap sampler in the sites: Merced (highly urbanized), Iztapalapa (medium-high urbanized) and Coyoacan (moderately urbanized). Urbanization levels were determined using a composite index based on population density, proportion of surface covered by construction and asphalt, and urban heat island intensity. A set of representative pollen sampling tapes were assayed under a light microscope at magnification of ×1,000 and converted to grains per cubic meter. The most representative pollen types found in the three sites were, regardless of urbanization levels were: Fraxinus, Cupressaceae/Taxodiaceae, Casuarina, Alnus, Myrtaceae, and Pinus. Total pollen concentration was greatest in the moderately urbanized area, although earlier blooming took place at the highly urbanized zone. Total pollen concentration in the medium-high urbanized site has the lowest because the green areas in this zone of MCMA are few. In a diurnal basis, the most abundant pollen types peaked near midday or in the afternoon evening at the three sites. A Spearman test showed a positive correlation among bihourly pollen concentrations, temperature and relative humidity in all sites, but wind speed just correlated in Iztapalapa and Coyoacan. The results obtained suggest that Urban Heat Island Intensity can disturb flowering periods and pollen concentrations, largely in the highly urbanized

  7. Optic Canal: Microanatomic Study

    OpenAIRE

    Slavin, Konstantin V.; Dujovny, Manuel; Soeira, Gelson; James I Ausman

    1994-01-01

    The microsurgical anatomy of the optic canal was defined on 20 cadaveric specimens. Anatomic parameters of the optic canal, optic nerve, ophthalmic artery, and adjacent structures were measured, and relations of these structures were noted. Five variants of the course of the ophthalmic artery relative to the optic nerve in the optic canal were found. Various aspects of microsurgery of the optic canal are discussed in relation to anatomic findings.

  8. Cross-Sectional Association between Length of Incarceration and Selected Risk Factors for Non-Communicable Chronic Diseases in Two Male Prisons of Mexico City.

    Directory of Open Access Journals (Sweden)

    Omar Silverman-Retana

    Full Text Available Mexico City prisons are characterized by overcrowded facilities and poor living conditions for housed prisoners. Chronic disease profile is characterized by low prevalence of self reported hypertension (2.5% and diabetes (1.8% compared to general population; 9.5% of male inmates were obese. There is limited evidence regarding on the exposure to prison environment over prisoner's health status; particularly, on cardiovascular disease risk factors. The objective of this study is to assess the relationship between length of incarceration and selected risk factors for non-communicable chronic diseases (NCDs.We performed a cross-sectional analysis using data from two large male prisons in Mexico City (n = 14,086. Using quantile regression models we assessed the relationship between length of incarceration and selected risk factors for NCDs; stratified analysis by age at admission to prison was performed. We found a significant negative trend in BMI and WC across incarceration length quintiles. BP had a significant positive trend with a percentage change increase around 5% mmHg. The greatest increase in systolic blood pressure was observed in the older age at admission group.This analysis provides insight into the relationship between length of incarceration and four selected risk factors for NCDs; screening for high blood pressure should be guarantee in order to identify at risk individuals and linked to the prison's health facility. It is important to assess prison environment features to approach potential risk for developing NCDs in this context.

  9. Blood transfusion and iatrogenic risks in Mexico city: anti-Trypanosoma cruzi seroprevalence in 43,048 blood donors, evaluation of parasitemia, and electrocardiogram findings in seropositive

    Directory of Open Access Journals (Sweden)

    Nidia Hernández-Becerril

    2005-04-01

    Full Text Available Iatrogenous transmission of Trypanosoma cruziby blood transfusion was suggested as a potential risk by Pellegrino (1949. Seropositive blood donors in Mexico were first reported in 1978, however, limited information is available due to small sampling, the use of heterogeneous serologic assays, and geographically limited studies. A wide survey carried out in 18 out of the 32 states of Mexico, showed a national mean of 1.6% seropositive among 64,969 donors, ranging from 0.2 to 2.8%. In the present study, we have screened 43,048 voluntary blood donors in a period of five years at the Instituto Nacional de Cardiología I. Chávez, a concentration hospital located in Mexico city which serves mainly the metropolitan area and accepts from all over the country. Standardized ELISA and IIF were used to identify seropositive individuals in addition to hemoculture, PCR and standard 12 lead ECG tests that were applied to a group of seropositive patients (29/161. The result showed a seropositivity of 0.37% (161/43,048. From the group of seropositive individuals 40% (12/29 were potential carriers of T. cruzi at the donation time and 5/29 had subclinical ECG abnormalities. Parasitological tests performed in 70 erythrocyte and platelet fractions from seropositive units (70/161 showed negative results. Our findings strongly support T. cruzi screening in the transfusion medicine practice and identify subclinical heart disease among seropositive blood donors.

  10. Fast Identification of Near-Trench Earthquakes Along the Mexican Subduction Zone Based on Characteristics of Ground Motion in Mexico City

    Science.gov (United States)

    Perez-Campos, X.; Singh, S. K.; Arroyo, D.; Rodríguez, Q.; Iglesias, A.

    2015-12-01

    The disastrous 1985 Michoacan earthquake gave rise to a seismic alert system for Mexico City which became operational in 1991. Initially limited to earthquakes along the Guerrero coast, the system now has a much wider coverage. Also, the 2004 Sumatra earthquake exposed the need for a tsunami early warning along the Mexican subduction zone. A fast identification of near-trench earthquakes along this zone may be useful in issuing a reliable early tsunami alert. The confusion caused by low PGA for the magnitude of an earthquake, leading to "missed" seismic alert, would be averted if its near-trench origin can be quickly established. It may also help reveal the spatial extent and degree of seismic coupling on the near-trench portion of the plate interface. This would lead to a better understanding of tsunami potential and seismic hazard along the Mexican subduction zone. We explore three methods for quick detection of near-trench earthquakes, testing them on recordings of 65 earthquakes at station CU in Mexico City (4.8 ≤Mw≤8.0; 270≤R≤615 km). The first method is based on the ratio of total to high-frequency energy, ER (Shapiro et al., 1998). The second method is based on parameter Sa*(6) which is the pseudo-acceleration response spectrum with 5% damping, Sa, at 6 s normalized by the PGA. The third parameter is the PGA residual, RESN, at CU, with respect to a newly-derived ground motion prediction equation at CU for coastal shallow-dipping thrust earthquakes following a bayesian approach. Since the near-trench earthquakes are relatively deficient in high-frequency radiation, we expect ER and Sa*(6) to be relatively large and RESN to be negative for such events. Tests on CU recordings show that if ER ≥ 100 and/or Sa*(6) ≥ 0.70, then the earthquake is near trench; for these events RESN ≤ 0. Such an event has greater tsunami potential. Few misidentifications and missed events are most probably a consequence of poor location, although unusual depth and source

  11. Characterization of Fine Particulate Matter (PM) and Secondary PM Precursor Gases in the Mexico City Metropolitan Area

    Energy Technology Data Exchange (ETDEWEB)

    Molina, Luisa T.; Molina, Mario J.; Volkamer, Rainer; de Foy, Benjamin; Lei, Wenfang; Zavaka, Miguel; Velasco, Erik

    2008-10-31

    This project was one of three collaborating grants funded by DOE/ASP to characterize the fine particulate matter (PM) and secondary PM precursors in the Mexico City Metropolitan Area (MCMA) during the MILAGRO Campaign. The overall effort of MCMA-2006, one of the four components, focused on i) examination of the primary emissions of fine particles and precursor gases leading to photochemical production of atmospheric oxidants and secondary aerosol particles; ii) measurement and analysis of secondary oxidants and secondary fine PM production, with particular emphasis on secondary organic aerosol (SOA), and iii) evaluation of the photochemical and meteorological processes characteristic of the Mexico City Basin. The collaborative teams pursued the goals through three main tasks: i) analyses of fine PM and secondary PM precursor gaseous species data taken during the MCMA-2002/2003 campaigns and preparation of publications; ii) planning of the MILAGRO Campaign and deployment of the instrument around the MCMA; and iii) analysis of MCMA-2006 data and publication preparation. The measurement phase of the MILAGRO Campaign was successfully completed in March 2006 with excellent participation from the international scientific community and outstanding cooperation from the Mexican government agencies and institutions. The project reported here was led by the Massachusetts Institute of Technology/Molina Center for Energy and the Environment (MIT/MCE2) team and coordinated with DOE/ASP-funded collaborators at Aerodyne Research Inc., University of Colorado at Boulder and Montana State University. Currently 24 papers documenting the findings from this project have been published. The results from the project have improved significantly our understanding of the meteorological and photochemical processes contributing to the formation of ozone, secondary aerosols and other pollutants. Key findings from the MCMA-2003 include a vastly improved speciated emissions inventory from on

  12. Long-range pollution transport during the MILAGRO-2006 campaign: a case study of a major Mexico City outflow event using free-floating altitude-controlled balloons

    Directory of Open Access Journals (Sweden)

    P. B. Voss

    2010-08-01

    Full Text Available One of the major objectives of the Megacities Initiative: Local And Global Research Observations (MILAGRO-2006 campaign was to investigate the long-range transport of polluted Mexico City Metropolitan Area (MCMA outflow and determine its downwind impacts on air quality and climate. Six research aircraft, including the National Center for Atmospheric Research (NCAR C-130, made extensive chemical, aerosol, and radiation measurements above MCMA and more than 1000 km downwind in order to characterize the evolution of the outflow as it aged and dispersed over the Mesa Alta, Sierra Madre Oriental, Coastal Plain, and Gulf of Mexico. As part of this effort, free-floating Controlled-Meteorological (CMET balloons, commanded to change altitude via satellite, made repeated profile measurements of winds and state variables within the advecting outflow. In this paper, we present an analysis of the data from two CMET balloons that were launched near Mexico City on the afternoon of 18 March 2006 and floated downwind with the MCMA pollution for nearly 30 h. The repeating profile measurements show the evolving structure of the outflow in considerable detail: its stability and stratification, interaction with other air masses, mixing episodes, and dispersion into the regional background. Air parcel trajectories, computed directly from the balloon wind profiles, show three transport pathways on 18–19 March: (a high-altitude advection of the top of the MCMA mixed layer, (b mid-level outflow over the Sierra Madre Oriental followed by decoupling and isolated transport over the Gulf of Mexico, and (c low-level outflow with entrainment into a cleaner northwesterly jet above the Coastal Plain. The C-130 aircraft intercepted the balloon-based trajectories three times on 19 March, once along each of these pathways; in all three cases, peaks in urban tracer concentrations and LIDAR backscatter are consistent with MCMA pollution. In comparison with the transport models

  13. Long-range pollution transport during the MILAGRO-2006 campaign: a case study of a major Mexico City outflow event using free-floating altitude-controlled balloons

    Science.gov (United States)

    Voss, P. B.; Zaveri, R. A.; Flocke, F. M.; Mao, H.; Hartley, T. P.; Deamicis, P.; Deonandan, I.; Contreras-Jiménez, G.; Martínez-Antonio, O.; Figueroa Estrada, M.; Greenberg, D.; Campos, T. L.; Weinheimer, A. J.; Knapp, D. J.; Montzka, D. D.; Crounse, J. D.; Wennberg, P. O.; Apel, E.; Madronich, S.; de Foy, B.

    2010-08-01

    One of the major objectives of the Megacities Initiative: Local And Global Research Observations (MILAGRO-2006) campaign was to investigate the long-range transport of polluted Mexico City Metropolitan Area (MCMA) outflow and determine its downwind impacts on air quality and climate. Six research aircraft, including the National Center for Atmospheric Research (NCAR) C-130, made extensive chemical, aerosol, and radiation measurements above MCMA and more than 1000 km downwind in order to characterize the evolution of the outflow as it aged and dispersed over the Mesa Alta, Sierra Madre Oriental, Coastal Plain, and Gulf of Mexico. As part of this effort, free-floating Controlled-Meteorological (CMET) balloons, commanded to change altitude via satellite, made repeated profile measurements of winds and state variables within the advecting outflow. In this paper, we present an analysis of the data from two CMET balloons that were launched near Mexico City on the afternoon of 18 March 2006 and floated downwind with the MCMA pollution for nearly 30 h. The repeating profile measurements show the evolving structure of the outflow in considerable detail: its stability and stratification, interaction with other air masses, mixing episodes, and dispersion into the regional background. Air parcel trajectories, computed directly from the balloon wind profiles, show three transport pathways on 18-19 March: (a) high-altitude advection of the top of the MCMA mixed layer, (b) mid-level outflow over the Sierra Madre Oriental followed by decoupling and isolated transport over the Gulf of Mexico, and (c) low-level outflow with entrainment into a cleaner northwesterly jet above the Coastal Plain. The C-130 aircraft intercepted the balloon-based trajectories three times on 19 March, once along each of these pathways; in all three cases, peaks in urban tracer concentrations and LIDAR backscatter are consistent with MCMA pollution. In comparison with the transport models used in the

  14. An Overview of Mexico’s Medical Tourism Industry: The Cases of Mexico City and Monterrey. version 1.0

    OpenAIRE

    Núñez, Emanuel Orozco; Arias, Rosa María Bejarano; Martínez, Matilde Elizabeth Aguilar; Larios, José Arturo Ruiz; Crooks, Valorie; Labonté, Ronald; Snyder, Jeremy; Nigenda, Gustavo

    2014-01-01

    In this report we offer some general information on Mexico and its health system before going into detail about key developments in its medical tourism industry. Complementing the main text, nine Appendices provide additional detailed insights. Appendix 1 offers a synthesis of media coverage of medical tourism in Mexico City’s main newspapers in recent years, while Appendix 2 is a synthesis of media coverage of 2 | P a g e medical tourism in Monterrey. In Appendix 3 we share a summary of poli...

