RESUMO
Lake Cajititlán is a shallow body of water located in an endorheic basin in western Mexico. This lake receives excess fertilizer runoff from agriculture and approximately 2.3 Hm3 per year of poorly treated wastewater from three municipal treatment plants. Thirteen water quality parameters were monitored at five sampling points within the lake over 9 years. The objective of this work was to characterize the spatial and temporal variations of the water quality and to identify the sources of data variability in order to assess the influence and the impact of different natural and anthropogenic processes. One-way ANOVA tests, principal component analysis (PCA), cluster analysis (CA), and discriminant analysis (DA) were implemented. The one-way ANOVA showed that biochemical oxygen demand and pH present statistically significant spatial variations and that alkalinity, total chloride, conductivity, chemical oxygen demand, total hardness, ammonia, pH, total dissolved solids, and temperature present statistically significant temporal variations. PCA results explained both natural and anthropogenic processes and their relationship with water quality data. The CA results suggested there is no significant spatial variation in the water quality of the lake because of lake mixing caused by wind. The most significant parameters for spatial variations were pH, NO3-, and NO2-, consistent with the configuration of point and nonpoint sources that affect the lake's water quality. The temporal DA results suggested that conductivity, hardness, NO2-, pH, and temperature were the most significant parameters to discriminate between seasons. The temporal behavior of these parameters was associated with the transport pathways of seasonal contaminants.
Assuntos
Monitoramento Ambiental , Lagos/química , Análise Multivariada , Qualidade da Água , Análise por Conglomerados , Análise Discriminante , Monitoramento Ambiental/métodos , México , Análise de Componente Principal , Estações do Ano , Poluentes Químicos da Água/análiseRESUMO
BACKGROUND: The importance of water to life is unquestionable. Most of the fresh water we use for daily activities comes from the aquifers, which in many cases due to misuse are overexploited and at risk. This article studies the aquifer that appeared in Laguna de Santiaguillo basin; it should be noted that the most important economic activity in the basin is agriculture. METHODS: By analyzing vector and demographic information, using GIS and with some field trips, the impact and risk on the level of disposition in every micro-basin that forms the basin were determined. RESULTS: The different modeling scenarios demonstrate that the basin and sub-basins that conform Santiaguillo are overexploited. DISCUSSION: The volumes concessioned are of such magnitude that they generate a condition of vulnerability to the activities of the basin and sustain the overexploitation conditions of the aquifer.
RESUMO
Lake Cajititlán is a shallow water body located in an endorheic basin in western Mexico at 1551 m a.s.l. The surface area is 1744 ha, maximum storage volume achieved is 70.89 Hm3, and maximum depth is 5.4 m at its maximum capacity. The lake has experienced significant changes in its level because of drought conditions in recent years. Because the lake has shallow features and is settled in a closed basin with rapid population growth, the lake water has suffered severe anthropogenic contamination causing damages in its intrinsic esthetic, social, environmental, and economic values.