In phytoremediation, plants are used to restore balance in an environment damaged by natural or man-made events. A subgroup of the broad phytoremediation category is rhizofiltration, which uses plants' root systems to filter toxic substances and excess nutrients in the soil via the movement of water in the soil and the ingestion of water by the plants. [1
9659005] Among the various plants for rhizofiltration, sunflowers have proven to be particularly effective in this task. They grow fast and are very tall. Their size and mass require a strong and broad root system. In addition, sunflowers have proven to be particularly efficient in absorbing heavy metals and radioactive isotopes into their biomass. By planting thousands of sunflowers in places with radioactive disasters (such as Chernobyl and Fukushima) radioactive material can be extracted from the ground without much excavation. The resulting sunflower plants are then treated as radioactive waste and treated as the soil (but much more efficiently).
This is also, and not by chance, the reason why the sunflower is the international symbol of nuclear disarmament.