Phytoremediation—Using Plants to Clean up Polluted Soil

(Conservation Currents, Northern Virginia Soil and Water Conservation District, Feb 2004)

Polluted soil poses a severe problem for both ecosystem health and land development. Because soil lies at the confluence of many natural systems, soil pollution can be spread to other parts of the natural environment. Groundwater, for instance, percolates through the soil and can carry the soil pollutants into streams, rivers, wells and drinking water. Erosion can create the same problem. Plants growing on polluted soil may contain harmful levels of pollutants themselves, and this can be passed on to the animals and people that eat them. Dust blown from polluted soil can be inhaled directly by passersby. Additionally, in an urban setting such as Fairfax County, polluted soil makes valuable open land unusable for parks, recreation or commercial development.

Despite the benefits of cleaning polluted soil, remediation often never takes place because of the cost and effort of the work. Both soil minerals and soil pollutants carry small electric charges that can cause each to bond with each other, thus making polluted soil very hard to clean. Additionally, soil is a dense medium. This causes excavation of polluted soil for off site treatment or disposal to be very expensive because of the time, labor and heavy machinery necessary to do the job. Therefore, cheaper on-site, or in-situ, remediation techniques have been the focus of much attention and research lately. One of the most interesting and promising of these in-situ techniques is phytoremediation.

Phytoremediation is the use of specialized plants to clean up polluted soil. While most plants exposed to high levels of soil toxins will be injured or die, scientists have discovered that certain plants are resistant, and an even smaller...

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