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Lanthanum and cerium toxicity to the freshwater green alga Chlorella fusca : applicability of the biotic ligand model.

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Aharchaou, Imad; Beaubien, Cédrick; Campbell, Peter G. C.; Fortin, Claude (2020). Lanthanum and cerium toxicity to the freshwater green alga Chlorella fusca : applicability of the biotic ligand model. Environmental Toxicology and Chemistry . DOI: 10.1002/etc.4707.

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Résumé

The environmental risk assessment of rare earth elements (REE) requires data on their potential toxicity. In this study, the toxicity of lanthanum (La) and cerium (Ce) was studied in relation to metal speciation in solution. For both La and Ce, the use of organic ligands demonstrated that the calculated free ion concentration was a good indicator of toxicity. Whether in the absence or presence of organic ligands, when based on free ion concentrations, the obtained half maximal effective concentrations were similar. When all generated data were pooled, Ce and La showed identical toxicity thresholds after 120 h of exposure with free ion concentration‐based EC₅₀ values [95% confidence intervals] of 0.48 [0.38 – 0.60] µM and 0.47 [0.36 – 0.61] µM for La³⁺ and Ce³⁺, respectively. The inhibition of algal growth was also correlated with the intracellular lanthanide concentrations, regardless of the ligand used. Finally, increasing the ambient calcium concentration protected the test algae by reducing the amount of lanthanide internalized into the cells. These results suggest that, at constant pH (5.5), REE accumulation and toxicity are linked to the free‐ion concentration and ambient Ca concentration, as predicted by the biotic ligand model (BLM).

Type de document: Article
Mots-clés libres: rare earth elements; lanthanides; metal speciation; algae; growth inhibition; metal uptake
Centre: Centre Eau Terre Environnement
Date de dépôt: 17 avr. 2020 18:08
Dernière modification: 17 avr. 2020 18:08
URI: http://espace.inrs.ca/id/eprint/10096

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