الفهرس 
Title : Toxicological effect of some heavy metals on nile tilapia (oreochromis niloticus) and remediation using biosorbent materials
ContantsOnly 14 pages are availabe for public view
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Abstract
The present study deals with acute and chronic toxicities of Cu, Zn, Pb, Cd (individually and in mixture) and the ameliorating effect of Spirulina platensis as food supplement in diet of Nile tilapia; Oreochromis niloticus. Acute toxicity tests were conducted to evaluate the 96-hr LC50 of metals, and then fish of the experimental groups were exposed to 10% of that dose as a sublethal chronic dose for 30 days. Fish were divided into four groups: a control (group 1), group 2 fed on conventional diet supplemented with 10% S. platensis, group 3 fed on conventional diet and exposed to 10% of the 96-hr LC50 and group 4 fed on 10% S. platensis supplemented diet and exposed to the same sublethal chronic dose. Metal concentrations in tissues (liver, gills and muscle), plasma indicative biomarkers of metabolic functions and histological characters were investigated. The studied tissues showed significant increase in metal concentrations in fish of group 3 associated with biochemical and histopathological alterations in comparison to other experimental groups. Results indicated that S. platensis supplemented diet improved the studied plasma biochemical parameters as well as tissue integrity and it showed a better effect on metabolic active tissues such as the liver and, to a lesser extent, the gills. Therefore, it could be concluded that administration of S. platensis supplemented diet was effective in ameliorating the metal toxic effects due its free radical scavenging properties and its chelating effect on metal ions. In another approach, modified rice husk (mRH) was investigated for the possibility of its use as a biosorbent material of metal ions in water. Biosorption efficiency of mRH, in batch systems, was evaluated at specific metal concentrations (10% of the 96-hr LC50), water temperature and pH through determination of contact time and amount of rice husk needed for adsorption