Since the early 1990s scientists have been studying a science called “phytoremediation.” The word comes from the ancient Greek “phyto” meaning “plant” and the Latin “remedium” meaning “restoring balance.”
Scientists have found that plants have the ability to clean up polluted water and soil by taking up the pollutants into their roots, stems and leaves. The EPA is using phytoremediation at several Superfund sites. It requires less equipment and labor than digging up and removing contaminated soil or pumping out polluted groundwater and is much more cost effective.
Plants help clean up many kinds of pollution including metals, pesticides, explosives, and oil. The plants also help prevent wind, rain, and groundwater from carrying pollution away to other areas.
Once inside the plant, depending on the chemical and the plant, the chemicals may be stored in the roots, stems or leaves (called hyperaccumulation), changed into less harmful chemicals within the plant, or changed into gases that are released into the air.
Near Fort Worth, Texas, the Air Force base has been planted with eastern cottonwoods to clean up trichloroethene (TCE) a toxic solvent used to clean jet fighters that has contaminated the groundwater. Poplars planted in Clackamus, Oregon clean up volatile organic compounds from illegal dumping activities. In England and China, water hyacinths are used to remove phosphorus from water, and in India to remove metals from textile manufacturing effluent.
Studies are being done on all types of plants and all types of soil pollutants. It’s been discovered that sunflowers soak up radioactive particles. A species of fern, Pteris vittata, removes arsenic from soil and retains it in all parts of the plant. Pumpkins and zucchini extract DDT from contaminated soil and transpire it into the air. Lupines have been found to extract a wide variety of herbicides and pesticides from soil and accumulate them in their seeds. Plants like potatoes attract creosote and it attaches to the roots and tubers.
So, it’s all good, right? Well, not exactly. For the home gardener, it sounds a note of caution. Every plant hasn’t been tested and neither has every contaminant. You can’t know whether a fruit or vegetable you have planted or a flower you are gathering for a bouquet has hyperaccumulated a particular pollutant or chemical.
To be safe, avoid the use of pesticides and herbicides, don’t use pressure treated lumber or railroad ties for landscaping, especially around or near vegetable gardens, and make sure that any manure you spread on your soil has been completely composted. Avoid eating plants that grow adjacent to a driveway, sidewalk or the roadside where they may be exposed to car exhaust, run-off of oil or other fluids, salt, or detergents from car washing.
Another downside: Not satisfied with the slow and steady clean-up performed by plants, scientists are hard at work genetically modifying plants to work faster, in some cases inserting genes from the livers of mammals into the plants to do the detoxifying. This unleashes the same potential for disaster that genetically modified foods have wrought on our health and environment.
Leave a Reply