ABSTRACT

Lake Manzalah is the largest of the Delta lakes of Egypt. Grab samples were collected from the bottom of the lake and subjected to mechanical and chemical analysis. The majority of samples are badly sorted with an average median diameter of 85.6 microns. The predominant type of sediment covering the bottom of the take is the complex type sand-silt-clay followed in abundance by the clayey sand and silty clay. There is a basinward increase in grain size of sediments. The average carbonate content is 34.88% and its distribution on the bottom generally follows the same pattern of the grain size distribution of sediments. The average organic matter content is 2.56% whereas the organic matter content increases with the decrease of median diameter of grains. The C:N ratio ranges between 5 an 17 with an average of 9.7. The average phosphorous content is 0.056%. The phosphorous content increases with the decrease of median diameter of grains. Available ferric iron in sediments ranges between 0.2 and 3% with an average of 1%. Interrelations between the grain size, carbonate, organic matter, phosphorous and available iron are discussed.