Some plant species that live naturally on soils that are rich in heavy metals have evolved biochemical mechanisms for extracting those metals from the soil and accumulating them to very high levels in their tissues. They are called hyperaccumulators. Some of them accumulate so much metal that it makes up 5% of their weight. This makes them toxic to insects and probably evolved as a defence mechanism. Plants have been found that hyperaccumulate copper, nickel, lead, cadmium, chromium, zinc, cobalt, mercury and selenium, so they are being planted on toxic waste sites where they remove the toxic metals from the soil. They can be burned in order to recover the metal in cases (copper and nickel) where the metal is valuable. With less valuable metals such as lead, the hyperaccumulating plants are much easier to dispose of than contaminated soil.
Tamarix is a unique tree species in that it lives up to 100 years in both waterlogged and saline soils, making it an ideal species to reverse environmental degradation. Under natural conditions, Tamarix disperses seeds through floodwater during the rain months. This natural method can be employed to regenerate the species in large areas by controlling and directing water flow from floods. Tamarix is a natural resource on which communities can depend for fuelwood, tools, and basket making. Planting Tamarix can be included in strategies to re-establish groundwater recharge, rejuvenate soil conditions, reduce waterlogging effects and salinization, and restore Tamarix populations.
Genetically modified bacteria are being tested for bioremdiation.