Study of the spatiotemporal variation of iron and manganese ions content in the Oued Moulouya water (North-East of Morocco)

Abstract

Oued Moulouya is one of the most important water resources, not only for water supply, but also for the agro-industrial development of the North-East region of Morocco. However, the remarkable modification in terms of physico-chemical quality of this water resource which is constantly expressed by high concentrations of various mineralogical and organic components. This calls for the necessary measures to be taken to remedy this pollution. To understand the contribution of each source of this imbalance, whether geological and/or anthropogenic, we conducted a study to monitor, during the both wet and dry periods, the spatiotemporal variations of iron and manganese ions at eight stations along the Oued Moulouya. The water samples collected were therefore analysed to determine their pH (in situ) and their contents in these two ions following the method of Inductive Coupled Plasma spectrometry. The results obtained showed disparities in the concentrations of various components between the two periods of the year: wet and dry periods. Thus, the two elements monitored (Fe and Mn), expressed their maximum levels during the dry period, with values of 21.75 mg/l and 4.9 mg/l. These values were recorded at the station near the city of Guercif. While the minimum concentrations of these elements were recorded upstream of the Oued during the rainy months with values of 0.047 mg/l for iron and 0.016 mg/l for manganese. Hence, it is concluded, that the variation of the content of these two elements Fe and Mn is influenced by the geochemical contribution, which occurs during the dry periods and decreases by the physical dilution during the rainy periods.