title: A biotic ligand model predicting acute copper toxicity for barley (Hordeum vulgare): influence of calcium, magnesium, sodium, potassium and pH.
abstract: 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 Mg(2+) and Ca(2+), but not Na(+) and K(+), linearly increased the EC50 (as Cu(2+) 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 CuHCO(3)(+), CuCO(3)(aq) and CuOH(+) complexes. Conditional binding constants were obtained for the binding of Cu(2+), CuHCO(3)(+), CuCO(3)(aq), CuOH(+), Mg(2+) and Ca(2+) with biotic ligand: logK(CuBL) 6.33, logK(CuHCO(3)BL) 5.71, logK(CuCO(3)BL) 5.70, logK(CuOHBL) 6.39, logK(MgBL) 2.92 and logK(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.
authors.affiliation: College of Resource Environment and Tourism, Capital Normal University, 105 North Road of Xisanhuan, Beijing 100048, China.
authors.forename: Xuedong
authors.initials: X
authors.lastname: Wang
authors.forename: Luo
authors.initials: L
authors.lastname: Hua
authors.forename: Yibing
authors.initials: Y
authors.lastname: Ma
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003300:Copper / Q000633:toxicity*; D001467:Hordeum / Q000187:drug effects* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008274:Magnesium / Q000737:chemistry*; D008962:Models, Theoretical; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*
chemical_list: D002412:Cations; D008024:Ligands; D003300:Copper; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium