A Possibility of Using Waterlily (Nymphaea alba L.) for Reducing the Toxic Effects of Chromium (Cr) in Industrial Wastewater

Abstract

This research work reports the potential of waterlily (Nymphaea alba L.) a hydrophyte, to accumulate heavy metals like Cr (III) in its roots, shoot and leaves without showing prominent visible symptoms of metal toxicity. Effluent was collected from Ravi which is one of the highly polluted river as compared to other rivers in Pakistan. One of the major reason is industrial wastewater, which is disposed untreated in the Ravi which is a major threat for aquatic life and toxic for human health. It further reports that the water of Ravi river is contaminated with heavy metals like Cd, Cr, Pb, Hg and Zn because their uptake by waterlily plants is an indication that these metals are responsible for polluting Ravi water and this issue need to be resolved on priority basis. In order to estimate the amount of heavy metals in waterlily, different tissues were processed for atomic absorption spectrometry (AAS) which revealed that Cd and Cr (later being in high concentration) were significantly accumulated by waterlily roots, stem and leaves, however, roots were more responsive as compared with aerial parts. Other metals were accumulated in negligible amount in roots, and almost no uptake was reported by stems and leaves. Various anatomical features were used as a tool to support the hypothesis of using waterlily as a hyperaccumulator of Cr in phytoremediation. Reduction fresh and dry weight of root and stem, decrease in chlorophyll content of leaves, inhibition in the cortical and vascular region of stem, and an increase in astrosclereids (supporting parenchyma) formation indicated that Cr was translocated to aerial parts. Increase in astrosclereids might be attributed a mechanism of defense or sensitivity of waterlily plants under Cr stress. (author)