Influencia del ph sobre el efecto tóxico inducido en clones de Dictyosphaerium Chlorelloides sensibles y resistentes a Cromo (VI)

Résumé

This paper explains the relationship between the environmental variations of pH and Chromium (VI) concentration, by their effect on populations of Dictyosphaerium chlorelloides, eukaryotic cosmopolitan microalgae of fresh water ecosystems. Two strains of D. chlorelloides were cultured in BG11 culture medium, being one of them sensitive to Cr (VI) and the other one resistant up to concentrations of 25 μg/ml, at pH values between 2.5 and 11 in order to determine their viability. When the pH range was determined (3-7.5), toxicity assays were done to obtain the minimum value of pH in which the microalgal populations did not vary significantly. The analysis of Cr (VI) exposure demonstrated a NOEC fitted to the pH value of 4.25. The IC50(72) values obtained at pH 7.5 and 4.25 showed significant statistic variations between both pH values, and there were not significant differences related to community growth in the sensitive strain, unlike the resistant one.