Finally, in water samples taken at the site, observed toxicity could be
explained by the concentration of contaminants measured. Thus, great
differences were found between the TIs calculated for A1 and A2 and
the rest of the samples (see Table 9). Samples A1 and A2 had the highest
toxicity indices, especially for Zn and Cu, with EC50 values between 0.6
and 2.2 to daphnia and algae. Samples A3, A5 and A9were the least toxic
to daphnia, corresponding with the low TIs measured in these samples.
Sample A9's TI for algae was lower than 1 and it did not show toxicity
towards this organism. By contrast, TI for daphnia was 1.6 and 100% of
immobilization was observed. The correlation between TIs and element
concentrations was stronger in aqueous samples than in soil samples
or leachates, which would indicate that the influence of intrinsic properties
of the medium on contaminant availability is lower in aqueous
samples than in soil samples as known.