Comparative ecotoxicity of three polluted industrial soils for the Collembola Folsomia candida

We tried to quantify the ecotoxicity of three industrial soil samples contaminated by different metals, using the Collembolan Folsomia candida as a biological model and mortality, growth and reproduction as parameters. The observed ecotoxicities are rather normal for the first such soil sample (aluminum factory) but are high for the second sample (ore treatment) and relatively low for the third one (zinc factory) considering its high metal concentrations. For these last two soil samples, an unusual ecotoxicity plotting is observed: two high ecotoxicity recordings fit with a low and high percentage of polluted soil to non-polluted soil and noticeably lower ecotoxicity recordings are observed between them. Chemical analyses of metals in pore waters show that arsenic probably explains part of such an unusual ecotoxicity curve. Otherwise, mortality and growth of the animals are less sensitive parameters than reproduction. Our experiments show that the results of the ecotoxicological assays of polluted soils are complex and difficult to interpret.