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Abstract
SUMMARY
A total number of 165 fish samples of fresh water fish investigated in this study were collected from five districts in Qena Governorate all over year. 115 fish samples from Tilapia nilotica 20 from each district except Nag-Hamady which 35 samples, and Clarias lazera 10 fish samples from each five stations ”Nag-Hamady, Qena, Kous, Luxor and Esna”.
Collected samples were examined organoleptically then analyzed for heavy metals content namely: cadmium, lead, copper and zinc.
Statistical analytical results for cadmium levels of Tilapia nilotica and Clarias lazera (ppm) fish caught from different districts in Qena Governorate revealed that as mean standard error. from Nag-Hamady were 0.3390.025 and 0.4500.090, respectively. from Qena were 0.3190.052 and 0.3660.059, respectively. In Kous were 0.4170.034 and 0.4060.070, respectively. In Luxor were 0.3940.030 and 0.3370.053, respectively. In Esna were 0.3420.030 and 0.2640.046, respectively.
The statistical analytical results of lead levels in T. nilotica and C. lazera fish (ppm) caught from different districts in Qena Governorate were expressed as mean standard error. from Nag-Hamady were 0.5300.085 and 0.2590.048, respectively. from Qena were 0.6900.170 and 0.3090.088, respectively. In Kous were 1.1240.209 and 0.2780.058, respectively. In Luxor were 0.5980.087 and 0.3670.085, respectively. In Esna were 0.4460.079 and 0.2750.050, respectively.
The statistical analytical results as mean standard error of copper levels in Tilapia nilotica and Clarias lazera (ppm) caught from Nag-Hamady were 1.5300.149 and 0.4700.086, respectively. from Qena were 1.4400.187. from Kous were 1.1140.138 and 0.4000.060, respectively. from Luxor were 1.0270.107 and 0.3530.084, respectively. from Esna were 0.9480.111 and 0.3950.101, respectively.
The statistical analytical results as mean standard error of zinc levels in T. nilotica and Clarias lazera (ppm) caught from Nag-Hamady were 6.4720.520 and 3.9030.501, respectively. from Qena were 9.3810.571 and 3.5840.253, respectively. In Kous were 10.0490.597 and 2.8990.206, respectively. from Luxor were 9.2570.692 and 2.6940.149, respectively. from Esna were 8.6050.441 and 3.3340.396 respectively.
The comparison between the obtained analytical results and the standard limit show for cadmium one sample (9%) of T. nilotica and 6 samples (12%) of C. lazera were within the permissible limits of E.O.S.Q.C. (1993), while 114 samples (99.1%) of T. nilotica and 44 samples 88% of C. lazera were over the permissible limit (0.1) ppm. But all samples of T. nilotica and C. lazera were over the permissible limits of FAO/WHO (1992) (0.05 ppm).
For lead 2 samples (1.7%) of T. nilotica and one sample 2% of C. lazera were within the permissible. Limits recommended by E.O.S.Q.C. (1993) (0.1 ppm) while 113 (98.3%) samples of T. nilotica and 49 (98%) samples of C. lazera over the permissible limits. According to permissible limits of FAO/WHO (1992) (0.5 ppm) 66 samples 57.4% of T. nilotica and 42 samples 84% were within the permissible. Limits while 49 samples (42.6%) of T. nilotica, 8 samples 16% of C. lazera were over the permissible limits.
Finally according to the standard limits 2.26 ppm obtained by Dreisbach and Roberston (1987) 111 samples 96.5 of T. nilotica and all samples of C. lazera were within the permissible limits while 4 samples 3.5% of T. nilotica were over the permissible limits.
For copper and zinc all samples (100%) of T. nilotica and C. lazera were within the permissible limits recommended by E.O.S.Q.C. (1993).
In T. nilotica there is a significant difference in mean value of zinc in Nag-Hamady and different districts also significant difference in mean of copper in Nag-Hamady, Esna, Luxor and Kous. Also, significant difference between Kous and all districts in the mean values of lead concentration.
There is a significant difference between T. nilotica and C. lazera in mean values of lead, copper and zinc.
Correlation coefficients between zinc and lead positive correlation while cadmium and copper ”negative correlation” in T. nilotica fish only.
The sources of environmental contamination by such estimated trace elements were also discussed, where sources of contamination should be avoided or reduced as possible from human diets. In addition periodical investigation for fish should be carried out