3.4. Toxicity evaluation
Table 3 shows the results of GI and EC50 measured in the extracts
of soil treated with the three different amendments. For CES
treatment, GI based on Lepidium sativum germination showed that
the initial soil toxicity was partially overcome (GI>50%). This effect
suggests the presence of toxic soluble elements in very low concentrations
(Pardo et al., 2011). In addition, the high toxicity of
untreated soil towards V. fischeri was effectively suppressed with
CES, regardless of the application rate. These results confirm the
reduction of the environmental risk prompted by CES (Table 1 e
Supplementary data) in terms of Pb and Zn mobility. The ES
treatment yielded similar results to CES with respect to soil toxicity.
Concerning the CWES treatment, the V. fischeri inhibition was
gradually reduced from CWES_T1 to CWES_T3, but only the higher
application rate (T3) was non-toxic to 50% of the bacteria population.
This smaller capacity of CWES to inhibit soil ecotoxicity may
be associated with its low ability to reduce the mobile fractions of
the metals, as pointed out in Fig. 2a and discussed previously in
Section 3.3.1.