Phytoremediation of lead, cobalt and zinc contaminated soils by giant ragweed (ambrosia artemisiifolia) : an honors thesis (HONRS 499)

Cobalt, Lead and Zinc are all heavy metals that strongly adsorb to soil. These have the potential to leach into water systems, underground, drinking or otherwise. If easily grown, hearty plants could take the metals into themselves and then be properly disposed of, former heavy metal dump sites could be cleaned of contamination. The soil could then, once again, be used properly and water systems would be less at risk from leachate. A major benefit of this innovative technology is that it is substantially lower in cost than conventional technologies, it produces "green belts," and it maintains a soil ecosystem.Giant Ragweed (Ambrosia artemisiifolia) was grown with soils that had been contaminated with specific concentrations of Cobalt (500 mg/kg), Lead (2000 mg/kg) and Zinc (500 mg/kg). At 120 days, the plants were cut off at soil level; the leaves were separated from the stems and placed into labeled bags. These were oven dried for 24 hours and a representative 0.5 g sample of each bag was weighed, digested and then analyzed for the amount of specific metal in the plant tissue by using an atomic absorption spectrometer.The same process was applied to the soil in the pots. It was air dried, digested and analyzed to determine how much of the contaminant remained after plant uptake. These two data sets were compared to establish a correlation between leaf uptake and metal concentration.We found that the leaves of the ragweed did take up significantly more lead and zinc than the control plants. We were unable to determine the effect of cobalt on the plants because we did not have a large enough sample size.Honors CollegeThesis (B.?.