Fig. 2. Comparison of Ca(NO3)2–extractable Zn in Blackwell contaminated soils, with and without amendments, and lethal Ca(NO3)2–extractable Zn in artificial soil toxicity test (from Conder and Lanno, 2000). The dark line represents the Ca(NO3)2–extractable Zn based, time-independent LC50 (incipient lethal level, ILL) calculated from the artificial soil Zn toxicity test conducted with the earthworm Eisenia fetida; symbols indicate lethal soil–amendment combinations or artificial soils.