Concentration of Lead and Zinc in Clarias gariepinus of River Nyamwamba in Kasese district, Western Uganda

Abstract

Aquatic organisms are best bio indicators used in biological assessment of water quality worldwide. However, relatively less attention has been paid to include fresh water fish for purposes of health and, water quality bio assessment particularly in River Nyamwamba. The river is continuously affected by natural ecosystem disturbances, and anthropogenic activities. In Western Uganda, fertile soils in the watersheds of River Nyamwamba support various human activities like agriculture and settlement that involve use of insecticides, pesticides containing heavy metals, which all end up in the river stream. Therefore, this study aimed at determining concentration (PH, turbidity, conductivity, temperature, Dissolved oxygen) in the water and Zinc and Lead in the water and in Clarias gariepinus in River Nyamwamba. During the study, Data produced were entered into a Microsoft Excel 2016 and, analyzed using descriptive statistics. Variation in the physicochemical and biological parameters at different sites were tested using One-way ANOVA at 5% level of significance in SPSS version 20, with post hoc test analysis to assess significant variation in the heavy metal (Pb, Zn) levels in organs (gills and muscles) of Clarias gariepinus. In the water samples, the concentration of zinc (0.02±0.000mg/L) was within the acceptable WHO limits of 5.0 mg/l, except lead (0.035±0.003) which was above the permissible limit of 0.01mg/l. Fish tissues also accumulated high levels of lead (2.65±0.05) mg/kg in the gills and muscles, which is above the permissible WHO limit of 2.0mg/kg. This makes the water and the water resources unsafe for human consumption.