Copper And Zinc Removal By Aquatic Plants In Constructed Wetland Ecosystem

Water pollution is a main factor causing the shortage of water supply, and the serious water pollution by heavy metals needs more efficient approach to improve water quality. As a new, cheap and ecological treatment technology, phytoremediation of contaminated water by heavy metals had attracted the attention of many scientists all over the world. To identify or breed suitable plant materials which can tolerate and accumulate multiple metals, fast growth and wide adaptation is of most importance for phytoremediation.The objectives of this study were to investigate heavy metal stress, uptake and accumulation characteristic on aquatic plants in Cu and Cu/Zn combined pollution treatments. Among 21 plants four aquatic plants, water hyacinth (Eichhornia crassipes), calamus (Acorus calamus Linn), canna (Canna indica Linn) and acorus tatarinowii (Acorus tatarinowii Schott) were selected in this study based on the screening experiment. The major results were summarized as follows:1. The tolerant and uptake effect of copper of four species of plantsFour species of aquatic plants, including water hyacinth, canna ,calamus and acorus tatarinowii were investigated for the tolerant and uptake effect of copper . It was indicated that the critical concentration of these four plants for surviving was 20, 30, 50 and 50mg L^-1, respectively. Uptake of copper varied among the species tested. And it had a general decrease trend with the increase of copper levels amended, if using the Accumulation Factor (AF) value as an indicator. The best absorb capacity was found in water hyacinth, of which the accumulation amount in roots was 2174.55 mg kg^-2, the 4.6 times as that of in acorus tatarinowii, at the amended level of 5 mg L^-1. The capacity of enrichment followed the order: water hyacinth > canna > calamus > acorus tatarinowii (with their accumulation index 434.91, 342.06,169.60, 95.18) for the treatment of 10 mg L^-1 amended level. And, all the species tested showed a better capacity for the enrichment of copper in the low amended level when compared with that of the high level amended.