الفهرس 
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Abstract
It was observed that the level of the studied nutrients in the present study was higher in the water of the drains than Burullus Lake and nearby Mediterranean Sea. Heavy metals concentrations detected in water except Cd were lower than those recorded by EPA for the permissible limits of heavy metals. The annual average of Zn, Ni, Cu and Pb concentrations in Burullus Lake sediments were higher than the permissible limits set by EPA. The level of heavy metals in water and sediments of the three studied locations (Burullus Lake, nearby Med. Sea and Burullus Lake’s drains) showed different patterns. The accumulation levels of heavy metals in muscle tissues of O. niloticus collected from Burullus Lake have been detected in the following order: Fe > Zn > Mn > Ni > Pb > Cu > Cd. The levels of all heavy metals detected in O. niloticus muscle tissues were under the permissible levels recommended by WHO. Organochlorines concentrations in water at Burullus Lake were within the permissible limits set by USEPA. PCBs were the major pollutants followed by cyclodienes, HCHs and finally DDTs in water of Burullus Lake. PCBs were the major pollutants followed by cyclodienes, HCHs and finally DDTs in sediments of Burullus Lake. None of the stations surveyed exceeded the Canadian sediment quality probable effect level guideline for the protection of aquatic biota for PCBs, p,ṕ-DDD, p,ṕ-DDE, p,ṕ-DDT, dieldrin, endrin, lindane, and heptachlor epoxide, which means that adverse effects on aquatic biota will not occur at these stations. The level of organochlorine pesticides in water of Burullus Lake, was higher than the drains and nearby Med. Sea, while the level of polychlorinated biphenyls was higher in the drains than nearby Med. Sea and Burullus Lake. It was observed that the level of organochlorine pesticides and polychlorinated biphenyls in sediments was higher in the drains than Burullus Lake and nearby Mediterranean Sea. The average concentration of OCPs and PCBs in fish samples collected from Burullus Lake showed a decreasing trend from PCBs > cyclodienes > DDTs > HCHs. Concentration of OCPs and PCBs in fish samples collected from the eastern sector of Burullus Lake was higher compared to that of the western and middle sectors. Organochlorines concentrations in fish samples collected from Burullus Lake were lower than the maximum permissible levels recommended by the National Academy of Sciences and National Academy of Engineering for the protection of aquatic biota, the Swedish Food Regulation and the US Food and Drug Administration (FDA).