International Journal of Marine Science, 2017, Vol.7, No.23, 214-228
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Figure 1 Location map and the sampling stations of the studied ports
1.2 Laboratory analyses
1.2.1 Granulometric analysis
The collected samples were packed in labeled polyethylene bags and immediately transported in ice-cooled box to
the laboratory. At the laboratory, these samples were air-dried, disaggregated, and about 100 g of the pre-dried
samples were sieved each one phi (Ø) interval to obtain textural properties according to Folk (1974). Seven
fractions were obtained: gravel (Ø−1 > 2.00 mm), very coarse sand (Ø0 = 2.00 to 1.00 mm), coarse sand (Ø1 =
1.00 to 0.50 mm), medium sand (Ø2 = 0.50 to 0.25 mm), fine sand (Ø3 = 0.250 to 0.125 mm), very fine sand (Ø4
= 0.125 to 0.063 mm) and mud “silt & clay” (Ø5 < 0.063 mm).
1.2.2 Geochemical analysis
For analysis of carbonate content and total organic matter, about 10 g of pre-dried bulk sediments were completely
grinded using agate mortar. The carbonate contents were determined by the method described by Gross (1971)
depending on acid-treatment weight-loss. One gram of each powdered sample was treated with 1N HCl acid then
the remaining insoluble residue was washed, dried at 60°C in oven, reweighted and the weight loss was converted
into carbonate percentage. The total organic matter (TOM) was determined by the ignition loss of one gram from
powdered samples at 550°C (Dean, 1974). The difference in weight was calculated as organic matter percentage.
The leachable forms of heavy metals were determined in the finest fractions of the collected samples (Ø3, Ø4 and
Ø5). From each fraction, 0.5 g was digested with a mixture of concentrated HNO3 and HClO3 (3:1) then
evaporated to near dryness. The digested samples were filtered and diluted with de-ionized water (Chester et al.,
1994). This method is adopted to determine the leachable heavy metals (oxides, hydroxides, carbonates and
sulphides). The concentrations of: Co, Cu, Zn, Ni, Cd, Mn, Fe and Pb were determined using flame Atomic
Absorption Spectrophotometer (AAS, GBC-932) at the National Institute of Oceanography and Fisheries (NIOF),
Hurghada, Egypt. To insure maximum accuracy, precision of the methods was confirmed by analysis of replicate
measurements for each metal in the sediments sample. The obtained results showed a satisfied precision of 3.9
–16.1. In addition, the AAS was adjusted to provide mean value of triplicate measurements of each metal and the
results were expressed in µg/g. the zero level of the AAS were adjusted by blanks and the quality control tools
were adopted to avoid possible contamination, meanwhile, the chemical reagents are of high analytical grade and
all of glassware were washed with diluted acid and later rinsed with double-distilled water before use.
