Size- and composition-dependent toxicity of synthetic and soil-derived Fe oxide colloids for the nematode Caenorhabditis elegans

Sebastian Höss, Andreas Fritzsche, Carolin Meyer, Julian Bosch, Rainer U. Meckenstock, Kai Uwe Totsche

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Colloidal iron oxides (FeOx) are increasingly released to the environment due to their use in environmental remediation and biomedical applications, potentially harming living organisms. Size and composition could affect the bioavailability and toxicity of such colloids. Therefore, we investigated the toxicity of selected FeOx with variable aggregate size and variably composed FeOx-associated organic matter (OM) toward the nematode Caenorhabditis elegans. Ferrihydrite colloids containing citrate were taken up by C. elegans with the food and accumulated inside their body. The toxicity of ferrihydrite, goethite, and akaganeite was dependent on aggregate size and specific surface area, with EC50 values for reproduction ranging from 4 to 29 mg Fe L-1. Experiments with mutant strains lacking mitochondrial superoxide dismutase (sod-2) showed oxidative stress for two FeOx and Fe3+-ions, however, revealed that it was not the predominant mechanism of toxicity. The OM composition determined the toxicity of mixed OM-FeOx phases on C. elegans. FeOx associated with humic acids or citrate were less toxic than OM-free FeOx. In contrast, soilderived ferrihydrite, containing proteins and polysaccharides from mobile OM, was even more toxic than OM-free Fh of similar aggregate size. Consequently, the careful choice of the type of FeOx and the type of associated OM may help in reducing the ecological risks if actively applied to the subsurface.

Original languageEnglish
Pages (from-to)544-552
Number of pages9
JournalEnvironmental Science and Technology
Volume49
Issue number1
DOIs
StatePublished - 6 Jan 2015
Externally publishedYes

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