Historical record of heavy metals in the mollusk shells of the Nile Delta

• Published in: Marine pollution bulletin 2024-12, Vol.209 (Pt B), p.117184, Article 117184
• Main Authors: Abdelhady, Ahmed A., Xiao, Jule, Fan, Jiawei, Zhang, Shengrui, Khalil, Mahmoud M., Ahmed, Mohamed S., Abdel-Raheem, Khalaf H.M., Hussain, Ali.M.
• Format: Article
• Language: English
• Subjects: Animal Shells - chemistry; Animals; Aquatic pollution; Environmental Monitoring; Geologic Sediments - chemistry; Heavy metals; Metals, Heavy - analysis; Mollusca - metabolism; Mollusca shells; Nile Delta; Sediment core; Water Pollutants, Chemical - analysis
• ISSN: 0025-326X; 1879-3363; 1879-3363
• DOI: 10.1016/j.marpolbul.2024.117184

Identifying the baseline status and the timing of ecosystem disturbances are essential for restoration programs. The historical bioaccumulation of heavy metals was assessed from an 80-cm-long core from the Manzala Lagoon (Nile Delta). The heavy metal concentrations increased slightly upward and peaked around 1964, after the completion of Aswan High Dam. The metal concentrations of shells are 2–3 times less than those of bulk sediment. The topmost sediments are enriched in Cd, Cu, and Pb above USEPA. Sediment type and sediment grain size have a minor effect on the heavy metal concentration in mollusk shells, suggesting a priority over bulk sediments. Although correlated, the shells of the grazer gastropod Melanoides tuberculata have the highest concentration of all metals relative to the suspension-feeder bivalves Cerastoderma glaucum and Saccostrea cuculata. This was attributed to the influences of the eco-physiological traits, which exert a similar influence on the bioaccumulation process of all metals. •A sharp increase in metals concentration in 1970 as result of AHD and industrialization.•Metal concentrations of the shells are 2/3 times less than those of bulk sediment.•Metal concentrations are higher in grazer gastropods than in suspension-feeder bivalves.•Sediment grain-size has no effect on the heavy metal concentration of the mollusk shells.•Eco-physiological traits exert similar influence of the bioaccumulation process of all metals.