Monitoring and Assessment of Surface Water Quality Using Physicochemical Parameters and Indexical Approaches in El Manzala Lake, Egypt.

Physiochemical parameters and the aquatic water quality index (AWQI) were employed to evaluate the surface water purity and identify the various geo-environmental factors influencing the ecological system in El Manzala Lake during two years 2020 and 2021. Water samples were obtained from 11 points, which collected around El Manzala Lake. The obtained analytical results reflected that the surface water in El Manzala Lake was of the semi-saline water type. The physicochemical data such as, T °C, pH, TDS, DO, COD, NO3, NO2, NH4, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn revealed mean values of 23.33, 8.3, 8378.05, 6.76, 97.81, 0.11, 0.08, 1.09, 0.00, 0.00, 0.01, 0.05, 0.00, 0.01, 0.01, and 0.01mg/L respectively in the order of Fe > Zn > Mn >Cu >Ni >Pb > Cr> Cd. The concentrations of trace elements in the collected water samples varied considerably, suggesting that the obtained samples were polluted by Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn at levels exceeding the acceptable limits recommended by the Canadian Council of Ministers of the Environment (CCME). Based on AWQI results across two years, about 45% of the water samples were classified as unsuitable, 36% of samples were very poor water, and 18% of samples were poor water for use in aquatic environments. As untreated urban and agricultural wastewaters flowed into the lake, the AWQI values increased from the northwest to the southeast directions, indicating a decline in the quality of the water close to the drainages downstream.