Evaluation of Pontederia crassipes as bioindicator of heavy metals in Lake Manzala, Egypt

Abstract

Heavy metals are among the most critical pollutants affecting aquatic ecosystems due to their persistence, toxicity, and bioaccumulation potential. Lake Manzala, the largest coastal lake in Egypt, is increasingly exposed to contamination from agricultural, industrial, and domestic discharges. This study evaluated the potential of Pontederia crassipes (water hyacinth) as a bioindicator and phytoremediator of heavy metals in three locations of Lake Manzala. Concentrations of iron (Fe), zinc (Zn), copper (Cu), lead (Pb), nickel (Ni), and cadmium (Cd) were determined in water and plant tissues using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Bioaccumulation was assessed using the Biological Accumulation Coefficient (BAC), Bioconcentration Factor (BF), and Translocation Factor (TF). The results showed that metal concentrations in water followed the order: Fe > Zn > Cu > Pb > Ni > Cd, with significantly higher levels (p < 0.05) recorded at the northeastern site. P. crassipes accumulated all metals predominantly in roots, with significantly higher concentrations than in leaves (p < 0.05). BF values exceeded 1 for all metals, indicating strong accumulation capacity, while TF values remained below 1, suggesting limited translocation to aerial parts. Significant positive correlations (p < 0.05) were observed between metal concentrations in water and plant tissues. These findings demonstrate that P. crassipes is an effective bioindicator and phytostabilizer of heavy metals in freshwater ecosystems. The study highlights its potential application in environmental monitoring and sustainable phytoremediation strategies for polluted aquatic ecosystems such as Lake Manzala.