Ecological Assessment of Physicochemical Pollution of Wadi Sebou (Gharb, Morocco)

Abstract

In Morocco, hydrological and hydrobiological surveys of wadis, river and stream are rare. In this research, we plan to attempt to characterize the physico-chemistry of surface waters of sixteen stations sampled at the level of the Sebou basin during the period 2013−2023. The diagnosis showed that this natural watercourse is highly enriched in oceanic salts. A large fluctuation in the chemical nature of the waters was recorded, as well as electrical conductivity (EC), which oscillates between 629 and 22,766 μS/cm. Hydrogen Potential ranges from 8.01 to 8.79 while remaining basic. Nitrate (NO3⁻) concentrations range from a maximum of 886.9 mg/l to a minimum of 0.24 mg/l. Similarly, the ammonium concentration varies from 0.04 to 15.34 mg/l. It was also noted that the waters were very rich in chloride ions (860.27 to 145.55 mg/l), in sodium Na+ ion (51 to 2,530 mg/l), in sulfate ions SO4-- (441.4 to 37.62 mg/l), in calcium ions Ca2+ (97.6 to 1,072.8 mg/l) and in magnesium ions Mg2+ (631.2 to 17.28 mg/l) which explains the high hardness of these waters. The concentrations of potassium ions (K+) range from 2.54 to 17.55 mg/l. The high alkalinity is due to the high concentrations of bicarbonate ions (75.64 to 362.34 mg/l). Our study concludes that the waters of the Sebou remain below the irrigation threshold authorized by Moroccan law when moving away from its Atlantic estuary. They are too degraded and we suggest that urban and industrial wastewater be pre-treated as a priority to reduce pollution of the natural environment.