  15. Size-resolved aerosol emission factors and new particle formation/growth activity occurring in Mexico City during the MILAGRO 2006 Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Kalafut-Pettibone A. J.; Wang J.; Eichinger, W. E.; Clarke, A.; Vay, S. A.; Blake, D. R.; Stanier, C. O.

    2011-09-01

    Measurements of the aerosol size distribution from 11 nm to 2.5 microns were made in Mexico City in March 2006, during the MILAGRO (Megacity Initiative: Local and Global Research Observations) field campaign. Observations at the urban supersite, referred to as T0, could often be characterized by morning conditions with high particle mass concentrations, low mixing heights, and highly correlated particle number and CO{sub 2} concentrations, indicative that particle number is controlled by primary emissions. Average size-resolved and total number- and volume-based emission factors for combustion sources impacting T0 have been determined using a comparison of peak sizes in particle number and CO{sub 2} concentration. Peaks are determined by subtracting the measured concentration from a calculated baseline concentration time series. The number emission and volume emission factors for particles from 11 nm to 494 nm are 1.56 x 10{sup 15} particles, and 9.48 x 10{sup 11} cubic microns per kg of carbon, respectively. The uncertainty of the number emission factor is approximately plus or minus 50 %. The mode of the number emission factor was between 25 and 32 nm, while the mode of the volume factor was between 0.25 and 0.32 microns. These emission factors are reported as log normal model parameters and are compared with multiple emission factors from the literature. In Mexico City in the afternoon, the CO{sub 2} concentration drops during ventilation of the polluted layer, and the coupling between CO{sub 2} and particle number breaks down, especially during new particle formation events when particle number is no longer controlled by primary emissions. Using measurements of particle number and CO{sub 2} taken aboard the NASA DC-8, the determined primary emission factor was applied to the Mexico City Metropolitan Area (MCMA) plume to quantify the degree of secondary particle formation in the plume; the primary emission factor accounts for less than 50 % of the total particle

  16. A Cross-Sectional Study of Prisoners in Mexico City Comparing Prevalence of Transmissible Infections and Chronic Diseases with That in the General Population.

    Directory of Open Access Journals (Sweden)

    Sergio Bautista-Arredondo

    Full Text Available To describe patterns of transmissible infections, chronic illnesses, socio-demographic characteristics and risk behaviors in Mexico City prisons, including in comparison to the general population, to identify those currently needing healthcare and inform policy.A cross-sectional study among 17,000 prisoners at 4 Mexico City prisons (June to December 2010. Participation was voluntary, confidential and based on informed consent. Participants were tested for HIV, Hepatitis B & C, syphilis, hypertension, obesity, and, if at risk, glucose and cholesterol. A subset completed a questionnaire on socio-demographic characteristics and risk behaviors. Positive results were delivered with counseling and treatment or referral.76.8% (15,517/20,196 of men and 92.9% (1,779/1,914 of women participated. Complete data sets were available for 98.8%. The following prevalence data were established for transmissible infections: HIV 0.7%; syphilis: Anti-TP+/VDRL+ 2.0%; Hepatitis B: HBcAb 2.8%, HBsAg 0.15%; Anti-HCV 3.2%. Obesity: 9.5% men, 33.8% women. Compared with national age- and sex-matched data, the relative prevalence was greater for HIV and syphilis among women, HIV and Hepatitis C in men, and all infections in younger participants. Obesity prevalence was similar for women and lower among male participants. The prevalence of previously diagnosed diabetes and hypertension was lower. Questionnaire data (1,934 men, 520 women demonstrated lower educational levels, increased smoking and substance use compared to national data. High levels of non-sterile tattooing, physical abuse and histories of sexual violence were found.The study identified that health screening is acceptable to Mexico City prisoners and feasible on a large-scale. It demonstrated higher prevalence of HIV and other infections compared to national data, though low rates compared to international data. Individual participants benefited from earlier diagnosis, treatment and support. The data collected

  17. The oxidative potential and biological effects induced by PM{sub 10} obtained in Mexico City and at a receptor site during the MILAGRO Campaign

    Energy Technology Data Exchange (ETDEWEB)

    Quintana, Raul [Instituto Nacional de Cancerologia, Mexico City (Mexico); Serrano, Jesus [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Gomez, Virginia [Instituto de Quimica, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Foy, Benjamin de [Earth and Atmospheric Sciences, Saint Louis University, St. Louis, MO (United States); Miranda, Javier [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Garcia-Cuellar, Claudia [Instituto Nacional de Cancerologia, Mexico City (Mexico); Vega, Elizabeth [Instituto Mexicano del Petroleo, Mexico City (Mexico); Vazquez-Lopez, Ines [Instituto Nacional de Cancerologia, Mexico City (Mexico); Molina, Luisa T. [Molina Center for Energy and the Environment, CA (United States); Massachusetts Institute of Technology, Cambridge, MA (United States); Manzano-Leon, Natalia [Instituto Nacional de Cancerologia, Mexico City (Mexico); Rosas, Irma [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Osornio-Vargas, Alvaro R., E-mail: osornio@ualberta.ca [Instituto Nacional de Cancerologia, Mexico City (Mexico); Department of Paediatrics, University of Alberta, 1048 RTF, 8308 114 St, Edmonton, AB T6G 2V2 (Canada)

    2011-12-15

    As part of a field campaign that studied the impact of Mexico City pollution plume at the local, sub-regional and regional levels, we studied transport-related changes in PM{sub 10} composition, oxidative potential and in vitro toxicological patterns (hemolysis, DNA degradation). We collected PM{sub 10} in Mexico City (T{sub 0}) and at a suburban-receptor site (T{sub 1}), pooled according to two observed ventilation patterns (T{sub 0} {yields} T{sub 1} influence and non-influence). T{sub 0} samples contained more Cu, Zn, and carbon whereas; T{sub 1} samples contained more of Al, Si, P, S, and K (p < 0.05). Only SO{sub 4}{sup -2} increased in T{sub 1} during the influence periods. Oxidative potential correlated with Cu/Zn content (r = 0.74; p < 0.05) but not with biological effects. T{sub 1} PM{sub 10} induced greater hemolysis and T{sub 0} PM{sub 10} induced greater DNA degradation. Influence/non-influence did not affect oxidative potential nor biological effects. Results indicate that ventilation patterns had little effect on intrinsic PM{sub 10} composition and toxicological potential, which suggests a significant involvement of local sources. - Highlights: > Transport-related changes in PM{sub 10} composition, oxidative potential and in vitro toxicity were studied. > Cu, Zn, and carbon levels were predominant in urban PM{sub 10}; receptor site PM{sub 10} was rich in soil elements. > SO{sub 4}{sup -2} was the only component increased in PM{sub 10} from the receptor during the influence periods. > PM{sub 10} oxidative potential correlates with Cu/Zn content but not with studied biological effects. > Ventilation patterns had little effect on PM{sub 10} composition and toxicity. - Mexico City ventilation patterns had little effect on the intrinsic PM{sub 10} composition and toxicological potential, which suggests a significant involvement of local sources as opposed to downwind transport.

  18. Study of radioactive contamination in silts and aerosols at Aldama City, Mexico, due to the operation of a yellow-cake processing plant.

    Science.gov (United States)

    Montelongo, Michel Y; Herrera, Eduardo F; Ramirez, Elias; Carrillo, Jorge I; Campos, Alfredo; Gomez, Ramón; Montero, Maria E; Rodriguez, Luis M

    2015-08-01

    The city of Aldama, Chihuahua, Mexico is located 30 km NNE of Chihuahua city. Three high-volume collectors with PM10 heads were placed in specific locations in Aldama during the year 2011 to measure radioisotope concentrations in the air. The city area of 16 km² was divided into 64 squares of 500 × 500 m. At the vertices of the grid, silt samples were taken between January and June 2011, before the rains began. The concentrations of natural, cosmogenic, and anthropogenic radioactive isotopes were calculated in both filters and silts samples. The isotopes selected for the measurement were ²³⁸U, ²³²Th, (7)Be, ¹³⁷Cs, and ⁴⁰K. Measurements of PM10 and silts were performed during 2011, coinciding with the accident at Fukushima, Japan, on March 11. For this reason, we could see the ¹³⁷Cs in PM10 increase between April and July; with the arrival of the rains, the ¹³⁷Cs concentration began to decrease in the air. The concentration of PM10 measured by the equipment located at the Mexican Uranium plant (URAMEX, initials in Spanish) that was processing radioactive ores exceeded the standard values in February and March, when the air velocity increases. At City Hall, the concentration of PM10 surpassed the value of the standard between May and July. This increased concentration is likely due to increased automobile traffic because City Hall is located in the city center. At a private home, the concentration of PM10 surpassed the standard on several days during the year because the home is located on the outskirts of the city, where most of the streets are not paved. Due to the high concentrations of PM10, especially at the collection point located at the private home, it is necessary to start taking steps to mitigate their spread before they cause health problems in the younger population and in older adults. PMID:26211631

  19. Report on FS survey for project of introduction of highly energy-efficient trolley buses into the Mexico Metropolitan Area in FY 1997; 1997 nendo chosa hokokusho (Mexico city eno sho energy gata trolley bus donyu project FS chosa)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Traffic jam and air pollution by automobiles are currently getting severe in the Mexico Metropolitan Area. Trolley buses were introduced for improving the environment more than ten years ago. Vehicles become too old for use, and their energy efficiency is low. In this project, 200 highly energy-efficient trolley buses are introduced to replace old inefficient trolley buses, which results in the improved traffic convenience in the City and enhanced energy efficiency. The new energy-efficient trolley buses are made of energy-efficient control VVVF inverters produced and exported by MELCO (Mitsubishi Electric Corporation), energy-efficient motors by MELMEX (Mitsubishi Electric Corporation, Mexico), and bodies by MASA which is a major manufacturer of bus bodies. The objective of this research is to analyze the background of introduction of new energy-efficient trolley buses and the effects of the present project. The results of analysis are going to be utilized for future promotion of the Joint Implementation and Clean Development Mechanism. 30 refs., 30 figs., 24 tabs.

  20. Measuring the electric energy services for the World Trade Center in Mexico city; Medicion de los servicios de energia electrica del World Trade Center de la ciudad de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez Nunez, Humberto; Robledo Vera, Humberto [Luz y Fuerza del Centro, Mexico, D. F. (Mexico)

    1997-12-31

    In conforming the project of measuring the electric power for the World Trade Center of Mexico City, the use of top technology has been considered that in its field represents the application for the first time in our country the automatic reading of the electric energy meters. In this paper the network for the supply of electric power to the World Trade Center is described as well as the measuring systems of this building and mention is made of the characteristics of the system components and the advantages of remote reading. General data is provided on this collection of buildings, the connections in its tower and a feeding one line diagram of the tower itself [Espanol] En la conformacion del proyecto de medicion de la energia electrica para el edificio World Trade Center de la Ciudad de Mexico, se ha considerado el uso de tecnologia de punta que en su campo representa la aplicacion por primera vez en nuestro pais de la lectura automatica de medidores de energia electrica. En esta ponencia se describen la red de suministro al World Trade Center, los sistemas de medicion de este edificio y se mencionan las caracteristicas de los componentes del sistema y las ventajas de las lecturas remotas. Se proporciona datos generales sobre el conjunto de este edificio, las derivaciones en su torre y un diagrama unifilar de alimentacion de la torre del mismo

  1. Root canal irrigants

    Directory of Open Access Journals (Sweden)

    Kandaswamy Deivanayagam

    2010-01-01

    Full Text Available Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are discussed. We performed a Medline search for English-language papers published untill July 2010. The keywords used were ′root canal irrigants′ and ′endodontic irrigants.′ The reference lists of each article were manually checked for additional articles of relevance.

