Biological Isotopy of Lithium in Littoral Zones

Lithium (Li) is key in the energy transition and massively used to produce mobile devices and electrical vehicles.

Yet its current consumption rate exceeds its river flux to the ocean, and it is poorly recycled, while Li excess is toxic for aquatic life and humans.

Although concentrations of Li and its isotopes have been measured in coastal waters, at river outlets, to study continental chemical weathering and climate controls, Li monitoring has been occasional.

Moreover, bias caused by anthropogenic inputs is not quantified.Combining a novel isotopic methodology with ecotoxicology and biology approaches, SeaLi2Bio will first determine and understand the littoral Li contamination sources, flux and controls, and quantify its current contribution to the Li cycle.

Plankton, macroalgae and bivalves will act as long-term bioindicators at reference sites located along urbanisation gradients.

The biological controls of Li isotopes will be determined by aquaculture of model organisms, over a range of representative environmental and metabolic conditions, and confronted to in situ measurements.

Upscaling from regional to global scale will be achieved with a multivariate statistical model accounting for geospatial data on watershed characteristics, population density and socioeconomic parameters.This project will also anticipate future environmental and health issues caused by Li contamination, focusing on the North Chile coast where Li levels are known as the highest, and using innovative health-monitoring tools (Cu-Zn isotopes).

Finally, the evolution of Li contamination will be simulated at the continental and global scale, following scenarios of energy transition impacting differently Li demand and waste.By disentangling the factors of Li contamination from the natural background, SeaLi2Bio will assemble a first robust reference for a global issue tied to the history of climate and its future evolution in response to reduction of fossil fuels use.