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.