  2. Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO2 retrievals during the MILAGRO field campaign

    Directory of Open Access Journals (Sweden)

    E. C. Wood

    2009-08-01

    Full Text Available Large sulfur dioxide plumes were measured in the Mexico City Metropolitan Area (MCMA during the MILAGRO field campaign. This paper seeks to identify the sources of these plumes and the meteorological processes that affect their dispersion in a complex mountain basin. Surface measurements of SO2 and winds are analysed in combination with radar wind profiler data to identify transport directions. Satellite retrievals of vertical SO2 columns from the Ozone Monitoring Instrument (OMI reveal the dispersion from both the Tula industrial complex and the Popocatepetl volcano. Numerical simulations are used to identify possible transport scenarios. The analysis suggests that both Tula and Popocatepetl contribute to SO2 levels in the MCMA, sometimes on the same day due to strong vertical wind shear. The evaluation of simulations with known sources and pollutants suggests that the combination of observations and meteorological models will be useful in identifying sources and transport processes of other plumes observed during MILAGRO.

  3. The economic value of fatal and non-fatal occupational risks in Mexico City using actuarial- and perceived-risk estimates.

    Science.gov (United States)

    Hammitt, James K; Ibarrarán, María Eugenia

    2006-12-01

    Compensating wage differentials are used to estimate marginal rates of substitution between income and both fatal and non-fatal occupational-injury risks in the Mexico City metropolitan area. Data are obtained by in-person survey of almost 600 workers and include workers' perceived risks of fatal and non-fatal occupational injury supplemented by actuarial-risk estimates from government statistics. Results using both actuarial- and perceived-risk estimates are reasonably consistent. Estimates of the value per statistical life are between 235,000 US dollars and 325,000 US dollars and estimates of the value per statistical non-fatal injury are between 3500 US dollars and 11,000 US dollars (2002 US dollars). These values are much smaller than corresponding estimates for higher-income countries but are compatible with the small number of prior estimates for lower-income countries. PMID:16929475

  4. Identification of heavy metals sources in the Mexico city atmosphere, using the proton induced x-ray analytical technique and multifactorial statistics techniques

    International Nuclear Information System (INIS)

    The objectives of this work are: to identify the heavy metals present in the air, and its concentrations. To know the behavior from the polluting chemical elements to the long of an annual cycle corresponding to 1990, based on the concentrations of the same ones, obtained through the PIXE technique. To identify the suitable statistical methods to use to the data of metals concentration in form of total suspended particle (PST), found in this investigation. To relate the concentrations and the meteorological parameters considered to be able to suggest the possible pollution sources. In function of the obtained results, to serve as base to the decisions making and measures control that are planned by diverse institutions focused to the problem of the atmospheric pollution in the Metropolitan area of Mexico City (ZMCM). (Author)

  5. Street vending and its ability to produce space: The case of the Tepito market in Mexico City downtown area

    OpenAIRE

    Oriard Colin, L. R.

    2015-01-01

    Street vending is a widespread phenomenon in the cities of the so-called developing countries. However, city planning systems have responded to the situation in a limited way, among other factors, because street vending is inherently difficult to regulate, especially from current paradigms of ‘public space’ (Brown 2006, Bhowmik 2010, Cross and Morales 2007). Street vending is explored in this thesis as an evolving and complex system that has become capable of transforming space; this perspect...

  6. Airborne particulate matter PM2.5 from Mexico City affects the generation of reactive oxygen species by blood neutrophils from asthmatics: an in vitro approach

    Directory of Open Access Journals (Sweden)

    Ceballos Guillermo

    2009-06-01

    Full Text Available Abstract Background The Mexico City Metropolitan Area is densely populated, and toxic air pollutants are generated and concentrated at a higher rate because of its geographic characteristics. It is well known that exposure to particulate matter, especially to fine and ultra-fine particles, enhances the risk of cardio-respiratory diseases, especially in populations susceptible to oxidative stress. The aim of this study was to evaluate the effect of fine particles on the respiratory burst of circulating neutrophils from asthmatic patients living in Mexico City. Methods In total, 6 subjects diagnosed with mild asthma and 11 healthy volunteers were asked to participate. Neutrophils were isolated from peripheral venous blood and incubated with fine particles, and the generation of reactive oxygen species was recorded by chemiluminescence. We also measured plasma lipoperoxidation susceptibility and plasma myeloperoxidase and paraoxonase activities by spectrophotometry. Results Asthmatic patients showed significantly lower plasma paraoxonase activity, higher susceptibility to plasma lipoperoxidation and an increase in myeloperoxidase activity that differed significantly from the control group. In the presence of fine particles, neutrophils from asthmatic patients showed an increased tendency to generate reactive oxygen species after stimulation with fine particles (PM2.5. Conclusion These findings suggest that asthmatic patients have higher oxidation of plasmatic lipids due to reduced antioxidant defense. Furthermore, fine particles tended to increase the respiratory burst of blood human neutrophils from the asthmatic group. On the whole, increased myeloperoxidase activity and susceptibility to lipoperoxidation with a concomitant decrease in paraoxonase activity in asthmatic patients could favor lung infection and hence disrupt the control of asthmatic crises.

  7. From slant column densities to trace gas profiles: Post processing data from the new MAX-DOAS network in Mexico City

    Science.gov (United States)

    Friedrich, M. M.; Stremme, W.; Rivera, C. I.; Arellano, E. J.; Grutter, M.

    2014-12-01

    The new MAX-DOAS network in Mexico City provides results of O4, HCHO and NO2 slant column densities (SCD). Here, we present a new numerical code developed to retrieve gas profiles of NO2 and HCHO using radiative transfer simulations. We present first results of such profiles from the MAX-DOAS station located at UNAM campus. The code works in two steps: First, the O4 slant column density information is used to retrieve an aerosol profile. As an a-priori aerosol profile, we use averaged ceilometer data measured at UNAM and scaled to the total optical depth provided by the Aeronet data base. In the second step, the retrieved aerosol profile information is used together with the trace gas (HCHO or NO2) SCDs to retrieve the trace gas profiles. The inversion is based on a gauss-newton iteration scheme and uses constrained least square fitting with either optimal estimation or Tihkonov regularization. For the latter, the regulation matrix is currently constructed from the discrete first derivative operator. The forward model uses the radiative transfer code VLIDORT. The inputs to VLIDORT are calculated using temperature and pressure information from daily radiosounde measurements and aerosol single scattering optical depths and asymmetry factors from the Aeronet data base for Mexico City. For the gas absorption cross sections we use the same values as were used for the SCD calculation from the recorded spectra using QDOAS. Besides demonstrating the functionality of the algorithm showing profile retrievals of simulated SCDs with added random noise, we present HCHO and NO2 profiles retrieved from SCDs calculated from the MAX-DOAS measurements at UNAM campus at selected days.

  8. Heavy metal pollution of the mid-canal of Kandy: an environmental case study from Sri Lanka

    Energy Technology Data Exchange (ETDEWEB)

    Dissanayake, C.B.; Niwas, J.M.; Weerasooriya, S.V.

    1987-02-01

    The mid-canal of Kandy, a 8-km effluent canal that runs through the city, collects massive quantities of domestic, municipal, and agricultural waste products. In this study, 37 samples from canal water and 13 from nearby drinking water wells were analyzed for their total Pb, Cd, V, Fe, and ferrous ion content. The following average values for the canal water were recorded: Pb, 269 micrograms/liter; Cd, 138 micrograms/liter; V, 18 micrograms/liter; total Fe, 4 mg/liter. These values indicate the relative levels of metal input from the effluent sources of the city of Kandy, the second largest city in Sri Lanka. The analysis of water from drinking wells near the canal showed high concentrations of metals, in some cases exceeding the maximum tolerance limits as recommended by WHO. The environmental impact of polluted city canals running through densely populated cities, particularly in developing countries, can assume serious proportions.

  9. The Effect of a Transfer Program for the Elderly in Mexico City on Co-Residing Children's School Enrollment

    OpenAIRE

    Gutierrez Emilio; Juárez González Laura; Rubli Adrian

    2015-01-01

    This paper studies whether the increase in government transfers, induced by an old-age pension program for individuals age 70 and older in Mexico, affects co-residing children's school enrollment, using a regression discontinuity analysis. Results suggest that while household composition and other household-level characteristics do not change significantly at the cutoff age for program eligibility, co-residing children's school enrollment increases significantly. This suggests that public res...

  10. The effect of a transfer program for the elderly in Mexico City on co-residing children's school enrollment

    OpenAIRE

    Gutierrez, Emilio; Juárez González, Laura; Rubli, Adrian

    2015-01-01

    This paper studies whether the increase in government transfers, induced by an old-age pension program for individuals age 70 and older in Mexico, affects co-residing children's school enrollment, using a regression discontinuity analysis. Results suggest that while household composition and other household-level characteristics do not change significantly at the cutoff age for program eligibility, co-residing children's school enrollment increases significantly. This suggests that public res...

  11. History of Abuse and Psychological Distress Symptoms among Female Sex Workers in Two Mexico-U.S. Border Cities

    OpenAIRE

    Ulibarri, Monica; Semple, Shirley J.; Rao, Swati; Steffanie A. Strathdee; Fraga-Vallejo, Miguel A.; Bucardo, Jesus; de la Torre, Adela; Salazar-Reyna, Juan; Orozovich, Prisci; Staines-Orozco, Hugo S.; Amaro, Hortensia; Magis-Rodriguez, Carlos; Patterson, Thomas L.

    2009-01-01

    This study examined histories of past emotional, physical, and sexual abuse as correlates of current psychological distress using data from 916 female sex workers (FSWs) who were enrolled in a safer-sex behavioral intervention in Tijuana and Ciudad (Cd.) Juarez, Mexico. We hypothesized that histories of abuse would be associated with higher symptom levels of depression and somatization, and that social support would moderate the relationship. Nonparametric correlations and a series of hierarc...

  12. Actors of Globalization? The Role of Informal Street Vendors in Globalization from Below in Tepito, Mexico City

    OpenAIRE

    Greschkow, Alice

    2015-01-01

    This thesis analyses how the interconnection between the so-called ‘globalization from below’ and street vending influences the changing patterns of informal employment in emerging market economies on the case study of Tepito, Mexico. It proposes the theoretical concept of globalization from below as a merger of three frameworks which were developed by Alejandro Portes, Gustavo Lins Ribeiro and Carlos Alba Vega in order to explore the interrelation among the three alleged dimen...

  13. Long-range pollution transport during the MILAGRO-2006 campaign: a case study of a major Mexico City outflow event using free-floating altitude-controlled balloons

    Directory of Open Access Journals (Sweden)

    P. B. Voss

    2010-02-01

    Full Text Available One of the major objectives of the Megacities Initiative: Local And Global Research Observations (MILAGRO-2006 campaign was to investigate the long-range transport of polluted Mexico City Metropolitan Area (MCMA outflow and determine its downwind impacts on air quality and climate. Six research aircraft, including the National Center for Atmospheric Research (NCAR C-130, made extensive chemical, aerosol, and radiation measurements above MCMA and more than 1000 km downwind in order to characterize the evolution of the outflow as it aged and dispersed over the Mesa Alta and Gulf of Mexico. As part of this effort, free-floating Controlled-Meteorological (CMET balloons, commanded to change altitude via satellite, made repeated profile measurements of winds and state variables within the advecting outflow. In this paper, we present an analysis based on the data from two CMET balloons that were launched near Mexico City on the afternoon of 18 March 2006 and floated downwind with the MCMA pollution for nearly 30 h. The repeating profile measurements show the evolving structure of the outflow in considerable detail: its stability and stratification, interaction with other air masses, mixing episodes, and dispersion into the regional background. Air parcel trajectories, computed directly from the balloon wind profiles, show three different transport pathways on 18–19 March: (a high-altitude advection of the top of the MCMA mixed layer, (b mid-level outflow over the Sierra Madre Oriental followed by decoupling and isolated transport over the Gulf, and (c low-altitude outflow with entrainment into a cleaner westerly jet below the plateau. The C-130 aircraft intercepted the balloon-based trajectories three times on 19 March, once along each of these pathways. In all three cases, distinct peaks in the urban tracer signatures and LIDAR backscatter imagery were consistent with MCMA pollution. The coherence of the high-altitude outflow was well preserved

  14. Using tradeable permits to achieve sustainability in the world's large cities. Policy design issues and efficiency conditions for controlling vehicle emissions, congestion and urban decentralization with an application to Mexico City

    International Nuclear Information System (INIS)

    Many large cities in the world have serious ground level ozone problems, largely the product of vehicular emissions and thus the argued unsustainability of current urban growth patterns is frequently blamed on unrestricted private vehicle use. This article reviews Mexico City's experience with vehicle use restrictions as an emissions control program and develops the conditions for optimal quantitative restrictions on vehicle use and for complementary abatement technologies. The stochastic nature of air pollution outcomes is modelled explicitly in both the static and dynamic formulations of the control problem, in which for the first time in the literature the use of tradeable vehicle use permits is proposed as a cost-effective complement to technological abatement for mobile emissions control. This control regime gives the authorities a broader and more flexible set of instruments with which to deal more effectively with vehicle emissions, and with seasonal and stochastic variation of air quality outcomes. The market in tradeable vehicle use permits would be very competitive with low transactions costs. This control policy would have very favorable impacts on air quality, vehicle congestion and on urban form and development. Given the general political resistance to environmental taxes, this program could constitute a workable and politically palatable set of policies for controlling greenhouse gas emissions from the transport sector. 7 figs., 1 appendix, 23 refs

  15. A Mobile Information System Based on Crowd-Sensed and Official Crime Data for Finding Safe Routes: A Case Study of Mexico City

    Directory of Open Access Journals (Sweden)

    Félix Mata

    2016-01-01

    Full Text Available Mobile information systems agendas are increasingly becoming an essential part of human life and they play an important role in several daily activities. These have been developed for different contexts such as public facilities in smart cities, health care, traffic congestions, e-commerce, financial security, user-generated content, and crowdsourcing. In GIScience, problems related to routing systems have been deeply explored by using several techniques, but they are not focused on security or crime rates. In this paper, an approach to provide estimations defined by crime rates for generating safe routes in mobile devices is proposed. It consists of integrating crowd-sensed and official crime data with a mobile application. Thus, data are semantically processed by an ontology and classified by the Bayes algorithm. A geospatial repository was used to store tweets related to crime events of Mexico City and official reports that were geocoded for obtaining safe routes. A forecast related to crime events that can occur in a certain place with the collected information was performed. The novelty is a hybrid approach based on semantic processing to retrieve relevant data from unstructured data sources and a classifier algorithm to collect relevant crime data from official government reports with a mobile application.

