Abstract
Water quality of Mexican tropical lake Chapala was assessed through multivariate statistical techniques, cluster analysis (CA) and principal component analysis (PCA) at ten different monitoring sites for ten physicochemical variables and six metals. This study evaluated and interpreted complex water quality data sets and apportioned of pollution sources to get better information about water quality. From descriptive statistics results, the highest concentrations of metals occurred during the dry season, and this trend was explained by the fact that an unusual rainy event occurred during the month of February 2009 and brought metals into the lake by runoffs from nearby mountains. According to international criteria for water consumption by aquatic organisms [USEPA], only Zn concentration values were below these criteria whereas the values of Ni, Pb, Cd and Fe were above the corresponding values set in these criteria (Ni: 52 μg·L-1, Pb: 2.5 μg·L-1, Cd: 0.25 μg·L-1, and Fe: 1000 μg·L-1). The correlations were observed by PCA, which were used to classify the samples by CA, based on the PCA scores. Seven significant cluster groups of sampling locations—(sites 4 and 5), (sites 3 and 9), (site 7), (site 10), (sites 2 and 6), (site 8) and (site 1)— were detected on the basis of similarity of their water quality. The results revealed that the stress exerted on the lake caused by waste sources follows the order: domestic > agricultural > industrial.
Highlights
The pollution of water sources such as lakes and rivers is a problem of global concern in large part because many of these water bodies are used as water supply sources for human consumption [1]
Alkalinity values were highest at sites S2A and S7A (318 and 340 mg∙L−1, respectively). These values can be attributed to the fact that bicarbonate ion entering the lake is dissociated to carbon dioxide which in turn is consumed by algae for their synthesis needs [28]
This site is located at the entrance of the Lerma River which in turn is the main contributor of suspended particles into Lake Chapala
Summary
The pollution of water sources such as lakes and rivers is a problem of global concern in large part because many of these water bodies are used as water supply sources for human consumption [1] This is because the uncontrolled human settlements have an impact on the water quality of these water bodies due to the lack of infrastructure (e.g. water treatment plants) that permits the appropriate treatment of domestic, municipal or industrial wastes (especially in the underdeveloped countries). Monitoring programs that provide representative and reliable information of the data are not implemented due to both spatial and temporal variations in water quality [10] This is due in part to the large amount of data generated from the measured physicochemical variables, which in turn makes difficult to interpret and to draw meaningful conclusions. The use of these techniques can help in the reliable management of water resources and provide a fast solution when facing pollution problems, especially those of water bodies used for human consumption [11] [12]
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