The demand for rare earth elements, which are used in the manufacture of many electronic devices, is growing all the time. Yet little is known about the risks posed to the environment by their extraction and end-of-life.
Claude Fortin, a professor at the Eau Terre Environnement Centre of the Institut national de la recherche scientifique (INRS) and co-director of Ecotoq, a strategic cluster funded by the FRQNT, was interested in gaining a better understanding of the impact of rare earth elements, which are found everywhere in nature, on two species of freshwater algae. These small single-celled organisms play an essential role in the food chain, CO2 sequestration and oxygen production.
With colleagues from UQAM and the Université de Montréal, Professor Fortin decided to test the bioavailability of two rare earth elements, i.e., their capacity to be assimilated by algae, thereby causing toxicity. For their study they focused on cerium and lanthanum, two of the most abundant rare earth elements.
The scientists set out to verify whether these elements “trick” algae into absorbing them via the same mechanisms as for essential minerals. They first looked at iron, an element that has the same charge as rare earths. They hypothesised that the addition of iron would have an impact on the uptake of rare earth elements by the algae, but this did not prove to be the case.
Like true detectives, the researchers continued their work by elimination and concluded that aluminium did not share a common pathway with rare earth elements either. They also found that the composition and pH of the water affected the bioavailability of cerium and lanthanum.
This work, which is ongoing, will eventually help to shed light on the mechanisms by which rare earth elements are absorbed by these small organisms, and thus inform Environment and Climate Change Canada and the Québec Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs, which are responsible for environmental regulation and for setting toxicity thresholds.