Effects of Heavy Metals on Anatomical Features of Water Lotus (Nelumbo nucifera) From Selected Locations in Alvan Ikoku Federal University of Education Owerri, Imo State, Nigeria

Abstract

The increasing contamination of aquatic ecosystems by these anthropogenic activities poses a significant threat to biodiversity and human health. Rapid urbanisation has raised a new challenge in managing water as the expansion of industrial activities and increasing population stepped up the demand for more fresh water resources for survival. The present study investigated the uptake and anatomical effects of potentially toxic elements (PTEs) by lotus (Nelumbo nucifera) cultivated in floating streams within Alvan Ikoku Federal University of Education Owerri, Imo State Nigeria. Samples of Water lotus (Nelumbo nucifera) were collected from three different locations within Alvan Ikoku Federal University of Education Owerri and labelled midstream, upstream and downstream respectively and analyzed using standard analytical protocols. The data generated was subjected to analysis of variance using SPSS software (version 22.0) comparison among mean values was calculated using Least Significant Difference (LSD). Results obtained showed Statistically significant (P<0.05) differences were observed in root diameter. The plants of downstream (846 µm) and upstream (746 µm) sites showed higher root diameter as compared to midstream site (557 µm). The higher values of epidermal thickness and cell area were noted in roots collected from upstream area (34.51 µm & 371.5 µm) and midstream (25.61 µm & 150 µm) respectively, while the least epidermal thickness was gotten from downstream (18.00 µm). No significant differences were observed in the thickness of leaf epidermis but the samples of midstream site displayed higher leaf epidermal area (12293) as compared to downstream (11262) and upstream (8790 µm2) sites. Plant samples from downstream site also displayed higher phloem area (325 µm2) as compared to upstream (329 µm2) and midstream site (141 µm2). The highest concentration of Cadmium was obtained from Agric Department with a mean value of 0.370±0.08 mg/L followed by samples gotten from Water lotus downstream (0.215±0.09 mg/L) while the least Cadmium concentration in the study locations was obtained from Nworie midstream with a mean value of 0.078±0.01 mg/L. values obtained for heavy metals were below WHO benchmark. The study provided valuable information on the necessity of continuous monitoring and pollution mitigation strategies to ensure the safety of floating stream garden-derived crops. These results demonstrate marginal contamination of water, with heavy metals, leading to water lotus ability to bio-concentrate and bioaccumulate, all of which are risk factors for aquatic macrophytes and for human health. This could be attributed to the dumping site by most of the inhabitants and discharge of industrial pollutants into the study areas. Public awareness and education about sources and health implications of heavy metals should be improved. Government should enforce the laws that ensure standard waste treatment by industrial plants before it is being discharged into water      bodies.