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CHEMICAL CHARACTERISTICS OF FISH POND BOTTOM SEDIMENT AS A FUNCTION OF ORGANIC MATTER CONTENT

Some chemical properties of sediment and distribution of some metals (iron, zinc, copper, manganese, cadmium and lead) were studied in the upper 10 cm of 12 fish ponds from four farms situated in different regions in Egypt namely, Abbassa, Sahl El-Tina, Wadi El-Raiyan and Belkas (Sharkia, Port Saeed, Fayoum and Dakahlia Governorate, respectively) to evaluate their stability for fish culture. The study showed that the sediment pH lied in the alkaline side and negatively correlated with organic matter contents. The sediment concentrations of nutrients, major ions and metals showed positive correlation (P<0.05) with organic matter. Organic matter in sediments of Abbassa & Sahl El-Tina ponds increased compared to the other ponds. The different studied variables (nutrients, major ions and metals) were greater (P<0.05) in ponds of Abbassa & Sahl El-Tina than those in Wadi El-Raiyan & Belkas ponds. Salinity increased in accordance with salinity of the origin soil rather than pond organic matter. Total carbon, organic carbon and total nitrogen concentrations showed the same trend of nutrients and metals. Carbon: nitrogen ratio values differ (P<0.05) among ponds of the four farms tested. The results revealed that pond organic matter influence the chemical composition of pond sediments. Pond bottom management practices included drying of pond bottoms between crops, liming and periodic sediment removal have to be performed use by producers to maintain relatively good bottom quality especially in old ponds (Abbassa & Sahl El-Tina). Pond sediments of this study generally had favourable quality for use in aquaculture.