Migration Behavior of 90Sr in the Soil–Plant System and Phytoremediation: A Review

90Sr is a representative anthropogenic radionuclide, widely released into the environment through atmospheric nuclear tests, nuclear accidents, and routine operations of nuclear facilities, resulting in long-term residual contamination in soils worldwide. Its long half-life, high mobility, and chemical similarity to calcium make it easy to enter the food chain through the soil–plant system, thereby posing a persistent threat to ecosystems and human health. Conventional physical and chemical remediation approaches are often costly, ecologically disruptive, and inefficient for large-scale applications, highlighting an urgent need for sustainable, in situ strategies. Moreover, existing knowledge on 90Sr behavior has largely been generated from isolated studies, lacking an integrated framework to guide remediation efforts. This review summarizes the migration mechanisms of 90Sr in the soil–plant system and the main factors influencing its transport and accumulation. In soil, the migration of 90Sr is jointly controlled by soil texture and mineral composition, competing cations, organic matter, soil pH, and moisture, with cation exchange acting as the main immobilization mechanism. Plant uptake and accumulation of 90Sr show distinct inter- and intra-species differences, and the distribution generally follows the pattern of vegetative organs > reproductive organs. This process is regulated by root activity, transpiration, and competition with Ca2+ transport channels. Agronomic practices such as liming, deep plowing, and balanced fertilization can effectively reduce the phytoavailability of 90Sr by promoting ion competition and modifying the rhizosphere environment. Meanwhile, phytoremediation offers a promising green approach for the remediation of contaminated soils. Overall, this review provides a theoretical basis and scientific reference for the risk management and bioremediation of 90Sr in soil–plant systems.