No abstract

The management of natural surface water resources requires an understanding and knowledge of water quality. The Lake Dayet Er-Roumi (classified as a Site of Biological and Ecological Interest (SIBE)) is the only permanent continental lake of low altitude in Morocco, this international attraction site is subject to various sources of anthropogenic pollution, in addition to the effects of climate change (thermal variability, lack of precipitation, etc.). The objective of this work is to quantify and assess the quality of the waters lake, and its tributaries through Spatio-temporal monitoring of several physicochemical parameters during two seasons (winter and summer) of the year 2019. All the physicochemical analysis (such as temperature, hydrogen potential, electrical conductivity, dissolved oxygen, nitrates, orthophosphates, and chlorides) were carried out at 7 study stations (5 stations at lake level and 2 stations representing the tributaries). Statistical calculation of the data set revealed high concentrations of chlorides in both seasons and orthophosphates during the summer season, with average nitrate concentrations during the winter season. The results obtained show that the pH of the water is basic with a very high electrical conductivity showing a load of water in different minerals. These results greatly exceed the standards of fish water quality and surface water quality. They show that the lake Dayet Er-Roumi is polluted. Strategies to limit the pollution of the lake must be implemented by decision-makers at all levels, in order to avoid several ecological problems (fish mortality for example).

The contamination of aquatic ecosystems with metals remains a serious environmental problem of growing concern. Sediments are often studied as reservoirs or wells for many chemical pollutants. They are micropollutant traps; they also indicate the watercourse's historical pollution, lagoons, and lakes…Lake Dayet Er-Roumi (SIBE) is the only permanent natural lake in the Khemisset region (Morocco); this wetland is affected by several forms of pollution that are mainly linked to human activities (agricultural, domestic, industrial, etc.). The objective of our study is to contribute, through qualitative and quantitative analysis, to the assessment of lake sediment pollution by Spatio-temporal monitoring of certain toxic heavy metals such as Mn, Zn, Cr, Cd. These sediments are collected on the level of the lake's surface; the concentration of heavy metals was measured by microwave plasma atomic emission spectroscope (MP-AES). Metal analyses carried out at three measuring points during the winter season reveal a high concentration of Zn, Cr, and Mn at all stations during the winter season, which far exceeds the recommended standards, with a low level of Cd. The contamination factor "FC" and the degree of contamination "DC" reveal polymetallic contaminations dominated by two elements, zinc, and Chromium, which are the most worrying. These results clearly show that lake Dayet Er-Roumi is polluted; strategies to limit the lake's pollution must be implemented to avoid several ecological problems (fish mortality, etc.).