Phytoremediation is a form of environmental cleanup which involves the use of plants and fungi. While phytoremediation can be slow and it does have some problems, it does carry some distinct advantages, and scientists are constantly refining it in the hopes of creating more solutions to the global issue of pollution. You may have seen some examples of phytoremediation in your community, ranging from the planting of fast-growing groundcover to prevent topsoil loss to the use of genetically engineered plants to pull heavy metals out of the group.
The concept of phytoremediation is actually fairly old, although people only realized the potential implications in the late 20th century. Farmers have been rotating crops for centuries in a form of phytoremediation, preventing the buildup of potentially hazardous substances in the soil and enriching the soil with plants like beans, which fix nitrogen in the soil to make it available to other plants. These practices gave birth to a wider practice of phytoremediation, which involves the use of plants to actively pull pollutants out of the ground and water.
There are a number of forms of phytoremediation. Many plants are capable of uptaking pollutants and storing them, meaning that people can plant trees or plants and then remove them after they have pulled the pollutants out of the soil. Plants can also be used to control the spread of pollution. Some plants will actively metabolize pollutants, breaking them down into harmless substances, while others stimulate the growth of microbes which can metabolize pollutants.
Incidentally, microbes are also used in environmental remediation. Several companies have actually genetically engineered microbes which eat things like oil and nuclear waste, and new extremophilic organisms are constantly being discovered in a range of environments. This suggests that bacteria may at some point be able to perform the bulk of environmental cleanup, playing the same role they have been playing for millennia.
There are, of course, some disadvantages to phytoremediation. It takes longer than some environmental remediation techniques, requiring patience and in some cases the installation of warning signage for future generations. Phytoremediation also comes with the risk of introducing dangerous substances into the food supply, as the plants used could be eaten or they could serve as a food source for food animals if the polluted site is not carefully controlled. Some plants also pollute as they intake pollutants, expressing various substances which can be carried by the water or wind.