Bioaccumulation of selected inorganic substances in the tissue of Oreochromis shiranus from Bunda Dam, Malawi
A study to assess and monitor the concentrations of sulphate, sodium, magnesium, calcium, chloride, iron and nitrate in Bunda Dam was carried out from May to November 1998. The same parameters, except nitrate and chloride, were also determined in the liver, gills, intestines and muscle of the fish Oreochromis shiranus from the same dam. Results showed that whilst the concentrations of all parameters in general were higher in September and October in the water, there were variations from month to month in the fish. Comparison of the overall concentrations in the water and fish showed that, for each parameter, there were higher concentrations (P<0.05) in the water than in the fish. Iron and magnesium were more concentrated in the liver while sulphate, calcium and sodium were more concentrated in the intestine. The concentrations of the parameters in both the water and the fish were below the hazard limits. The results suggest that the intensive farming activities taking place around the dam and the presence of the sewage pond nearby have no significant effect on the levels of chemicals in the dam water or its fish.