Contrasting effects of chloride on the toxicity of silver to two green algae, Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii.
Short-term silver toxicity was determined for two freshwater algae, Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii, in the presence and absence of chloride. Silver speciation in the exposure media was controlled and algal growth was measured over 6 h. For P. subcapitata, an alga with low Ag uptake fluxes, silver toxicity could be predicted on the basis of the free Ag+ concentration, in the presence or absence of significant complexation by chloride ions, as predicted by the biotic ligand model (BLM). For C. reinhardtii, an alga with high Ag uptake fluxes, silver toxicity was better predicted by the concentration of all labile dissolved Ag species than by free silver, a result that is consistent with diffusion through the unstirred layer surrounding the cell surface being the rate-limiting step in silver uptake. For both species, growth inhibition could be predicted on the basis of the Ag intracellular quota in the presence or absence of chloride, indicating that silver toxicity is a direct result of intracellular accumulation rather than cell surface interactions.
Lee
Dae-Young
DY
INRS-Eau, Terre et Environnement, Université du Québec, Institut National de la Recherche Scientifique, 490 de la Couronne, Quebec City, Que., Canada G1K 9A9.
Fortin
Claude
C
Campbell
Peter G C
PG
D002712:Chlorides / Q000378:metabolism*; D000460:Chlorophyta / Q000187:drug effects* / Q000254:growth & development; D020128:Inhibitory Concentration 50; D016015:Logistic Models; D012834:Silver / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity*; D013997:Time Factors
D002712:Chlorides; D012834:Silver