from gypsymoths to toxic wastes (Long, 1998). There are several advantages in using phytoremediation: 1.Aesthetically pleasing and publicly accepted. 2.Solar driven. 3.Works with metals and slightly hydrophobic compounds, including many organics. 4.Can stimulate bioremediation in the soil closely associated with the plant root. Plants can stimulate microorganisms through the release of nutrients and the transport of oxygen to their roots. 5.Relatively inexpensive - phytoremediation can cost as little as $10 - $100 per cubic yard whereas metal washing can cost $30 - $300 per cubic yard. 6.Even if the plants are contaminated and unusable, the resulting ash is approximately 20-30 tons per 5000 tons soil. 7.Having ground cover on property reduces exposure risk to the community (i.e. lead). 8.Planting vegetation on a site also reduces erosion by wind and water. 9.Can leave usable topsoil intact with minimal environmental disturbance. 10.Generates recyclable metal rich plant residue. 11.Eliminates secondary air or water- borne wastes (Black 1997).There are, however, certain disadvantages as well: 1. It can take many growing seasons to clean up a site. 2. Plants have short roots. They can clean up soil or groundwater near the surface in-situ, typically 3 - 6 feet, but cannot remediate deep aquifers without further design work. 3. Trees have longer roots and can clean up slightly deeper contamination than plants, typically 10-15 feet, but cannot remediate deep aquifers without further design work . 4.Trees roots grow in the capillary fringe, but do not extend deep in to the aquifer. This makes remediating DNAPLs with plants and trees not recommended. 5.Plants that absorb toxic materials may contaminant the food chain. 6.Volatization of compounds may transform a groundwater pollution problem to an air pollution problem. 7.Returning the water...
