Phytoremediation of heavy metal contaminated buriganga riverbed sediment by Indian mustard and marigold plants

Locally available Indian mustard (Brassica juncea) and Marigold (Tagetes patula) plants can be used in a cost-effective, environment-friendly approach for treatment of landfills developed using heavy metal contaminated Buriganga riverbed sediments. In this study heavy metal uptake by Indian mustard and Marigold plants from heavy metal contaminated Buriganga riverbed sediments were assessed. Initial characterization of the Buriganga riverbed sediments showed concentrations of chromium, lead, copper, and zinc in the sediments higher than the toxicity reference values given for these heavy metals in soil for terrestrial plants, and soil invertebrate. The average background concentration of chromium, lead, copper, and zinc in the Buriganga riverbed sediments were found to be 141.5 mg/kg, 34.9 mg/kg, 38.7 mg/kg, and 287.5 mg/kg, respectively. Hence the newly developed area using such landfills poses a great threat to the surrounding flora and fauna. It was observed that both Indian mustard and Marigold plants accumulated these heavy metals in different parts of the plant from the contaminated sediments and were able to maintain a growth rate of more than 90% compared to that in noncontaminated soil. The results indicated rapid phytoextraction of most heavy metals by the Indian mustard during its final growth phase, whereas rapid phytoextraction of most heavy metals was observed in case of Marigold in its initial growth phase. Total chromium, lead, copper, and zinc uptakes (in mg/kg of plant dry weight) by Indian mustard plant in 12 weeks were 102.6, 28.9, 53, and 1861.5, respectively. The uptakes (in mg/kg of plant dry weight) of the same heavy metals by Marigold plant in 12 weeks were found to be 112.3, 104.25, 82.5, and 716.75, respectively. Marigold showed higher uptake efficiency for chromium, lead, and copper, while Indian mustard was found to be more efficient for zinc uptake. Hence both of these plants can be appropriately used as necessary for treating heavy metal contaminated landfills developed using Buriganga riverbed sediments. (c) 2015 American Institute of Chemical Engineers Environ Prog, 35: 117-124, 2016