Native plants play a crucial role in phytoremediation, serving as natural cleaners of contaminated environments. They effectively mitigate a range of contaminants, from metals to oil, and are most effective in areas with low contaminant levels, as high concentrations can hinder their growth and slow down the cleanup process. The deep roots of these plants also prevent the spread of contaminants by wind, rain, and groundwater, keeping the surrounding areas and water table safe.
How does it work?
So, how does phytoremediation work? It all starts with the plant roots. They absorb water and nutrients from the contaminated soil, sediment, or groundwater. Once inside the plant, these harmful chemicals are either removed or broken down through natural processes, effectively cleaning the environment.
These contaminants are then:
- Stored in the roots, stems, or leaves;
- Converted to less harmful chemicals in the plant or its root zone;
- Changed to vapors, which are released into the air;
- Sorb or stick contaminants to the plant’s roots where soil bacteria can break down the contaminants into less harmful chemicals.
Where groundwater is contaminated, trees are used like pumps to draw it up through the roots to prevent it from moving or further contaminating clean areas of the water table. This method of phytoremediation is called “hydraulic control.”
Constructed wetlands provide another form of phytoremediation. Their construction may require excavation or regrading to allow water to flow through without necessitating pumping. Native grasses and emergent perennials may be planted in the wetland to provide additional filtration and wetland stability. A wetland may be created at a site to treat acid mine drainage or as a final treatment step for water discharged from other treatment systems. Water treated with constructed wetlands tends to have deficient concentrations of contaminants.
Certain plants are better at removing contaminants than others. Plants used in phytoremediation must tolerate and survive the types and concentrations of pollutants in the area. They must be able to grow and survive with the site’s sunlight and moisture levels. Their roots must grow deep enough to reach the contamination. Poplars and willows have deep, extensive roots and are widely used for hydraulic control, to clean deeper soil contamination, or to clean contaminated groundwater.
How long does phytoremediation take?
The length of time required for complete phytoremediation depends on several factors:
- Concentration levels of contaminants: high levels take longer than low levels.
- Depth of contamination: large and deep contaminated areas take longer than small ones.
- Growing time of plants: plants with long growing times work more effectively.
- Length of growing season: A remediation site in an area with a short growing season will take longer to restore.
- Loss of plants: Plants damaged by extreme weather, insects, disease, or wildlife may need to be replaced.
Even under the best conditions, phytoremediation may take years to clean up a site.
Phytoremediation is a low-risk and attractive method of cleaning up contaminants. Fences or other barriers may be needed to deter wildlife from eating or damaging plants. In some cases, plants may release chemical vapors into the air, a process called phytovolatilization. If this occurs, regular air sampling is needed to ensure the plants are not releasing harmful vapor levels.
How will I be affected?
Phytoremediation causes little disruption to a site or neighboring area. However, during site preparation, equipment noise, dust, or odor may occur. The soil may require grading or tilling with heavy equipment to shape it for holding water, and backhoes may be used to plant larger trees and shrubs.
The plants used in completing the project can make the site more attractive and increase biodiversity. Using native plants is encouraged since they are better adapted and less likely to attract unwanted wildlife damage.
What are the benefits of phytoremediation over other methods of site cleanup?
- By using native plant processes, less equipment, less labor, and fewer site disturbances are required.
- Native trees, shrubs, and plants help control soil erosion and improve air quality.
- Phytoremediation allows a site to be cleaned without large-scale excavation, soil hauling, or groundwater pumping.
- Phytoremediation is proven to work.
Forrest Keeling grows a vast selection of native plants, which we produce using our patented RPM-production technology. RPM production offers superior survivability with 2X faster growth. Native species are important to our mission to ‘restore Earth’s ecosystem one tree at a time.’ We have the inventory and expertise to help you with phytoremediation projects of any scope. Contact a team member during the planning phase of your next project. We can give recommendations and information on native plant availability.
Forrest Keeling… it’s where the best trees begin!