Toxicity assessment of green energy by-product, lithium, using a novel suite of eight Australian aquatic-species tests from a Global Biodiversity Hotspot

Abstract Due to recent advances in green energy initiatives in response to climate change impacts, lithium exploration and production are rapidly increasing, with concomitant elevated lithium in discharges to waterways. However, lithium toxicity to aquatic species is not well understood, particularly in relation to sublethal effects. As such, lithium has become an element of interest for environmental regulators, particularly in Western Australia, currently the largest producer of lithium globally. This study provides the first published assessment of lithium toxicity using locally-relevant freshwater species from southwest Australia—a Global Biodiversity Hotspot and location of the world’s largest lithium mine. Here, chronic toxicity of lithium was assessed using a novel suite of eight temperate southwest Australian aquatic-species tests undertaken in moderately hard water reflective of the region. Sensitivity to lithium based on no (significant) effect concentration (N(S)EC), from most to least sensitive was: cladoceran, Ceriodaphnia dubia cladoceran, Simocephalus exspinosus green alga, Chlamydomonas oviformis, green alga, Scenedesmus sp. green alga, Tetradesmus obliquus hydroid, Hydra viridissima green alga, Chlorella sp. pulmonate snail, Glyptophysa georgiana. Environmentally relevant concentrations resulted in toxicity in all species. Reproduction was affected in snail and cladoceran species, while population growth and cell yield were inhibited in hydroid and algal species respectively. Both N(S)ECs and median effect concentrations (EC50s) ranged from 862–2,830 µg/L and 1,120–5,760 µg/L respectively (0.45 µm filtered). Southwest Australian species were in some cases more sensitive to lithium than their international and interstate counterparts, highlighting the necessity for appropriate species test selection for this bioregion. This dataset is available to inform environmental risk assessment and future aquatic guideline value derivation through species-sensitivity-distributions.