  16. The usefulness of air quality monitoring and air quality impact studies before the introduction of reformulated gasolines in developing countries. Mexico City, a real case study

    Energy Technology Data Exchange (ETDEWEB)

    Bravo, H.A.; Torres, R.J. [Universidad Nacional Autonoma de Mexico (Mexico). Section de Contaminacion Ambiental

    2000-07-01

    Urban air pollution is a major environmental problem in several developing countries in the world. This phenomenon seems to be related to the growth of both the urban population in large cities and the number of old and poorly maintained car fleets. The expected rise of population in the next century in countries which suffer from lack of capital for air pollution control, means that there is a great potential for the worsening of the air quality. The worldwide promote policy to phase out lead in gasolines has not proved to be an adequate option in improving the environmental quality. Mexico City Metropolitan Area (MCMA) represents a case in which the introduction of reformulated gasolines in an old car fleet has resulted in the reduction of the airborne lead levels but has worsened the ozone concentration of its urban atmosphere. This paper critically analyzes the chronological evolution of the ozone air pollution problem in MCMA after the successive occurrence of several changes in the formulation of low leaded and unleaded gasolines. It also presents evidences of the usefulness potential of air quality monitoring activities and air quality impact studies on the definition of realistic fuel reformulation policies of developing countries. (author)

  17. Root canal irrigation

    NARCIS (Netherlands)

    L. van der Sluis; C. Boutsioukis; L.M. Jiang; R. Macedo; B. Verhaagen; M. Versluis

    2015-01-01

    The aims of root canal irrigation are the chemical dissolution or disruption and the mechanical detachment of pulp tissue, dentin debris and smear layer (instrumentation products), microorganisms (planktonic or biofilm), and their products from the root canal wall, their removal out of the root cana

  18. The Root Canal Biofilm

    NARCIS (Netherlands)

    Sluis, van der L.W.M.; Boutsioukis, C.; Jiang, L.M.; Macedo, R.; Verhaagen, B.; Versluis, M.; Chávez de Paz, E.; Sedgley, C.M.; Kishen, A.

    2015-01-01

    The aims of root canal irrigation are the chemical dissolution or disruption and the mechanical detachment of pulp tissue, dentin debris and smear layer (instrumentation products), microorganisms (planktonic or biofilm), and their products from the root canal wall, their removal out of the root cana

  19. The Development of Culture Industry along Canal Cities and Strategy of Image Dissemination ---From the Perspective of Regional Operation between Huaian and Yangzhou%运河城市文化产业发展与形象传播战略——以淮安、扬州区域协同为视角

    Institute of Scientific and Technical Information of China (English)

    张沭宁

    2012-01-01

    文章提出京杭运河苏北段沿岸城市淮安、扬州开展区域文化、旅游产业协同发展战略,认为可以依托运河文化主题强化文化、旅游合作以及创意产业融合,开展产权共享、影视演艺、创意设计等多层次合作,构建“大文化、大旅游、大产业”业态和多样性文化旅游区,这对于传播运河沿岸城市的文化形象、合作打造运河文化品牌都有积极意义。%The author of this paper propounds that the cities such Huaian and Yangzhou along Great Canal (the nothern section of Jiangsu province) should employ the strategy of cooperating the regional culture and tourism industry, and suggest that, on the basis of canal culture, we should integrate culture, tourism cooperation and creative industry and carry out more cooperations about property sharing, film and performance and creative design, forming the pattern of "big culture, big tourism and big industry" and of diverse culture, which plays an important role in disseminating the cultural image of coastal cities along the Great Canal and creating the cultural brand about the canal

  20. Evaluation of the volatility basis-set approach for the simulation of organic aerosol formation in the Mexico City metropolitan area

    Directory of Open Access Journals (Sweden)

    A. P. Tsimpidi

    2010-01-01

    Full Text Available New primary and secondary organic aerosol modules have been added to PMCAMx, a three dimensional chemical transport model (CTM, for use with the SAPRC99 chemistry mechanism based on recent smog chamber studies. The new modelling framework is based on the volatility basis-set approach: both primary and secondary organic components are assumed to be semivolatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. This new framework with the use of the new volatility basis parameters for low-NOx and high-NOx conditions tends to predict 4–6 times higher anthropogenic SOA concentrations than those predicted with the older generation of models. The resulting PMCAMx-2008 was applied in Mexico City Metropolitan Area (MCMA for approximately a week during April 2003 during a period of very low regional biomass burning impact. The emission inventory, which uses as a starting point the MCMA 2004 official inventory, is modified and the primary organic aerosol (POA emissions are distributed by volatility based on dilution experiments. The predicted organic aerosol (OA concentrations peak in the center of Mexico City, reaching values above 40 μg m−3. The model predictions are compared with the results of the Positive Matrix Factorization (PMF analysis of the Aerosol Mass Spectrometry (AMS observations. The model reproduces both Hydrocarbon-like Organic Aerosol (HOA and Oxygenated Organic Aerosol (OOA concentrations and diurnal profiles. The small OA underprediction during the rush-hour periods and overprediction in the afternoon suggest potential improvements to the description of fresh primary organic emissions and the formation of the oxygenated organic aerosols, respectively, although they may also be due to errors in the simulation of dispersion and vertical mixing. However, the AMS OOA data are not specific enough to prove that the model reproduces the organic aerosol

  1. Groundwater flow in a transboundary fault-dominated aquifer and the importance of regional modeling: the case of the city of Querétaro, Mexico

    Science.gov (United States)

    Carrera-Hernández, J. J.; Carreón-Freyre, D.; Cerca-Martínez, M.; Levresse, G.

    2016-03-01

    The city of Querétaro, located near the political boundary of the Mexican states of Querétaro and Guanajuato, relies on groundwater as it sole water supply. Groundwater extraction in the city increased from 21 × 106 m3/yr in 1970 to 104 × 106 m3/yr in 2010, with an associated drawdown of 100 m in some parts of the aquifer. A three-dimensional numerical groundwater-flow model has been developed that represents the historical evolution of the aquifer's potentiometric levels and is used to simulate the effect of two scenarios: (1) a 40 % reduction in the extraction rate from public water supply wells in early 2011 (thus reducing the extraction to 62 × 106 m3/yr), and (2) a further reduction in 2021 to 1 × 106 m3/yr. The modeling results project a temporary recovery of the potentiometric levels after the 40 % reduction of early 2011, but a return to 2010 levels by 2020. If scenario 2 is implemented in 2021, the aquifer will take nearly 30 years to recover to the simulated levels of 1995. The model also shows that the wells located in the city of Querétaro started to extract water from part of the aquifer beneath the State of Guanajuato in the late 1970s, thus showing that the administrative boundaries used in Mexico to study and develop water resources are inappropriate, and consideration should be given to physical boundaries instead. A regional approach to studying aquifers is needed in order to adequately understand groundwater flow dynamics.

  2. Water, Cities and Peri-urban Communities: Geographies of Power in the Context of Drought in Northwest Mexico

    OpenAIRE

    Díaz-Caravantes, Rolando E.; Margaret Wilder

    2014-01-01

    The urban-peri-urban interaction is frequently studied with a focus on the necessities of urban expansion, chronicling the concerns of land annexation, housing construction and infrastructure. However, in arid regions such as Mexicoʼs drought-prone northwest, the research on peri-urban issues must increasingly focus on the under-examined issue of the power geometries that are reshaping the contours of access to water in fast-growing areas. This paper examines geographies of power of the ur...

  3. Determination of Rn222 in samples of well water and domicile of the cities of Chihuahua and Aldama, Mexico

    International Nuclear Information System (INIS)

    The study of the content of dissolved Rn222 is presented in underground water and of domicile of the cities of Chihuahua and Aldama of the State of Chihuahua. The existence of the Rn222 in the underground waters comes from its constant production in the rocks of the terrestrial bark. It has been determined that the radon is a noble gas of more solubility in the water, this solubility induces high concentrations in underground water, as well as bigger risk to the health in the human body once ingested or inhaled. Of the 32 wells studied in the cities of Chihuahua and Aldama, the content of dissolved Rn222 in the water of 22 of them is bigger than 11 Bq/l and of 73 studied samples of water of domiciles 47 show bigger values that 11 Bq/l. These radon contents are attributable to the uraniferous rocks present in the aquifers. (Author)

  4. Tracing Processes in Poverty Dynamics: A Tale of Peri-urban Small-scale Farmers in Mexico City

    OpenAIRE

    Yadira Méndez-Lemus; Antonio Vieyra

    2014-01-01

    Many peri-urban areas in developing regions are associated with poverty. The poor peri-urban resident may have moved in and established in precarious conditions, or may have resided in the area before the urban encroachment and so have a rural background. Former poor rural residents living on the fringes of cities are considered to be very vulnerable since they are subjected to a livelihood transmutation while they try to escape from poverty. Drawing on longitudinal quantitative and qualitati...

  5. Prevalence and correlates of HIV and sexually transmitted infections among female sex workers and their non-commercial male partners in two Mexico-USA border cities.

    Science.gov (United States)

    Robertson, Angela M; Syvertsen, Jennifer L; Ulibarri, Monica D; Rangel, M Gudelia; Martinez, Gustavo; Strathdee, Steffanie A

    2014-08-01

    Female sex workers (FSWs) acquire HIV and other sexually transmitted infections (STIs) through unprotected sex with commercial and non-commercial (intimate) male partners. Little research has focused on FSWs' intimate relationships, within which condom use is rare. We sought to determine the prevalence and correlates of HIV/STIs within FSWs' intimate relationships in Northern Mexico. From 2010 to 2011, we conducted a cross-sectional survey of FSWs and their non-commercial male partners in Tijuana and Ciudad Juárez, Mexico. Eligible FSWs and their verified male partners were aged ≥18 years; FSWs reported lifetime use of heroin, cocaine, crack, or methamphetamine and recently exchanged sex (past month). Participants completed baseline questionnaires and testing for HIV, chlamydia, gonorrhea, and syphilis. We determined the prevalence and correlates of individuals' HIV/STI positivity using bivariate probit regression. Among 212 couples (n = 424), prevalence of HIV was 2.6 % (n = 11). Forty-two (9.9 %) tested positive for any HIV/STIs, which was more prevalent among women than men (12.7 % vs. 7.1 %, p < 0.05). FSWs with regular sex work clients were less likely to test positive for HIV/STIs than those without regular clients. Similarly, male partners of FSWs who had regular clients were 9 % less likely to have HIV/STIs. Higher sexual decision-making power was protective against HIV/STIs for women. Men who recently used methamphetamine or reported perpetrating any conflict within steady relationships were more likely to test positive for HIV/STIs. Within FSWs' intimate relationships in two Mexican-US border cities, nearly one in ten partners tested positive for HIV/STIs. Couple-based prevention interventions should recognize how intimate relationship factors and social contexts influence HIV/STI vulnerability. PMID:24488651

  6. Evaluation of ecological quality in peri-urban rivers in Mexico City: a proposal for identifying and validating reference sites using benthic macroinvertebrates as indicators

    Directory of Open Access Journals (Sweden)

    Angela Caro-Borrero

    2015-08-01

    Full Text Available Conservation and management of aquatic ecosystems that are significantly influenced by urban activities requires the classification and establishment of potential reference sites. However, in Latin American countries, policies are not available that outlines the identification and evaluation of such sites. Therefore, this study represents a proposal for evaluating the ecological quality of peri-urban rivers in the conservation soil (CS areas/zones of Mexico City. The proposal accounts for the zone’s physicochemical, hydromorphological, and bacteriological characteristics along with its macroinvertebrate richness. Our evaluation was performed using a canonical correspondence analysis (CCA and indicator values (IndVal calculated for different species. River headwaters serve/work as a good physicochemical point for potential references sites. However, the hydromorphology of the CS has been gradually modified by numerous hydraulic alterations within the peri-urban zone. Using the CCA and IndVal, two types of sites were confirmed: sites in a good state of conservation and quality and sites modified by human activity, featuring lower discharge flow, poor quality hydromorphological values and Oligochaeta class organisms. At the sites featuring a good state of conservation and quality, higher hydromorphological values were positively correlated with discharge flow and certain macroinvertebrate taxa, including Nemouridae, Podonominae, Tanypodinae, Acarina, Baetis, Tipula, Antocha, Atopsyche, Glossosoma, Polycentropus, Hesperophylax and Limnephilus. In the sites modified by human activity, the genus Simulium was classified as a disturbance-tolerant organism. The river reach within the urban zone is basically an open-air drainage ditch. Evaluations of the ecological quality of the riparian zone were used to identify the most important hydromorphological qualities and discharge flow parameters and to select the most appropriate factors that should be

  7. Design of canals

    CERN Document Server

    Swamee, P K

    2015-01-01

    The book presents firsthand material from the authors on design of hydraulic canals. The book discusses elements of design based on principles of hydraulic flow through canals. It covers optimization of design based on usage requirements and economic constraints. The book includes explicit design equations and design procedures along with design examples for varied cases. With its comprehensive coverage of the principles of hydraulic canal design, this book will prove useful to students, researchers, and practicing engineers. End-of-chapter pedagogical elements make it ideal for use in graduate courses on hydraulic structures offered by most civil engineering departments across the world.

