title: Development of a biotic ligand model (BLM) predicting nickel toxicity to barley (Hordeum vulgare).
abstract: A biotic ligand model (BLM) was developed to predict nickel toxicity, affecting root growth of barley (Hordeum vulgare), in nutrient solutions. The extent to which Ca(2+), Mg(2+), Na(+), K(+) ions and pH each influenced nickel toxicity was determined. Higher activities of Mg(2+) linearly increased the 4d EC50 Ni (2+) , while Ca(2+), Na(+), K(+) and H(+) activities did not significantly influence Ni(2+) toxicity. Stability constants for the binding of Ni(2+) and Mg(2+) to the biotic ligand were obtained: logK(NiBL)=5.27 and logK(MgBL)=3.47. Further, it was calculated that on average 57% of the biotic ligand sites needed to be occupied by nickel to induce 50% root growth inhibition. Auto-validation of the BLM indicated that predicted EC50s differed from the observed EC50s by a factor of less than 2, indicating that the BLM concept may also be used to predict metal toxicity to terrestrial plants.
authors.affiliation: Ghent University, Laboratory of Environmental Toxicology and Aquatic Ecology, J. Plateaustraat 22, 9000 Gent, Belgium. Koen_Lock@hotmail.com
authors.forename: Koen
authors.initials: K
authors.lastname: Lock
authors.forename: Hilde
authors.initials: H
authors.lastname: Van Eeckhout
authors.forename: Karel A C
authors.initials: KA
authors.lastname: De Schamphelaere
authors.forename: Peggy
authors.initials: P
authors.lastname: Criel
authors.forename: Colin R
authors.initials: CR
authors.lastname: Janssen
mesh_terms: D001467:Hordeum / Q000187:drug effects* / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008954:Models, Biological; D009532:Nickel / Q000633:toxicity*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D018570:Risk Assessment; D012987:Soil / Q000032:analysis / Q000592:standards; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D008024:Ligands; D012987:Soil; D012989:Soil Pollutants; D009532:Nickel