When about 80 percent of your clients come in the door and say, 'We live informally, but we need a living room and dining room for resale,' you realize the tail is wagging the dog. Though slower, phytoremediation costs much less than other methods of brownfield decontamination like trucking soil to a processing plant for chemical and mechanical cleansing and then returning it to the site. Phytoremediation works by extracting, containing, or degrading the contaminants. Extraction involves planting species that take up and accumulate contaminants in their shoots and leaves. Harvesting the plant removes the contaminant from the site.
Containment uses plants to immobilize the contaminants.
Certain trees, for example, can sequester large concentrations of metals in their root systems. Other plants use elements of organic toxins as food and, in the process, detoxify them. But phytoremediation is no panacea. For one thing, it won't be effective on every contaminated site - particularly the profoundly contaminated sites of the Superfund variety. And it's still experimental, with valid questions about its effects on the food chain and air quality requiring more research.