HUMAN CONTACT:
Clearly, careful monitoring is needed to ensure that contaminants are not entering the food chain or creating a hazard for humans. For this reason, it is important to consider with care both the type of contaminant as well the type of phytoremediation to be used. For example, phytoextraction of lead (lead stored in plant biomass) would not be appropriate for a human-inhabited site. However, phytodegradation or phytovolatilization of an organic contaminant (contaminant broken down by plant enzymes and stored or volatilized as harmless compounds) could be implemented safely around humans. It is also important to remember that well-planned phytoremediation sites will be carefully monitored and harvested, and may therefore present less of a hazard than sites left unmitigated.

DEPTH OF CONTAMINATION
Phytoremediation of soils is most useful at sites with shallow, low-level contamination. The effectiveness of plants is, in effect, limited to the depth of the plant roots themselves. This problem can be addressed in several ways. First, plants with deep roots such as trees (15’ deep roots) or plants such as alfalfa (7’ deep roots) should be used where possible. If the contamination lies in soils too deep for roots to penetrate, deep plowing can be used before planting and at various times during treatment to bring deeper soils up to the root level. If groundwater is too deep for roots to reach, it can be pumped to the surface of the soil and used for irrigation. This technique would not be appropriate where the contaminant would endanger humans or the ecology of the site.

EXTENT OF CONTAMINATION
On some sites, the level of contamination is too high for phytoremediation to work effectively. If the contamination levels are too high for a species to thrive, or if there is simply too much contaminant for plants to take up in an acceptable amount of time, phytoremediation can be used as a “finishing” or “polishing” step to remove final traces of contaminants and restore soil tilth. Additionally, when soils cannot be remediated fully, plants may be used to stabilize the contaminant in situ so that it does not move off-site or enter the groundwater.

POTENTIAL FOR OVERLAP OF PHYTOREMEDIATION AND LANDSCAPE DESIGN
· Trees used for borders, shade, and windbreaks can also be used for groundwater remediation or controlling the movement of a contaminated plume of water.
· Phytoremediation sites can provide an ecological patch in urban/industrial areas.
· Plants used for phytoremediation can be combined in planting design with native and ornamental plants to create a visually pleasing landscape as well as a more diverse habitat for wildlife.
· Phytoremediation, when appropriate, can create an excellent opportunity for community-building and education. School or community groups can volunteer to plant, maintain, and monitor a site in their community to create pocket parks, community gardens, or playgrounds with land that might otherwise be considered an unusable brownfield.