Hydrogeochemical Indicators of Water Quality Degradation and Inferred Biological Stress in Razzaza Lake, Central Iraq

Razzaza Lake is considered one of the largest lakes in central Iraq. It extends across the governorates of Karbala and Anbar. The lake's surface area has markedly decreased, and its water level has dropped due to severe climatic changes in recent years, which have caused a significant decrease in freshwater recharge coupled with high evaporation rates. This study aims to evaluate the evaluation of the lake's hydrochemical and environmental characteristics, as well as its pollution levels, in order to determine water quality and its suitability for aquatic life and human investment. Eight samples of water were collected from the water surface (depths of 20-30 cm) in February 2026. Analysis of major anions and cations, and ammonia, in addition to total dissolved solids and electrical conductivity were conducted. Hydrochemical parameters, such as Na%, sodium adsorption ratio, and Magnesium Adsorption Ratio, besides the hydrochemical formula are computed. Elevated total dissolved solids indicates the water is brackish. The Piper diagram indicates the lake's water facies, revealing the Ca–Mg–Cl–SO₄ type. Evaporation, as determined by the Durov diagram, is the dominant factor in the lake's hydrochemical evaluation. High NH4 and K concentrations, exceeding international freshwater standards, indicate a serious ecological imbalance in hydrogeochemical structure, with clear deviations from normal water concentrations. This has led to decreased oxygen levels, increased alkalinity, and elevated pH. These conditions promoted eutrophication, inhibited nitrification, prevented the conversion of NH4 to NO2, and increased nitrogenous concentrations. The high NH4 and K levels indicate intensifying organic pollution, significantly impairing the lake's self-purification capacity. The study concluded that the Lake is under pressure from environmental degradation and serious hydrochemical deterioration, which may lead to ecological collapse unless decisive and effective measures are taken to reduce pollution from fertilizers and sewage.