Spatial and Tissue-Specific Accumulation of Heavy Metals in Tilapia (Oreochromis niloticus) Fish from Nguru River

Abstract

The concentration of heavy metals namely, Lead, Arsenic, chromium, copper and Zinc (Pb, As, Cr, Cu, Zn) were determined in Tilapia fish samples collected from three (3) selectedareasofNguru River during raining season. The fishes were carefully dissected and the muscles, liversand gills were sampled and prepared for digestion, afterward the level of heavy metals wereassessed using atomic absorption spectroscopy (AAS). The results showed that all metalsidentified in this study follow the same accumulation pattern, with liver having the highest concentration (As:11681µg/kg, Cu:36.87µg/kg, Cr:252.50µg/kg, Zn:11688.11µg/kg), followedby gills (As:543.39µg/kg, Cu:16.04µg/ kg, Cr:499.44µg/kg, Zn:9438.93µg/kg), andmuscles(As:479.58µg/kg, Cu:14.29µg/kg, Cr:252.50µg/kg, Zn:7233µg/kg). Lead was not  detectedinall the tissue samples. However, the concentrations of heavy metals in the muscles of fishescollected from all the sites were  within the permissible levels and are safe for the humanconsumption and public health.