The major goal of this study is to determine the bioaccumulation of heavy metals in the tissues and bones of Red Hybrid Tilapia (Oreochromis niloticus) and Mackerel (Rastrelliger kanagurta) taken from two distinct sites in Terengganu state, Malaysia, namely Kijal and Paka. Zinc (Zn), copper (Cu), nickel (Ni), and lead (Pb)were the metals examined. Soil analysis also was carried out for the same elements. The tissues and bones of the fishes were separated before further analysis was made. Drying process technique was used to determine the moisture content for all samples at 80°C for 24 hours. Water content ranged between 70 & 77%. Triplicate samples were evaluated by using Atomic Absorption Spectrophotometer (AAS) to find out heavy metals concentration. Oven and Teflon beakers were used to fully digest all solid samples at 120oC for 3 hours. Highest readings of Zn, Ni and Pb were found in the fish bone for the samples collected from both mentioned locations. However, different pattern was noticed for Cu where higher values were found in the tissues for the same samples. Values of Pb in the tissues were higher than the acceptable value in edible fish by Food and Agriculture Organization (FAO); 1 ppm and Malaysian Food Act (MFR) & World Health Organization (WHO); 2 ppm, whereas values of Cu, Zn were in the acceptable range set by the same organizations. No values recommended for Ni by MFR. In general heavy metals in the bones and tissues from both locations can be sorted in descending order as follows; Pb>Zn>Cu>Ni. Soil samples collected from both locations showed different pattern where high concentration was found for Zn followed by Pb then Cu and Ni. Moreover analysis for soil samples collected from Paka River showed higher content for all elements compared to Kijal. More investigation is needed to clarify whether this contamination is solely from industry or due to geology of the area.
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Research on the impact of heavy metals and their accumulation in ecosystem elements of Lake Burullus is still scarce. Therefore, this study focuses on the relationship between the levels of heavy metals in the lake water, plankton communities and Nile tilapia (Oreochromis niloticus). The mean annual concentrations of Fe, Zn, Cu, Mn, Pb and Cd in water and fish samples were 527.8, 366.7, 162.6, 137.3, 119.8 and 3.6 μg l−1, and 70.8, 43.6, 8.05, 1.2, 0.14 and 0.045 μg g−1 dry weight (d.w.), respectively. The study demonstrated the relationship between the accumulation of metals in fish muscles and their levels in the lake water (p < 0.05; r = 0.7–0.9), with the metal content in O. niloticus muscles being mostly below the permissible limits. The obtained results showed that the levels of the metals in the lake water are not correlated with phytoplankton and zooplankton, and their groups, except copper and zinc, are negatively correlated with phytoplankton (r = −0.45 and −0.58, respectively). The study concluded that the concentrations of the analyzed metals in Lake Burullus did not reach the effective levels that would have a significant impact on the distribution of phytoplankton and zooplankton, or a hazardous effect on O. niloticus and its safety for human consumption.
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