Toxic Potency Evaluation of Metal-Doped River Water (Cr, Cu and Pb), on Allium cepa L. An Albanian Case

Different natural and anthropogenic sources, have progressively increased metal concentration, posing a serious environmental and ecological concern with regard to bio-accumulation tendency and toxicity. In the present research the Allium cepa L. test was used to assess the toxicological tendency of some surface water samples taken in rivers, Drini and Buna (North Albania) and to evaluate the toxic potency of three metals (copper, chromium and lead) experimentally added in analyzed natural waters. The roots of onion bulbs were grown in river samples mixed with three doses, representing the corresponding ? EC50, ? EC50 and EC50 concentrations of K2Cr2O7, CuSO4, Pb(NO3)2 salts (EC50-s were evaluated in a preliminary root growth inhibition test for 96 h). Toxicity endpoints on roots exposed to unloaded and metal-loaded samples, such as: length and morphological aberrations, mitotic index, frequencies of micronuclei, chromosomal aberration and types were evaluated and compared. A. cepa assay exhibited different sensitivities according to water quality of river samples, metals and corresponding concentrations. A certain difference of cytogenetic endpoints between two groups of natural samples was detected. The results showed strong toxic potency of these metals, revealing that metal excess in natural waters as the Drini and Buna Rivers could cause remarkable phyto- and genotoxic effects on onion roots meristem. The most frequent chromosomal abnormalities resulted: c-mitosis, stickiness, bridges/fragments and micronuclei, demonstrating high genotoxic and clastogenic induced effects. This approach proved to be valuable and appropriate in early warning detection and in bio-monitoring the heavy metal pollution in natural water bodies.