Plutonium in plants: uptake, transport within the plant, radiation effects. Review

Plutonium is an artificial radionuclide that poses a significant environmental hazard due to its high radiotoxicity and long half-life (24,100 years for 239Pu). Plutonium released into the environment mainly as a result of man-made activities, including nuclear tests, accidents (Chernobyl, Fukushima) and emissions from nuclear fuel cycle enterprises. The review systematizes data on the behavior of plutonium in the soil-plant system, including the mechanisms of uptake, transport and biological effects. The main factor determining the mobility of plutonium is its oxidation state (III-VI), which affects its solubility and complexation. The bioavailability of plutonium is significantly affected by soil characteristics: soil type, pH, organic matter and mineral content. The role of chelates, which form complex, stable compounds with metal ions that can increase the plutonium uptake by plants, is of particular interest. Plutonium transfer factors vary over an extremely wide range, which reflects the difficulty of predicting the amount of its uptake by plants. The mechanisms of intracellular transport of plutonium remain poorly understood. A hypothesis is put forward about the possible competition of plutonium with iron for the plant transport systems. Radiobiological effects in plants are caused by the combined action of plutonium, namely its chemical toxicity and alpha-radiation. This is expressed in the form of the occurrence of chromosomal aberrations, micronuclei and other cytogenetic disorders. Modern research methods, including genetic, cytogenetic, cytological studies and autoradiography of ultra-thin sections, are needed to gain a deeper understanding of the processes of plutonium absorption and transport inside the plant, as well as the radiation effects caused by plutonium. This will make it possible to clarify the mechanisms of the plutonium radiobiological effects at the cellular level and develop more accurate models of its behavior in the soil-plant system.