  8. Estudio seroepidemiológico de borreliosis de Lyme en la Ciudad de México y el noreste de la República Mexicana Seroepidemiologic survey of Lyme Borreliosis in Mexico City and the Northeast region of the country

    Directory of Open Access Journals (Sweden)

    Guadalupe Gordillo-Pérez

    2003-10-01

    Full Text Available OBJETIVO: Investigar mediante métodos serológicos la infección por B burgdorferi en individuos del Distrito Federal y la zona noreste de México. MATERIAL Y MÉTODOS: Se obtuvo una muestra representativa de sueros del Distrito Federal y la zona noreste de México, obtenidas en la Encuesta Seroepidemiológica Nacional de 1987-1988. Se detectaron anticuerpos IgG vs B burgdorferi por ELISA, confirmados con Western blot. En este trabajo se utilizó estadística descriptiva. RESULTADOS: Fueron estudiados 2 346 sueros; 297 (12.6% fueron positivos por inmunoensayo enzimático, y 122/297 fueron confirmados por Western blot. La seroprevalencia fue de 3.43% en el Distrito Federal y 6.2% en la zona noreste del país. Tamaulipas fue el estado con la seroprevalencia más alta. CONCLUSIONES: La prevalencia de casos seropositivos sugieren que la infección por B burgdorferi ocurre en el noreste de México y el Distrito Federal. Es necesario identificar casos clínicos y buscar el vector infectado para confirmar la presencia de la enfermedad de Lyme en México.OBJECTIVE: To detect serological evidence of B burgdorferi infection in individuals from Mexico City and from the Northeast Region of the country. MATERIAL AND METHODS: A representative sample size of serum from Mexico City and the states of the Northeast of Mexico were taken from serum samples corresponding to the 1987-1988 national survey were obtained from the National Serum Bank. Antibodies against B burgdorferi were detected by ELISA and confirmed with Western blot (WB assays. Data were analyzed using descriptive statistics. RESULTS: A total of 2 346 serum samples were tested; 297 (12.6% were positive for ELISA, and 122 of 297 were confirmed by WB. Seroprevalence was 3.43% in Mexico City and 6.2% in the Northeast region of the country. Tamaulipas was the state with the highest seroprevalence. CONCLUSIONS: The prevalence of seropositive cases shows that borrelial infection is present in the

  9. Characterization of ambient aerosols in Mexico City during the MCMA-2003 campaign with Aerosol Mass Spectrometry: results from the CENICA Supersite

    Directory of Open Access Journals (Sweden)

    D. Salcedo

    2006-01-01

    Full Text Available An Aerodyne Aerosol Mass Spectrometer (AMS was deployed at the CENICA Supersite, during the Mexico City Metropolitan Area field study (MCMA-2003 from 31 March-4 May 2003 to investigate particle concentrations, sources, and processes. The AMS provides real time information on mass concentration and composition of the non-refractory species in particulate matter less than 1 µm (NR-PM1 with high time and size-resolution. In order to account for the refractory material in the aerosol, we also present estimates of Black Carbon (BC using an aethalometer and an estimate of the aerosol soil component obtained from Proton-Induced X-ray Emission Spectrometry (PIXE analysis of impactor substrates. Comparisons of AMS + BC + soil mass concentration with other collocated particle instruments (a LASAIR Optical Particle Counter, a PM2.5 Tapered Element Oscillating Microbalance (TEOM, and a PM2.5 DustTrak Aerosol Monitor show that the AMS + BC + soil mass concentration is consistent with the total PM2.5 mass concentration during MCMA-2003 within the combined uncertainties. In Mexico City, the organic fraction of the estimated PM2.5 at CENICA represents, on average, 54.6% (standard deviation σ=10% of the mass, with the rest consisting of inorganic compounds (mainly ammonium nitrate and sulfate/ammonium salts, BC, and soil. Inorganic compounds represent 27.5% of PM2.5 (σ=10%; BC mass concentration is about 11% (σ=4%; while soil represents about 6.9% (σ=4%. Size distributions are presented for the AMS species; they show an accumulation mode that contains mainly oxygenated organic and secondary inorganic compounds. The organic size distributions also contain a small organic particle mode that is likely indicative of fresh traffic emissions; small particle modes exist for the inorganic species as well. Evidence suggests that the organic and inorganic species are not always internally mixed, especially in the small modes. The aerosol seems to be neutralized most

  10. Evaluation of the air quality regarding total suspended particles and heavy metals (Pb, Cd, Ni, Cu, Cr) in the Hermosillo city, Sonora, Mexico, during a yearly period

    International Nuclear Information System (INIS)

    In the present study, the air quality of the city of Hermosillo, Sonora, Mexico was assessed considering total suspended particulates (tsp) and heavy metals (Pb, Cd, Ni, Cu, Cr) from June 2001 through May 2002 in three monitoring sites Centro (Mazon), Nor este (CESUES) and Noroeste (CBTIS). The filter-samples used for that purpose were provided by the Air Quality Evaluation and Improvement Program (PEMCA) of the municipality of Hermosillo. The sampling method was based on high volume sampling frequency set every 6 days with non-simultaneous sampling among the three sampling sites. Filters were dissolved for metal determination by acidic-extraction, and then analyzed by flame atomic absorption spectrophotometry. Results indicate that tsp concentrations at Centro and Noroeste sites were frequently higher than the maximum daily permissible level (260 μg/m3), while in the three sites the annual average was higher than the maximum annual permissible level (75 μg/m3) both established in the standard NOM-024-Ssa-1993 (Ssa 1994a). According to the Air Quality Standard Index (US EPA 1992a), used in Mexico by Air Quality Metropolitan Index (IMECA) the results indicate that the air quality in the city of Hermosillo regarding tsp was placed between no satisfactory and poor. In regard to heavy metals (Pb, Cd, Ni, Cu, Cr), concentrations detected were below the maximum permissible levels and/or criteria taking into account the standard NOM-026-Ssa-1993 (Ssa 1994b), the Who criterion (2000), the European Union criterion (Cec 2003), and the European Environmental Agency criteria (EEA 2004). Such findings would mean that airborne metals are of no concern; however, air quality is still classified as no satisfactory due to high particulate matter concentrations. Keeping air quality parameters monitoring is recommended in order to get extensive data for use in risk studies of air quality and health (morbidity/mortality), as well as topographic conditions, meteorological and urban

  11. Expectativas de migración internacional en estudiantes de enfermería en México, Distrito Federal Migration expectations among nursing students in Mexico City

    Directory of Open Access Journals (Sweden)

    Yetzi Rosales-Martínez

    2010-06-01

    Full Text Available OBJETIVO: Analizar los factores asociados con la expectativa de migrar al extranjero en estudiantes de licenciatura en enfermería de escuelas públicas en México, Distrito Federal. MATERIAL Y MÉTODOS: Se realizó un estudio transversal con una muestra no probabilística de 420 estudiantes. Se construyó un modelo logístico multivariado. RESULTADOS: El 69% de los informantes expresó la intención de migrar para trabajar (65% o estudiar (26%. El 50% elegiría como destino Canadá, seguido de España y Estados Unidos. Las variables asociadas con la expectativa de migrar fueron: edad, ingreso, tener familiares en el extranjero y percibir malas condiciones laborales/salarios en México. CONCLUSIONES: Los resultados concuerdan con la literatura internacional. Los bajos salarios, malas condiciones laborales y escasas posibilidades de desarrollarse profesionalmente en México contribuyen a generar la expectativa de migrar en la población de estudio. Adicionalmente, la percepción optimista de los estudiantes sobre el mercado extranjero y la demanda laboral de países desarrollados coadyuvan a enfatizar dicho fenómeno.OBJECTIVE: To analyze the factors associated with the expectations to migrate abroad among nursing students in Mexico City. MATERIAL AND METHODS: A cross-sectional study was conducted with a non-random sample of 420 students. A logistic regression model was estimated. RESULTS: A total of 69% of the informants expressed their intention to move abroad, to look for employment (65% and/or to continue their studies (26%. Of those, 50% would choose Canada as their destination, followed by Spain and the United States. The variables associated with migration expectations were: age, income, having relatives abroad, and perception of poor labor conditions and low wages in Mexico. CONCLUSIONS: Results are consistent with international literature. Low wages, poor labor conditions and the limited possibilities for professional development in

  12. Modelling constraints on the emission inventory and on vertical diffusion for CO and SO2 in the Mexico City Metropolitan Area using Solar FTIR and zenith sky UV spectroscopy

    OpenAIRE

    B. de Foy; W. Lei; Zavala, M; Volkamer, R.; Samuelsson, J.; Mellqvist, J.; B. Galle; Martínez, A.-P.; Grutter, M.; L. T. Molina

    2006-01-01

    Emissions of air pollutants in and around urban areas lead to negative health impacts on the population. To estimate these impacts, it is important to know the sources and transport mechanisms of the pollutants accurately. Mexico City has a large urban fleet in a topographically constrained basin leading to high levels of carbon monoxide (CO). Large point sources of sulfur dioxide (SO2) surrounding the basin lead to episodes with high concentrations. An Eulerian grid model (CAMx) and a partic...

  13. Modelling constraints on the emission inventory and on vertical dispersion for CO and SO2 in the Mexico City Metropolitan Area using Solar FTIR and zenith sky UV spectroscopy

    OpenAIRE

    B. de Foy; W. Lei; Zavala, M; Volkamer, R.; Samuelsson, J.; Mellqvist, J.; B. Galle; Martínez, A.-P.; Grutter, M.; A. Retama; L. T. Molina

    2007-01-01

    Emissions of air pollutants in and around urban areas lead to negative health impacts on the population. To estimate these impacts, it is important to know the sources and transport mechanisms of the pollutants accurately. Mexico City has a large urban fleet in a topographically constrained basin leading to high levels of carbon monoxide (CO). Large point sources of sulfur dioxide (SO2) surrounding the basin lead to episodes with high concentrations. An Eulerian grid m...

  14. Modelling constraints on the emission inventory and on vertical dispersion for CO and SO2 in the Mexico City Metropolitan Area using Solar FTIR and zenith sky UV spectroscopy

    OpenAIRE

    B. de Foy; W. Lei; Zavala, M; Volkamer, R.; Samuelsson, J.; Mellqvist, J.; B. Galle; A.-P. Martínez; Grutter, M.; A. Retama; L. T. Molina

    2007-01-01

    Emissions of air pollutants in and around urban areas lead to negative health impacts on the population. To estimate these impacts, it is important to know the sources and transport mechanisms of the pollutants accurately. Mexico City has a large urban fleet in a topographically constrained basin leading to high levels of carbon monoxide (CO). Large point sources of sulfur dioxide (SO2) surrounding the basin lead to episodes with high concentrations. An Eulerian grid model (CAMx) and a partic...

