不同pH值条件下镍对大麦的急性毒性

Effect of pH on nickel acute toxicity to barley(Hordeum vulgare)

采用水培实验,研究不同pH值条件下镍对大麦的急性毒性.结果表明,当溶液pH值从4.5增加到8.3,以Ni2+活度表示的大麦根伸长的半抑制浓度[EC50(Ni2+)]降低了86%.基于生物配体模型理论方程的线性分析表明,pH值改变引起的EC50(Ni2+)的变化不完全是H+竞争的作用.在形态分析的基础上,采用剂量效应方程对数据进行了拟合,同时考虑了Ni2+和NiCO3毒性以及H+竞争后,显著提高了方程的拟合程度,预测和实测大麦根伸长也具有较好的相关性(R2=0.95).因此,pH值的改变导致H+与生物配体(大麦根)结合的Ni2+竞争,并引起Ni2+向NiCO3形态的转化.

The effect of pH on the acute toxicity of nickel to barley root elongation was investigated in solution culture. The effective concentrations,which reduced root elongation by 50%,based on free Ni^2＋ activity（EC50（Ni^2＋）） reduced about 10 times when pH was from 4.5 to 8.3. Based on biotic ligand model theory,the nonlinear relationship between EC50（Ni^2＋） and H^＋ activity in this study indicated that the increased toxicity with increasing pH was not only due to decreasing H^＋ competition. The logistic dose-response curve showed that considering the H＋ competition and NiCO3 plus Ni^2＋ as the dose improved the data fit significantly（R^2=0.95） than only the free Ni^2＋ activity was considered. Thus,the effects of pH on nickel acute toxicity to barley need to consider H^＋ competition for biotic ligand（barley root） and NiCO3 transformed from free Ni^2＋.