.Sediments in Suez

Grain size composition
The spatial distribution of sedimentary faces is illustrated in Fig. 2, and the sedimentological analysis data are simplified by the classification [gravel, sand and pan
(slit and clay)] as shown in Table 1. In addition, the grain size parameters: mean size, skewness, Kurtosis and sorting are given
in Table 1. Grain size analysis indicated the different
depositional environments of the sediment (Shata, 2000). In the present study, sandy sediments were dominated most of the investigated area, which cover the offshore part of the bay. Coarse-grained sediments were distributed in the inshore stations, which
are commonly low in depth. As well as, clear increasing trend of the silt-clay fraction with offshore stations was recorded. Sedimentological study on the Suez Bay showed that the mean size of sediments
ranged from 0.19 Ø at station 8 to 3.16 Ø at station 14 (i.e. from coarse to very fine sand).
Sorting varied from 0.52 Ø to 2.56 Ø (i.e. from moderately to very poorly sorted). Its
oscillation reflected the unstable condition in the bay (Lotfy, 2002). The frequency
distributions of mean size and sorting showed that there was general tendency for sorting to
improve with the graphic mean size values, and the sorting improve shoreward. The
skewness of Suez Bay sediments ranged between -0.43 to 0.15. About 35 % of the
samples were positively skewed (i.e. finely skewed), while 65 % of the sediments were
negatively skewed (i.e. coarsely skewed). Related to the nearing to the shore, the
sediments had no distinct distributions (i.e. had wide range from negatively skewed to
positively skewed). The kurtosis values of the Suez Bay sediments ranged between 0.61 Ø and 2.50 Ø.
Heavy metals
The concentrations of heavy metals in the
bulk sediments of Suez Bay are shown inTable 2. The sequence of metals
contamination follows the decreasing order:
Fe > Mn > Zn > Pb > Ni > Co > Cr > Cu > Cd. At the offshore area, station 2 had high
concentrations of metals, particularly Cu (25.92 μg/g), Ni (22.53 μg/g), Pb (30.52
μg/g) and Zn (67.29 μg/g). This station is affected by heavily oil processing at Zietyia
Port and the effect of ships discharges which used antifouling paints containing metals
such as Cu. Inshore station (No. 13) of the same area recorded the absolute highest value of Cu (34.52 μg/g). Offshore and inshore stations (No. 8, 9 and 15) located in front of
the electric power stations were characterized by high concentration of Co, Ni, Cr and Fe in
their sediments, which is mainly due to the use of metal alloys in bombs and containers
for heating the water steam to produce electricity. High concentration of Cd at
offshore station (No. 5) in front of Adabyia Port, as well as Pb and Zn at the inshore
station (No. 17) may be due to the loading and unloading activities in this area, in
addition to the wastes of some industries (as vegetable oil factories and chemical
industries) near this station. The variety of the concentrations of heavy metals in bulk
sediments of Suez Bay may be attributed to the effect of type and amount of pollutant
arrives to it and the characteristic nature of the area (Mohapatra, 1988).
The influence of grain size on metal contents in sediments can be partially corrected by analyzing the same particle size class for all samples. The < 63 μm fraction
was chosen in order to minimize the loss of metal by desorption (Carral et al., 1995).
Spatial distribution of heavy metals in sediment of the study area revealed that Suez
Bay may be affected by different sources of pollution (sewage and garbage from the Suez City and ships awaiting transit area, industrial effluents including oil refineries, fertilizer
plant, power stations and other industries). Table 3 shows the concentrations of heavy
metals in the same grain size (< 63 μm). High concentrations of Cd, Co and Fe in the
inshore and Cu in the offshore of Port Tawfiq at the entrance of the Suez Canal reflected the
navigation activities through the canal and the effect of ships pass and transit using
antifauling paint including these metals (Cu, Cd and Fe). In addition the influence of
electric power stations to introduce special metals as Ni and Cr to the inshore and
offshore sediment samples near those stations
(No. 8, 9 and 15). The characteristics metalsfor oil pollution activities such as V, Cu and Pb (FAO, 1992) were highly found at stations 2 and 13, which are the offshore and inshore
stations of Zietyia Port and oil refineries concentrated at that area. The corresponding
increase of heavy metals in sediments of some stations than others indicated that the
industrial effluents from the nearby region were the primary source of pollutant input in
the area (Lin and Chen, 1996).

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