  15. Acceso universal al Programa de VIH/SIDA de la Ciudad de México: resultados a seis años Universal access, six years results in the Mexico City HIV/AIDS Program

    Directory of Open Access Journals (Sweden)

    Carmen Soler Claudín

    2009-02-01

    Full Text Available OBJETIVO: Analizar los resultados del Programa de Medicamentos Antirretrovirales Gratuitos del Programa de VIH/SIDA de la Ciudad de México (PVSCM en la población afectada del Distrito Federal. MATERIAL Y MÉTODOS: Se sistematizaron y analizaron datos de la Coordinación del PVSCM sobre atención médica, tratamiento antirretroviral (ARV y resultados de laboratorio especializado en un análisis retrospectivo del periodo 2001-2006, para evaluar su efecto en los pacientes atendidos. RESULTADOS. Se incluyen datos de 5 146 pacientes que recibieron tratamiento ARV. Al final del periodo, 74% de ellos permanecía vigente, 12.1% se perdió en el seguimiento y 13.9% había fallecido. CONCLUSIONES: En el Distrito Federal, durante el periodo evaluado se logró la ampliación de cobertura, eficacia en el tratamiento ARV e incremento de la sobrevida de los pacientes.OBJECTIVE: To analyze the results of the Free Antiretroviral Medication Program of the Mexico City HIV/AIDS Program among the affected population in Mexico City. MATERIAL AND METHODS: A retrospective analysis was conducted of medical attention, antiretroviral treatment and specialized laboratory results data from 2001 to 2006 from patients who sought services from the Mexico City HIV/AIDS Program. RESULTS: Data from 5 146 patients who were undergoing ARV are presented. At the end of the period studied, 74% were current, 12.2% were not found for follow-up and 13.9% had died. CONCLUSIONS: During the period evaluated, wider coverage was achieved in Mexico City as well as increased efficiency in ARV treatment and increased patient survival.

  16. Impact of the Popocatepetl's volcanic activity on the air quality of Puebla City, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Juarez, A. [Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Puebla, Puebla (Mexico); Gay, C. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, UNAM, Mexico, D.F. (Mexico); Flores, Y. [Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Puebla, Puebla (Mexico)

    2005-01-01

    In this work we report measurements of atmospheric pollutants in Puebla City, including those registered during the period characterized by intense volcanic activity from Popocatepetl volcano between December 2000 and January 2001. We used a gaussian air dispersion model to calculate the impact of sulfur compounds from volcanic emissions on the measurements of these compounds in the stations belonging to Puebla City Atmospheric Monitoring Network. The data show that during the analyzed period, this volcanic emissions affected the air quality, increasing the indexes of PM{sub 1}0, CO and sulfur compounds. Also, the results of applying a Gaussian air dispersion model to these sulfur compounds explains the measurements from Tecnologico station for days with intense volcanic activity and wind coming from the volcano to Puebla City. [Spanish] En este trabajo se reportan mediciones de contaminantes atmosfericos en la ciudad de Puebla, incluyendo las registradas durante el periodo caracterizado por una intensa actividad del volcan Popocatepetl, entre diciembre de 200 y enero de 2001. Aplicamos un modelo de dispersion gaussiano para calcular el impacto de las emisiones volcanicas de compuestos de azufre en las mediciones de estos compuestos en las estaciones de la Red de Monitoreo Atmosferico de la ciudad de Puebla. Los datos muestran que durante el periodo analizado, las emisiones volcanicas afectaron la calidad del aire incrementando los indices de PM{sub 1}0, CO y compuestos de azufre. Ademas, los resultados del modelo gaussiano de dispersion del aire para los compuestos de azufre, explican las mediciones de la estacion Tecnologico para los dias con intensa actividad volcanica y viento viniendo del volcan hacia la ciudad de Puebla.

  17. Measurements of volatile organic compounds at a suburban ground site (T1 in Mexico City during the MILAGRO 2006 campaign: measurement comparison, emission ratios, and source attribution

    Directory of Open Access Journals (Sweden)

    D. M. Bon

    2010-10-01

    Full Text Available Volatile organic compound (VOC mixing ratios were measured with two different instruments at the T1 ground site in Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO campaign in March of 2006. A gas chromatograph with flame ionization detector (GC-FID quantified 18 light alkanes, alkenes and acetylene while a proton-transfer-reaction ion-trap mass spectrometer (PIT-MS quantified 12 VOC species including oxygenated VOCs (OVOCs and aromatics. A GC separation system was used in conjunction with the PIT-MS (GC-PIT-MS to evaluate PIT-MS measurements and to aid in the identification of unknown VOCs. The VOC measurements are also compared to simultaneous canister samples and to two independent proton-transfer-reaction mass spectrometers (PTR-MS deployed on a mobile and an airborne platform during MILAGRO. VOC diurnal cycles demonstrate the large influence of vehicle traffic and liquid propane gas (LPG emissions during the night and photochemical processing during the afternoon. Emission ratios for VOCs and OVOCs are determined from early-morning enhancement ratios and compared to emission ratios calculated from the PMF results. Average emission ratios for non-oxygenated species relative to CO are on average a factor of 2 higher than measured for US cities. Emission ratios for OVOCs are estimated and compared to literature values the northeastern US and to tunnel studies in California. Positive matrix factorization analysis (PMF is used to provide insight into VOC sources and processing and to estimate OVOC emission ratios. Three PMF factors were distinguished by the analysis including the emissions from vehicles, the use of liquid propane gas and the production of secondary VOCs + long-lived species. The total PIT-MS signal was summed to estimate the fraction of identified vs. unidentified VOC species.

  18. Measurements of volatile organic compounds at a suburban ground site (T1 in Mexico City during the MILAGRO 2006 campaign: measurement comparison, emission ratios, and source attribution

    Directory of Open Access Journals (Sweden)

    D. M. Bon

    2011-03-01

    Full Text Available Volatile organic compound (VOC mixing ratios were measured with two different instruments at the T1 ground site in Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO campaign in March of 2006. A gas chromatograph with flame ionization detector (GC-FID quantified 18 light alkanes, alkenes and acetylene while a proton-transfer-reaction ion-trap mass spectrometer (PIT-MS quantified 12 VOC species including oxygenated VOCs (OVOCs and aromatics. A GC separation system was used in conjunction with the PIT-MS (GC-PIT-MS to evaluate PIT-MS measurements and to aid in the identification of unknown VOCs. The VOC measurements are also compared to simultaneous canister samples and to two independent proton-transfer-reaction mass spectrometers (PTR-MS deployed on a mobile and an airborne platform during MILAGRO. VOC diurnal cycles demonstrate the large influence of vehicle traffic and liquid propane gas (LPG emissions during the night and photochemical processing during the afternoon. Emission ratios for VOCs and OVOCs relative to CO are derived from early-morning measurements. Average emission ratios for non-oxygenated species relative to CO are on average a factor of ~2 higher than measured for US cities. Emission ratios for OVOCs are estimated and compared to literature values the northeastern US and to tunnel studies in California. Positive matrix factorization analysis (PMF is used to provide insight into VOC sources and processing. Three PMF factors were distinguished by the analysis including the emissions from vehicles, the use of liquid propane gas and the production of secondary VOCs + long-lived species. Emission ratios to CO calculated from the results of PMF analysis are compared to emission ratios calculated directly from measurements. The total PIT-MS signal is summed to estimate the fraction of identified versus unidentified VOC species.

  19. Measurements of volatile organic compounds at a suburban ground site (T1) in Mexico City during the MILAGRO 2006 campaign: Measurement comparison, emission ratios, and source attribution

    Energy Technology Data Exchange (ETDEWEB)

    Bon, D.M.; Springston, S.; M.Ulbrich, I.; de Gouw, J. A.; Warneke, C.; Kuster, W. C.; Alexander, M. L.; Baker, A.; Beyersdorf, A. J.; Blake, D.; Fall, R.; Jimenez, J. L., Herndon, S. C.; Huey, L. G.; Knighton, W. B.; Ortega, J.; Vargas, O.

    2011-03-16

    Volatile organic compound (VOC) mixing ratios were measured with two different instruments at the T1 ground site in Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO) campaign in March of 2006. A gas chromatograph with flame ionization detector (GC-FID) quantified 18 light alkanes, alkenes and acetylene while a proton-transfer-reaction ion-trap mass spectrometer (PIT-MS) quantified 12 VOC species including oxygenated VOCs (OVOCs) and aromatics. A GC separation system was used in conjunction with the PIT-MS (GC-PIT-MS) to evaluate PIT-MS measurements and to aid in the identification of unknown VOCs. The VOC measurements are also compared to simultaneous canister samples and to two independent proton-transfer-reaction mass spectrometers (PTR-MS) deployed on a mobile and an airborne platform during MILAGRO. VOC diurnal cycles demonstrate the large influence of vehicle traffic and liquid propane gas (LPG) emissions during the night and photochemical processing during the afternoon. Emission ratios for VOCs and OVOCs relative to CO are derived from early-morning measurements. Average emission ratios for non-oxygenated species relative to CO are on average a factor of {approx}2 higher than measured for US cities. Emission ratios for OVOCs are estimated and compared to literature values the northeastern US and to tunnel studies in California. Positive matrix factorization analysis (PMF) is used to provide insight into VOC sources and processing. Three PMF factors were distinguished by the analysis including the emissions from vehicles, the use of liquid propane gas and the production of secondary VOCs + long-lived species. Emission ratios to CO calculated from the results of PMF analysis are compared to emission ratios calculated directly from measurements. The total PIT-MS signal is summed to estimate the fraction of identified versus unidentified VOC species.

  20. Tropospheric ozone sources and wave activity over Mexico City and Houston during MILAGRO/Intercontinental Transport Experiment (INTEX-B Ozonesonde Network Study, 2006 (IONS-06

    Directory of Open Access Journals (Sweden)

    L. Ladino

    2008-09-01

    Full Text Available During the INTEX-B (Intercontinental Chemical Transport Experiment/ MILAGRO (Megacities Initiative: Local and Global Research Observations experiments in March 2006 and the associated IONS-06 (INTEX Ozonesonde Network Study; http://croc.gsfc.nasa.gov/intexb/ions06.html, regular ozonesonde launches were made over 15 North American sites. The soundings were strategically positioned to study inter-regional flows and meteorological interactions with a mixture of tropospheric O3 sources: local pollution; O3 associated with convection and lightning; stratosphere-troposphere exchange. The variability of tropospheric O3 over the Mexico City Basin (MCB; 19° N, 99° W and Houston (30° N, 95° W is reported here. MCB and Houston profiles displayed a double tropopause in most soundings and a subtropical tropopause layer with frequent wave disturbances, identified through O3 laminae as gravity-wave induced. Ozonesondes launched over both cities in August and September 2006 (IONS-06, Phase 3 displayed a thicker tropospheric column O3 (~7 DU or 15–20% than in March 2006; nearly all of the increase was in the free troposphere. In spring and summer, O3 laminar structure manifested mixed influences from the stratosphere, convective redistribution of O3 and precursors, and O3 from lightning NO. Stratospheric O3 origins were present in 39% (MCB and 60% (Houston of the summer sondes. Comparison of summer 2006 O3 structure with summer 2004 sondes (IONS-04 over Houston showed 7% less tropospheric O3 in 2006. This may reflect a sampling contrast, August to mid-September 2006 instead of July-mid August 2004.

  1. Recycling of solid wastes in Mexico City in livestock and agricultural production systems as a sustainable alternative

    OpenAIRE

    H. Losada; Cortes, J; Rivera, J.; Vargas, J.

    2011-01-01

    The use of solid organic wastes (manure and  fruit and vegetable refusals) as a way to recycle rubbish from peri-urban areas for the production of crops for local consumption, has been designated by some researchers as an alternate method to partially reduce city waste disposal problems as well as to generate employment and promote the consumption of local products. This model production has also been suggested as a closed system ideally suited for urban environments in order to reduce the us...

  2. Mexico City Aerosol Analysis during MILAGRO using High Resolution Aerosol Mass Spectrometry at the Urban Supersite (T0). Part 2: Analysis of the Biomass Burning Contribution and the Modern Carbon Fraction

    Energy Technology Data Exchange (ETDEWEB)

    Aiken, Allison; de Foy, B.; Wiedinmyer, Christine; DeCarlo, Peter; Ulbrich, Ingrid M.; Wehrli, M. N.; Szidat, S.; Prevot, A. S. H.; Noda, J.; Wacker, L.; Volkamer, Rainer M.; Fortner, Edward; Wang, J. X.; Laskin, Alexander; Shutthanandan, V.; Zheng, J.; Zhang, Renyi; Paredes-Miranda, Guadalupe L.; Arnott, W. P.; Molina, Luis; Sosa, G.; Querol, X.; Jimenez, J. L.

    2010-06-16

    Submicron aerosol was analyzed during the MILAGRO field campaign in March 2006 at the T0 urban supersite in Mexico City with a High-Resolution Aerosol Mass Spectrometer (AMS) and complementary instrumentation. Positive Matrix Factorization (PMF) of high resolution AMS spectra identified a biomass burning OA (BBOA) component, which includes several large plumes that appear to be from forest fires within the region. Here, we show that the AMS BBOA concentration at T0 correlates with fire counts in the vicinity of Mexico City and that most of the BBOA variability is captured when the FLEXPART model is used for the dispersion of fire emissions as estimated from satellite fire counts. The resulting FLEXPART fire impact index correlates well with the observed BBOA, CH3CN, levoglucosan, and potassium, indicating that wildfires in the region surrounding Mexico City are the dominant source of BBOA at T0 during MILAGRO. The impact of distant BB sources such as the Yucatan is very small during this period. All fire tracers are correlated, with BBOA and levoglucosan showing little background, acetonitrile having a well-known tropospheric background of ~100-150 ppt, and PM2.5 potassium having a background of ~160 ng m-3 (two-thirds of its average concentration), which does not appear to be related to BB sources.

