摘要

The effects of selected cations and pH on the acute toxicity of copper (Cu) to barley root elongation were investigated to develop an appropriate biotic ligand model (BLM). The results showed that increasing activities of Mg2+ and Ca2+, but not Na+ and K+, linearly increased the EC50 (as Cu2+ activity). Unchanged EC50 at solution pH less than 6.5 and sharply decreased EC50 with increasing of solution pH when greater than 6.5 can be explained by toxicity of the CuHCO3,+ CuCO3(aq) and CuOH+ complexes. Conditional binding constants were obtained for the binding of Cu2+, CuHCO3+, CuCO3(aq), CuOH+, Mg2+ and Ca2+ with biotic ligand: log K-CuBL 6.33, log K-CuHCO3BL 5.71, log K-CuCO3BL 5.70, log K-CuOHBL 6.39, log K-MgBL 2.92 and log K-CaBL 1.96. Using the estimated constants, a BLM was successfully developed to predict Cu toxicity to barley root elongation as a function of solution characteristics.