Spatiotemporal dynamics and machine learning-based risk assessment of heavy metal contamination in surface waters and Nile Tilapia in Egypt

Environmental Challenges, vol. 20, pp. 101209

Abstract

Heavy metals are persistent pollutants that can devastate human health and ecosystems. In this study, we collected surface water and fish samples from various locations across five governorates in Egypt. We examined the spatiotemporal distribution of 13 heavy metals in the surface water and Nile tilapia and assessed the ecological and human health risks associated with these metals. Moreover, we utilized statistical and machine learning approaches, including principal component analysis (PCA) and linear discriminant analysis (LDA), to explore the relationships between the metals themselves and between the metals and specific governorates or seasons. Our spatiotemporal analysis revealed that aluminum (Al) and iron (Fe) are more concentrated across all governorates every season than other metals. The ecological risk assessment indicates a higher risk for Al and a moderate risk for Fe. Our findings suggest that concentrations of Fe, Cd, Pb, Mn, Al, Ni, and Hg in surface water from aquaculture exceeded national and international standards, posing risks to aquatic ecosystems. In fish, Cd levels surpassed the thresholds set by global standards but remain below the Egyptian limits, indicating a need for ongoing monitoring. Furthermore, Mn concentrations significantly exceed the limits established by Egyptian regulations and the FAO, necessitating ongoing monitoring. The human health risk assessment reveals no health risks associated with dermal exposure to metals in surface water. However, there is a moderate carcinogenic risk associated with ingesting Nile tilapia due to the presence of cadmium, barium, nickel, and chromium. PCA and LDA results provide insights into the interactions among metals, allowing us to identify which metal is unique in a particular governorate as well as the potentials of co-occurrences of various metals, which opened avenues for a deeper investigation into potential sources of metal and the cumulative effects of clustered metals on human health and the consequences of simultaneous exposure. Collectively, our study highlighted the foreseeable risk of heavy metals to human health and advocated for examining potential sources of pollution, implementing monitoring programs, imposing strict regulations, applying safety interventions, conducting public awareness campaigns, and screening programs to reduce the hazardous effects on human health and the environmental system.

Authors 5

1. Mohamed Ali Hussein

   American University in Cairo

   Affiliation as printed

   Institute of Global Health and Human Ecology, School of Sciences and Engineering, The American University in Cairo, P.O. Box 74, New Cairo 11835, Egypt

2. Samir Nabhan Shamma

   American University in Cairo

   Affiliation as printed

   Institute of Global Health and Human Ecology, School of Sciences and Engineering, The American University in Cairo, P.O. Box 74, New Cairo 11835, Egypt

3. Hani Sewilam Aachen UNESCO Chair in Hydrological Changes and Water Resources Management

   RWTH Aachen University · American University in Cairo

   Affiliation as printed

   Center for Applied Research on the Environment and Sustainability (CARES), School of Sciences and Engineering, The American University in Cairo, AUC Avenue, P.O. Box 74, New Cairo 11835, Egypt

   UNESCO Chair in Hydrological Changes and Water Resources Management, RWTH Aachen University, 52062 Aachen, Germany

4. Tamer Shoeib

   American University in Cairo

   Affiliation as printed

   Department of Chemistry, School of Sciences and Engineering, The American University in Cairo, Cairo, Egypt

5. Anwar Abdelnaser corresponding

   American University in Cairo

   Affiliation as printed

   Institute of Global Health and Human Ecology, School of Sciences and Engineering, The American University in Cairo, P.O. Box 74, New Cairo 11835, Egypt