A heavy metals-contaminated site in the central Taiwan of 1.3 hectare was used to study the feasibility of phytoremediation. Because irrigation canal was located in the eastern part, it thus has higher concentration of As, Cr, Ni and Zn in relative to others. Some of them were beyond the control standards of SGPR Act. After planting 33 species of various yard plants in the 8 blocks with two replicates for one month. The suitable 12 plants for two times-large area study included Chinenesis Ixora, Verbena bipinnatifida, Rainbow pink, Bojers Spurge, Kalanchoe, Scandent Scheffera umbrella tree, Purslane, Croton, Japanese Serissa, Cannaceae, French marigold, and Sunflower. These 12 plants have higher concentration and total removal of Cu, Cr, Ni, and Zn in the shoot after large area-planting in this contaminated site for 1 month in relative to the initial plants. For most of the plants, roots have higher concentrations in relative to shoots. The accumulated Cu, Cr, and Ni concentration in the shoots of these 12 plants also increased after extending the growing period from 1 month to 2 months. The decrease of temperature has negative effect on the accumulation of metals by these plants. Because of the low applying rate of EDTA and DTPA (3 mmol kg-1 soil), there was no identical effect on applying chelating agents on increasing the concentration and total removal of metals in the shoots of these 12 plants. Experimental results of this study show that phytoremediation, planting yard plants in the metals-contaminated site, was efficient to reduce the metal concentration in the contaminated site. The period for these 12 plants to decrease the current metal concentration in soil to the monitoring standards of cropped lands of SGPR Act is about 3~20 years. Farmers could earn more incomes by planting the seeds of these plants in the contaminated site and then sell their seedlings or flowers in the market. This phytoremediation technique also can promote the land reuse for upland crops or transfer the contaminated soils into another agricultural enterprise management system. The other benefit of this land use is for saving the water resources after cultivating with cutting flower in the contaminated region.

phytoremediation, heavy metal, yard flowers, chelating agent