Chromium Uptake on Speciation and Phytotoxicity by Hydroponics with Aquatic Plants
The accumulation and toxicity of hexavalent chromium [Cr(VI)] to Water Hyacinth and Water Pennyworth was discussed using hydroponics technique. These plant species were chosen to find their chromium (Cr) accumulation abilities. Hydroponics experiments were prepared by adding Cr(VI) of 0, 5, 10 and 15 mg/L initial concentrations as potassium dichromate to water in containers at a nursery for 7, 15, 21 and 30 days and the adverse symptoms of plants were observed. After harvesting, the plants were cut into two parts, roots and floating part, and analyzed for Cr(VI), trivalent chromium [Cr(III)] and total chromium (TCr). The injury symptoms were weighted as toxicity score compare with control plot, toxicity scores of Water Hyacinth and Water Pennyworth were 76.85% and 80.56%, respectively, at a Cr(VI) concentration of 15 mg/L, at 30 days. The whole part of Water Hyacinth has gradually accumulated TCr at 1.29, 1.78, 2.62 and 3.32 mg/g of plant on a dry weight basis, at a pulse Cr(VI) input of 15 mg Cr(VI)/L, at 7, 15, 21 and 30 days, respectively. While, the TCr accumulation by Water Pennyworth at 0.74, 1.10, 1.26 and 1.23 mg/g. Interestingly, roots of plant an important role and potential to reduce toxic Cr(VI) to nontoxic Cr(III). Cr has absorbed mainly in Cr(III) specie and immobilized in root part by Water Hyacinth and Water Pennyworth, and subsequently accumulated and detoxified Cr into roots and floating part tissues. Water Hyacinth showed potential and suitable than Water Pennyworth for the Cr removal of contaminated waste water.