From the spectral analysis shown in Fig. 2, three and two different relaxation peaks reflect the dielectric response of root and shoot plant samples, respectively. The peaks are denoted as HN1, HN2 and HN3 while their maxima are identified at different frequencies. The lower frequency relaxation peak, indicated as NH1, arises at ~ 1.26 Hz for root is ascribed to the ionic conduction of the samples which causes a steady increase in dielectric loss spectra, as it has been shown in Fig. 1b. Meanwhile, it appears at relatively higher frequency (~ 25 Hz) for shoot, probably due to weaker binding of heavy metals within shoot. The frequency region below HN1 peak determines the range in which charge carriers are mobile over long distances while in the region above the peak, the carriers are confined to potential wells being mobile over short distances. Both NN2 and NH3 peaks determined at higher frequencies are probably associated to different types of polarization mechanisms. Since the water hyacinth plant is composed of cellulose, lignin and some metal oxides [18], local variation in conductivity across the internal interfaces is expected. Hence, its dielectric properties are assumed to be affected by interfacial polarization mechanism (IP). Based on this assumption, in addition to comparable dielectric data reported for tree leaves [23], we may attribute both NH2 and NH3 to different types of interfacial polarizations.