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- La BVA es una colección de recursos educativos que tratan sobre temas ambientales que conciernen al estado de Chihuahua, México. Este repositorio temático está intencionado para beneficio de la sociedad y sin fines de lucro, con el objetivo de facilitar el acceso al conocimiento ambiental sobre la zona.
Recent Submissions
Acción pública local: una alternativa para dotar de agua potable a las colonias de la periferia de Ciudad Juárez, Chihuahua
(Estudios demograficos y urbanos, 2018-04-20) Córdova Borjórquez, Gustavo
Cave and cliff swallows as indicators of exposure and effects of environmental contaminants on birds from the Rio Grande, Texas
(OAKTrust, 2004-11-15) Musquiz, Daniel
Cave (Petrochelidon fulva) and cliff swallows (Petrochelidon pyrrhonota) were collected along the Rio Grande and evaluated as potential indicators of environmental contamination. The Rio Grande receives toxic substances from agricultural, industrial, municipal, and non-point sources; consequently, high levels of contaminants have been detected in birds, mammals, fishes and sediments. Swallows were obtained from 8 sites between Brownsville and El Paso, as well as from a reference site in Burleson County, 320 miles north of the nearest site of the Rio Grande. Blood samples were analyzed by flow cytometry, a technique that allows the detection of DNA damage in blood and other tissues. Plasma samples were analyzed for thyroid hormones using a radioimmunoassay technique. Organochlorines and trace metal analysis was limited to a few samples. DDE and PCB levels were below levels known to cause reduced hatching, embryo mortality, and deformities, Hg, Pb, and As were below detection, and Se, Ni and Cr concentrations were lower than levels known to cause harm in birds. Neither species showed sex-related differences in chromosome damage. Cave swallows from the Del Rio area had the highest levels of DNA variation, which may be indicative of DNA damage, possibly from PAHs exposure. Previous studies indicate that sediment samples from tributaries near Del Rio have high levels of chromium compared to other sites along the Rio Grande. A significant increase in DNA variation between sampling years was detected in cave swallows from Llano Grande Lake. Wildlife samples collected from Llano Grande Lake have recorded high levels of DDE and PCBs; in addition, this urban/agricultural contaminant sink appears to be affected by PAH exposure. T3 levels were below the detection limit of the radioimmunoassay. There were no gender related differences in T4 levels in cave swallows. Cave swallows sampled from Laredo had significantly higher T4 levels than those from birds at other sites during 1999. It was not possible to determine thyroid hormone disruption in plasma samples. Thyroid hormone and flow cytometry data were useful in establishing baseline data. Areas of concern based on genotoxic data include Llano Grande Lake, Del Rio, and El Paso.
Los cursos de agua compartidos entre México y los Estados Unidos de América y la variable medioambiental. Una aproximación
(Revistas jurídicas UNAM, 2006-01-01) Anglés Hernández, Marisol
This paper examines U.S.-Mexico relations regarding border waters. In the semi-arid border region from Mexico-U.S. the tensions about the use of water, its pollution, and its equitable distribution have increased. Even though there are many obstacles, the cooperation on management of shared resources and jointly addressing transboundary environmental problems has gotten strengthen gradually. The author shows some of the successes and failures of the ambitious border policy initiatives and treaties about the border and emphasizes that Mexico and the U.S. face a great challenge, certainly, it is necessary to consider climatic change to may define planning strategies for water management, and its equitable distribution; urban development, and improvement of the environment in the border area.
Microbial contamination and chemical toxicity of the Rio Grande
(BMC Microbiology, 2004-04-22) Mendoza, Jose; Botsford, James; Hernandez, Jose; Montoya, Anna; Saenz, Roswitha; Valles, Adrian; Vazquez, Alejandro; Alvarez, María
Background
The Rio Grande River is the natural boundary between U.S. and Mexico from El Paso, TX to Brownsville, TX. and is one of the major water resources of the area. Agriculture, farming, maquiladora industry, domestic activities, as well as differences in disposal regulations and enforcement increase the contamination potential of water supplies along the border region. Therefore, continuous and accurate assessment of the quality of water supplies is of paramount importance. The objectives of this study were to monitor water quality of the Rio Grande and to determine if any correlations exist between fecal coliforms, E. coli, chemical toxicity as determined by Botsford's assay, H. pylori presence, and environmental parameters. Seven sites along a 112-Km segment of the Rio Grande from Sunland Park, NM to Fort Hancock, TX were sampled on a monthly basis between January 2000 and December 2002.
Results
The results showed great variability in the number of fecal coliforms, and E. coli on a month-to-month basis. Fecal coliforms ranged between 0–106 CFU/100 ml while E. coli ranged between 6 to > 2419 MPN. H. pylori showed positive detection for all the sites at different times. Toxicity ranged between 0 to 94% of inhibition capacity (IC). Since values above 50% are considered to be toxic, most of the sites displayed significant chemical toxicity at different times of the year. No significant correlations were observed between microbial indicators and chemical toxicity.
Conclusion
The results of the present study indicate that the 112-Km segment of the Rio Grande river from Sunland Park, NM to Fort Hancock, TX exceeds the standards for contact recreation water on a continuous basis. In addition, the presence of chemical toxicity in most sites along the 112-Km segment indicates that water quality is an area of concern for the bi-national region. The presence of H. pylori adds to the potential health hazards of the Rio Grande. Since no significant correlation was observed between the presence of H. pylori antigens and the two indicators of fecal contamination, we can conclude that fecal indicators cannot be used to detect the presence of H. pylori reliably in surface water.
La competencia espacial por el aseguramiento hídrico México-Estados Unidos: el caso de los Sistemas Acuíferos Transfronterizos en la región Paso del Norte
(Revista Académica Del CISAN-UNAM, 2017-12-11) Hatch Kuri, G.
Mexico and the United States have a historic relationship in the political distribution of their transbor-der water. Nevertheless, with the deepening and importance of the North American Free Trade Agree-ment (nafta), transborder aquifer systems emerge as strategic reservoirs in the process of building water security on the border shared by the two nations. This article examines the case of Paso del Norte and the details of the competition for access and appropriation of transborder groundwater in recent decades based on asymmetrical institutional processes and mechanisms that have led to local political tensions. It also analyzes the implications and challenges Mexico must take on regarding the legal and institutional vacuums regulating these systems and reflects on the importance of designing a sovereign, interdependent water policy to foster cooperation for equitable distribution of transborder groundwater.