Study on water quality along the coastal zone of Abu- Qir Bay, Mediterranean Sea, Alexandria, Egypt

Study on water quality along the coastal zone of Abu- Qir Bay,
Mediterranean Sea, Alexandria, Egypt
Souad El- Sayed El- Gohary*; Mona F. El-Naggar*; Hermine Ramzy Zaki*
*National Institute of Oceanography and Fisheries, Alexandria, Egypt
Received 5th November 2011, Accepted 29th December 2011
Abstract
The present study aims to determine the physico-chemical parameters of Abu-Qir Bay, and throw
light on the effect of pollution on the area of study. The nutrient concentrations in the coastal zone of the
bay were in the following ranges: 7.39-26.37 µmol./l for ammonium in summer and 3.23–18.67 µmol./l
in winter, 0.12–1.40 µmol./l and 0.29–1.52 µmol./l for nitrite and 1.16-0.53 µmol./l, 0.29-0.99 µmol./l
for nitrate during summer and winter seasons respectively. Dissolved inorganic phosphate ranged from
0.20 to 0.53 µmol./l, 0.41±0.15 µmol./l in summer and from 0.33 to 1.08 µmol./l, 0.76 ± 0.34 µmol./l in
winter. Reactive silicate ranged from 0.09 to 0.19 µmol./l, 0.30 ± 0.21 µmol./l and 0.11-0.85 µmol./l,
0.76 ± 0.29 µmol./l during summer and winter seasons respectively. The results for ammonium
concentrations showed a remarkable increase in the level of nitrogen. The different of inorganic nitrogen
forms were in the following order: NH4 > NO2 > NO3. The concentrations of dissolved oxygen ranged
from 2.149 to 7.31 ml./l with a mean value of 5.01 ± 1.86 ml/l, during summer and 4.21-10.49 ml/l with
an average of 6.79 ± 2.4 ml/l, in winter season. Biochemical oxygen demand had concentrations ranged
from 1.98 to 3.50 mg/l, 2.99 ± 0.60 mg/l, 2.14 -3.71 mg/l with a mean value of 3.15 ± 0.70 mg/l during
summer and winter seasons, respectively. The concentrations of chemical oxygen demand ranged from
6.39 to 17.15 mg/l, with a mean value of 7.99 ± 2.7 mg/l were determined during summer season. The
averages of phosphate and silicate concentrations were 0.41 ± 0.15 µM/l, 0.30 ± 0.21 µM/l and 0.76 ±
0.34 µM/l, 0.76 ± 0.29 µM/l, during summer and winter seasons respectively. The dissolved inorganic
nitrogen, reactive inorganic phosphate and silicate had ratios of 39.6:1:0.7. The maximum and minimum
water temperature averages were measured in summer (26.34 ± 0.23ºC) and in winter (16.06 ± 0.31ºC)
indicate that temperature is a seasonal dependant. Low pH values (7.72-8.07) and (7.34-7.42) during
summer and winter seasons, respectively. The salinity levels were dependant on the amount of
freshwater discharged from the effluents of land-based sources, reflecting low levels of salinity (28.70
psu) near the discharging points. The winter season showed higher values of salinity might be owed to;
winter closure period (low flow), the shallowness of the bay with increasing the rate of evaporation and
wind directions. Monitoring of Abu-Qir Bay water Quality is recommended for short and long term
variations of water quality and mitigate outbreak of health disorders to determine the impacts on the
aquatic ecosystem.
Keywords: Abu-Qir Bay, nutrient salts, hydrographic conditions.