Assessment of the ecological and human health implications of heavy metals and microbial load content of the Ankobra River, Ghana

Abstract

This study focused on heavy metals and microbial pollution assessment of the Ankobra River in Ghana and evaluated their resultant toxic effects on humans and the aquatic environment referring to water and fish species (Clarias gariepinus, Sarotherodon melanotheron and Pseudotolithus brachygnathus). Atomic Absorption Spectrophotometry was used for the assessment of Cd, Pb, Ni, Zn, Mn, As, Hg, Co and Cr; while the Pour Plate Count Method was deployed for the study of the microbes E.coli, Coliform, Yeast and Moulds. A total of 240 fish specimens and 60 water samples were analyzed over the period September, 2017 to August, 2018. The recorded concentrations of Mn, Zn, and Hg in the fish species were above the recommended limits for human consumption (WHO, 2008). The levels of Cd, As, Hg, Co and Pb in surface water were also above the recommended limits (WHO, 2008). Human health risk assessment of the heavy metals suggest that the population dependent on the resource are not exposed to Non-carcinogenic risks. However, the consumption of As, Pb, Cd, Ni, Mn and Cr from the fish and water poses carcinogenic risks to humans. Ecological health risk of the heavy metals posed to the river was found to be low. E. coli, coliform, yeast and mould counts in fish species and water were above recommended limits for human consumption (International Organization for Standardization, 2014). The count of bacteria species observed in the fish species and water were all above the ISO (2014) acceptable limits. Bacterial assemblage in this study are of public health significance. This study concludes that anthropogenic activities along the Ankobra River are deteriorating the quality of fish and water and pose significant adverse health risks to consumers.