Cross-species Extrapolation of Phytotoxicity Prediction Models for Nickel and Copper Added to Soil
土壤中铜和镍的植物毒性预测模型的种间外推验证

During the process of deriving ecological thresholds for metals added to soils based on SSD (species sensitivity distribution) principles, normalization of the ecotoxicity data with metal toxicity prediction models can eliminate the effect of soil property discrepancy. However, the available toxicity prediction models were based on limited species. Applicability of copper and nickel phytotoxicity prediction models of bok choy, tomato and barley to other non-model higher plants was studied and the intra-species variability of the non-model plants' toxicity thresholds before and after normalization was compared in this study. The probability of cross-species extrapolation of phytotoxicity prediction models for nickel and copper added to soil was probed, and the application boundary of the cross-species extrapolation was confirmed. The methodological issues for the development of copper and nickel ecological thresholds in soil were solved. Results showed that the bok choy nickel phytotoxicity model could be used to predict the toxicity thresholds for mustard and green chilli. After normalization the intra-species variability coefficients of their toxicity threshold decreased from 1.18 and 1.25 to 0.31 and 0.06, respectively. However, the nickel phytotoxicity models of bok choy, tomato and barley could not predict the toxicity thresholds for steam lettuce or leaf lettuce accurately in the soil with pH<6.0. The ratio of measured toxicity threshold to the toxicity threshold calculated with nickel phytotoxicity models ranged from 3.2 to 6.8. The bok choy copper phytotoxicity prediction model could predict the toxicity thresholds for wheat, cucumber and green chilli more accurately than the tomato and barley models. The intra-species variability coefficient of cucumber toxicity threshold decreased from 0.83 to 0.14 after normalization with tomato copper phytotoxicity prediction model. The barley copper phoyotoxicity model could be used to predict and normalize the toxicity thresholds for rice, onion, mustard, cabbage and radish which intra-species variability coefficients decreased significantly after normalization. All the results in this study provide quantitative evidence to support cross-species extrapolation of copper and nickel phytotoxicity prediction models in soils.