Total Levels of Mercury Concentrations in Marine Fish - Kumasi, Ghana

Abstract

Fish is an excellent source of high biological value protein, is low in saturated fat, and contains polyunsaturated fatty acids and some vitamins. Mercury occurs naturally in the environment as a result of human activities. In aquatic environments, inorganic mercury is converted into methylmercury (the most common form of organic mercury) by microorganisms present in sediment through accumulations in the aquatic food chain, including in fish and shellfish. Fish absorb methyl mercury from water as it passes over their gills and as they feed on organisms. The objective of the study is to determine mercury pollution levels in fresh fish in Central Market, Kumasi, Ghana. A total of 42 fished were sampled randomly in separate labelled zip lock bags and stored in cold ice chest at different periods comparing of 27 different species after identification. Individual edible fish dorsal muscle tissue was taken and wet dried and analyzed using Cold Vapor Atomic Absorption Spectroscopy (CV-AAS) method which is really simple, accurate and rapid. The concentration of mercury in fish samples from the marine sea were determined with a mixture of HNO3, HClO4 and H2SO4 for complete oxidation of the organic tissue. The results showed that there was substantial amount of mercury in the fish samples ranged from 15.29 - 981.99 ng/g or ppb wet weight which is less than the FAO/WHO limits of 0.5 ppm wet weight. The study showed low concentrations of mercury in the fish species which do not appear to contribute any significant mercury exposure to the general population. It suggests that a relatively clean marine environment due to minimal industrial activity in the region that has not yet been significantly impacted by mercury contamination.

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

“…However, local studies within ecosystems that are sensitive to Hg input indicate aquatic ecosystems in Africa can have elevated Hg levels of concern in fish and other aquatic food items used by humans, especially when associated with ASGM activities. Concentrations in high trophic level fish from lakes and rivers in Burkina Faso, Egypt, Ghana, Kenya, Senegal, South Africa, Tanzania, Zimbabwe as well as estuaries in Cote d’Ivoire have documented Hg levels of concern for human consumption (Ouédraogo and Amyot 2013 ; Hanna et al 2015 ; Niane et al 2015 ; Rajaee et al 2015 ; Gbogbo et al 2017 ; Walters et al 2017 ; Elawady et al 2019 ; Mason et al 2019 , 2022 ; Debrah et al 2020 ; Makaure et al 2023 ; van Rooyen et al 2023 ).…”