Phytoremediation of lead and zinc contaminated soils using Mirabilis Jalapa

This paper describes a laboratory scale experiment that has the aim to verify the possibility to use the vegetable species Mirabilis jalapa for the decontamination of soils with different zinc and lead content. The use of the phytoextraction or phytostabilization strategy was evaluated. The experiment was divided into two parts. During the first part Mirabilis jalapa was planted in soils artificially contaminated with different Zn (500 ppm, 1000 ppm, 2000 ppm) and Pb concentrations (400 ppm, 600 ppm, 800 ppm). Every experiment was made using two replicates. In the second part Montevecchio soils were diluted with vegetative soil and compost with a dilution factor 4 and 8 (600-1700 ppm Zn; 5700-19000 ppm Pb). Each part of the experiment lasted one year. Mirabilis jalapa extraction capacity demonstrated to be lower than literature values and in particular seemed to be higher during the first growing season in comparison with the second one. The preferential accumulation of metals in the roots and the reduction of bioavailable metal fraction seem to demonstrate that Mirabilis jalapa can be used for phytostabilization processes.