Resumen

SANDOVAL VILLASANA, Ana María et al. Physicochemical, microbiological and toxicological evaluation of the environmental degradation of the atoyac river, Mexico. INCI [online]. 2009, vol.34, n.12, pp.880-887. ISSN 0378-1844.

A high degree of deterioration has been registered in the Atoyac river, Mexico, since 1995, due to local residences and industrial development. The aim of this study was to evaluate current environmental conditions at nine stations during the drought season along 85km of the river and to establish the relationship between current legislation parameters and toxicity and mutagenicity tests. Environmental quality was quantified using field observations (color, odor, temperature, CE, pH, and DO), physicochemical (SST, SDT, SSe, DBO₅, DQO, GyA, N_total, N_org, P_total, P_org and orthophosphates), heavy metals (As, Cd, Cu, Cr, Cr⁺⁶, Hg, Ni, Pb, Zn, Al, Fe y Mn), microbiological (fecal coliforms) by comparison with the maximum permissible level (MPL) NOM-001-ECOL-1996 and CE-CCA-001/89, and toxicity (Vibrio fischeri, Daphnia magna) and mutagenicity (Salmonella/microsome, or Ames test) analysis. Values for DO, DBO₅ and DQO were 2-6, 11-270 and 22-1841mg·l^-1, respectively. Concentrations of heavy metals were below the MPL except at stations 5 (0.002mg·l^-1 Hg) and 8 (0.13mg·l^-1 Cr⁺⁶). Fecal coliform bacteria were above the MPL at all stations. Values for Vibrio fischeri, Daphnia magna and the Ames test were 2-28 UT, 1-4 UT and 5-63 RM, respectively, which indicated toxicity and mutagenicity from stations 3 to 9. The high level of contamination in this zone indicates that it is necessary to evaluate adherence to approved standards and to modify the existing regulations in order to include additional contamination parameters.

Palabras clave : Calidad del Agua; Metales Pesados; Río Atoyac; Toxicidad.