Assessment of ecological risk and metal contamination caused by the Lihoud River emissary along the Bay of Tangier Littoral in Morocco (Southwestern Mediterranean Sea)

Abstract

This study aimed to evaluate the environmental risks and metal contamination at Marqala Beach, a popular destination. Wet and dry beach sediments were collected from along this coastline for a full comprehensive analysis of the area. The assessment involved both physicochemical characterization of the sediments and determination of heavy metal contamination levels. Various pollution indices, including the geo-accumulation index (Igeo), enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), pollution load index (PLI), potential ecological risk factor (Ef), and potential ecological risk index (RI) were used to evaluate the ecological and health risk. These indices highlight the impact of human activities and indicate that contamination is primarily due to elevated levels of As, Cr, Zn, and Pb. Furthermore, X-ray fluorescence (XRF) analysis showed that SiO2 was the dominant element in the sediment samples, followed by CaO and Al2O3. This suggests a mineralogical and compositional combination. X-ray diffraction (XRD) characterization confirmed quartz dominance and the presence of aluminosilicate and calcium silicate minerals, aligning with XRF findings. Additionally, the scanning electron microscope (SEM) analysis revealed a non-crystalline structure with a sandy texture, as evidenced by the macrostructure and granulometric analyses, while the polluted sediments showed smaller particle sizes, consisting of tiny particles (oxides) and organic matter on quartz crystals.