EGYPTIAN JOURNAL OF AQUATIC RESEARCH 1687-4285 VOL. 31 NO. 2, 2005: 224-238. *Corresponding author E-mail: khalid19670@yahoo.com HEAVY METALS CONTENT AND GRAIN SIZE OF SEDIMENTS FROM SUEZ BAY, RED SEA, EGYPT EL-MOSELHY, KH. M.* and ABD EL-AZIM, H. National Institute of Oceanography and Fisheries (NIOF), Suez, Egypt P.O. Box 182, Suez Keywords: Sediments, Grain size, Heavy metals, Suez Bay. ABSTRACT Heavy metals distribution (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) and grain size analysis were investigated in the inshore and offshore sediments of Suez Bay (northern part of the Gulf of Suez). Data of the grain size indicated that sandy sediments dominated most of the study area, covering the offshore part of the bay; while coarse-grained sediments were distributed in the nearshore stations. Concentration of metals in the bulk sediments and < 63 µm fraction (Fe > Mn > V > Zn > Pb > Ni > Co > Cr > Cu > Cd) revealed the effect of the pollution sources, specially at the stations in front of the sources. Where the stations in front of the petroleum activities were characterized by high levels of V, Cu and Pb, while the stations in front of electric power stations had high values of Cr and Ni. In addition, the inter-elemental relationships between the studied metals showed the importance of the pollution sources which affect the metals content of sediment, whereas Ni was strongly associated with V (r = 0.975) indicating that the metals resulted from the same sources. Determination of metals in 7 grain size fractions of sediments indicated that the distributions of metals in inshore and offshore sediments depended on the amount/type of pollutant and the nature of the sediment composition. Most of the studied metals were gradually increased with decreasing the grain size of sediments and chiefly associated with the clay (and silt) forming mineral phases. This trend reflects combination effects of possible industrial pollution with the natural constituents of sediments. INTRODUCTION Sediments show strong tendency to accumulate contaminant, especially heavy metals, and analysis of these sediments thus constitutes a rapid means of obtaining time integrated information concerning a range of limnological variables (Carral et. al., 1995). Knowledge of sedimentology and chemistry (heavy metals) of the sediments deposited in marine area is a key condition for identification of their sources and assessment of their transport-dispersion patterns. It is very important also for every environmental study requiring discrimination between natural and anthropogenic conditions of particulate material and the trace element associated with them; in particular, this knowledge is essential in the analysis of heavy metals distribution. Comparison of heavy metals distribution with grain size allowed the identification of the area where the sediment fine fraction appears affected by heavy metal anthropogenic contamination (Leoni and Sartori, 1996). The investigated area (Suez Bay) is located between longitudes 32 o 28 \ and 32 o 35 \ E and latitudes 29 o 53 \ and 29 o 57 \ N. The bay is shallow extension of the Gulf of Suez, roughly elliptic in shape, with its major axis in the NE - SW direction (Fig. 1). The average length along major axis is about 13.2 km, its average width along minor axis is about 8.8 km. The mean depth is 10 m, and