Physico-chemical characteristics of different water types in El-Mex Bay, Alexandria, Egypt

A comprehensive environmental study was carried out in four seasons (summer, autumn, winter, and spring) through 2003-2004 for evaluating the effect of contamination with different types of pollutants sewage, agricultural and industrial wastes discharged into El-Mex Bay on its water quality. Temperature, salinity, pH, dissolved oxygen, Nutrient salts (NH₃, NO₂, NO₃, PO₄, SiO₄) and major constituent of sea water (Ca, Mg, Na, K) are measured at both surface and bottom water at 12 stations representing the bay. El-Mex Bay is characterized by the presence of two water layers overlying each other, an upper brackish layer and a lower diluted sea water layer. Surface layer is specified into three different water types according to salinity values: (i) water type "L" land drainage waste water with salinity<10, (ii) water type "M" "mixed sea water with land drainage" with 102/l), pH (7.68), major constituents (Ca=0.08, Mg=0.11, Na=3.89 and K=0.06 g/l) and high concentrations of nutrient salts (NH₃=227.35, NO₂=14.32, NO₃=82.75, PO₄=19.69 and SiO₄=140.69 μmol/l). Water type "D" is characterized by high values of oxygen (12.3 mgO₂/l), pH (8.17), major constituents (Ca=0.33, Mg=0.96, Na=31.66 and K=0.56 g/l) and low nutrient salts content (NH₃=2.1, NO₂=0.47, NO₃=2.48, PO₄=0.55 and SiO₄=2.74 μmol/l).