Work

Free Gd3+ concentration drives the accumulation of Gd and its subsequent toxicity to the green alga Chlamydomonas reinhardtii

Year: 2026

Type: article

Abstract: The use of gadolinium (Gd)-based contrast agents for medical imaging analyses has led to extensive enrichment of Gd in aquatic systems, which is often quantified as positive Gd anomalies. This study aims to evaluate the bioavailability and toxicity of Gd3+ and 2 Gd-based contrast agents (Gd dihydrogen salt hydrate [Gd-DTPA] and gadobutrol monohydrate [Gd-BT-DO3A]) on the green alga Chlamydomonas reinhardtii in the presence and absence of dissolved organic matter (DOM). Growth inhibition tests were performed over 72 hr at pH 6. The chemical equilibrium software Visual MINTEQ was used to calculate the speciation of Gd in exposure media and verify the applicability of the biotic ligand model. Limited bioaccumulation of Gd was detected when algae were exposed to Gd-DTPA or Gd-BT-DO3A, both in the presence and absence of DOM. As for inorganic Gd, the presence of DOM decreased Gd toxicity. The 72 hr-EC50 values based on the total concentration of Gd were estimated at 3.7 [2.9-4.7] µM of Gd for the exposure to Gd without DOM and 6.6 [5.9-7.5] µM of Gd in the exposure with DOM. Internalized Gd by cells and estimated free ion concentrations were strongly linked to toxicity, which confirms the applicability of the biotic ligand model. Moreover, the 72 hr-EC50 estimations based on free Gd3+ ion concentrations were statistically indistinguishable at the 95% confidence level for the exposure conditions with and without DOM: 1.0 [0.6-2.0] µM and 2.1 [1.4-3.1] µM, respectively. These results highlight the central role of chemical speciation determination in assessing the ecotoxicity of metals and that the free Gd ion drives its toxicity to the green alga C. reinhardtii.

Source: Environmental Toxicology and Chemistry

DOI: 10.1093/etojnl/vgag107

Authors: Aissatou Y Sow, Duc Huy Dang, Claude Fortin

Institutions: Institut National de la Recherche Scientifique, Trent University

Language: English

Topic: Environmental Toxicology and Ecotoxicology

Subfield: Health, Toxicology and Mutagenesis

Field: Environmental Science

Domain: Physical Sciences

SDG: Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $3,500