Effectiveness of common macrophytes for phytoremediation of hexavalent Cr prevalent in chromite mining areas

Hexavalent chromium Cr(VI) is carcinogenic. To reduce Cr(VI) toxicity, a study was undertaken to assess the effectiveness of common macrophytes in the range of Cr concentration prevalent in chromite mining areas at Sukinda, Odisha, India. The metal varied from 0.09 to 2.14 mg/L during 2016 - 2019 and indicated that approximately equal to 70% waterbodies are contaminated with Cr(VI). Phytoremediation experimentation using five common macrophytes resulted in Pistia stratiotes, Salvinia minima and Ipomoea aquatica as suitable species by remediating 57 to 100% Cr(VI) from 0.2 to 1.0 mg/L within 54 days. S. minima had then found to remove 1 to 1.8 and 1.6 to 2.8 times more Cr (total) than P. stratiotes and I. aquatica respectively from a level of 0.5 to 2.5 mg/L Cr(VI) within 49 days. Irrespective of plant-duration, P. stratiotes excelled over S. minima by 59 to 68% and I. aquatica by 55 to 89% in BCF value. S. minima thus proved best by removing maximum Cr per unit time while the combination of S. minima and P. stratiotes would have promise in respect of generating low volume of remediated biomass in phytoremediation of Cr(VI). Novelty statement Macrophytes differ in their response to remove metal, screening against a given metal concentration suggests the suitable species and testing signifies their effectiveness of remediating metal from contaminated sources.