title: Ni uptake by a green alga. 1. Validation of equilibrium models for complexation effects.
abstract: Short-term (< 60 min) internalization fluxes (J(int)) by the green alga Chlamydomonas reinhardtii were measured in the presence of a variety of ligands forming hydrophilic (citric, diglycolic, or nitrilotriacetic acids), amphiphilic (Suwannee River fulvic and humic acids), and hydrophobic (oxine, diethyldithiocarbamate) Ni complexes. Free nickel concentrations, ranging from 10(-10) to 10(-3) M, were evaluated by thermodynamic modeling and by a resin exchange technique. Ni internalization appeared to occur via a single transport site that was characterized by a conditional stability constant (pH 6.0, I = 10(-2) M) of 10(5.1) M(-1). In the presence of humic substances, Ni uptake could be quantitatively predicted on the basis of Ni2+ concentrations for two algae: C. reinhardtii and Chlorella kesslerii. In the presence of the hydrophobic ligands, an increase in permeability was observed due to the formation of neutral, lipophilic complexes.
authors.affiliation: CABE (Analytical and Biophysical Environmental Chemistry), University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva 4, Switzerland.
authors.forename: Isabelle A M
authors.initials: IA
authors.lastname: Worms
authors.forename: Nalini
authors.initials: N
authors.lastname: Parthasarathy
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Wilkinson
mesh_terms: D000327:Adsorption; D000818:Animals; D001578:Benzopyrans / Q000737:chemistry; D001692:Biological Transport; D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D004050:Ditiocarb / Q000737:chemistry; D006812:Humic Substances; D006912:Hydroxyquinolines / Q000737:chemistry; D007700:Kinetics; D008024:Ligands; D008954:Models, Biological; D009532:Nickel / Q000737:chemistry / Q000378:metabolism*; D010539:Permeability; D013816:Thermodynamics
chemical_list: D001578:Benzopyrans; D006812:Humic Substances; D006912:Hydroxyquinolines; D008024:Ligands; D009532:Nickel; D004050:Ditiocarb; C005023:fulvic acid