Hydrographic observations on pollution in Abu Kir Bay, Alexandria, Egypt

Abstract

      Abu Kir Bay is a semicircular bay lying 30 km nort of Alexandria be­tween Rosetta peninsula and Abu Kir peninsula. The Water circulation in the Bay is largely dependent on the mixing of the inflowing Mediterranean water with waters discharged into the Bay by 3 main sources of land runoff: a) brackish water from the adjoining Lake Edku through El-Maadiya Channel, b) industrial polluted water pumped out into the Bay the El-Tabia pumping station, c) river water discharged from the Rosetta branch of the Nile river.

      The last mentioned source is, however, of little importance since the damming of the Nile. 

      The circulation pattern in the southwestern part of Abu Kir Bay has been studied based on the distribution of surface salinity and oxygen content of 12 stations selected to represent the different water types occurring in the Bay and adjoining Lake Edku. In the area investigated it has been possible to identify 4 types of water: a) proper seawater, Type S (salinity > 38‰); b) diluted seawater, Type D, (salinity 38-35‰); c) mixed water which is subdi­vided into Type M₁ (salinity 35-20‰) and Type M₂ (salinity 20-5‰), d) proper Lake water, Type L (salinity < 5‰).

      While water Type D occurred exclusively in the Bay and the Type L occurred always in Lake Edku, the presence of mixed water (M₁ and M₂) either in the Lake or in the Bay was controlled by the velocity and frequency of the prevailing northerly winds and the amount of agricultural drain water reaching the Lake. Usually, increased amounts of drain water occurred in summer and coincided with low velocity northerly winds, thus favouring a lake-sea current and water Types M₁ and M₂ occurred in the Bay.

      The reverse condition occurred in winter and seawater was pushed south­wards when Types M₁ and M₂ occurred inside the lake.

      The circulation pattern concerning the distribution of the 4 water types in the area and the effect and extent of the industrial polluted water in the southwestern part of Abu Kir Bay is detailed.