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Table 4 Seasonal variations of heavy metals concentrations (μg/g dry weight) in liver tissue of Oreochromis niloticus

From: Seasonal assessment of some heavy metal pollution and Metallothionein gene expression in cultured Oreochromis niloticus

Heavy metal Winter Spring Autumn Summer
Cadmium 5.6 ± 0.23a < 0.05 < 0.05 < 0.05
Copper 36.3 ± 1.3b 68.8 ± 1.9a 28.6 ± 0.17b 15.8 ± 2.6c
Lead 1.6 ± 0.01b 1.2 ± 0.05c 2.1 ± 0.006a < 0.05
Zinc 3.8 ± 0.01c 18.8 ± 0. 3b 60.1 ± 1.5a 14.8 ± 1.7c
  1. Data shown as mean ± SEM (n = 6), mean values with unlike superscript letters were significantly different (p ≤ 0.05)
  2. FAO (1983) limits in fresh muscle (mg/Kg): Cd (0.5), Cu (30), Pb (0.5) and Zn (30)
  3. EOS (1993) MPL limits in fish (mg/Kg): Cd (0.5), Cu (20), Pb (2) and Zn (40)