Resumo

GUZMAN-COLIS, G et al. Evaluation of pollutants in water and sediments of the San Pedro river in the state of Aguascalientes. Universidad y ciencia [online]. 2011, vol.27, n.1, pp.17-32. ISSN 0186-2979.

The San Pedro river is the main surface water body in the state of Aguascalientes. It crosses the state from north to south, covering a distance along a straight line of approximately 90 km until it meets the Santiago river in the state of Jalisco. In order to determine the level of pollution in the river and the probable infiltration of pollutants to the aquifer of the valley of Aguascalientes, water and sediment samples were collected from 50 sites along the river. Samples were also taken from 17 wells located near the river (less than 300 m). Two sampling campaigns were carried out, one during the dry season and the other after the rainy season. The pH, dissolved oxygen, BOD₅, COD, total-P, total-N, phenols, anilines, detergents (MBAS), fecal coliforms and heavy metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Pb and Zn) were determined. The water of the San Pedro river presented high concentrations of organic matter, total-P, total-N, detergents and fecal coliforms. Some sites showed a moderate Al and Fe pollution. According to the United States Environmental Protection Agency criteria, all the sediment samples were polluted by As, 50% by Pb and Zn, 25% by Cu, and approximately 13% by Mn and Cr. Three sediment samples presented a moderate pollution by Fe, and another three by Hg. The results obtained for the wells did not show conclusive evidence of pollution of the aquifer by the surface water.

Palavras-chave : Water pollution; heavy metals; sediments; river; aquifer.

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