Accumulation of heavy metals in a food fish, Mystus gulio inhabiting Bolgoda Lake, Sri Lanka




Bioaccumulation potential of selected heavy metals viz. Pb, Cd, Cr, Cu, and Zn in muscle, gills and liver of food fish, Mystus gulio (Anguluwa) inhabiting in Bolgoda Lake were assessed by analyzing metal levels in the fish collected from four main locations: Weras Ganga, North Lake, Bolgoda Ganga and South Lake. In addition, water and sediment samples were taken concurrently from the sampling locations for determination of the metal levels. The metal levels were analysed by atomic absorption spectrometry using standard procedures. Dissolved total metal levels in lake water (in µg L-1) varied depending on the sampling location: Pb 23.2-36.3, Cd 6.1-12.6, Cr 3.9-61.4, Cu 5.7-38, and Zn 11.6-35.1. The sediment associated metals in the lake (in µg g-1 dry weight) showed irregular distribution of metal contamination reflecting many individual metal inputs: Pb 6.5-759.4, Cd 0.8-4.2, Cr 22.6- 214.8, Cu 13.2-135.5 and Zn 58.2-227.6. Metal accumulation levels in the edible muscle tissue (in µg g-1 wet weight) of the fish showed a wide range: Pb, 0.01-24.1, Cd, not detected - 0.3, Cr, 0.01-0.4, Cu, 0.1 – 37.7, and Zn, 2.5-18.5. The levels of Pb in edible muscle of the fish collected from Weras Ganga and Bolgoda Ganga and the level of Cd in the fish from Weras Ganga exceeded the food safety limits specified by the international authorities. Accumulation of metal levels in the liver tissues of the fish was significantly higher than that in the muscle tissue. In the gill tissue, no consistent tissue specific pattern was evident in relation to the accumulated metal levels. The results revealed that Pb and Cd are accumulating in the fish tissues at alarming levels. Accumulated Cd, Cu and Zn levels in the fish collected from Weras Ganga are comparatively higher than the respective levels in the fish from South Lake. The results emphasize the importance of monitoring heavy metals in the food fish species in Bolgoda Lake regularly for the safety of fish consumers.


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