Physical and Chemical Properties of Egypt’s Coastal Wetlands; Burullus Wetland as a Case Study

Abstract

Egypt’s coastal wetlands are located along the Mediterranean coast; four in the northern part of the Nile Delta (Manzala, Burullus, Mariout and Edko) and one in the northern part of the Sinai (Bardawil). According to the map of the world distribution of arid areas, northern Egypt belongs to the Mediterranean arid region. The climatic conditions are warm summer (20–30°C) and mild winter (10–20°C). The aridity index ranges between 0.03 and 0.2 in the northern areas and less than 0.03 in the south (hyperarid region).

In the Delta wetlands, the annual mean water temperature is 22.3°C, while the annual mean water transparency and water depths are 31.0 and 115.8 cm respectively. The annual mean water chlorosity is 1.9 g l⁻¹, while in Bardawil salinity ranges between 38.5 and 74.5‰. Water in these wetlands is alkaline throughout the year. The annual mean pH is 8.6. On the other hand, the annual mean alkalinity was 257.8 mg l⁻¹.

The annual mean dissolved oxygen (DO), chemical (COD) and biological (BOD) oxygen demands are 8.6, 4.6 and 3.6 mg l⁻¹, respectively. The concentrations of dissolved salts have the following sequence: SiO₂ > NO₃ > PO₄ > NO₂, with annual means of 41.7, 2.8, 1.2 and 1.1 μg-at. l⁻¹. The concentrations of heavy metals have the following sequence: Zn > Fe > Cu > Cd > Pb, with annual means of 8.5, 6.2, 5.9, 3.8 and 3.6 μg-at. l⁻¹. Most of the estimated heavy metals of the water near to the southern shores were higher than those near the northern shores due to pollutants of drainage water. The comparison of the dissolved salts in the water of Delta wetlands in 2015, with those of the 1980s, indicates a tremendous increase due to an increases of agricultural drainage waters that are rich in fertilizers and discharge into these wetlands from the southern drains.