Biomonitoring and phytoremediation of Cr (VI) contaminated water: A study on bioaccumulation and morphological responses in Eichhornia crassipes

This study examined the potential of the aquatic macrophyte Eichhornia crassipes for bioaccumulating hexavalent chromium and its effects on the plant’s morphology. The macrophytes were exposed to different concentrations of Cr (VI) (0 – 100 mg L-1) in 20% full-strength Hoagland nutrient solution for ten days. Changes in the Cr (VI) concentrations were measured in the media and in specific plant tissues, i.e., roots, shoot, and leaves. The bioconcentration factor (BCF) in all plant parts and the translocation factor (TF) within plant tissues were calculated twice during the experiment. Results demonstrated that E. crassipes accumulated high concentrations of Cr (VI) in all plant tissues examined in 20 a dose-specific manner. High BCF was observed in the plant roots for concentrations up to 60 mg L-1, after which accumulation in shoots and leaves were greater than roots. The results from E. crassipes survivorship indicated that 40 mg L-1 is the threshold concentration for their survival under Cr (VI) stress. Morphological changes in the plants were examined by monitoring the change in the number of leaves and plant height under varying Cr (VI) concentrations. Impeded growth was observed due to increasing Cr (VI) concentration with maximum growth in the control group with no Cr (VI). Evapotranspiration losses were monitored and found to be minimal in experimental groups with high concentrations, displaying a negative correlation with Cr (VI) contamination. Physico-chemical parameters including pH, Electrical Conductivity, Oxidation Reduction Potential, and colour were also found to be significantly correlated with Cr (VI) concentration and time. The results demonstrated significant Cr (VI) accumulation in E. crassipes as well as noticeable morphological changes, making E. crassipes a suitable organism for biomonitoring and remediating Cr-contaminated sites over a relatively short time-period.