When plants suck in water from the earth, they also absorb contaminants from the soil. To many plants, these contaminants are toxic, but some species are able to cope with the toxins. These plants can be used to clean up industrial pollution, agricultural runoffs and other sources of soil contamination. Because growing plants is cheaper than hauling the soil off for treatment and does not disturb the land, these species provide an excellent option in the fight against soil pollution.
Wetlands have been known to reduce runoff for some time. They lie between dry ground and open water, which allows them to catch pollutants before they trickle into streams, rivers and lakes. Cattails seem to be promising phytoremediation plants. According to Cleantechnica.com, they can trap many different pollutants, including heavy metals, pharmaceuticals and phosphorous. These same cattails can then be harvested as a biofuel, providing a renewable alternative to fossil fuels.
Many plants simply tolerate heavy metals, industrial pollutants and other toxins, but others actually thrive on them. These plants are called hyperaccumulators, and they can safely store heavy metals or other pollutants at levels far higher than other plants can tolerate, making them a crucial part of phytoremediation. Indian mustard, for example, was used to clean the soil around an abandoned factory which had been contaminated with lead. According to Harvard Design Magazine, the mustard was able to clean 75 percent of the lead from the top 20 inches of the soil, reducing lead contamination to safe levels in less than two years.
Sunflowers are a dramatic, beautiful plant which produces tasty seeds. To victims of the Chernobyl nuclear disaster, they are much more. Special strains of sunflower plants have been used to clean soil contaminated by radiation around the plant. These plants can remove and store the radioactive elements cesium 137 and strontium 90 from the soil, helping to restore the area to a natural, safe level of background radiation.