A Water Quality Index (WQI) is a useful statistical tool for simplifying, reporting and interpreting complex information obtained from any body of water. A simple number given by any WQI model explains the level of water contamination. The objective was to develop a WQI for the water of the Luis L. Leon dam located in the state of Chihuahua, Mexico. Monthly water samples were obtained in 2009; January 10, February 12, March 8, May 20, June 10, July 9, August 12, September 10, October 11, November 15 and December 13. Ten sampling sites were randomly selected after dividing the study area using a geographic package. In each site, two samples at the top depth of 0.20 m and 1.0 m were obtained to quantify physical-chemical parameters. The following 11 parameters were considered to calculate the WQI; pH, Electrical Conductivity (EC), Dissolved Oxygen (DO), color, turbidity, ammonia nitrogen, fluorides, chlorides, sulfates, Total Solids (TS) and phosphorous (P). The data analysis involved two steps; a single analysis for each parameter and the WQI calculation. The resulted WQI value classified the water quality according to the following ranges: <2.3 poor water; from 2.3 to 2.8 good water; and >2.8 excellent water. The results showed that the WQI values changed from low levels (WQI < 2.3) in some points during autumn time to high levels (WQI > 2.8) most of the year and the variation was due to time of sampling generally rainy season.
Lago de Colina (Colina Lake) is located about 180 km south of the city of Chihuahua (Mexico), and during the Semana Santa (Holy Week) vacation period its recreational use is high. The objective of this study was to quantify coliform and heavy metal levels in this water body before and after the Holy Week vacation period in 2010. Twenty sampling points were randomly selected and two water samples were collected at each point near the surface (0.30 m) and at 1 m depth. After the Holy Week vacation the same twenty points were sampled at the same depths. Therefore, a total 80 water samples were analyzed for fecal and total coliforms and levels of the following metals: Al, As, B, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Se, Si and Zn. It was hypothesized that domestic tourism contaminated this water body, and as a consequence, could have a negative impact on visitor health. An analysis of variance (ANOVA) study was performed for each element and its interactions considering a factorial design where factor A was sample date and factor B was sample depth. Fecal coliforms were only detected at eight sampling points in the first week, but after Holy Week, both fecal and total coliforms were detected at most sampling points. The concentrations of Al, B, Na, Ni and Se were only statistically different for factor A. The levels of Cr, Cu, K and Mg was different for both date and depth, but the dual factor interaction was not significant. The amount of Ca and Zn was statistically different due to date, depth and their interaction. No significant differences were found for any factor or the interaction for the elements As, Fe and Mn. Because of the consistent results, it is concluded that local tourism is contaminating the recreational area of Colina Lake, Chihuahua, Mexico.
Recreational water use provides important benefits for human health; nevertheless, there can be adverse effects if the water is polluted. Aim of this work was to develop a Recreational Water Quality Index (RWQI) for Colina Lake in Mexico. Water samples were collected from March 2011 to February 2012 at seven random locations and at three depths (0.30 m, 1.0 m and 2.0 m). Parameters analyzed were pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), temperature (T), turbidity, total hardness (TH) chlorides (Cl-) and total (TC) and fecal coliforms (FC). Statistical analyses were made considering a 12↔3 factorial arrangement design while the RWQI was calculated for the 0.30 m depth. In general, results for parameters did not differ according to sampling depth or the interaction, but there were statistical differences according to sampling month. The RWQI indicates that water quality is generally adequate for recreational purposes.
There is a general belief that high levels of arsenic are found in waters of the northern states of Mexico. In order to test this hypothesis, research was conducted with the objective of determining arsenic levels in waters of the San Pedro River located in the state of Chihuahua, Mexico. From October 2005 to August 2006 on a monthly basis, water samples were collected at five points along the San Pedro River. Three repetitions were collected at each point resulting in a total of 165 water samples. Total arsenic concentration was L -1 detected in an Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-POE) model 2100 by Perkin Elmer. The arsenic concentrations in waters of the San Pedro River ranged from 0.0110 mg L -1 to 0.587 mg L -1 with a mean of 0.104 mg L -1 ± 0.234 mg. Most samples were over the maximum permissible value established as Mexican and international standards. A quadratic projection was observed between the basic points through the fifth point; these results might be influenced by the decrease of flow and the decrease of the drainage level. These results confirm the hypothesis that waters in northern Mexico contain high levels of arsenic that potentially might be harmful to the whole ecosystem and being potentially dangerous to human development and health.
La creciente demanda de productos y satisfactores de origen maderable requiere de información actuali- zada respecto a la condición y posibles cambios en uso del suelo y vegetación. Las imágenes del satélite LANDSAT TM representan una herramienta importan- te para generar mapas que identifiquen y detallen la extensión del disturbio de las áreas asociadas con la actividad forestal. El objetivo fue cuantificar el grado de deforestación en la región centro-norte de la Sierra Madre Occidental en Chihuahua, México. Dos fueron los objetivos específicos: el primero fue examinar las relaciones de datos espectrales del sensor LANDSAT- TM5 y TM7 para detectar cambios en la masa fores- tal; el segundo fue identificar los cambios de cubierta forestal a través de un análisis de componentes prin- cipales. A partir de una composición de imágenes se generó otra imagen clasificada por el método no su- pervisado con los mismos tipos de cubierta para am- bos períodos. Además se realizó un análisis de com- ponentes principales para detectar cambios espacia- les y temporales. La comparación de imágenes clasi- ficadas representó una buena opción para identificar cambios en la cobertura forestal. De 88,842 ha repor- tadas por el Inventario Nacional Forestal como áreas deforestadas, 35.2 % (31,275 has.) fue sobreestimado comparado con los resultados de este estudio. Las tasas de deforestación anual fluctuaron entre 1.9% en Basogachi y 2.7 % en San Juanito. Los mapas gene- rados mostraron la presencia de grandes superficies deforestadas con cambios drásticos que ocurrieron en un tiempo relativamente corto.
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