210Pb and 137Cs dating models as tracers of recent sedimentary processes of the shallow lake under anthropogenic activity

One of Egypt’s most vulnerable aquatic wetlands is Lake Edku, the third-largest lake in the Nile Delta. Many wastes are found in the water due to anthropogenic activities and contamination of nearby cities, fish farms, and agricultural areas, particularly through drains, which result in several ecological issues. Despite this, sedimentary processes are used as archives, providing a unique opportunity to document the changes the environment has undergone over the past 100 years. To study the sedimentation and age of Lake Edku, this study employed a high-purity Germanium gamma spectroscopy (HPGe) system to create a chronological sequence of four sedimentary cores based on the analysis of 210Pbex and 137Cs. Determining element concentrations was also done at the Second Research Reactor (ETRR-2) in Egypt using instrumented neutron activation analysis (INAA-k0 technique). Several dating models for 210Pb and 137Cs were employed. According to the study, the constant rate of supply (CRS) model proved to be the most reliable for dating sediment cores, exhibiting a high degree of agreement with the chronology determined by the 137Cs approach. The direct release of massive volumes of industrial and home wastewater is one of the most likely anthropogenic inputs that have contributed to increased silt deposition, particularly during the 1990s. The vertical profile of metals reveals the history of metal deposition, making it easier to understand the characteristics of accumulation in various sedimentary layers. The amount of heavy metals in sediments is influenced by the rate of sedimentation at the sampling site, as well as the emission from sources due to sediment dilution. Because sedimentation rates vary so much, the anthropogenic contribution is reflected far more effectively by the metals deposition flux (DMF) than by their concentrations. Overall, the post-dam transformation of Lake Edku demonstrates a shift from Nile-controlled sedimentation to a drainage-dominated system, resulting in accelerated sedimentation rates, nutrient enrichment, and severe ecological deterioration.