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Derivation of ecological risk threshold (the threshold concentration value that protect a certain proportion of species within the acceptable hazard level) of lead (Pb) is a yardstick and plays a key role in formulating soil protection policies, while the research about deducing soil Pb ecological risk threshold is still limited. In this study, toxicological data of Pb based on 30 different test endpoints was collected from our experiment and literature, and applied into interspecific extrapolation by species sensitivity distribution (SSD) method to derive the hazard concentration for 5% of species (HC 5 , that can protect 95% of species), the prediction models according to different soil properties were established. The results showed that EC 10 (the effective concentrations of Pb that inhibit 10% of endpoint bioactivity) ranged from 205.6 to 1596.3 mg kg 1, and hormesis induced by Pb were up to 118%. Toxicity data were corrected by leaching and aging process before SSD curves fitting. HC 5 was then derived and prediction model was developed, as LogHC 5 = 0.134 pH + 0.315 LogOC + 0.324 LogCEC + 1.077. The prediction model was well verified in the field test, indicating that can correctly estimate Pb ecotoxicity thresholds in different soils. This study provides a scientific frame for deriving the ecological risk threshold of Pb and is of great significance for ecological species protection. [Display omitted] • Prediction model established can correctly predict soil Pb ecotoxicity. • EC 10 of Pb derived from dose-response curves ranged from 205.6 to 1596.3 mg∙kg 1. • Exogenous Pb induced hormetic dose-response relationship and the maximum stimulation was more than 118%. • Toxicity threshold of Pb was corrected by leaching and aging process. [ABSTRACT FROM AUTHOR]

Currently, the scientific basis for establishing soil environmental criteria is lacking. In order to establish reasonable soil environmental criteria values suitable for soils with different properties, this study selected soils from 16 different sites to determine the toxicity threshold of Zn based on toxicity tests of barley root elongation. In addition, leaching treatments were set up in seven soils with different properties to eliminate the influence of the accompanying anions (Cl-) on the determination of the Zn toxicity threshold. The results indicated that the toxicity thresholds of different soils vary greatly. The EC 10 and EC 50 ranges of barley root elongation in 16 kinds of non-leached soils were 18.5 mg kg−1 to 1618.7 mg kg−1 and 277.9 mg kg−1 to 3179.8 mg kg−1, respectively. The hormesis effect appeared in the dose response of Zn, and relative barley root elongation reached more than 150%. Leaching significantly reduced the Zn toxicity in acidic soils. The variation ranges of the leaching factor (LF) in the seven soils were LF 10 = 1.1–9.3, LF 50 = 1.0–3.2. The LF prediction model indicated that pH explained 81.4% of the LF variation (p < 0.01). The soil pH, cation exchange capacity (CEC), and conductivity (EC) explained 97.8% of the EC 50 variation in the leached soil (p < 0.01). The results provide reference values for Zn environmental criteria. • Zn toxicity thresholds for barley root elongation in soils with different properties vary greatly. • Hormesis appeared in the dose-response of Zn for barley root elongation. • The effect of leaching is more obvious in acidic soil and the soil pH explained 81.4% of the LF variation (p < 0.01). • The soil pH, CEC, and EC explained 97.8% of the EC 50 variation in leached soil (p < 0.01). [ABSTRACT FROM AUTHOR]