  3. Reconstruction of Trajectories, Mixing, and Dispersion of a Mexico City Pollution Outflow Event Using In-Situ Observations From Free-Floating Altitude-Controlled Balloons

    Science.gov (United States)

    Voss, P.; Zaveri, R.; Hartley, T.; Deonandan, I.; Deamicis, P.; Martinez Antonio, O.; Contreras Jiménez, G.; Greenberg, D.; Estrada, M.; Flocke, F.; Madronich, S.; Kleinman, L.; Springston, S.; Hubbe, J.; de Foy, B.; Mao, H.

    2007-12-01

    The phenomenal growth of megacities, particularly in the developing world, has fueled interest in their effects on climate and air quality on the local, regional, and global scales. During the MILAGRO 2006 campaign, aircraft, satellites, and ground stations were coordinated to make the most intensive measurements to date of the transport and transformation of emissions from a tropical megacity. Likely the most certain case of long-range transport observed during the campaign occurred on March 18-19 when the DOE G1 and NCAR C-130 aircraft made coordinated observations within the Mexico City Metropolitan Area and the C-130 then intercepted the remnants of this urban air 24 hours later and 800 kilometers downwind near the U.S. boarder. Confidence in this event was significantly increased by two free-floating altitude-controlled balloons that remained embedded in the airmass while making repeated profile measurements of winds, thermal structure, and humidity during the transport process. This time series of quasi-Lagrangian soundings is probably the most comprehensive set of in-situ meteorological observations made in a long-range transport event. The profile data from the balloons is used to reconstruct trajectories and estimate mixing and dispersion throughout an advecting slab of the atmosphere. When combined with aircraft, satellite, and surface measurements, the balloon data provide a unique view of an advecting megacity plume that can be used to constrain both meteorological and photochemical models.

  4. Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO2 retrievals during the MILAGRO field campaign

    Directory of Open Access Journals (Sweden)

    L. T. Molina

    2009-12-01

    Full Text Available Large sulfur dioxide plumes were measured in the Mexico City Metropolitan Area (MCMA during the MILAGRO field campaign. This paper seeks to identify the sources of these plumes and the meteorological processes that affect their dispersion in a complex mountain basin. Surface measurements of SO2 and winds are analysed in combination with radar wind profiler data to identify transport directions. Satellite retrievals of vertical SO2 columns from the Ozone Monitoring Instrument (OMI reveal the dispersion from both the Tula industrial complex and the Popocatepetl volcano. Oversampling the OMI swath data to a fine grid (3 by 3 km and averaging over the field campaign yielded a high resolution image of the average plume transport. Numerical simulations are used to identify possible transport scenarios. The analysis suggests that both Tula and Popocatepetl contribute to SO2 levels in the MCMA, sometimes on the same day due to strong vertical wind shear. During the field campaign, model estimates suggest that the volcano accounts for about one tenth of the SO2 in the MCMA, with a roughly equal split for the rest between urban sources and the Tula industrial complex. The evaluation of simulations with known sources and pollutants suggests that the combination of observations and meteorological models will be useful in identifying sources and transport processes of other plumes observed during MILAGRO.

  5. Ethnobotanical, micrographic and pharmacological features of plant-based weight-loss products sold in naturist stores in Mexico City: the need for better quality control

    Directory of Open Access Journals (Sweden)

    Patricia Marta Arenas

    2013-09-01

    Full Text Available The consumption of dietary supplements and herbal mixtures to promote weight loss is a common practice in the West. This study was undertaken in Mexico City, surveying stores selling "natural products" at subway stations. The aims of this paper were as follows: to compile a record of plant products marketed as slimming aids and of retailer perceptions of these products; to review the pharmacological and ethnobotanical literature on the species declared; and to create an optical micrograph of a subset of products to verify the accuracy of the list of component plant species shown on the labels. We applied the techniques of observation, semi-structured interviews and free-listing at the retail stores. Results are presented for the 75 species recorded in the 41 weight-loss products surveyed, showing which plant parts are used, the geographical distribution of the species, pharmacological effects, dosage, route of administration and method of preparation, as well as ethnobotanical information derived from fieldwork. We discuss the values assigned to the species used. Microscopic analyses revealed that many of the plant ingredients declared were absent, highlighting the need for greater quality control and safety of these herbal remedies.

  6. The impact of a Bus Rapid Transit system on commuters' exposure to Benzene, CO, PM 2.5 and PM 10 in Mexico City

    Science.gov (United States)

    Wöhrnschimmel, Henry; Zuk, Miriam; Martínez-Villa, Gerardo; Cerón, Julia; Cárdenas, Beatriz; Rojas-Bracho, Leonora; Fernández-Bremauntz, Adrián

    Carbon monoxide (CO), benzene and other volatile organic compounds (VOCs) and suspended particles PM 2.5 and PM 10 were measured inside public transportation vehicles, before and after a new Bus Rapid Transit (BRT) system was implemented in Mexico City in June 2005. The objective was to evaluate the BRT system's impact on commuters' exposure to these air pollutants. The BRT system replaced conventional transport modes along 20 km of Insurgentes Avenue, and features confined corridors and new articulated diesel buses. We assessed the impact of the transportation mode on commuters' exposure using least squares regression models. We also analyzed the chemical composition of VOCs to evaluate the possible origin of these species. The implementation of the BRT system resulted in reductions in commuters' exposure to CO, benzene and PM 2.5 ranging between 20% and 70%. No significant reductions in PM 10 exposure were observed. Lower commuting times further reduced total commuters' exposure. Major sources affecting VOCs inside all transport modes are likely to be related to traffic and to emissions from the use of Liquefied Petroleum Gas. The results suggest that BRT systems could in general be an effective means of reducing human exposure to traffic related air pollutants and associated health impacts.

  7. Characterization of Escherichia coli Isolates from an Urban Lake Receiving Water from a Wastewater Treatment Plant in Mexico City: Fecal Pollution and Antibiotic Resistance.

    Science.gov (United States)

    Rosas, Irma; Salinas, Eva; Martínez, Leticia; Cruz-Córdova, Ariadnna; González-Pedrajo, Bertha; Espinosa, Norma; Amábile-Cuevas, Carlos F

    2015-10-01

    The presence of enteric bacteria in water bodies is a cause of public health concerns, either by directly causing water- and food-borne diseases, or acting as reservoirs for antibiotic resistance determinants. Water is used for crop irrigation; and sediments and aquatic plants are used as fertilizing supplements and soil conditioners. In this work, the bacterial load of several micro-environments of the urban lake of Xochimilco, in Mexico City, was characterized. We found a differential distribution of enteric bacteria between the water column, sediment, and the rhizoplane of aquatic plants, with human fecal bacteria concentrating in the sediment, pointing to the need to assess such bacterial load for each micro-environment, for regulatory agricultural purposes, instead of only the one of the water, as is currently done. Resistance to tetracycline, ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole was common among Escherichia coli isolates, but was also differentially distributed, being again higher in sediment isolates. A distinct distribution of chloramphenicol minimum inhibitory concentrations (MIC) among these isolates suggests the presence of a local selective pressure favoring lower MICs than those of isolates from treated water. Fecal bacteria of human origin, living in water bodies along with their antibiotic resistance genes, could be much more common than typically considered, and pose a higher health risk, if assessments are only made on the water column of such bodies. PMID:26198413

  8. Sustainability and urban environment: the case of the metropolitan zone of Mexico city; Sustentabilidad y medio ambiente urbano: el caso de la zona metropolitana de la ciudad de Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Mar Juarez, Elizabeth; Melgar Paniagua, Eva Margarita; Tavera Sanchez, Lina [Programa de Investigacion en Medio Ambiente y Seguridad, Instituto Mexicano del Petroleo (Mexico)

    2004-06-15

    In the next years, Mexico will face the following challenges: to maintain economic, social and urban rates of growth among others, higher than the demographic ones with the purpose of guaranteeing a better quality of life and mitigating gas discharges of green house effect without jeopardizing the development of the country. In an eminently urban country, these goals are made first in local form as it is the case of the metropolitan zone of the city of Mexico City (ZMCM), with different actions to mitigate the effects of the high development that this region has had. The objective is to try to modify the perception that one has had of it at the beginning of the 90's decade when it was denominated by Time magazine (January 1989) as the waiting room of an ecological Hiroshima and as urban gas chamber. The official answer conformed it: the creation of a Network of Atmospheric Monitoring, the implantation of programs like the Pro Air, the Today Does Not Circulate among others. Even with these actions in mind the objective does not glimpse clearly in the short term to reach a development with environmental sustainability. The work premise is to analyze different actions oriented to diminish in a 20% the emissions of polluting agents using clean and renewable energies such as natural gas and solar, among others, without trying to originate radical changes and that can be applied in other cities of the country. In parallel form one sets out to sustain these actions with the present environmental programs and to quantify the sustainability with three indicators (variation of polluting emissions, the level of fossil resources and costs to the health). The development of the investigation is based on the definition of a reference scenario (on the base of the present tendencies) and another alternative scenario having as analysis tool the computational platform denominated ENPEP (Energy and Power Evaluation Program) developed by National Argonne National Laboratory

  9. Doing Business in Mexico

    OpenAIRE

    World Bank; International Finance Corporation

    2006-01-01

    This report investigates the scope and manner of regulations that enhance business activity and those that constrain it. Quantitative indicators on business regulations and their enforcement have been created for 12 cities and states, which can now be compared with Mexico City, and to 154 countries around the world. The indicators cover four "Doing Business" topics: starting a business, registering property, getting credit and enforcing contracts. The 12 cities and states are: Aguascalientes,...

  10. Experience in the transport and disposal of uranium mill tailings from Aldama City to Sierra Pena Blanca in Chihuahua, Mexico

    International Nuclear Information System (INIS)

    In the process of decontamination, transport and disposal of uranium mill tailings, in the state of Chihuahua, Mexico, was necessary the multidisciplinary and multi institutional task to select mainly the site for the final disposal. The uranium mill tailings content Ra-226 which half live time is 1600 years, therefore the site should be adequately stable, a remote place of population, and which containment will survive for thousand of years. The decontamination of site where the uranium mill tailings were 25 years ago, required the application of norms from regulator organism. For the transport of uranium mill tailings was necessary that the vehicles had devices to reduce the dispersion of material in the road. The selection of the site was product of balance between the cost of transport and the final disposal. To typify the site, studies of hydrology, meteorology, ecology, geology and seismology were performed. On the other hand, the decision to locate the deposit in the site was due to dispersion of material by the rain, wind and bowls. (authors). 3 refs., 1 fig., 1 tab

  11. Mexico City normal weight children exposed to high concentrations of ambient PM2.5 show high blood leptin and endothelin-1, vitamin D deficiency, and food reward hormone dysregulation versus low pollution controls. Relevance for obesity and Alzheimer disease.

    Science.gov (United States)

    Calderón-Garcidueñas, Lilian; Franco-Lira, Maricela; D'Angiulli, Amedeo; Rodríguez-Díaz, Joel; Blaurock-Busch, Eleonore; Busch, Yvette; Chao, Chih-kai; Thompson, Charles; Mukherjee, Partha S; Torres-Jardón, Ricardo; Perry, George

    2015-07-01

    Millions of Mexico, US and across the world children are overweight and obese. Exposure to fossil-fuel combustion sources increases the risk for obesity and diabetes, while long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above US EPA standards is associated with increased risk of Alzheimer's disease (AD). Mexico City Metropolitan Area children are chronically exposed to PM2.5 and O3 concentrations above the standards and exhibit systemic, brain and intrathecal inflammation, cognitive deficits, and Alzheimer disease neuropathology. We investigated adipokines, food reward hormones, endothelial dysfunction, vitamin D and apolipoprotein E (APOE) relationships in 80 healthy, normal weight 11.1±3.2 year olds matched by age, gender, BMI and SES, low (n: 26) versus high (n:54) PM2.5 exposures. Mexico City children had higher leptin and endothelin-1 (pchildren. Mexico City APOE 4 versus 3 children had higher glucose (p=0.009). Serum 25-hydroxyvitamin Dchildren. Leptin is strongly positively associated to PM 2.5 cumulative exposures. Residing in a high PM2.5 and O3 environment is associated with 12h fasting hyperleptinemia, altered appetite-regulating peptides, vitamin D deficiency, and increases in ET-1 in clinically healthy children. These changes could signal the future trajectory of urban children towards the development of insulin resistance, obesity, type II diabetes, premature cardiovascular disease, addiction-like behavior, cognitive impairment and Alzheimer's disease. Increased efforts should be made to decrease pediatric PM2.5 exposures, to deliver health interventions prior to the development of obesity and to identify and mitigate environmental factors influencing obesity and Alzheimer disease. PMID:26037109

  12. Invasive alien species water hyacinth Eichhornia crassipes as abode for macroinvertebrates in hypertrophic Ramsar Site, Lake Xochimilco, Mexico.

