METAL POLLUTION LOADING, MANZALAH LAGOON, NILE DELTA, EGYPT - IMPLICATIONS FOR AQUACULTURE

High cultural enrichment factors are found for Hg (13 x), Pb(22.1 x), and other potentially toxic metals (e.g., Sn, Zn, Cu, Ag) in the upper 20 cm of sediment cores from the southeastern Ginka subbasin of Manza lah lagoon, Nile delta, Egypt. Cores from other areas of the lagoon sh ow little metal loading. Metal loading followed the closure of the Asw an High Dam, the availability of abundant cheap electricity, and the d evelopment of major power-based industries. Industrial wastes containi ng potentially toxic metals are dumped into the Nile delta drain syste m. The load carried by Bahr El-Baqar drain discharges into the Ginka s ubbasin, which acts as a sink and results in metal loading of the sedi ment deposited there. Further development of aquaculture in this subba sin, of food-stuff agriculture on recently reclaimed lagoon bottom, or where irrigation waters come from Bahr El-Baqar drain or its discharg e should be halted or strictly limited until potentially toxic metals in the drain waters and sediment are removed and polluted input drasti cally reduced. This environmental assessment of heavy metals in aquacu lture or agriculture development should extend to other waterbodies in the northern Nile delta, particularly Idku lagoon and lake Mariut, wh ere industrial metal-bearing wastes discharge into the waterbodies.