Algal bioaccumulation and toxicity of platinum are increased in the presence of humic acids.

Hourtané, Océane; Rioux, Geneviève; Campbell, Peter G. C.; Fortin, Claude ORCID: https://orcid.org/0000-0002-2479-1869 et Wilkinson, Kevin J. (2022). Algal bioaccumulation and toxicity of platinum are increased in the presence of humic acids. Environmental Chemistry , vol. 19 , nº 4. pp. 144-155. DOI: 10.1071/EN22037.

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Résumé

Rationale: There is a growing interest for platinum in ecotoxicology, mainly because of its use in automobile exhaust catalysts. When it reaches aquatic ecosystems, platinum can interact with ligands such as natural organic matter. According to the Biotic Ligand Model, the formation of such complexes should reduce metal bioavailability. As a consequence, toxicity should decrease in the presence of organic matter. Methodology: This study focused on the uptake of platinum by two microalgae species (Chlorella fusca and Chlamydomonas reinhardtii) and its subsequent inhibitory effects on growth (96 h). Cells were exposed to platinum (5 to 300 µg L⁻¹) at three concentrations (0, 10 and 20 mg C L⁻¹) of standard Suwannee River Humic Acid. Platinum bound to humic acid was determined experimentally using partial ultrafiltration to relate metal uptake and toxicity to speciation. Results: Unexpectedly, results show that platinum toxicity, expressed as ultrafiltrable Pt (not bound to humic acid) and total Pt concentrations, is enhanced in the presence of humic acid for both algae. For C. fusca, the EC₅₀ values decreased from 93 to 37 and 35 µg L⁻¹ of ultrafiltrable Pt in the presence of respectively 0, 10 and 20 mg C L⁻¹ and from 89 to 36 and 0.31 µg L⁻¹ for C. reinhardtii. Discussion: In contradiction with the Biotic Ligand Model, the results show that the presence of SRHA can significantly and importantly increase platinum uptake and toxicity as determined in two unicellular green algae, C. reinhardtii and C. fusca. The present work raises the issue of the impact of platinum on microalgae under realistic environmental conditions (ubiquitous presence of organic matter), primary producers being of great ecological importance.

Type de document:	Article
Mots-clés libres:	bioavailability; biotic ligand model; effects; green algae; growth inhibition; metal; natural organic matter; uptake
Centre:	Centre Eau Terre Environnement
Date de dépôt:	17 mai 2023 14:40
Dernière modification:	17 mai 2023 14:40
URI:	https://espace.inrs.ca/id/eprint/13300

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