CHARACTERIZATION OF HEAVY METALS IN WATER AND SILVER CAT FISH (Crysichthysnigrodigitatus)AT DADIN KOWA DAM, GOMBE STATE, NIGERIA

Abstract

The study assessed the concentrations of selected heavy metals in water and Silver catfish (Chrysichthysnigrodigitatus) from Dadin Kowa Dam, Gombe State, Nigeria, with the aim of evaluating potential environmental and public health risks. Water and fish tissue samples were collected from three stations (A, B, and C) and analyzed for arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), and zinc (Zn) using the Atomic Absorption Spectrophotometry (AAS) Perkin Elmer 400ASS device. The results revealed that arsenic (0.103–0.317 mg/L), cadmium (0.025–0.173 mg/L), and chromium (0.198–0.638 mg/L) in water exceeded the World Health Organization (WHO, 2016) permissible limits of 0.010, 0.003, and 0.050 mg/L, respectively. Lead (Pb) levels (0.003– 0.025 mg/L) were slightly above the limit of 0.010 mg/L, while zinc (0.056– 0.523 mg/L) was found to be below the recommended limit of 5.000 mg/L. In fish tissues, arsenic (0.002–0.032 mg/kg) and chromium (0.066–0.119 mg/kg) exceeded WHO permissible levels, indicating evidence of bioaccumulation. Cadmium (0.000–0.009 mg/kg), lead (0.000–0.008 mg/kg), and zinc (0.015–0.184 mg/kg) remained within acceptable limits. Transfer factor analysis showed generally low levels of bioaccumulation (TF < 1), with zinc exhibiting the highest uptake (0.48 in B), reflecting its biological role, while toxic metals such as arsenic and cadmium showed minimal transfer. The revealed significant contamination of water by arsenic, cadmium, and chromium, posing potential ecological and human health risks. The detection of arsenic and chromium above safe limits in fish tissues further suggests dietary exposure concerns for local communities. The study recommends continuous monitoring of heavy metals in water and aquatic organisms in DadinKowa Dam by relevant environmental and public health agencies to track pollution levels and trends in the interest of protecting public health and environment.