A critical need to control thallium contamination in aquatic ecosystem for the age of low carbon

Thallium (Tl) is a typical toxic metals whose contamination in aquatic ecosystems may increase in the coming decades and become a critical environmental concern. However, our understanding towards the transfer-transformation-mitigation pathways and related mechanism of Tl stemming from different pollution sources remains inadequate, potentially hindering effective pollution prevention, management, and monitoring strategies in the face of escalating Tl contamination in aquatic environments. This review seeks to offer a thorough analysis of the primary sources of Tl pollution, and clarify its environmental impacts in water bodies. To date, apart from the well-known sources of Tl pollution (i.e. industrial activities involving Tl-bearing sulfide minerals, including pyrite, sphalerite, galena, and carlin-type gold deposits), large quantities of Tl pollutants may stem from the extraction and industrial activities of other Tl-enriched critical metallic minerals (e.g. Li, and rare earth element) as the global shift towards clean and renewable energy sources. Relevant studies have demonstrated that elevated levels of Tl in aquatic environments exert profound detrimental effects on benthic and ichthyofauna in aquatic ecosystem. These impacts may lead to a series of alterations at the physiological, biochemical, and genomic expression levels. Notably, there is no consolidated Tl concentration limits for wastewater discharge globally regardless of relatively consistent drinking water standards. Such disruptions can, in turn, compromise the survival and demographic structure of these organisms, ultimately jeopardizing human beings through complex trophic networks. Given the urgency of this situation, there is a pressing need for establishing function-dependent water quality benchmarks with regards to various Tl-containing or polluted aquatic environments, thus to curb the growing thallium contamination for the age of low carbon.