²¹⁰Po in fresh water: Sources, environmental fate, global distribution and analytical challenges

Polonium-210 (²¹⁰Po) is a naturally occurring alpha-emitter whose complex chemistry in freshwater governs its mobility, persistence, and potential for bioaccumulation. Alongside natural backgrounds, anthropogenic activities, including fossil fuel combustion, mining, and future nuclear technologies-represent growing sources of ²¹⁰Po to aquatic environments. Despite increasing attention from public-health and radiation-safety communities, its environmental behavior and associated risks remain incompletely characterized. This review integrates interdisciplinary knowledge to provide a comprehensive perspective on ²¹⁰Po sources, environmental fate, global distribution, and analytical challenges in fresh water systems. We present complex environmental behavior of ²¹⁰Po, where physicochemical conditions (pH, redox, organic matter) govern its speciation, mobility, and bioavailability, leading to significant bioaccumulation and biomagnification across aquatic food webs. Furthermore, our analysis, presenting the first global open-source database of ²¹⁰Po in freshwater, reveals a distribution with widespread low background levels contrasting sporadic, highly elevated local hotspots by orders of magnitude. This spatial heterogeneity underscores substantial differences in potential human exposure across regions and demographic groups. While the performance comparison of existing analytical method shows their limited suitability for different monitoring scenarios due to the concerns of spatiotemporal representativeness, methodological consistencies and preparation convenience. These limitations restrict reliable long-term risk assessment and delay early contamination detection. This review highlights the urgent need for strengthening analytical capabilities and developing coordinated international monitoring strategies to ensure environmental preparedness and effective protection of water resources and public health.