|Role of phosphorus and nitrogenous species in water quality of a coastal Egyptian heavily polluted Mediterranean basin|
Saad, M.A.H.; Younes, W.A.N. (2006). Role of phosphorus and nitrogenous species in water quality of a coastal Egyptian heavily polluted Mediterranean basin. IJOO 1(1): 1-19
In: International Journal of Oceans and Oceanography. Research India Publications: Delhi. ISSN 0973-2667, more
|Authors|| || Top |
- Saad, M.A.H.
- Younes, W.A.N.
Abu-Qir Bay, a semi-enclosed heavily polluted Mediterranean basin in Egypt, is receiving huge amounts of untreated sewage and industrial wastewaters via Tabia Pumping Station (TPS). The distribution of phosphorus and nitrogenous species in this bay and in its effluents was investigated, to illustrate the role played by these nutrients in its water quality. The maximum and minimum temperature averages in July (summer) and January (winter) indicate that temperature is a season dependant. Low pH values coincided with intensive industrial wastewater discharges via TPS. Salinity decreased near discharges regions. The annual mean surface salinity value was lower than the bottom annual mean, reflecting the influence of freshwater discharges. The annual mean total suspended matter (TSM) in the surface water was lower than that for the bottom water. The increase in TSM values in TPS discharges confirms that TPS was the main contributor of TSM. The extraordinary high bottom dissolved inorganic phosphorus (DIP) values might be resulted from extensive production of effluents from the phosphate fertilizers factory. The high average surface DIP value in front of TPS confirms the external input of domestic and industrial discharges. The effluents of land-based sources showed higher dissolved organic phosphorus (DOP) values compared with the marine region. The DIP/DOP ratios indicate that DOP was predominant in the surface water, while the reverse occurred in the bottom water. Both water layers near TPS showed the maximum regional average particulate phosphorus (PP) values and the maximum seasonal average PP values in October. The latter was statistically correlated with TSM content. The regression equation of nitrate against salinity confirmed that land based sources seemed to be not the main source of nitrate in the bay. The annual surface and bottom nitrate means were nearly similar, due to shallowness of the bay water column. The increase in nitrite content with depth coincided with nitrate reduction in the relatively oxygen-poor bottom water. A significant positive correlation was found between nitrite and nitrate in the surface water. However, the correlation with ammonium was not significant, indicating that nitrate reduction rather than ammonium oxidation was the major internal source of nitrite. Ammonium was the predominant species of dissolved inorganic nitrogen (DIN) fraction. The increase in ammonium concentrations with depth coincided with decomposition of organic matter in the deposited discharged wastes. Nitrite and ammonium decreased away from land-based sources. Dissolved organic nitrogen (DON) constituted most of total dissolved nitrogen (TDN) in both water layers. Statistical correlations indicate that DON might be associated with biological activities. The significantly negative correlation between DON and particulate nitrogen (PN) in both water layers in addition to the regression equation against TSM indicate that PN levels were mainly derived from TPS.