    Science.gov (United States)

    Rocha-Ramirez, A; Robles-Valderrama, E; Ramirez-Flores, E

    2014-11-01

    This paper presents information on the density, diversity and functional feeding groups of macroinvertebrate assemblages associated with water hyacinth in Antiguo Canal Cuemanco, part of Lake Xochimilco in Mexico City. Rare (low frequency and density) and dominant (high frequency and density) taxa prevailed in the assemblages, with the most predominant being Hyalella azteca, Chironomus plumosus and Ischnura denticollis. Nonmetric Multidimensional Scaling confirmed two climatic seasons: warm-rainy and cold-dry; the former with the highest diversity and density of taxa. Canonical Correspondence Analysis showed that conductivity, nitrates and turbidity explained the density variations of taxa. Antiguo Canal Cuemanco waters are spatially homogeneous with the characteristics of hypertrophic shallow lakes, inhabited by scrapers and gathering-collectors. The species found were tolerant to organic pollution. PMID:25522508

  13. Canals, River Irrigation Company Canal, Published in 2002, Duchesne County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Canals dataset, was produced all or in part from Other information as of 2002. It is described as 'River Irrigation Company Canal'. Data by this publisher are...

  14. Canals, Yellowstone Feeder Canal, Published in 2002, Duchesne County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Canals dataset, was produced all or in part from Other information as of 2002. It is described as 'Yellowstone Feeder Canal'. Data by this publisher are often...

  15. Canals, Dry Gulch Canal, Published in 2002, Duchesne County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Canals dataset as of 2002. It is described as 'Dry Gulch Canal'. Data by this publisher are often provided in UTM coordinate system; in a Transverse Mercator...

  16. Canals, Lake Canal, Published in 2002, Duchesne County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Canals dataset, was produced all or in part from Other information as of 2002. It is described as 'Lake Canal'. Data by this publisher are often provided in...

  17. Canals, Little Blackhawk Canal, Published in 2002, Duchesne County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Canals dataset, was produced all or in part from Other information as of 2002. It is described as 'Little Blackhawk Canal'. Data by this publisher are often...

  18. In Situ Measurements of Aerosol Mass Concentration and Spectral Absorption at Three Location in and Around Mexico City

    Science.gov (United States)

    Chaudhry, Z.; Martins, V.; Li, Z.

    2006-12-01

    As a result of population growth and increasing industrialization, air pollution in heavily populated urban areas is one of the central environmental problems of the century. As a part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) study, Nuclepore filters were collected in two size ranges (PM10 and PM2.5) at 12 hour intervals at three location in Mexico during March, 2006. Sampling stations were located at the Instituto Mexicano del Petroleo (T0), at the Rancho La Bisnago in the State of Hidalgo (T2) and along the Gulf Coast in Tampico (Tam). Each filter was analyzed for mass concentration, aerosol scattering and absorption efficiencies. Mass concentrations at T0 ranged from 47 to 179 μg/m3 for PM10 with an average concentration of 96 μg/m3, and from 20 to 93 μg/m3 for PM2.5 with an average concentration of 41 μg/m3. Mass concentrations at T2 ranged from 12 to 154 μg/m3 for PM10 with an average concentration of 51 μg/m3, and from 7 to 50 μg/m3 for PM2.5 with an average concentration of 25 μg/m3. Mass concentrations at Tam ranged from 34 to 80 μg/m3 for PM10 with an average concentration of 52 μg/m3, and from 8 to 23 μg/m3 for PM2.5 with an average concentration of 13 μg/m3. While some of the extreme values are likely linked to local emissions, regional air pollution episodes also played important roles. Each of the sampling stations experienced a unique atmospheric condition. The site at T0 was influenced by urban air pollution and dust storms, the site at T2 was significantly less affected by air pollution but more affected by regional dust storms and local dust devils while Tam was influenced by air pollution, dust storms and the natural marine environment. The spectral mass absorption efficiency was measured from 350 to 2500 nm and shows large differences between the absorption properties of soil dust, black carbon, and organic aerosols. The strong spectral differences observed can be related to differences in

  19. Ear canal cholesteatoma.

    Science.gov (United States)

    Holt, J J

    1992-06-01

    Although cholesteatomas are more commonly found in the middle ear and the mastoid, the disease can occur in the external ear canal. All cases of ear canal cholesteatoma treated by the author were reviewed. There were nine ears in seven patients, who had an average age of 62 years. The lesions ranged in size from a few millimeters to extensive mastoid destruction. Smaller lesions can be managed by frequent cleaning as an office procedure. Larger lesions require surgery, either canaloplasty or mastoidectomy. The otolaryngologist should suspect this disease in the elderly. Microscopic examination of the ear with meticulous cleaning of all wax, especially in elderly patients, is most useful in detecting early disease. Frequent applications of mineral oil to the canal should be used in the management of the disease and to prevent recurrence. PMID:1376388

  20. Multistate nested canalizing functions

    CERN Document Server

    Adeyeye, J O; Laubenbacher, R; Li, Y

    2013-01-01

    The concept of a nested canalizing Boolean function has been studied over the course of the last decade in the context of understanding the regulatory logic of molecular interaction networks, such as gene regulatory networks. Such functions appear preferentially in published models of such networks. Recently, this concept has been generalized to include multi-state functions, and a recursive formula has been derived for their number, as a function of the number of variables. This paper carries out a detailed analysis of the class of nested canalizing functions over an arbitrary finite field. Furthermore, the paper generalizes the concept further, and derives a closed formula for the number of such generalized functions. The paper also derives a closed formula for the number of equivalence classes under permutation of variables. This is motivated by the fact that two nested canalizing functions that differ by a permutation of the variables share many important properties with each other. The paper contributes ...

  1. Spinal canal stenosis

    International Nuclear Information System (INIS)

    Spinal stenosis is a narrowing of the spinal canal by a combination of bone and soft tissues, which can lead to mechanical compression of spinal nerve roots or the dural sac. The lumbal spinal compression of these nerve roots can be symptomatic, resulting in weakness, reflex alterations, gait disturbances, bowel or bladder dysfunction, motor and sensory changes, radicular pain or atypical leg pain and neurogenic claudication. The anatomical presence of spinal canal stenosis is confirmed radiologically with computerized tomography, myelography or magnetic resonance imaging and play a decisive role in optimal patient-oriented therapy decision-making. (orig.)

  2. syndrome du canal carpien

    OpenAIRE

    boukraa, kheira; merniz, nacera

    2012-01-01

    Le canal carpien est la principale cause des acroparesthésies de la main. I La forme habituelle est la forme sensitive pure primitive de la femme en période I post ménopausique. Le traitement médical suffit le plus souvent. La constatation et l'installation de signes déficitaires neurologiques sont une indication à un traitement chirurgical. Le syndrome du canal carpien peut être un mode de début d'une polyarthrite u rhumatoïde.

  3. Prevalencia de violencia doméstica en la ciudad de Durango Prevalence of domestic violence in the city of Durango, Mexico

    Directory of Open Access Journals (Sweden)

    Gloria Alvarado-Zaldívar

    1998-11-01

    Full Text Available Objetivo. Caracterizar y determinar, desde un enfoque de género, la prevalencia de los diferentes tipos de violencia que se presentan en la ciudad de Durango, Dgo., México. Material y métodos. Con un diseño transversal se entrevistaron 384 mujeres casadas, o bien, unidas al momento del estudio o alguna vez, residentes de la ciudad de Durango. El tamaño de la muestra se distribuyó en forma proporcional en seis sectores de la ciudad, seleccionados al azar y representativos de los niveles socioeconómicos alto, medio y bajo. En cada sector se realizaron 64 entrevistas. El instrumento de medición fue un cuestionario con 184 preguntas cerradas y 22 abiertas, que incluía datos de identificación, sociodemográficos y reproductivos, así como reactivos específicos para la violencia física, emocional y sexual. Resultados. La mediana de edad del grupo estudiado fue de 41.5 años, con un rango de 12 a 48 años. La prevalencia de violencia doméstica fue: alguna forma de violencia sexual, 42%; física, 40%, y emocional, 39%. Conclusiones. Se reconoce que el problema de la violencia, en sus diferentes formas, es un hecho altamente prevalente que pone en peligro el bienestar del núcleo familiar. Se observó una mayor prevalencia de violencia doméstica en presencia de factores tales como: antecedente de violencia, alcoholismo y/o consumo de drogas en algún miembro de la familia.Objective. To characterize and determine the prevalence of the different types of gender-associated violence in the city of Durango, Mexico. Material and methods. With a transversal design, 384 women residents of the city of Durango, either living with or having lived with someone before, were interviewed. The sample was proportionately distributed in 6 city sectors which were randomly chosen and representative of the high middle and low socioeconomic levels. Sixty-four interviews were conducted in each city sector. The questionnaire consisted of 184 closed and 22 open

  4. Evaluation of the Volatility Basis-Set Approach for Modeling Primary and Secondary Organic Aerosol in the Mexico City Metropolitan Area

    Science.gov (United States)

    Tsimpidi, A. P.; Karydis, V. A.; Pandis, S. N.; Zavala, M.; Lei, W.; Molina, L. T.

    2007-12-01

    Anthropogenic air pollution is an increasingly serious problem for public health, agriculture, and global climate. Organic material (OM) contributes ~ 20-50% to the total fine aerosol mass at continental mid-latitudes. Although OM accounts for a large fraction of PM2.5 concentration worldwide, the contributions of primary and secondary organic aerosol have been difficult to quantify. In this study, new primary and secondary organic aerosol modules were added to PMCAMx, a three dimensional chemical transport model (Gaydos et al., 2007), for use with the SAPRC99 chemistry mechanism (Carter, 2000; ENVIRON, 2006) based on recent smog chamber studies (Robinson et al., 2007). The new modeling framework is based on the volatility basis-set approach (Lane et al., 2007): both primary and secondary organic components are assumed to be semivolatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. The emission inventory, which uses as starting point the MCMA 2004 official inventory (CAM, 2006), is modified and the primary organic aerosol (POA) emissions are distributed by volatility based on dilution experiments (Robinson et al., 2007). Sensitivity tests where POA is considered as nonvolatile and POA and SOA as chemically reactive are also described. In all cases PMCAMx is applied in the Mexico City Metropolitan Area during March 2006. The modeling domain covers a 180x180x6 km region in the MCMA with 3x3 km grid resolution. The model predictions are compared with Aerodyne's Aerosol Mass Spectrometry (AMS) observations from the MILAGRO Campaign. References Robinson, A. L.; Donahue, N. M.; Shrivastava, M. K.; Weitkamp, E. A.; Sage, A. M.; Grieshop, A. P.; Lane, T. E.; Pandis, S. N.; Pierce, J. R., 2007. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 315, 1259-1262. Gaydos, T. M.; Pinder, R. W.; Koo, B.; Fahey, K. M.; Pandis, S. N., 2007. Development and application of a three- dimensional aerosol

  5. The evolutionary genetics of canalization.

    Science.gov (United States)

    Flatt, Thomas

    2005-09-01

    Evolutionary genetics has recently made enormous progress in understanding how genetic variation maps into phenotypic variation. However why some traits are phenotypically invariant despite apparent genetic and environmental changes has remained a major puzzle. In the 1940s, Conrad Hal Waddington coined the concept and term "canalization" to describe the robustness of phenotypes to perturbation; a similar concept was proposed by Waddington's contemporary Ivan Ivanovich Schmalhausen. This paper reviews what has been learned about canalization since Waddington. Canalization implies that a genotype's phenotype remains relatively invariant when individuals of a particular genotype are exposed to different environments (environmental canalization) or when individuals of the same single- or multilocus genotype differ in their genetic background (genetic canalization). Consequently, genetic canalization can be viewed as a particular kind of epistasis, and environmental canalization and phenotypic plasticity are two aspects of the same phenomenon. Canalization results in the accumulation of phenotypically cryptic genetic variation, which can be released after a "decanalizing" event. Thus, canalized genotypes maintain a cryptic potential for expressing particular phenotypes, which are only uncovered under particular decanalizing environmental or genetic conditions. Selection may then act on this newly released genetic variation. The accumulation of cryptic genetic variation by canalization may therefore increase evolvability at the population level by leading to phenotypic diversification under decanalizing conditions. On the other hand, under canalizing conditions, a major part of the segregating genetic variation may remain phenotypically cryptic; canalization may therefore, at least temporarily, constrain phenotypic evolution. Mechanistically, canalization can be understood in terms of transmission patterns, such as epista