Determination of total mercury in finfishes and shellfishes using direct mercury analyser

Abstract

Heavy metal contamination of the environment, particularly, the aquatic environment is of great public health significance in the modern world. Mercury occurs naturally in the environment. Mercury or its compounds have been used in chior-alkali plants and as fungicides in agriculture and horticulture. It is found in minute quantities in all living organisms. Trace metals can be accumulated in fish via food chain and water. Aquatic organisms are extensively used in pollution monitoring programmes (UNEP, 1993; Uthe et al., 1991). Fishes are considered as good indicators for heavy metal contamination in aquatic systems because they occupy different trophic levels at different growth stages (Zhang et al., 2007). Once mercury enters the ecosystem, naturally occurring bacteria convert it to a form called methyl mercury or dimethyl mercury by a process known as biomethylation or bacterial methylation. Methyl mercury is toxic to human beings and predatory fishes such as large tuna, swordfish and shark can have mercury concentrations in their bodies that are 10,000 times higher than those of their surrounding waters (NRDC, 2010). EU and US regulation of 1997 made residue monitoring mandatory for seafood. Contamination may occur at any stage of production, processing and marketing. regulatory limits are set for some of these contaminants.