Pollution Load Index and Ecological Risk Assessment of Sediment Heavy Metals in Lake Edku, Egypt

Coastal lagoons, like lake Edku in north Egypt, are vital ecosystems that offer a wide variety of ecosystem services, including wildlife habitats. However, many are experiencing severe human impacts due to their proximity to urbanization. The main objectives of this study were to determine the concentrations of major and trace elements in lake Edku sediments, and to assess their ecological risk impacts based on Contamination Degree (Cd), Pollution Load Index (PLI), and Potential Ecological Risk Index (PERI). During March 2022, six sampling stations (S1 through S6) were established across the lake, and a total of 14 elements were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). Our analyses indicate that sediment collected from sampling stations near to sources of wastewater runoff is the most polluted. For example, S1, which is located near to wastewater discharge, had the highest concentration of Cr, Co, Ni, Cu, Zn, Cd, and Pb (90.9, 23.1, 58.7, 55.2, 81.4, 0.5, and 12.8 µg/g, respectively). Evaluating the sediment PERI revealed that sampling stations S1, S2, and S4 had moderate ecological risk (150 < average PERI < 300), indicating there is a negative environmental impact on the living organisms and water quality of lake Edku. Because lake Edku is important for biodiversity conservation, continuous monitoring of metal contamination should be a top priority, as well as improving the efficiency of wastewater treatment facilities to ensure removal of metals before discharging to coastal ecosystems.