Copper toxicity in a natural reference soil: ecotoxicological data for the derivation of preliminary soil screening values

The risk assessment of contaminated soils is conventionally done with the support of soil screening values (SSVs). Since SSVs are still unavailable for many European countries, including Portugal, standardized toxicity tests are urgently claimed for their derivation. Hence, this work aimed the generation of toxicity values for copper (Cu) in a natural reference soil (PTRS1) targeting different terrestrial species, endpoints and soil functions, as to derive a preliminary Cu SSV. For this, the Assessment Factor approach was applied, which allowed calculating predicted no effect concentrations (PNEC) for Cu that will be the basis for SSV proposal. In order to increase the reliability of the PNEC, and hence of the SSV, a lab/field factor was applied to correct the toxicity values used for PNEC determination. Cu affected urease, cellulase and nitrogen mineralization activities. The EC50 values calculated for the invertebrates reproduction were 130.9, 165.1 and 191.6 mg Cu Kg−1soildw for Eisenia andrei, Enchytraeus crypticus and Folsomia candida, respectively. Cu inhibited seed germination mainly for Lactuca sativa, whilst it was toxic for the growth of different plant species (EC50s between 89 and 290.5 mg Cu Kg−1soildw). Based on the outcomes gathered, we proposed SSVs for Cu ranging between 26.3 and 31.8 mg Kg−1 soildw, which is above the background values reported and below all the EC20s recorded for the species and endpoints herein analyzed. Overall, this work describes a procedure that could be easily followed by other European countries wishing to derive SSVs adjusted to their soils.