Physico-Chemical and Biological Characteristics of the Oum Er Rbia Estuary (North Atlantic Moroccan Coast): Impact of Urban Wastewater

This study aimed to monitor abiotic factors at three stations in the Oum Er Rbia estuary, not far from the mouth. The stations were situated upstream (S1), in front (S2) and downstream (S3) from the discharge of urban wastewater from the town of Azemmour, which is discharged directly without treatment near the estuary mouth. The selection of these stations appeared appropriate to assessing the quality of the waters, which are influenced by both marine hydrodynamics resulting from very low freshwater inflows and sewage discharges. Monitoring of several parameters, including temperature, pH, dissolved oxygen, conductivity, salinity, turbidity, as well as the content of chlorophyll a and pheopigments, enabled the examination of the impact of marine hydrodynamics and the and the specific characteristics of the three surveyed stations. The analyses were performed using R software version 4.2.0. The results obtained indicate that the studied physico-chemical and biological parameters exhibited variations with significant correlations. Statistical approaches allowed the determination of profiles for stations S1, S2 and S3. It is evident that S1 (located slightly far from the discharge) showed a profile that tended to differ from the other two stations, S2 and S3, especially for certain parameters (temperature, pH, turbidity, and chlorophyll a ). On the other hand, all stations were impacted to some extent by the discharge of wastewater during rising tides. The present study can serve as an assessment tool to support decision-making regarding the physico-chemical quality of the waters of the Oum Er Rbia estuary.