Ecological Risk Assessment of Metal Pollution along Greater Cairo Sector of the River Nile, Egypt, Using Nile Tilapia, Oreochromis niloticus, as Bioindicator

Table 3

Metal concentrations in muscle of O. niloticus (mg/kg dry wt.).

	Cu					Zn
	Site 1; (G)	Site 2; (M)	Site 3; (I)	Site 4; (K)	Seasonal; mean	Site 1; (G)	Site 2; (M)	Site 3; (I)	Site 4; (K)	Seasonal; mean
Winter	5.53 ± 1.23^aA	4.02 ± 0.13^abAB	2.66 ± 0.32^bA	3.24 ± 0.34^bA	3.86	25.57 ± 0.86^aB	29.45 ± 1.24^aB	25.84 ± 2.32^aAB	27.83 ± 3.55^aA	27.17
Spring	8.89 ± 0.72^aB	7.82 ± 2.32^abA	4.36 ± 0.65^bA	4.67 ± 0.29^abA	6.44	55.81 ± 6.49^aA	42.68 ± 3.69^abA	32.82 ± 5.68^bA	30.93 ± 2.54^bA	40.56
Summer	4.37 ± 0.73^aB	2.19 ± 0.43^aB	2.67 ± 0.28^aA	3.15 ± 1.82^aA	3.10	33.74 ± 1.39^aB	32.16 ± 0.27^aB	20.48 ± 0.68^cB	27.71 ± 2.21^bA	28.52
Autumn	5.90 ± 0.62^aB	4.70 ± 0.10^aAB	3.00 ± 0.71^bA	2.37 ± 0.17^bA	3.99	27.83 ± 1.86^abB	25.55 ± 1.73^abB	22.61 ± 1.73^bAB	28.56 ± 1.45^aA	26.14
Annual mean	6.17	4.68	3.17	3.36	4.35^#	35.74	32.46	25.44	28.76	30.60^#
	Mn					Cd
	Site 1; (G)	Site 2; (M)	Site 3; (I)	Site 4; (K)	Seasonal; mean	Site 1; (G)	Site 2; (M)	Site 3; (I)	Site 4; (K)	Seasonal; mean
Winter	2.92 ± 0.68^aAB	1.62 ± 0.69^aA	2.74 ± 0.72^aA	1.60 ± 0.31^aAB	2.22	0.01 ± 0.01^aB	0.08 ± 0.04^aA	0.03 ± 0.01^aB	0.01 ± 0.01^aB	0.033
Spring	4.45 ± 0.34^aA	0.81 ± 0.26^cA	2.49 ± 0.74^bA	2.46 ± 0.45^bA	2.55	0.08 ± 0.04^aA	0.05 ± 0.04^aA	0.05 ± 0.01^aA	0.07 ± 0.02^aA	0.063
Summer	0.36 ± 0.03^bC	1.06 ± 0.30^aA	0.89 ± 0.08^aA	1.09 ± 0.06^aB	0.85	0.05 ± 0.01^aAB	0.07 ± 0.02^aA	0.06 ± 0.01^aA	0.09 ± 0.01^aA	0.068
Autumn	1.49 ± 0.69^aBC	1.12 ± 0.18^aA	3.10 ± 2.08^aA	1.79 ± 0.23^aAB	1.88	0.05 ± 0.01^aAB	0.02 ± 0.01^bA	0.05 ± 0.01^aA	0.02 ± 0.01^bB	0.034
Annual mean	2.31	1.15	2.31	1.74	1.87^#	0.048	0.053	0.048	0.048	0.049^#
	Pb					Fe
	Site 1; (G)	Site 2; (M)	Site 3; (I)	Site 4; (K)	Seasonal; mean	Site 1; (G)	Site 2; (M)	Site 3; (I)	Site 4; (K)	Seasonal; mean
Winter	0.05 ± 0.03^aB	0.53 ± 0.37^aB	0.03 ± 0.01^aC	0.36 ± 0.05^aAB	0.24	28.46 ± 7.72^aB	26.90 ± 7.25^aA	27.44 ± 9.31^aA	31.04 ± 5.55^aB	28.46
Spring	1.56 ± 0.52^aA	2.07 ± 0.32^aA	0.24 ± 0.04^bB	0.18 ± 0.04^bB	1.01	145.03 ± 4.21^aA	34.26 ± 5.24^bA	71.36 ± 33.82^bA	50.19 ± 8.04^bA	75.21
Summer	0.90 ± 0.25^aAB	0.53 ± 0.06^abB	0.17 ± 0.05^abB	0.48 ± 0.05^bA	0.52	17.70 ± 0.84^bB	32.02 ± 2.81^aA	13.76 ± 1.70^bA	25.69 ± 2.36^aB	22.29
Autumn	0.24 ± 0.08^abB	0.43 ± 0.07^aB	0.46 ± 0.02^aA	0.15 ± 0.10^bB	0.32	29.20 ± 2.90^aB	26.11 ± 2.20^aA	27.61 ± 6.58^aA	28.65 ± 11.95^aB	27.89
Annual mean	0.69	0.89	0.23	0.29	0.52^#	55.10	29.82	35.04	33.89	38.46^#

Data are represented as means of 16 samples ± SE.
Statistically significant differences () are shown with different superscript lowercase letters in the same raw and different superscript capital letters in the same column for each of the measured metals.
G, Giza; M, Manyal; I, Imbaba; and K, Kanater.
^#The mean of all measurements for each metal.