Ecological toxicity (ECx) of Pb and its prediction models in Chinese soils withdifferent physiochemical properties

The lack of toxicological data becomes the main bottleneck of ecological risk assessment of lead (Pb) in Chinese soils.The present study assessed Pb toxicity on three underground test endpoints (barley root elongation, earthworm avoid-anceresponse, and substrate-induced respiration (SIR) of microorganism)in 10 different soils. Hormetic dose-responseinduced by Pb was>118 % for earthworm avoidance response. EC10and EC50(the effective concentrations of Pb thatinhibit 10 % or 50 % of endpoint bioactivity and also represents the toxicity threshold of Pb) after leaching increasedby 0.32-8.73 times, and 1.02-3.75 times, respectively. Leaching factor (LF) prediction models indicated pH and cationexchange capacity (CEC) were the vital predictors for LF10and LF50, explaining 60.6 % and 73.1 % of variations, re-spectively. SIR was one sensitive test endpoint for Pb toxicity, with the lowest of EC10and EC50values (from 373.7to 1008.5 mgmiddotkg-1, and from 837.1 to 2869.0 mgmiddotkg-1, respectively). The best prediction models between ECxandsoil properties is LogEC50= 1.324Log(pH) + 0.423Log(CEC) + 1.742 (R2=0.761,p<0.01). The results displayedsignificant implications for deriving ECxof Pb, and provided a scientific basis for soil ecological risk assessment of Pb.

Automated summary

This study assessed the toxicity of lead in different soils and established prediction models. The results have significant implications for deriving the toxicity threshold of lead and soil ecological risk assessment.