title: Influence of calcium, magnesium, sodium, potassium and pH on copper toxicity to barley (Hordeum vulgare).
abstract: The extent to which Ca(2+), Mg(2+), Na(+), K(+) ions and pH independently influence copper toxicity to barley (Hordeum vulgare) was assessed by measuring root growth in nutrient solutions. Increased Ca(2+) activity resulted in a sixfold decrease in [EC50(cu2+)] values, while a positive relationship between the cation activity and the EC50 was expected. Increased Mg(2+) activity resulted in a twofold increase in [EC50(cu2+)] values. Na(+), K(+) and H(+) activities did not significantly affect Cu(2+) toxicity. The obtained results indicated that competition for binding sites between Cu(2+) and cations such as Ca(2+), Mg(2+), Na(+), K(+) and H(+) is not an important factor in determining Cu(2+) toxicity to H. vulgare. However, the EC50s could, with one exception, be predicted within a factor three based on the free Cu(2+) activity, indicating that the free Cu(2+) activity cannot only be used to predict metal toxicity to aquatic, but also to terrestrial organisms.
authors.affiliation: Laboratory of Environmental Toxicology and Aquatic Ecology, Ghent University, J. Plateaustraat 22, 9000 Ghent, Belgium. Koen_Lock@hotmail.com
authors.forename: K
authors.initials: K
authors.lastname: Lock
authors.forename: P
authors.initials: P
authors.lastname: Criel
authors.forename: K A C
authors.initials: KA
authors.lastname: De Schamphelaere
authors.forename: H
authors.initials: H
authors.lastname: Van Eeckhout
authors.forename: C R
authors.initials: CR
authors.lastname: Janssen
mesh_terms: D001667:Binding, Competitive; D002122:Calcium Chloride / Q000378:metabolism*; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D001467:Hordeum / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008278:Magnesium Sulfate / Q000378:metabolism*; D008954:Models, Biological; D018517:Plant Roots / Q000187:drug effects; D011189:Potassium Chloride / Q000378:metabolism*; D015203:Reproducibility of Results; D018570:Risk Assessment; D012965:Sodium Chloride / Q000378:metabolism*; D012989:Soil Pollutants / Q000378:metabolism / Q000633:toxicity*
chemical_list: D008024:Ligands; D012989:Soil Pollutants; D012965:Sodium Chloride; D011189:Potassium Chloride; D008278:Magnesium Sulfate; D003300:Copper; D002122:Calcium Chloride; C029892:cupric chloride