Using Thlaspi plants to clean zinc-contaminated soil
The hypothesis that the amount of zinc removed from the soil by the Thlapsi plant will not be significant, has been proven to be true. However, phytoremediation is a time-consuming process, and is hence more effective in rehabilitating soil over the long term.
The use of phytoremediation to remove contaminants from soil and pond water has been gaining popularity over the past 20 years. This is because it is very cost-effective and environmentally friendly, compared to soil excavation works. However, phytoremediation is a very time-consuming process, and cannot prevent the contamination of groundwater.
The science fair project may be repeated using spinach instead of the Thlaspi plant, to compare the effects of other plants on the zinc content in soil.
The science fair project may also be modified to compare the rehabilitating abilities of other types of plants, like sunflowers, in removing other types of minerals.
Phytoremediation - http://en.wikipedia.org/wiki/Phytoremediation
Phytoremediation: using plants to clean up soils- http://www.allbusiness.com/agriculture-forestry-fishing.../981489-1.html