Nanoscale interpretation of sewage-derived heavy metal contamination and its impact on algal communities in Euphrates River sediments, Anbar Governorate, Iraq

Heavy metal pollution is a severe environmental and health problem, especially in the city and industrial areas where the wastewater from the industries is untreated and comes with the toxic metals that leak into the aquatic ecosystems. The study that is carried out between December 2023 and December 2024 is aimed at the seasonal collection (summer, autumn, winter, and spring) of environmental samples, water and sediments, precisely, from five middle locations along the Euphrates River in Anbar, Iraq: Haditha, Anah, Rawa, Al-Ubaidi, and Al-Qa'im, which are located at –approximately– 34.14049, 34.41008, 34.55312, 34.41542, and 34.38621 latitudes, respectively. The main reasons for selecting these places are hazardous waste exposure, pollution sources, and lack of environmental protection. The main goal of the research is to find out the differences in the spatial and seasonal distributions of the heavy metal elements zinc (Zn), chromium (Cr), and nickel (Ni) in riverbed sediments. In addition, parameter such as pH presence are taken into account as factor of water quality. In addition to bulk chemical assessment, a nano-scale interpretative framework is applied to evaluate the role of fine-grained sediment particles in controlling heavy metal retention and bioavailability. Predicted nano-scale enrichment patterns indicate stronger association of Zn and Cr with reactive sediment surfaces at sewage-impacted sites, enhancing ecological stress on algal communities. This approach provides a mechanistic perspective linking sediment chemistry, nano-scale processes, and biological responses.