Environmental pollution has been improved by reducing the original sources of the pollution. Phytoremediation (by plants which remove toxins) is a cost effective way to improve the damage to the environment. There are many plants which remove toxins from water or soil. These plants are called hyperaccumulators. This article is about the current state of phytoremediation.
The toxins come from industry, vehicle exhaust, metals from mining and metal manufacture, insecticides/pesticides, city wastes, agricultural wastes and fertilizers. Heavy metals in soils and water are a serious problem for the environment and for human health.
The potentially toxic heavy metals include arsenic (As), copper (Cu), cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), mercury (Hg) and zinc (Zn.) The metals can be absorbed by plants and cause acute or chronic toxicity to people who consume those plants. The heavy metals interfere with the chemical processes of the plants and inhibit plant growth. The metals interfere with the normal soil organisms, also.
Biologic remediation includes use of microorganisms and special plants to move the underground metals to the parts of the plants above the ground (phytoremediation.) Testing has shown that many Brassica species plants exhibited good removal of Cd and Zn. A total of 400 plants have been identified as useful for phytoremediation. Alyssum species/ are useful for removing Ni from soils. Fern species can remove As from soils.
Rhizofiltration is the removal of toxins from polluted water into plant biomass. A number of plants have been found to have the ability to remove heavy metals from hydroponic (water) solutions. Water hyacinth removes chemicals from wastewater treatment systems.
New methods are needed for recovering the toxins from the aerial biomass of the plants after their removal from the roots.
CONCLUSION: A cost-effective method of removal of toxins from soils is seen in phytoremediation (removal of toxins by specific plants). Certain plants have been found to be hyperaccumulators, which pull the toxins from the roots in the water or soil up into the aerial parts of the plants.
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